I ■ THE DISTRIBUTION OF METAL IMPURITIES IN ELECTROLYTIC NICKEL DEPOSITS By H a r la n V ance O gle A THESIS S u b m itte d t o t h e S c h o o l o f G ra d u a te S t u d i e s o f M ic h ig a n S t a t e C o lle g e o f A g r ic u ltu r e ^ an d A p p lie d S c ie n c e i n p a r t i a l f u l f i l l m e n t o f t h e r e q u ir e m e n ts f o r th e d e g re e o f DOCTOR OF PHILOSOPHY D e p a rtm e n t o f C h e m is try 1953 THE DISTRIBUTION OF METAL IMPURITIES IN ELECTROLYTIC NICKEL DEPOSITS By H a r la n V ance O gle / AN ABSTRACT S u b m itte d t o t h e S c h o o l o f G ra d u a te S t u d i e s o f M ic h ig a n S t a t e C o lle g e o f A g r i c u l t u r e a n d A p p lie d S c ie n c e i n p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e m e n ts f o r t h e d e g re e o f DOCTOR OF PHILOSOPHY i D e p a rtm e n t o f C h e m is tr y Y e ar A pp ro v ed 1953 H a r la n V ance O gle THESIS ABSTRACT I s o - c u r r e n t d e n s i t y c u r v e s o n a n ^ i n c l i n e d c a th o d e ” a r e i l l u s t r a t e d f o r s e v e ra l c u rre n t d e n s ity r e g io n s . S p e c tr o g r a p h ic m e th o d s w ere u s e d i n th e a n a ly s e s f o r th e m e ta l i m p u r i t i e s . T he c o n c e n t r a t i o n d i s t r i b u t i o n o f alu m in u m , b o r o n , cadm ium , c a l c i u m , c o b a l t , c o p p e r , i r o n , l e a d , m ag n e siu m , m a n g a n e s e , s i l i c o n , an d z in c i n e l e c t r o l y t i c n i c k e l d e p o s i t s a s i n f l u e n c e d b y c u r r e n t d e n s i t y , p H , c h l o r i d e c o n t e n t , some o r g a n ic c o n s t i t u e n t s , a n d th e e f f i c i e n c y o f n i c k e l d e p o s i t i o n i s r e p o r t e d . G e n e ra l t r e n d s o f t h e d e p o s i t i o n r a t e s f o r t h e i m p u r i t i e s a n d o f t h e r e l a t i v e e n e rg y e f f i c i e n c i e s f o r im p u rity d e p o s itio n s a re d is c u s s e d . to ACKNOWLEDGMENTS The a b l e g u id a n c e o f D r . D . T . E w in g , t h e a w a rd , a n d t h e r e n e w a l o f a G ra d u a te C o u n c il F e llo w s h ip w ere s i n c e r e l y a p p r e c i a t e d and a r e g r a t e f u l l y a c k n o w le d g e d . TABLE OF CONTENTS PAGE INTRODUCTION Im p u r itie s a F a c to r i n E le c t r o d e p o s i ti o n . ............. E f f e c t o f S e v e r a l F a c t o r s o n t h e C o d e p o s itio n o f Some Im­ ..................................... p u r itie s in E le c tro d e p o s itio n . U n iq u e n e s s o f S p e c tr o c h e m ic a l A n a l y s i s an d t h e I n c l i n e d C a th o d e f o r a S tu d y o f t h e D i s t r i b u t i o n o f I m p u r i t i e s i n D e p o s i t s ................................... EXPERIMENTAL E l e c t r o d e p o s i t i o n C o n d i ti o n s and B a t h s ............................................. C a th o d e P r e p a r a t i o n f o r D e p o s i t i o n ....................................................... D e p o s i t - t h i c k n e s s M e a s u re m e n ts ................................................................ S o l u t i o n S am ples A n a ly s e d ............................................................................ M e ta l S am p les .A n a ly z e d ................................................................................... S p e c tr o c h e m ic a l A n a ly s is E l e c t r o d e s .................................................................................................... S p e c tro g r a p h ................................................. S p a rk e x c i t a t i o n ............................................. P h o t o g r a p h i c ............................................................................................... P r o c e d u r e ...................................................................................................... RESULTS C a th o d ic C u r r e n t E f f i c i e n c i e s , O b s e r v a tio n s o f D e p o s itio n s an d D e p o s i t s ...................................................................................................... P r e c i p i t a t e F o r m a tio n ....................................................•• • ♦ ......................... C u r r e n t D e n s ity C a l c u l a t i o n s ........................................ A n a ly s e s N ic k e l A n o d e ................ P r e c i p i t a t e fo rm ed d u r i n g d e p o s i t i o n ...................................... E l e c t r o d e p o s i t i o n s o l u t i o n s ........................................................... E l e c t r o d e p o s i t s .............................. D e p o s i t - s o l u t i o n C o n c e n t r a t i o n R a tio ........................................... DISCUSSION C a th o d ic C u r r e n t E f f i c i e n c y . . . ................................................................ C a th o d e L a y e r a n d P r e c i p i t a t e F o r m a tio n ........................................... I s o —c u r r e n t D e n s ity C u rv e s an d t h e I n c l i n e d C a t h o d e .. . . . . . D e p o s i t - s o l u t i o n C o n c e n t r a t i o n R a tio O r i g i n . . . . . . . ............................................................................................ A p p lie d t o M e ta l I m p u r i t i e s G e n e ra l Form o f D i s c u s s i o n .......................... 1 1 2 k 5 $ 6 6 6 6 6 7 7 9 9 10 10 10 10 10 10 30 30 31 32 32 TABLE OF CONTENTS - Continued PAGE DISCUSSION - C o n tin u e d A lum inum ................................................................................................... B o r o n .......................................................................... C adm ium ..................................................................................................... C a lc iu m ..................................................................................................... C o b a l t ........................................................................................................ C o p p e r ....................................................................................................... I r o n ............................................................................................................ L e a d .......................................................................................................... M ag n esiu m ................................................................................................ M a n g a n e se .................................................................................... S i l i c o n ..................................................................................................... Z i n c ............................................................................................................ B la c k D e p o s i t s ............................................................................................................. D e p o s i t i o n R a te s f o r I m p u n i t i e s ................................................................... R e l a t i v e E n e rg y E f f i c i e n c i e s f o r I m p u r it y D e p o s i t i o n s .................. SUMMARY C a th o d ic C u r r e n t E f f i c i e n c y ............................. .................. ............................ C a th o d e L a y e r a n d P r e c i p i t a t e F o r m a ti o n ................................................ I s o - c u r r e n t D e n s i t y C u rv e s a n d t h e I n c l i n e d C a t h o d e . . . . E f f e c t , o n I m p u r i t y D i s t r i b u t i o n o f C u r r e n t D e n s i t y ........................ p H . . ........................................................................................................................ C h lo rid e C o n c e n t r a t i o n . ................................................................... O r g a n ic C o n s t i t u e n t s ........................... ...................................................... N i c k e l C o d e p o s i t i o n .................................................................................... D e p o s i t i o n R a te s f o r I m p u r i t i e s ................................... R e l a t i v e E n e r g y E f f i c i e n c i e s f o r I m p u r i t y D e p o s i t i o n s ................. BIBLIOGRAPHY..................... 33 3J4. 35 36 36 37 38 1*0 1*0 1*1 1*2 1*3 1*1* 1*3> 1*7 1*8 1*8 1*8 1*8 1*9 1*9 1*9 h9 1*9 50 51 \ L / LIST OF TABLES TABLE 1. PAGE The e f f e c t o f a n i n c r e a s e i n t h e s o l u t i o n c o n c e n t r a t i o n o f a n i m p u r i t y , o r t h e c u r r e n t d e n s i t y , o r t h e pH o n t h e d e p o s i t c o n c e n t r a t i o n o f a n i m p u r i t y a s i n d i c a t e d i n some o f t h e l i t e r a t u r e ........................ . ....................................................................... 3 2. The a n a l y t i c a l l i n e p a i r s ................. ............................................................. 8 3. G e n era l c h a r a c t e r i s t i c s o f th e e le c t r o d e p o s it i o n s and th e d e p o s i t s .................................... 11 The m e t a l i m p u r i t y c o m p o s itio n s o f t h e e l e c t r o l y t i c n i c k e l an o d e a n d a p r e c i p i t a t e 9 fo rm e d d u r i n g d e p o s i t i o n ........................ 12 The m e t a l i m p u r i t y c o m p o s itio n o f t h e 2 .2 pH W a tts ty p e s o l u t i o n ............................................................................... 13 T he m e t a l I m p u r i t y c o m p o s itio n o f t h e lu 7 pH W a tts ty p e s o l u t i o n ........................................................................................................................ lU T he m e t a l i m p u r i t y c o m p o s itio n o f t h e o r g a n ic t y p e s o l u t i o n (pH 3 . 2 ) ...................................................................................... * . . . . ......................... IS T he m e t a l i m p u r i t y c o m p o s itio n o f t h e c h l o r i d e ty p e s o l u ­ t i o n (pH 2 . 0 ) ............................................................................................................ 16 k. 5. 6. 7. 8. 9. 10. ; 11. 12. T he i m p u r i t y c o m p o s itio n o f d e p o s i t I-A o b t a i n e d from t h e 2 .2 pH W a t ts ty p e s o l u t i o n a t a c u r r e n t o f i*.3 a m p ./d m . 2 o f c a th o d e s u r f a c e ............................................................................................. 17 The i m p u r i t y c o m p o s itio n o f d e p o s i t I-B o b t a i n e d from t h e 2 .2 pH W a tts t y p e s o l u t i o n a t a c u r r e n t o f 1 .1 am p ./d m . 2 o f c a th o d e s u r f a c e .............................................................................................. 16 The i m p u r i t y c o m p o s itio n o f d e p o s i t I-C o b t a i n e d from t h e . 2 .2 pH W a tts ty p e s o l u t i o n a t a c u r r e n t o f 0 .2 2 amp ./d m . o f c a th o d e s u r f a c e .......................... 19 The i m p u r i t y c o m p o s itio n o f d e p o s i t XX-A o b t a i n e d from t h e k . 7 pH W a tts t y p e s o l u t i o n a t a c u r r e n t o f h .3 a m p ./d m . 2 13. o f c a th o d e .....s u r f a c e .............................................................................................. 2<-) The i m p u r i t y c o m p o s itio n o f d e p o s i t I I —B o b t a i n e d from t h e 1+.7 pH W a t ts t y p e s o l u t i o n a t a c u r r e n t o f 1 .1 am p ./d m . 2 o f c a th o d e s u r f a c e ............................................................................................. 2^ LIST OF TABLES - Continued TABLE lk . PAGE The i m p u r i t y c o m p o s itio n o f d e p o s i t I I - C o b t a i n e d from t h e k .7 pH W a t ts t y p e s o l u t i o n a t a c u r r e n t o f 0 .2 2 amp./dm. 2 o f c a th o d e s u r f a c e ................................. 22 15. The i m p u r i t y c o m p o s itio n o f d e p o s i t I I I - A o b t a i n e d fro m t h e o r g a n i c t y p e s o l u t i o n (pH 3 . 2 ) a t a c u r r e n t o f k .3 a ® p ./ dm. o f c a th o d e s u r f a c e ................................................................................... 23 16. The i m p u r i t y c o m p o s itio n o f d e p o s i t I I I - B o b t a i n e d fro m t h e o r g a n i c t y p e s o l u t i o n (pH 3 .2 ) a t a c u r r e n t o f 1 .1 a m p ./ dm . 2 o f c a th o d e s u r f a c e ............................................................... 2k 17. The i m p u r i t y c o m p o s itio n o f d e p o s i t I I I - C o b t a i n e d from t h e o r g a n i c t y p e s o l u t i o n (pH 3 .2 ) a t a c u r r e n t o f 0 .2 2 a m p ./ dm .2 o f c a th o d e s u r f a c e ................................................................................... 25 The i m p u r i t y c o m p o s itio n o f d e p o s i t IV-A o b t a i n e d from t h e c h l o r i d e t y p e s o l u t i o n (pH 2 .0 ) a t a c u r r e n t o f k .3 am p. / ................................................................... dm. 2 o f c a th o d e s u r f a c e . 26 The i m p u r i t y c o m p o s itio n o f d e p o s i t XV-B o b t a i n e d from t h e c h l o r i d e t y p e s o l u t i o n (pH 2 . 0 ; a t a c u r r e n t o f 1 .1 a m p ./ d m .2 o f c a th o d e s u r f a c e ........................................................................... 27 The i m p u r i t y c o m p o s itio n o f d e p o s i t IV-C o b t a i n e d from t h e c h l o r i d e t y p e s o l u t i o n (pH 2 .0 ) a t a c u r r e n t o f 0 .2 2 a m p ./ dm .2 o f c a th o d e s u r f a c e .................................................................. 28 18. 19. 20. L IS T OF FIGURES FIGURE 1. I s o - c u r r e n t d e n s i t y c u r v e s f o r a n i n c l i n e d c a th o d e i n am p eres p e r s q u a r e d e c i m e t e r , c a th o d e c u r r e n t k . 3 am p ./d m *2 2. I s o - c u r r e n t d e n s i t y c u r v e s f o r a n i n c l i n e d c a th o d e i n am p eres p e r s q u a r e d e c i m e t e r , c a th o d e c u r r e n t 1 .1 a m p ./d m . 2 3. I s o - c u r r e n t d e n s i t y c u r v e s f o r a .A i n c l i n e d c a th o d e i n a m p e re s p e r s q u a r e d e c i m e t e r , c a th o d e c u r r e n t 0 .2 2 am p ./d m . 2 h. The c o n c e n t r a t i o n d i s t r i b u t i o n o f alu m in u m . 5. The c o n c e n t r a t i o n d i s t r i b u t i o n o f b o r o n . 6. The c o n c e n t r a t i o n d i s t r i b u t i o n o f cadm ium . 7. The c o n c e n t r a t i o n d i s t r i b u t i o n o f c a l c i u m . 8. The c one e n t r a t i on d i s t r i b u t i o n o f c o b a l t . 9. The c o n c e n t r a t i o n d i s t r i b u t i o n o f c o p p e r . 10. The c one e n t r a t i o n d i s t r i b u t i o n o f i r o n . 11. The c o n c e n t r a t i o n d i s t r i b u t i o n o f l e a d . 12. The c o n c e n t r a t i o n d i s t r i b u t i o n o f m agnesium 13. The c o n e e n t r a t i o n d i s t r i b u t i o n o f m anganese llu The c o n c e n t r a t i o n d i s t r i b u t i o n o f s i l i c o n . 15. The c o n c e n t r a t i o n d i s t r i b u t i o n o f z i n c . 1 INTRODUCTION I t i s p r a c t i c a l l y im p o s s ib le to o b ta in and m a in ta in an aqueous s o l u t i o n c o n t a i n i n g o n ly one e l e c t r o - d e p o s i t a b l e m e t a l . Blum and Hogaboom ( l ) h a v e c o n c lu d e d fro m s t u d i e s o f t h e e f f e c t s o f i m p u r i t i e s i n p l a t i n g s o l u t i o n s t h a t s m a ll c o n c e n t r a t i o n s may s i g n i f i c a n t l y a f f e c t t h e d e p o s i t i o n o f o t h e r m e t a l s , w h e th e r c o d e p o s i t e d o r n o t . DuMond a n d C ohen ( 2 ) h a v e s t a t e d t h a t d i f f e r i n g r e s u l t s f o r t h e e x a c t v a lu e o f t h e F a r a d a y m ig h t p o s s i b l y b e t r a c e d i n c e r t a i n i n s t a n c e s t o »i n c l u s i o n s " o f e le c tr o ly te in th e d e p o s it c o a tin g . I t i s a l s o known t h a t t r a c e a n d s m a ll a m o u n ts o f i m p u r i t i e s i n a n e l e c t r o d e p o s i t o f n i c k e l a f f e c t , so m e tim e s t o a m a rk e d d e g r e e , t h e c h e m ic a l a n d p h y s i c a l p r o p e r t i e s o f t h i s d e p o s i t ( 1 ,3 ,U ,5 > ,6 ,7 ) . Thus a s tu d y o f th e e f f e c t o f v a rio u s f a c t o r s o n th e d e p o s it c o n c e n tr a tio n o f m e ta l im p u r itie s p r e s e n t i n e l e c t r o p l a t i n g s o l u t i o n s i s i m p o r t a n t t o t h o s e who d e s i r e t o know m ore c o n c e r n i n g t h e f u n d a m e n ta ls i n v o l v e d i n e l e c t r o d e p o s i t i o n a s w e l l a s t o t h o s e who w is h t o o b t a i n e l e c t r o d e p o s i t s w i t h c e r t a i n c h e m ic a l and p h y s ic a l p r o p e r t i e s . T h e re atee su m m arized i n T a b le 1 some o f t h e p u b l i s h e d r e s u l t s r e ­ g a rd in g th e e f f e c t c e r t a i n f a c t o r s have o n th e c o n c e n tr a tio n o f an im p u rity in th e e le c t r o d e p o s it . T h is t a b l e l i s t s f o u r t e e n o f t h e im­ p u r i t i e s fo u n d i n e l e c t r o l y t i c n i c k e l d e p o s i t s , an d show s how t h e d e p o s i t c o n c e n t r a t i o n o f some o f t h e s e i m p u r i t i e s v a r i e s w i t h a n i n c r e a s e 2 i n th e s o l u t io n c o n c e n tr a tio n o f th e im p u rity , o r th e c u r r e n t d e n s ity , o r t h e pH . I n g e n e r a l , s t u d i e s o f i m p u r i t y d e p o s i t i o n s fro m n i c k e l p l a t i n g s o l u t i o n s h a v e b e e n c o n f i n e d t o one i m p u r i t y r a t h e r t h a n a m ix tu r e o f i m p u r i t i e s a s w as d o n e i n t h i s r e s e a r c h . S p e c tr o c h e m ic a l a n a l y s i s i s u s e f u l f o r q u a n t i t a t i v e l y d e te r m in in g th e c o n c e n tr a tio n o f s e v e r a l m e ta ls , s im u lta n e o u s ly , u n d e r c o n d itio n s o f l i m i t e d sa m p le q u a n t i t i e s a n d s m a l l c o n c e n t r a t i o n s . E le c tro d e p o s i­ t i o n o n a n i n c l i n e d c a th o d e ( 8 ) i s a c c o m p lis h e d o v e r a r a n g e o f c u r r e n t d e n s i t i e s i n one o p e r a t i o n . T o g e t h e r t h e y f u r n i s h a m eans o f s t u d y i n g t h e e f f e c t o f c u r r e n t d e n s i t y u p o n t h e d e p o s i t c o n c e n t r a t i o n o f s m a ll a m o u n ts o f m e t a l i m p u r i t i e s c o d e p o s i t e d u n d e r i d e n t i c a l c o n d i t i o n s . T h e s e t e c h n i q u e s w e re u t i l i z e d t o s t u d y t h e d e p o s i t i o n s o f tw e lv e m e t a l i m p u r i t i e s fro m f o u r t y p e s o f n i c k e l d e p o s i t i o n s o l u t i o n s . pH f o r e a c h s o l u t i o n w as h e l d a c o n s t a n t d u r i n g d e p o s i t i o n . t e m p e r a t u r e w as a c o n s t a n t f o r a l l d e p o s i t i o n s . The The T he volum e o f t h e s o l u t i o n s u s e d w as s u f f i c i e n t t o m a i n t a i n t h e s o l u t i o n c o n c e n t r a t i o n s r e l a t i v e l y c o n s ta n t d u rin g th e d e p o s i ti o n s . 3 TABLE 1 THE EFFECT OF AN INCREASE OF THE RESPECTIVE VARIABLES ON THE DEPOSIT CONCENTRATION OF THE IMPURITT S o lu tio n C o n c e n tra tio n o f Im p u n ity C u rre n t D e n s ity in c re a s e ( 10) d e c re a se ( 10) C o b a lt lin e a r in c re a s e ( 1 1 , 12) maximum ( 1 3 ) 0 . 3 amp ./d m . 2 i n c r e a s e (ll± ) C opper lin e a r in c re a s e ( 1 2 , 15) d e c re a se ( 13) maximum ( 1 5 ) n e a r pH o f 1 minimum ( 7 ) 2 -3 amp ./d m .2 in c re a s e (?) maximum ( 1 7 ) 0 . 5 - 1 .3 a m p ./d m . 2 i n c r e a s e (1 8 ) M anganese i n c r e a s e ( 20) in c r e a s e ( 21) O xygen minimum ( 7) 2 amp ./dm .2 in c re a s e ( 7) I m p u r it y pH B o ro n ( 9 ) Cadmium C a rb o n ( 7 ) C h lo rin e (7 ) H y d ro g e n Iro n lin e a r in c re a s e ( 16) L ea d (1 9 ) Sodium ( 9 ) S u l f u r (7 ) Z in c lin e a r in c re a s e ( 12) d e c re a se ( 5 , 22) k EXPERIMENTAL T he c o m p o s it i o n s o f t h e e l e c t r o d e p o s i t i o n b a t h s u s e d w e re a s fo llo w s s t h e W a t t s ty p e -2 U 0 g . / l . o f n i c k e l o u s s u l f a t e h e p t a h y d r a t e , ' US g . / l . ° f n i c k e l o u s c h l o r i d e h e x a h y d r a t e , a n d 30 g . / l . o f b o r i c a c i d ; t h e o r g a n i c t y p e — 263 g . / l . o f n i c k e l o u s s u l f a t e , 60 g . / l . o f n i c k e l o u s c h l o r i d e , 3k g . / l . o f b o r i c a c i d , 7 . 5 g . / l . o f n i c k e l b e n z e n e - d i s u l f o n a t e , a n d O .lU m l .A * ° f t r i a m i n o t o l y l d i p h e n y l - r a e t h a n e c h l o r i d e $ t h e c h l o r i d e t y p e - - 3 00 g . / l . o f n i c k e l o u s c h l o r i d e a n d 30 g . A » ° f b o r i c a c i d . The p H *of t h e s o l u t i o n s w as a d j u s t e d w i t h s u l f u r i c a c i d , h y d r o c h l o r i c a c i d , o r n i c k e l o u s c a r b o n a t e a s n e e d e d t o 2 .2 o r U .7 f o r t h e W a t ts t y p e s o l u ­ t i o n , t o 3 .2 f o r t h e o r g a n i c t y p e s o l u t i o n , a n d t o 2 . 0 f o r t h e c h l o r i d e ty p e s o l u t i o n . E le v e n m e t a l i m p u r i t i e s , t e n m i l l i g r a m s o f e a c h p e r l i t e r o f s o l u t i o n , w e re a d d e d t o t h e s o l u t i o n s a s a c h l o r i d e o r s u l f a t e , e x c e p t f o r s i l i c o n w h ic h w as a d d e d a s so d iu m m e t a - s i l i c a t e , a s f o llo w s * b i - v a l e n t c a l c i u m , cadm ium , c o b a l t , c o p p e r , i r o n , m a g n e siu m , m a n g a n e s e , l e a d , z i n c , a n d t r i - v a l e n t a lu m in u m . T r i - v a l e n t chrom ium w as a d d e d t o o n e U .7 pH W a tts t y p e s o l u t i o n . E l e c t r o d e p o s i t i o n s w e re c a r r i e d o u t a t t h r e e c u r r e n t s } n a m e ly , U .3 , 1 . 1 , a n d 0 .2 2 a m p ./d m . 2 o f c a th o d e s u r f a c e . D u rin g d e p o s i t i o n s t h e t e m p e r a t u r e s o f t h e b a t h s w e re m a i n t a i n e d a t 5 5 ° C , T he s o l u t i o n s w e r e s t i r r e d e l e c t r o m a g n e t i c a l l y , t h e s o l u t i o n p a s s i n g t h e c a th o d e f a c e to w a r d t h e a n o d e a t a r a t e o f s i x t y c e n t i m e t e r s p e r m in u te w hen a c u r r e n t o f U.3 amp ./d m . 2 o f c a th o d e s u r f a c e w as p a s s e d . * D e te r m in e d e l e c t r d m e t r i c a l l y . 5 T he t w o - l i t e r v o lu m e s o f p l a t i n g s o l u t i o n s w e re p l a c e d i n a * c y l i n d r i c a l j a r , tw e n ty c e n t i m e t e r s i n d i a m e t e r , w h ic h h a d a h o llo w * c y l i n d e r , e i g h t a n d o n e - h a l f c e n t i m e t e r s i n d i a m e t e r , t h a t w as c e n t r a l l y lo c a te d to in c re a s e th e e f f ic ie n c y o f s t i r r i n g . The f i v e b y n in e c e n t i m e t e r s t e e l c a th o d e w as so p o s i t i o n e d t h a t t h e r e w as a f o r t y - f i v e d e g r e e a n g le b e tw e e n i t s f a c e a n d t h e f a c e o f t h e e i g h t b y f i v e c e n t i ­ m e te r, b agg ed, e le c t r o l y ti c n ic k e l an o d e. The s e p a r a t i o n b e tw e e n t h e c e n t e r s o f t h e a n o d e a n d t h e c a th o d e w as s i x a n d o n e - h a l f c e n t i m e t e r s . P r i o r t o t h e e l e c t r o d e p o s i t i o n p r o c e s s t h e c a th o d e s u r f a c e s w ere c l e a n e d b y ( a ) s u c c e s s i v e im m e rs io n s i n c a r b o n t e t r a c h l o r i d e , a c e t o n e , an d w a t e r , ( b ) a n o d ic e l e c t r o c l e a n i n g a t a t e m p e r a t u r e o f 95° C . a n d a c u r r e n t d e n s i t y o f 12 amp. /d m . 2 f o r two m in u te s i n a l i t e r s o l u t i o n c o n t a i n i n g 21 g . o f so d iu m h y d r o x i d e , V~> g . o f sodium m e t a - s i l i c a t e , 18 g . o f t r i - s o d i u m p h o s p h a t e , 6 g . o f sodium c a r b o n a t e , an d 7 1 /2 g . o f so d iu m a c e t a t e , a n d ( c ) im m e rs io n i n a d i l u t e h y d r o c h l o r i c a c i d s o l u t i o n an d r i n s i n g i n w a t e r . N ic k e l w as d e p o s i t e d fro m a 2 .2 pH W a tts t y p e s o l u t i o n , w h ic h h a d b e e n p u r i f i e d a c c o r d i n g t o t h e p r o c e d u r e o f E w in g , R o m in s k i, a n d K in g ( 2 3 ) , t o form a n i c k e l b a s e f o r d e p o s i t s n u m b ered I - A , I - B , I-C , I I - C , a n d I I I - C . The Roman n u m e ra l r e f e r s t o t h e t y p e o f s o l u t i o n , t h e l e t t e r t o a d e p o s i t o b t a i n e d from t h a t s o l u ­ t i o n a s d e n o te d i n T a b le 3 . To d e te r m in e t h e d e p o s i t t h i c k n e s s d i s t r i b u t i o n on a n i n c l i n e d c a th o d e f o r t h e t h r e e c u r r e n t s u s e d , we d i v i d e d t h e d e p o s i t s num bered 3 , h , a n d 5 a s l i s t e d i n T a b le 3 i n t o f i v e m i l l i m e t e r s q u a r e s e c t i o n s . The t h i c k n e s s o f t h e d e p o s i t a t t h e c e n t e r o f e a c h o f t h e s e s e c t i o n s * Made o f g l a s s . 6 was th e n d e te rm in e d w ith th e a i d o f a c a l i b r a t e d Magne-Gage ( 2 i i) . The t h ic k n e s s e s o f d e p o s i t s num bered I - A , I - B , and I-C w ere c a l c u l a t e d from th e w e ig h t and m ea su re d s u r f a c e d im e n sio n s o f s t r i p p e d , one c e n tim e te r sq u a re s e c t i o n s o f t h e d e p o s i t s . The s o l u t i o n sam p les which' w ere s p e c tr o c h e m ic a lly a n a ly s e d w ere sam ples o f t h e p l a t i n g s o l u t i o n s b e f o r e and a f t e r e a c h d e p o s i t i o n p r o c e s s and r e p r e s e n t a t i v e sa m p le s o f s t r i p p e d d e p o s i t s numbered I - A , I - B , and I-C w h ich w ere d i s s o l v e d i n h y d r o c h lo r ic and n i t r i c a c i d . S p e c tro c h e m ic a l a n a ly s e s w ere made o f r e p r e s e n t a t i v e one c e n t i ­ m e te r s q u a re s e c t i o n s o f d e p o s i t s num bered I - A , I - B , I - C , I I - A , I I - B , I I - C , I I I - A , I I I - B , I I I - C , IV -A , IV-B and IV -C . C o n c e rn in g s p e c tr o c h e m ic a l a n a l y s e s , s p e c i a l l y p u r i f i e d g r a p h ite e l e c t r o d e s w ere u s e d f o r th e s o l u t i o n a n a ly s e s and a s c o u n te r e l e c t r o d e s f o r t h e a n a ly s e s o f t h e m e ta l d e p o s i t s . A m ed iu m -sized s p e c tr o g r a p h w i t h q u a rtz o p t i c s and a C ornu ty p e o f p rism was u s e d w ith a n e n tr a n c e s l i t w hich h ad d im e n sio n s o f two by tw e n ty - f iv e th o u s a n d th s m i l l i m e t e r s . A q u a rtz c o n d e n sin g l e n s was u se d t o c o ll i m a te t h e l i g h t from t h e s p a r k so u rc e a t t h e lo w e s t w a v e le n g th u sed . The s p a r k s o u r c e , w hich had a t h r e e - q u a r t e r K .V .A . i n p u t , c o n s i s t e d o f a tr a n s f o r m e r t h a t had a r a t i n g o f 2$,000 v o l t s o n th e se c o n d a ry when 110 v o l t s was im p re ss e d on t h e p r im a r y , a 1 .2 m i l l i h e n r y in d u c ta n c e u n i t , a 0 .01$ m ic r o f a r a d c a p a c i t o r , and a n e le c t r o d e gap o f t h r e e m i l l i m e t e r s . The eaqposure tim e was f i v e s e c o n d s . 7 The S p ectru m A n a ly s is N o. 1 e m u ls io n s w ere d e v e lo p e d i n D 19 d e v e lo p e r f o r f i v e m in u te s a t 1 8 .5 ° C . The I n t e r n a l S ta n d a r d M ethod (2 £ ) was u s e d . The c a l i b r a t i o n c u rv e f o r t h e em u ls.io n was o r i g i n a l l y d e te rm in e d w ith t h e a i d o f a lo g a ri-tjh m ie ,^ ste p p e d s e c t o r . c h e c k e d w ith some o f t h e n i c k e l r e f e r e n c e l i n e s w h ic h a r e l i s t e d t o g e t h e r w ith t h e a n a l y t i c a l l i n e s i n T a b le 2 . The Be 3 1 3 0 .U A . l i n e (2 6 ) w as u s e d a s a n a u x i l i a r y i n t e r n a l s ta n d a r d l i n e i n t h e s o l u t i o n a n a l y s e s . o f 0 .0 0 3 g . A * s o l u t i o n s a m p le s . B e r y lliu m h ad a c o n c e n t r a t i o n 8 * TABLE 2 THE ANALYTICAL LINE PAIRS E le m e n t L in e N ic k e l R e f e r e n c e L in e Aluminum 3 0 9 2 .7 A . 3 9 6 1 .5 3 1 8 1 .7 A . 3 9 7 3 .6 B oron 2i*97.7 251*0.0 C a lc iu m ' 3 1 7 9 .3 3 9 6 8 .5 3 1 8 1 .7 3 9 7 3 .6 Cadmium 21UU.U 2 1 6 1 .2 C o b a lt 2 3 7 8 .6 2 3 6 2 .1 C opper 2 1 3 6 .0 327I4.O 2 1 6 1 .2 3 2 8 6 .9 Iro n 2599.1* 251*0 .0 M agnesium 2 7 9 5 .5 2 8 5 2 .1 2 8 2 1 .3 2 8 2 1 .3 M anganese 2 5 7 6 .1 251*0 .0 . 2 8 3 3 .1 2 8 2 1 .3 S ilic o n 25i 6 . i 251*0 .0 Z in c 331*5.6 3 2 8 6 .9 E lem en t L ead 9 RESULTS A g e n e r a l d e s c r i p t i o n o f t h e d e p o s i t s , t h e c u r r e n t s u s e d , th e c a th o d e c u r r e n t e f f i c i e n c i e s o b t a i n e d , an d o b s e r v a t i o n s made d u r in g t h e d e p o s i t i o n p r o c e s s c o n c e r n in g t h e n e c e s s i t y o f pH a d j u s t m e n t s , v i s i b l e g a s s in g a t t h e c a t h o d e , an d w h e th e r o r n o t a p r e c i p i t a t e w as fo rm ed a r e in c lu d e d i n T a b le 3 . I n a d d i t i o n t o t h e e le v e n i m p u r i t i e s ad d ed t o t h e o t h e r s o l u t i o n s , t e n m il l ig r a m s o f t r i - v a l e n t chrom ium w as ad d ed t o a U.7 pH W a tts ty p e s o l u t i o n . D u rin g e l e c t r o l y s i s a t a c u r r e n t o f U .3 amp ./dm .2 o f c a th o d e s u r f a c e a l a r g e am ount o f g a s s i n g o c c u r r e d a t t h e c a th o d e , a p r e c i p i t a t e fo rm e d , a n d t h e s o l u t i o n r e q u i r e d c o n tin u o u s pH a d ju s tm e n t. A b l a c k , p i t t e d , c ru m b ly d e p o s i tj f o r m e d o n t h e c a th o d e . I n i t i a l l y t h i s b l a c k d e p o s i t a p p e a re d a t t h e h i g h c u r r e n t d e n s i t y end o f th e i n c l i n e d c a th o d e j t h e n i t a p p e a re d a t s u c c e s s i v e l y lo w e r c u r r e n t d e n s i t y a r e a s o f t h e p l a t e a s m ore p l a t e s w ere r u n . The c a th o d e c u r r e n t e f f i c i e n c y d e c r e a s e d fro m f i f t y t o tw e n ty -o n e p e r c e n t i n t h e s i x p l a t e s m ade. No f u r t h e r w ork was a tte m p te d w i t h s o l u t i o n s c o n t a i n i n g chrom ium . I t was n o t i c e d t h a t w h e n ev e r a p r e c i p i t a t e fo rm e d , i t a p p e a re d f i r s t a t t h e c a th o d e s u r f a c e an d t h e n l a t e r i t was d i s t r i b u t e d g e n e r a l l y th r o u g h o u t t h e s o l u t i o n , d e p o s i t i n g o n t h e s u r f a c e o f t h e c o n t a i n e r and t h e o u t s i d e o f t h e anode b a g . A t no tim e d i d a n y o f t h e p r e c i p i t a t e a p p e a r o n t h e i n s i d e o f t h e anode b a g . An a n a l y s i s o f t h e p r e c i p i t a t e w h ic h a p p e a re d d u r in g t h e f o r m a tio n o f d e p o s i t num ber I I - C a s w e l l a s a n a n a l y s i s o f t h e e l e c t r o l y t i c n i c k e l anode i s g iv e n i n T a b le U. • 10 The c o n v e r s io n o f d e p o s i t t h i c k n e s s e s i n t o c u r r e n t d e n s i t i e s f o r d e p o s i t s num bered 3> U, a n d $ , c h e c k e d , g e n e r a l l y w i t h i n f i v e p e r c e n t , th e r e s u l t s o b t a i n e d from t h e on e c e n t i m e t e r s q u a r e , s t r i p p e d s e c t i o n s o f d e p o s i t s num bered I - A , I - B , ,and I - C . The l a r g e s t d i f f e r e n c e s o c c u r r e d a t t h e v e r y h ig h a n d t h e v e r y lo w c u r r e n t d e n s i t i e s . The m ore Im pure d e p o s i t s h a d a n a p p a r e n t c u r r e n t d e n s i t y w h ic h w as a b o u t t e n p e r c e n t low a t t h e h i g h e s t c u r r e n t d e n s i t i e s a n d a b o u t t h e same p e r c e n ta g e h ig h a t t h e lo w e s t c u r r e n t d e n s i t i e s . From t h i s i n f o r m a t i o n t h e d a t a f o r t h e i s o - c u r r e n t d e n s i t y c u r v e s o f F i g u r e s 1 , 2 , and 3 w ere o b t a i n e d . The a n a l y s e s o f t h e e l e c t r o d e p o s i t i o n s o l u t i o n s a r e g iv e n i n T a b le s $ s 6 , 7 , an d 8 . In c lu d e d i n t h e s e t a b l e s a r e t h e c a l c u l a t e d c o n c e n t r a t i o n s o f n i c k e l an d b o ro n a s c a l c u l a t e d from t h e q u a n t i t i e s o f th e r e s p e c t i v e s u b s ta n c e s u s e d i n m ak in g t h e s o l u t i o n s . The a n a l y s i s l i s t e d u n d e r e a c h sa m p le num ber i s t h e c o m p o s itio n o f t h e s o l u t i o n a t th e s t a r t o f t h e d e p o s i t i o n w h ic h y i e l d e d a p l a t e w i t h t h i s same n u m b er. The l a s t sam p le num ber f o r e a c h s o l u t i o n r e p r e s e n t s t h e s o l u t i o n com­ p o s i t i o n a f t e r th e l a s t d e p o s i t w as m ad e. T hus t h e a n a l y s i s g iv e n f o r s o l u t i o n sam p le I-A w as t h e c o m p o s itio n o f t h e d e p o s i t i o n s o l u t i o n a t t h e s t a r t o f t h e d e p o s i t i o n p r o c e s s w h ic h p ro d u c e d d e p o s i t I - A . The c o m p o s itio n s o f t h e d e p o s i t s o b t a i n e d a t h i g h , m o d e r a te , and low c u r r e n t s from t h e low pH W a t t s , t h e h ig h pH W a t t s , t h e o r g a n i c , and t h e c h l o r i d e t y p e s o l u t i o n s a r e l i s t e d i n T a b le s 9 th r o u g h 2 0 . A d e p o s it- s o lu tio n c o n c e n tra tio n r a t i o f o r a c e r t a i n c u rr e n t d e n s ity i n a p a r t i c u l a r s o l u t i o n i s o b t a i n e d when t h e p e r c e n t c o n c e n t r a t i o n v a lu e o f t h e I m p u r ity i n t h e r e s u l t a n t d e p o s i t i s d i v i d e d b y t h e a v e ra g e c o n c e n t r a t i o n i n t h e b a th i n gram s o f i m p u r i t y p e r o n e -h u n d re d gram s o f n ic k e l. TABLE 3 GENERAL CHARACTERISTICS OF THE ELECTRODEPOSITIONS AND THE DEPOSITS Cathode C u rre n t E f fic ie n c y P er C ent D uring D e p o sitio n P ro cess pH A djustm ent V is ib le P r e c ip i­ C athodic N ecessary ta te G assing Formed D ep o sit D e s c rip tio n (in c lu d e s c o lo r ; l i g h t , g ra y , b la c k ; f i n i s h ; m a tte , s e m i- b r ig h tt o th e r ite m s; s t r e s s e d , red d ish -b ro w n o r v e lv e ty brown t i n g e , e t c .) S o lu tio n Type D ep o sit No. W atts ( p u r if ie d ) pH 2 .2 3 k.3 k 5 1 .1 0.22 100 100 91 no no no no no no no no no g ra y , m a tte , s e m i-b rig h t a t h ig h c . d . g ra y , m atte g ra y , m atte I-A* I-B * I-C * 1*.3 1 .1 0.22 100 100 96 no no no no no no no no no g r a y ,m a tte ,s e m i-b rig h t a t h ig h c . d . g ra y ^ m a tte ,m o ttle d below 0 .9 amp ./d m .2 g r a y p a a tte , re d d is h tin g e in c r e a s in g tow ard h ig h c . d . ed g e. yes l i g h t , s e m i- b r ig h t, s tr e s s e d yes l i g h t , s e m i-b rig h t above 1 amp./dm. in c r e a s in g ly d a rk below ; r . - b . tin g e below 0 .5 amp./dm ,2 b la c k W atts pH 2 .2 W atts pH k.7 O rganic pH 3 .2 C h lo rid e pH 2 .0 C u rren t amp ./d m .2 o f Cathode II-A k.3 66 c o n tin u o u sly II-B 1 .1 53 c o n tin u o u sly n-c* 0.22 5 .6 c o n tin u o u sly above 7 amp ./dm .2 h ig h c . d . edge no yes IH -A 1*.3 91 c o n tin u o u sly H I-B 1 .1 91 c o n tin u o u sly ni-c* 0 .2 2 63 c o n tin u o u sly no y es IV-A IV-B IV-C U.3 1 .1 0 .22 102 108 106 no no no no no no no no no above 9 amp./dm .2 no yes yes l i g h t w ith red d ish -b ro w n t i n g e , s e m i-b rig h t 1 .8 to 3 .0 amp ./d m .2 l i g h t , m a tte , r . - b . t i n g e , se m i-b rig h t above 1 amp./dm.2 l i g h t , m a tte , and r . - b . tin g e above O .ll; amp ./dm .2 , r e s t l a r g e b la c k s p o ts g ra y , m a tte , v .b . tin g e g ra y , m a tte , v .b . tin g e g ra y , m a tte , v . b . tin g e down t o 0 .2 2 amp./dm .2 , in c r e a s in g £ . - b . tin g e up to 0 .2 2 amp./dm.2 * S ig n if ie s t h a t t h i s d e p o s it was made on an e l e c t r o l y t i c n ic k e l d e p o s it which had been p re v io u s ly o b ta in e d by d e p o s itio n on a s t e e l p l a t e from a p u r i f i e d , low pH W atts ty p e s o lu tio n . H H 12 TABLE k THE IMPURITY COMPOSITIONS OF THE ELECTROLYTIC NICKEL ANODE AND A PRECIPITATE FORMED DURING DEPOSITION E lem en t E le c tro ly tic N ic k e l Anode P e r C e n t b y W eig h t P r e c i p i t a t e Formed D u rin g I I - C D e p o s itio n Aluminum O.OII4 0.0$h B oron O.OOlt 0 .1 6 Cadmium 0 .0 0 6 0 .0 1 8 C alciu m O.OOI46 0 .0 2 8 C o b a lt 0 .3 1 tra c e C opper 0.063 0 .1 2 Iro n o .o ia p l u s N i c k e l , o v e r $0 Lead 0 .03U £ 0 Cl 0 .0 3 9 M agnesium 0 .0 0 2 0 .00$$ M anganese 0.003 0 .0 0 7 1 S ilic o n 0 .0 2 6 0 .3 S Z in c 0 .0 1 2 0 .0 1 6 2 .0 7 .0 5 .0 3 .0 FIG. I. ISO-CURRENT DENSITY CURVES FOR AN INCLINED CATHODE. (AMPERES PER SQUARE DECIMETER) (CATHODE CURRENT 4 .3 AMP./DM. 2 ) 3 .0 0 .5 0 2 .5 1.0 0 .7 5 0 .7 5 FIG. 2. ISO-CURRENT DENSITY CURVES FOR AN INCLINED CATHODE. (AMPERES PER SQUARE DECIM ETER) (CATHODE CURRENT 1.1 A M P ./D M . 2 ) 030 022 0.18 0.15 0.13 0.15 FIG. 3. ISO-CURRENT DENSITY. CURVES FOR AN INCLINED CATHODE. (AMPERES PER SQUARE DECIMETER) (CATHODE CURRENT. 0 . 2 2 AMP./DM. 2 ) 13 TABLE 5 THE METAL IMPURITY COMPOSITION OF THE 2 .2 pH WATTS TYPE SOLUTION ( N i c k e l c o n c e n t r a t i o n , 62 g r a m s / l i t e r ) E le m e n t Grams o f I m p u r ity /1 0 0 Grams o f N ic k e l ♦S am ple I-A I-B I-C I-D Aluminum 0 .0 3 6 B o ro n 8 .5 Cadmium 0 .0 Uo 0 .0 3 9 0 .0 3 7 0 .0 1 6 o .o il* 0 .0 1 3 0 .0 0 5 7 C alc iu m 0 .0 3 9 0 .0 3 6 0 .0 3 I4 0.031* C o b a lt 0 .1 9 0 .1 8 0 .1 7 0 .1 6 C o p p er 0 .1 3 0 .1 1 0 .0 6 1 0 .0 2 6 Iro n 0 .0 6 7 0 .0 6 0 0 .0 6 3 0 .0 6 5 L ead 0 .0 3 5 0 .0 3 2 0 .0 2 3 0 .0 1 8 M agnesium 0 .1 6 0 .1 8 O .lU 0 .1 5 M anganese 0 .0 7 3 0 .0 7 1 0 .0 6 9 0 .0 7 3 S ilic o n 0 .0 3 9 0.031* 0.0U 7 0 .0 3 9 Zinc, 0 .0 2 6 0.0214 0.0214 0 .0 1 8 * The analysis listed under each sample is the composition of the solution at the start of the deposition which yielded a deposit with the same number. 11* TABLE 6 THE METAL IMPURITY COMPOSITION OF THE 1*.7 pH WATTS TYPE SOLUTION ( N ic k e l c o n c e n t r a t i o n , 62 g r a m s / l i t e r ) E lem en t Grams o f Im p u rity /lO O Grams o f N ic k e l •S a m p le I I - A h -b II-C II-D Aluminum 0 .0 1 6 B oron 8 .5 Cadmium 0 .0 1 9 0 .0 2 7 0 .0 1 8 0 .0 1 8 0 .0 1 8 0 .0 1 8 0 .0 1 8 C alciu m 0 .0 1 6 o .o ii* 0.019 0 .0 1 3 C o b a lt 0 .0 5 3 0 .0 5 5 0 .0 5 3 0.01*7 C opper 0 .0 5 5 0 .0 6 3 0.01*2 0.021* Iro n 0 .0 1 7 0.030 0.01*0 0 .0 2 8 Lead 0.021* 0 .0 2 7 0.021* O.Oll* M agnesium 0 .0 1 8 0 .0 1 8 0 .0 1 6 O.Oll* M anganese 0 .0 2 1 0 .0 1 8 O.Oll* 0.011* S ilic o n 0 .0 2 3 0 .0 2 9 0.021* 0.021* Z in c 0 .0 1 6 0 .0 1 6 0 .0 1 7 0 .0 1 2 * The a n a l y s i s l i s t e d u n d e r e a c h sam p le i s t h e c o m p o s itio n o f t h e s o l u t i o n a t th e s t a r t o f t h e d e p o s i t i o n w h ic h y i e l d e d a d e p o s i t w i t h t h e same n u m b er. 15 TABLE 7 THE METAL IMPURITY COMPOSITION OF THE ORGANIC TYPE SOLUTION, pH 3 .2 ( N ic k e l c o n c e n t r a t i o n , 70 g r a m s / l i t e r ) E le m e n t Grams o f I m p u r ity /1 0 0 Grams o f N ic k e l ■"Sample I I I - A III-B m -c III-D Aluminum 0 .0 3 7 B oron 8 .5 Cadmium 0.03U 0 .0 3 9 0 .0 3 3 0 .0 1 6 0 .0 1 3 0 .0 1 2 0 .0 0 9 3 C alcium 0 .0 3 0 0 .0 3 7 0 .0 3 6 0 .0 3 9 C o b a lt 0 .0 5 1 0 .0 5 6 0 .0 5 6 0.05 U C opper 0 .0 5 7 0 .0 5 6 o .o U i 0 .0 3 3 Iro n 0 .0 3 1 0 .0 3 0 0 .0 3 5 0 .0 3 5 0 .0 3 2 0 .0 3 0 0.021; 0 .0 2 0 Magnesium 0 .0 6 U 0 .0 7 1 0 .0 7 6 0 .0 7 6 M anganese o .o iU o .o ii* 0.011; 0.011; S ilic o n 0 .0 1 7 0 .0 1 7 0 .0 1 7 0 .0 1 7 Z in c 0.021; 0 .0 2 0 0 .0 2 0 0 .0 1 9 Lead » * The analysis listed under each sample number is the composi­ tion of the solution at the start of the deposition which yielded a deposit with the same number. 16 TABLE 8 § to o THE METAL IMPURITY COMPOSITION OF THE CHLORIDE TYPE SOLUTION, pH 2 .0 (N ic k e l c o n c e n t r a t i o n , 7 k g r a m s / l i t e r ) E lem ent •'Sam ple IV-A Aluminum 0 .0 2 7 B oron 7 .1 Cadmium I m p u rity /1 0 0 Grams o f N ic k e l IV-B IV-D IV-C 0 .0 2 7 0 .0 2 6 0 .0 2 7 0 .0 1 2 0 .0 1 2 0 .0 1 1 0 .0 0 9 3 C alciu m O .O ll; 0 .0 1 5 0 .0 1 5 0 .0 1 5 C o b a lt 0.U2 0 .3 7 o.ia 0.1*3 C opper 0 .0 6 3 0 .0 6 9 0 .0 6 1 0 .0 5 3 Iro n 0 .0 5 0 0 .0 6 2 0 .0 7 0 0 .0 8 8 Lead 0 .0 3 k 0 .0 2 9 0 .0 3 0 0 .0 2 9 M agnesium 0 .0 3 2 0 .0 2 7 0 .0 3 1 0 .0 3 k M anganese 0 .0 2 0 0 .0 1 9 0 .0 2 0 0 .0 2 3 S ilic o n 0 .018 0 .0 1 8 0 .0 1 8 0 .0 1 9 Z in c 0 .0 1 8 0 .0 1 9 0 .0 1 8 0 .0 1 8 * The a n a l y s i s l i s t e d u n d e r e a c h sam ple num ber i s t h e com posi­ t i o n o f t h e s o l u t i o n a t t h e s t a r t o f t h e d e p o s i t i o n w hich y i e l d e d a d e p o s i t w i t h t h e same num ber. 17 TABLE 9 THE IMPURITY COMPOSITION OF DEPOSIT I-A OBTAINED FROM THE 2 .2 pH WATTS TYPE SOLUTION AT A CURRENT OF h .3 AMPA/DM.2 OF CATHODE SURFACE E le m e n t _____________C o n c e n t r a t i o n . P e r C e n t b y W e ig h t C u r r e n t D e n s i t y o f D e p o s it S e c t i o n i n a m p . / d m . 2 9 .6 8 .0 lu'O 2 .h 1 .9 1 .6 Aluminum 0 .0 1 0 0.0095 0 .0 0 9 8 0 .0 0 9 5 0 .0 0 9 3 0 .0 0 9 0 B oron 0.0031 0 .0 0 3 1 0 .0 0 2 8 0 .0 0 3 0 0 .0 0 3 0 0.0030 Cadmium 0 .0 1 3 0 .0 1 3 0 .0 2 0 0 .0 2 2 0 .0 2 7 0 .0 3 2 C a lc iu m 0 .0 0 7 9 o .0 0 3 5 o.ooU o 0.0031 0 .0 0 2 8 0 .0 0 2 9 C o b a lt 0.6U 0 .6 5 0 .7 8 1 .1 1 .3 1 .5 C opper 0.056 0.0614 0 .0 7 2 0 .0 9 7 0 .1 1 O .li* Iro n 0 .1 7 0 .1 6 o .i5 0 .2 8 0 .2 6 0 .3 7 L ead 0 .0 3 3 0 .0 2 7 o .o ia o.oU o 0 .0 U 5 0 .0 k3 M agnesium 0 .0 0 2 5 0 .0 0 1 7 0.0015 0 .0 0 1 6 0 .0 0 1 1 0 .0 0 1 1 0 .0 0 2 8 0 .0 0 2 0 0 .0 0 1 8 _ 0 .0 1 7 0 .0 1 1 0 .0 1 0 0 .0 1 9 0 .0 1 9 0 .0 2 1 M anganese S ilic o n Z in c 0 .0 2 7 0 .0 2 5 0 .0 2 6 18 TABLE 10 THE IMPURITY COMPOSITION OF DEPOSIT I-B OBTAINED FROM THE 2 .2 pH WATTS TYPE SOLUTION AT A CURRENT OF 1 .1 AMP ./E M .2 OF CATHODE SURFACE E lem en t ____________ C o n c e n t r a t i o n . P e r C e n t by W e ig h t C u r r e n t D e n s i t y o f D e p o s it S e c t i o n , amp . '/dm .2 l.U 1 .1 0 .8 1 0 .£ 6 0 . 1+3 Aluminum 0.010 0 .0 0 9 5 0.010 0.0090 0 .0 0 9 3 B oron 0 .0 0 3 1 0 .0 0 3 1 0 .0 0 3 1 0 .0 0 3 3 0 .0 0 3 3 Cadmium 0 .0 2 7 0 .0 3 3 0.038 0.01+5 0.01+9 C alciu m 0 .0036 0 .0 0 2 8 0 .0 0 3 9 0.0038 0 .001+6 C o b a lt 1 .5 1 .6 1.8 2.2 2 .3 C opper 0 .1 3 0 .1 7 0 .1 9 0 .2 7 0.36 Iro n o.l+H 0 .3 9 0.51; 0.61 0.62 Lead 0.014; 0.01+5 o.oi+5 0.050 0.060 M agnesium 0.0030 0.0012 0 .0 0 1 7 0 .0011+ 0 .0 0 1 7 M anganese 0.0022 0.0020 S ilic o n 0 .0 1 3 0.010 Z in c 0 .0 2 6 0 .021; 0.025 0.030 0 .0 2 6 19 TABLE 11 THE IMPURITY COMPOSITION OF DEPOSIT I-C OBTAINED FROM THE 2 .2 pH WATTS TYPE SOLUTION AT A CURRENT OF 0 .2 2 AMP ./DM .2 OF CATHODE SURFACE E lem en t C o n c e n t r a t i o n . P e r C e n t b y W eig h t C u r r e n t D e n s ity o f D e p o s it S e c t i o n , amp 7 /d in .2 0 .2 6 0 .2 1 O .lU 0 .1 1 Aluminum 0 .0 0 9 8 0 .0 0 9 8 0 .0 0 9 8 0 .0 0 9 $ B oron 0 .0 0 3 0 0 .0 0 2 8 0 .0 0 3 1 0 .0 0 3 0 Cadmium 0 .0 U 6 0 .0 $ 1 0 .0 $ 2 0 .0 $ 2 C alciu m 0 .0 0 3 6 0 .0 0 2 9 0 . 00U0 0 .0 0 3 3 C o b a lt 2 .2 2 .2 1 .7 1 .3 C opper 0 .1 $ O .lU 0 .1 8 0 .2 0 Iro n 0 .6 1 o .$ o 0 .3 U 0 .2 2 Lead O.OU6 0.0U 6 0 .0 6 0 0 .0 $ $ M agnesium 0 .OOlU 0 .0 0 1 3 0 .0 0 1 8 0 .0 0 1 U M anganese 0 .0 0 2 2 0 .0 0 2 1 0 .0 0 2 2 0 .0 0 2 2 S ilic o n 0 .0 0 8 7 0 .006U 0 .0 0 9 8 0.00 7 0 Z in c 0 .0 2 $ 0 .0 2 3 0 .0 2 $ 0 .0 2 9 20 TABLE 12 THE IMPURITY COMPOSITION OF DEPOSIT II- A OBTAINED FROM THE k .7 pH WATTS TYPE SOLUTION AT A CURRENT OF k .3 AMP./DM. 2 OF CATHODE SURFACE E lem en t C o n c e n t r a t i o n , P e r C e n t b y W eig h t C u r r e n t D e n s ity o f D e p o s it S e c t i o n , amp ./dm 8 .3 k .l 1 .9 Aluminum 0.0098 0 .009$ 0.0090 B oron 0.088 o .030 0 .0 1 8 Cadmium 0.026 0.030 0 .0 3 8 C alciu m 0.016 0 .0 0 3 5 o .0 0 3 k C o b a lt 0 .1 7 0 .2 8 0 .3 3 C o p p e r- 0 .069 0.061 0.081 Iro n 8.6 1 .0 0 .3 k Lead 0.038 0 . 0U6 0 .0 k 7 M agnesium 0.0026 0.00 i k o .o o ik M anganese 0.012 0.00U 7 0 .0 0 2 5 S ilic o n 0.015 0 .0 1 0 0 .0 1 1 Z in c 0 .0 1 8 0 .0 2 2 0 .0 2 7 r 21 TABLE 13 THE IMPURITY COMPOSITION OF DEPOSIT I I - B OBTAINED FROM THE 1*.7 pH WATTS TYPE SOLUTION AT A CURRENT OF 1 .1 AMP ./DM . 2 OF CATHODE SURFACE E le m e n t C o n c e n tr a tio n ,P e r C e n t b y W eig h t C u r r e n t D e n s i t y o f D e p o s it S e c t i o n , am p./dm 1.1* 0 .8 1 0 .5 6 0.1*5 Aluminum 0 .0 0 9 0 0 .0 0 8 6 0 .0 0 8 8 0 .0 0 9 0 B o ro n O.Oll* 0 .0 1 7 0 .0 2 3 0 .0 1 6 Cadmium 0 .01*8 0 .0 5 3 0 .0 5 7 0 .0 5 8 C a lc iu m 0 .0 0 2 6 0 .0 0 3 5 0.0031* 0 .0 0 2 8 C o b a lt 0 . 1*1* 0.1*9 0.1*1 0 . 1*1* C o p p er 0 .1 2 0 .2 1 0.31* 0 . 1*8 Iro n 0 .2 9 0 .2 0 0.26 0 .2 9 L ead 0 .0 5 3 0 .0 6 3 0 .0 6 5 0 .0 7 1 M agnesium 0 .0 0 1 0 0 .0 0 1 0 0 .0 0 1 1 0 .0 0 0 8 8 M anganese 0 .0 0 2 5 0 .0 0 2 1 0 .0 0 2 0 0 .0 0 2 1 S ilic o n 0 .0 1 2 0 .0 1 0 0 .0 1 0 0 .0 1 1 Z in c 0 .0 2 3 0 .0 3 6 0 .0 2 9 0 .0 3 I* 22 TABLE 11* THE IMPURITY COMPOSITION OF DEPOSIT I I - C OBTAINED FROM THE b .7 pH WATTS TYPE SOLUTION AT A CURRENT OF 0 .2 2 A M ^ ./tM .2 OF CATHODE SURFACE E le m e n t '______C o n c e n t r a t i o n . P e r C e n t B y W e ig h t C u r r e n t D e n s i t y o f D e p o s i t S e c t i o n , a m p ./d m .2 0 . 30* 0 .2 2 * 0 .1 b * 0 .1 1 * Aluminum 0 .0 0 0 6 2 0 .0 0 0 7 2 0 .0 0 0 7 1 0 .0 0 0 8 1 B o ro n 0 .0 2 8 0 .0 2 b 0 .0 2 3 0 .0 0 7 1 Cadmium 0 .0 8 0 0 .0 7 b 0 .0 6 5 0 .0 6 0 C a lc iu m 0 .0 0 0 1 1 0 .0 0 0 1 3 0 .0 0 0 0 7 6 0 .0 0 0 0 9 5 C o b a lt 0 .0 0 9 0 0 .0 0 8 0 0 .0 0 9 0 0 .0 0 7 0 C opper 3 .3 3 .5 3 .3 3 .8 Iro n 0.01*1; 0 .0 6 6 0 .1 1 0 .1 5 L ead 0 .6 0 0 .6 b 0 .6 3 0 .6 b M agnesium 0 .0 0 0 3 b 0 .0 0 0 3 3 0.00035 0 .0 0 0 3 3 M anganese 0.00051 0 .0 0 0 5 7 0 .0 0 0 5 8 0 .0 0 0 5 9 S ilic o n 0 .0 0 2 2 0 .0 0 2 5 0.0026 0 .0 0 2 7 Z in c 0 .0 2 0 0 .0 1 9 0 .0 2 0 0 .0 2 3 * B la c k D e p o s i t 23 TABLE 15 THE IMPURITY COMPOSITION OF DEPOSIT I I I - A OBTAINED FROM THE ORGANIC TYPE SOLUTION (pH 3 . 2 ) AT A CURRENT OF 1*.3 AMP ./E M .2 OF CATHODE SURFACE E le m e n t _________ C o n c e n t r a t i o n . P e r C e n t b y W eig h t C u r r e n t D e n s ity o f D e p o s it S e c t i o n , amp ./d m 8 .3 3 .9 1 .9 Aluminum 0 .0 1 3 0 .0 1 0 0 .0 1 0 B o ro n 0 .0 0 7 8 0.001*2 0.001*6 Cadmium 0 .0 1 6 0 .0 1 8 0 .0 2 8 C alc iu m o .0 0 5 0 0 .0 0 3 2 0 .0 0 3 0 C o b a lt 0 .2 0 0 .2 5 0 .3 8 C o p p er 0 .0 3 1 0.01*9 0 .0 8 1 Iro n 0 . 1*0 0 .1 1 0 .0 9 0 L ead 0 ,0 3 b 0.01*6 0 .0 5 8 M agnesium 0 .0 0 1 7 0 .0 0 1 6 0 .0 0 1 3 M anganese 0 .0 0 2 9 0 .0 0 2 2 0 .0 0 2 0 S ilic o n O.Oll* 0 .0 1 1 0 .0 1 1 Z in c 0 .0 2 3 0 .0 2 3 0 .0 2 9 2k TABLE 16 THE IMPURITY COMPOSITION OF DEPOSIT I I I - B OBTAINED FROM THE ORGANIC TYPE SOLUTION (pH 3 .2 ) AT A CURRENT OF 1 .1 AMP ./E M .2 OF CATHODE SURFACE E lem ent C o n c e n t r a t i o n . P e r C e n t b y W eight C u r r e n t D e n s ity o f D e p o s it S e c t i o n , am p ./d m .^ l.H 1 .1 0 .5 6 0 .U 5 Aluminum 0 .0 1 1 0 .0 1 0 0 .0 1 1 0 .0 1 1 B oron 0 .0014-8 0 .0 0 5 1 0 .0 0 7 9 0 .008U Cadmium 0 .0 3 2 0 .0 3 7 0 .0 lt5 0.0149 C alciu m 0 .0 0 3 8 0 .0 0 2 5 0 .0 0 3 0 0 .0 0 2 7 C o b a lt 0.U 8 0 .5 6 0 .6 3 0 .5 8 C opper 0 .0 6 7 0 .0 8 7 0 .2 2 0.214 Iro n 0 .1 3 0 .1 2 0 .3 1 0.140 Lead 0 .0 5 8 0 .0 6 6 0 .0 7 2 0 .0 7 1 M agnesium 0 .0 0 1 2 0 .0 0 1 1 0 .0 0 1 1 0 .0010 M anganese 0 .0 0 1 9 0 .0 0 1 9 0 .0 0 1 9 0 .0 0 2 2 S ilic o n 0 ,009li 0 .0 1 0 0 .0 1 0 0 .0 1 2 Z in c 0 .0 2 8 0 .0 3 1 0 .0 3 6 0 .0 3 6 25 TABLE 17 THE IMPURITY COMPOSITION OF DEPOSIT I I I - C OBTAINED FROM THE ORGANIC TYPE SOLUTION (pH 3 . 2 ) AT A CURRENT OF 0 .2 2 AMP./fcM.2 OF CATHODE SURFACE E le m e n t C o n c e n t r a t i o n . P e r C e n t b y W e ig h t C u r r e n t D e n s ity o f D e p o s it S e c t i o n , amp ./dm ."2~~ 0 .3 0 0 .1 9 0 .1 6 0 .1 2 * Aluminum 0 .0 3 6 O.OI43 0 .0 6 2 0 .0 3 3 B oron 0 .0 3 9 0 .0 3 k 0 .0 k 8 0 .2 7 Cadmium 0 .0 5 0 0 .0 U 6 0.0H 8 0 .0 6 6 C a lc iu m 0 .0031 0 .0 0 3 0 0 .0 0 3 3 0 .0 0 0 0 5 C o b a lt 0 .3 2 0 .3 0 0 .2 k 0 .1 1 C opper 0 .1 8 0 .2 6 0 .2 9 1 .9 Iro n -' . 1 .2 1 .0 2 .1 0 .2 2 L ead 0 .0 6 5 0 .0 5 9 0 .0 6 0 0 .3 2 M agnesium 0 .0 0 1 2 0 .0 0 1 1 0 .0 0 1 1 M anganese 0 .0 0 2 1 0 .0 0 1 8 0 .0 0 1 9 0 .0 0 0 3 k S ilic o n 0 .0 1 7 0 .0 1 0 0 .0 1 6 0 .0 1 k Z in c 0 .0 3 1 0 .0 2 9 0 .0 2 7 0 .0 5 9 * B la c k D e p o s it - 0 .0 0 0 3 5 26 TABLE 18 THE IMPURITY COMPOSITION OF DEPOSIT IV-A OBTAINED FROM THE CHLORIDE TYPE SOLUTION (pH 2 .0 ) AT A CURRENT OF *4.3 AMP ./E M .2 OF CATHODE SURFACE E le m e n t _____________C o n c e n t r a t i o n , P e r C e n t b y W eig h t_________ C u r r e n t D e n s i t y o f D e p o s i t S e c t i o n , amp ./dm 9 .6 5 .2 3 .9 2 .9 1 .9 Aluminum O .O ll 0 .0 0 9 3 0 .0 0 9 0 0 .0 0 9 0 0 .0 1 0 B o ro n o .o o l a 0 .0 0 3 3 0 .0 0 3 3 0.003*4 0 .0 0 3 8 Cadmium 0 .0 1 5 0 .0 1 9 0 .0 2 6 0 .0 3 0 0 .0 3 9 C alc iu m 0 .0 0 7 7 0 .0 0 2 5 0 .0 0 2 2 0 .0 0 3 5 0 .0 0 2 I4 C o b a lt 0 .5 9 0 .7 8 0 .9 7 1 .0 1 .3 C o p p er 0.02*4 0 .0 3 2 0 .0*46 0 .0 5 6 0 .0 9 8 Iro n 0.06*4 0 .0 6 U 0 .0 7 0 0 .0 9 9 0 .1 5 Lead O.Okh O.OI48 0 .0 5 5 0.0514 0 .0 5 9 M agnesium 0 .0 0 1 2 0 .0 0 1 0 0.0008*4 0 .0 0 1 1 0 .0 0 0 9 6 M anganese 0 .0 0 2 1 0 .0 0 2 1 0 .0 0 2 0 0 .0 0 2 1 0.002*4 S ilic o n 0 .0 1 0 0.009*4 0 .0 0 8 5 0 .0 1 0 0 .0 1 1 Z in c 0.02*4 0 .0 1 9 0 .0 2 6 0 .0 2 2 0 .0 2 5 27 TABLE 19 THE IMPURITY COMPOSITION OF DEPOSIT IV-B OBTAINED FROM THE CHLORIDE TYPE SOLUTION (pH 2 . 0 ) AT A CURRENT OF 1 .1 AM P./EM .2 OF CATHODE SURFACE E le m e n t C o n c e n t r a t i o n . P e r C e n t b y liiT elg h t C u r r e n t D e n s i t y o f D e p o s i t S e c t i o n , amp ./d in .2 0 .1*3 l.k 0 .6 6 Aluminum 0 .0 0 8 6 0 .0 0 8 6 0 .0 1 2 B oron 0 .0 0 3 1 0 .0 0 3 2 o.oolO* Cadmium 0.01*2 O.Olj.8 0 .0 5 3 C a lc iu m 0 .0 0 2 6 0 .0 0 5 5 0 .0 0 2 7 C o b a lt 1 .3 i .i 1 .0 C o p p er 0 .1 2 0 .2 7 0 .3 5 Iro n 0 .1 9 0 .3 2 0 .3 h L ead 0 .0 5 5 0 .0 7 1 0 .0 6 8 M agnesium 0 .00088 0 .0 0 1 3 0 .0 0 1 1 M anganese 0 .0 0 2 2 0 .0 0 2 3 0 .0 0 2 5 S ilic o n 0 .0 1 1 0 .0 1 1 0 .0 1 2 Z in c 0 .0 2 2 0 .0 2 5 0 .0 3 0 28 TABLE 20 THE IMPURITY COMPOSITION OF DEPOSIT IV-C OBTAINED FROM THE CHLORIDE TYPE SOLUTION (pH 2 .0 ) AT A CURRENT OF 0 .2 2 AMP./DM.2 OF CATHODE SURFACE E le m e n t C o n c e n t r a t i o n . P e r C e n t b y "W eight C u r r e n t D e n s i t y o f D e p o s i t S e c t i o n , amp ./dm .'2 0 .2 6 0 .1 3 0 .1 1 • Aluminum 0 .0 1 0 0 .0 1 0 0 .0 1 0 B o ro n 0 .0 0 3 0 0 .0 0 3 2 0 .0 0 3 2 Cadmium 0 .0 5 U 0 .0 5 I; 0 .0 6 1 C a lc iu m 0 .0 0 2 9 0 .0 0 2 £ 0 .0 0 2 7 C o b a lt 0 .2 9 0 .1 5 0 .1 3 C o p p er' 0 .3 9 0 .it9 0 .5 8 Iro n 0 .0 ^ 0 o .o U3 0.031; L ead 0 .0 7 U 0 .0 7 7 0 .0 8 1 ; M agnesium 0 .0010 0 .0 0 1 1 0 .0 0 1 1 M anganese 0 .0 0 2 1 0 .0 0 2 3 0 .0 0 2 3 S ilic o n 0 .0 1 1 0 .0 3 U 0 .0 U2 Z in c 0 .0 2 2 0 .0 2 0 0 .0 2 0 29 I n F i g u r e s U t h r o u g h 15 t h i s c o n c e n t r a t i o n r a t i o v e r s u s c u r r e n t d e n s i t y i s p l o t t e d l o g a r i t h m i c a l l y f o r t h e tw e lv e m e ta l I m p u r i t i e s an d th e f o u r b a t h s . B la c k d e p o s i t s a r e r e p r e s e n t e d i n t h e s e f i g u r e s b y s o l i d b l a c k p o i n t s w hose c u r v e s a r e n o t c o n n e c te d t o t h e r e g u l a r d e p o s i t c u rv e s. The t r e n d s fo u n d from c a l c u l a t i o n s o f i m p u r ity d e p o s i t i o n r a t e s a n d r e l a t i v e e n e r g y e f f i c i e n c i e s f o r im p u r i t y d e p o s i t i o n s a r e p r e s e n t e d in th e d is c u s s io n s e c tio n . ( DEPOSIT-SOLUTION CONCENTRATION RATIO 2.0 1.0 0.50 0.10 0 .0 5 0 0.010 0.10 FIG. 4 . 0.50 1.0 5;o CURRENT DENSITY, AMP. PER S O . DM. CONCENTRATION DISTRIBUTION OF ALUMINUM. ( I), C HLORIDE; (2 ), W A T T S LOW P H , (3), ORGANIC; AND (4), W A TTS HIGH PH TYPE B A T H . DEPOSIT- SOLUTION CONCENTRATION RATIO 0.050 0.010 00050- 0.01 QOOOd 0.10 FIG. 5 . 0 .5 0 1.0 10. 5.0 CURRENT OENSITY, AMP. PER SQ. DM. CONCENTRATION DISTRIBUTION OF BORON. ( I ) , CHLORIDE; (fc), W A T T S LOW PH ; (3), ORGANIC, AND (4), W A TTS HIGH PH TYPE B A T H . RATIO CONCENTRATION -SOLUTION 5 .0 i- c?) . O *O £ 0 ,8 0 0.10 C U R RE N T FIG. S. 0 .5 0 DENSITY, 1.0 AMR PER SQ . 5 .0 DM. CONCENTRATION DIE TR 3 J T I 0 N OF CADMIUM. ( I) , CH LO RID Ei (2), W A T T S LOW P H ; ( 3 ) , O RG A N IC; AND ( 4 ), W A T T S HIGH PH TY PE B A T H . 10 1.0 DEPOSIT-SOLUTION CONCENTRATION RATIC 0 .5 0 0.10 0 .0 5 0 - 0.010 00050 0 .5 0 C U R REN T FIG. 7 . D E N S ITY , ID i.O AMR .-E R i K DM. CONCENTRATION DISTRBUT.ON OF CA l C iCM. (I), CHLORIDE} (25, WATTS LOW PH4 13), ORGANIC; AND (4), WATTS HIGH PH TYPE BATH. RA f CONCENTRATION DEPOSIT-SOLUTtON 1.0 0 .5 0 0.10 0.10 CURRENT FIG. 8 . CONCENTRATION 0 .5 0 DENSITY, 10 1.0 AMR PER DISTRIBUTION OF SQ. COBALT. (I), CHLORIDE, ( 2 ) , WATTS LOW P H , (3), ORGANIC , AND ( 4 ) , WATTS HIGH PH T Y P E BATH. DEPOSIT-SOLUTION ONCENTRATION RATIO 100 DEPOSIT-SOLUTION CONCENTRATION RATIO 400 5.0 0 .5 0 0 .4 0 0.10 CURRENT FIG. 10. CONCENTRATION O' vD DENSITY, SQ. DISTRIBUTION (I), CHLORIDE , ( 2 ) , WATTS AND ( 4 ), WATTS HIGH PH OF DM. IRON. LOW PH j (3), ORGANIC; TYPE BAT H. 50 50 1.0 0 .5 0 0.10 CURRENT FIG. II. 0 .5 0 DENSITY, 1.0 AMP PER 5 .0 SO. DM. 10 CONCENTRATION DISTRIBUTION OF LEAD. (I), CHLORIDE, ( 2 ) , WATTS LOW PH , ( 3 ) , ORGANIC, AND (4 ), WATTS HIGH PH TYPE BATH. 0.15 0.10 DEPOSIT-SOLUTION o tc o. 0.050 (0.010 a io CURRENT FIG. 12. 0 .5 0 DENSITY, t.o AMf? PER SQ. 5.0 DM. CONCENTRATION DISTRIBUTION OF MAGNESIUM. (I), CHLORIDE, (2 ), WATTS LOW PH , (3), ORGANIC, &ND (4 ), WATTS HIGH PH TYPE BATH. 10 t.o o §CE 11 0 ,5 0 8 1 010 g 0 .0 5 0 5o 0.010 0.10 CURRENT FIG. 13. 0 .5 0 DENSITY, 1.0 AMP. PE R 5 .0 SO . DM. CONCENTRATION DISTRIBUTION OF MANGANESE. (I), CHLORIDEj (2 ) , WATTS LOW PH* (3), ORGANIC, AND (4), WATTS HIGH PH TYPE BATH. 10 2.51 £u 0 .5 0 0.10 0.10 CURRENT FIG. 14. 0 .5 0 DENSITY, 10 1.0 AMP PER SQ. DM. CONCENTRATION DISTRIBUTION OF SILICON. (I), CHLORIDE, (2 ), WATTS LOW PH , (3 ), ORGANIC, AND (4), WATTS "HIGH PH TYPE BATH. DEPOSIT-SOLUTION CONCENTRATION RATIO 5 .0 0 .5 0 0.10 CURRENT FIG. 15. 0 .50 DENSITY, 1.0 AMR PER 5.0 SQ. DM. CONCENTRATION DISTRIBUTION OF ZINC. (I), CHLORIDE * (2), WATTS LOW PH •, (3 ), ORGANIC, AND (4 ),WATTS HIGH PH TYPE BATH. 10 30 DISCUSSION The i m p u r i t i e s p r e s e n t i n t h e s o l u t i o n a f f e c t e d t h e c a th o d ic c u r r e n t e f f i c i e n c i e s t o s u c h a n e x t e n t t h a t t h e r e w as a r e v e r s a l o f t h e g e n e r a l t r e n d , w h ich i s t h a t a n i n c r e a s e i n e f f i c i e n c y o c c u r s when t h e pH i s i n c r e a s e d ( 1 , 7 ) . The p r e s e n c e o f t h e t e n m illig r a m s o f t r i - v a l e n t chrom ium p e r l i t e r o f s o l u t i o n i n c o m b in a tio n w i t h t h e o t h e r i m p u r i t i e s p r e s e n t i n t h e h ig h pH W a tts ty p e s o l u t i o n d e c r e a s e d th e e f f i c i e n c y e v e n m o re . A s s o c ia t e d w i t h t h e low c u r r e n t e f f i c i e n c i e s o b ta in e d i n t h e h ig h pH s o l u t i o n s , t h e r e w as v i s i b l e g a s s i n g d u r in g d e p o s i t i o n a t t h e h ig h e r c u r r e n t d e n s i t i e s ; g a s s i n g s t a r t e d a t a lo w e r c u r r e n t d e n s i t y i n th e h i g h e r pH b a t h . I n a g re e m e n t w ith t h e r e s u l t s o f o t h e r s ( 1 ,7 ) a d e c r e a s e i n c u r r e n t d e n s i t y r e s u l t e d i n a d e c r e a s e i n t h e c a t h o d ic c u r r e n t e f f i c i e n c y . The f o r m a tio n o f t h e p r e c i p i t a t e o c c u r r e d o n ly d u r in g e l e c t r o l y s i s i n t h e two h i g h e s t pH s o l u t i o n s and a lw ay s a p p e a re d f i r s t a t th e c a th o d e s u r f a c e ,o h o h b o f t h e p r e b i p i t a t e w as e v e r fo u n d i n s i d e t h e anode b a g . I n t h e e l e c t r o l y s e s o f t h e s e tw o s o l u t i o n s i t w as n e c e s s a r y t o add a c i d c o n ti n u o u s l y i n o r d e r t o m a i n t a i n t h e pH c o n s t a n t , and t h e c a th o d ic c u r r e n t e f f i c i e n c y w as lo w e r th a n t h a t o f t h e o t h e r s o l u t i o n s . I t has b e e n n o te d ( 1 ,2 7 ) t h a t a h i g h e r pH e x i s t s i n t h e c a th o d e l a y e r th a n i n t h e s o l u t i o n p r o p e r , e s p e c i a l l y when t h e c a th o d ic c u r r e n t e f f i c i e n c y i s 31 l e s s t h a n o n e h u n d re d p e r c e n t . A f t e r c a l c u l a t i n g t h e r a t i o o f th e p r e c i p i t a t e c o n c e n t r a t i o n to t h e s o l u t i o n c o n c e n t r a t i o n f o r t h e v a r i o u s m e t a l i m p u r i t i e s , t h e i m p u r i t i e s w e re a r r a n g e d a c c o r d in g t o t h e i r o r d e r o f d e c r e a s i n g r a t i o v a l u e ; n a m e ly , i r o n , c o p p e r , s i l i c o n , alum inum , c a lc iu m , l e a d , z i n c , cadm ium , m a n g a n e se , m ag n esiu m , b o r o n , an d c o b a l t . W ie s n e r ( 2 8 ) h a s fo u n d t h a t t h e o r d e r o f i n c r e a s i n g s o l u b i l i t y a t h i g h e r pH v a lu e s i n a b o r i c a c i d - b u f f e r e d , c o n c e n tr a te d s o l u t i o n o f n i c k e l s u l ­ f a t e i s a s fo llo w s * t r i - v a l e n t i r o n , and alum inum ; b i - v a l e n t c o p p e r , z i n c , i r o n , cadm ium , a n d n i c k e l . A c o m p a ris o n o f t h e two o r d e r s shows t h a t e x c e p t f o r t h e r e v e r s a l o f t h e o r d e r o f c o p p e r an d alu m in u m , t h e e le m e n ts common to b o th a p p e a r i n t h e same o r d e r . A c o rre la tio n o f th is i n f o r m a ti o n w o u ld i n d i c a t e t h a t t h e pH o f t h e l a y e r o f s o l u t i o n a d j a c e n t t o t h e c a th o d e i s s u f f i c i e n t l y h i g h e r t h a n t h e b o d y o f t h e s o l u t i o n t o c a u s e t h e f o r m a tio n o f t h e p r e c i p i t a t e . The i s o - c u r r e n t d e n s i t y c u rv e s f o r i n c l i n e d c a th o d e s a s shown i n F i g u r e s 1 , 2 , a n d 3 w ere o b t a i n e d from c a l c u l a t i o n s b a s e d on t h e v a lu e o f t h e F a r a d a y ( 2 9 ) , t h e d e n s i t y o f e l e c t r o d e p o s ite d n i c k e l ( 7 ) , d e p o s itio n tim e , and d e p o s it th ic k n e s s . The c u rv e s i l l u s t r a t e how , i n g e n e r a l , t h e c u r r e n t d e n s i t y 1 i l e s s i n th o s e p o r t i o n s o f t h e c a th o d e w h ic h a r e m ore d i s t a n t from t h e a n o d e . The c u rv e s a l s o i l l u s t r a t e how t h e c u r r e n t d e n s i t y i n c r e a s e s to w a rd s t h e ed g es an d e s p e c i a l l y to w a rd t h e c o r n e r s , t h e a d j a c e n t c e n t r a l p o r t i o n o f th e p l a t e , w hich may be c l o s e r t o t h e anode^ h a v in g a lo w e r v a l u e . S e v e r a l i n v e s t i g a t o r s ( 1 2 ,1 5 ,1 6 ) h av e fo u n d t h a t a l i n e a r r e l a t i o n ­ s h i p e x i s t s b e tw ee n t h e d e p o s i t an d s o l u t i o n c o n c e n t r a t i o n s f o r c o b a l t , 32 c o p p e r, i r o n , and z in c . T hus a r a t i o o f t h e d e p o s i t an d t h e s o l u t i o n c o n c e n t r a t i o n f o r a n i m p u r i t y i s a c o n s t a n t u n d e r a g iv e n s e t -of co n ­ d i t i o n s , a t l e a s t f o r t h o s e i m p u r i t i e s j u s t m e n tio n e d . A lth o u g h a l i n e a r r e l a t i o n s h i p may n o t e x i s t b e tw e e n t h e d e p o s i t and s o l u t i o n co n ­ c e n t r a t i o n s f o r some o f t h e o t h e r i m p u r i t i e s , t h e d e p o s i t - s o l u t i o n c o n c e n t r a t i o n r a t i o f u r n i s h e s a c o n v e n ie n t m eans o f c o r r e l a t i n g and c o m p a rin g t h e d i f f e r e n c e s i n i m p u r i t y d e p o s i t i o n s fo u n d i n t h e v a r i o u s c u r r e n t d e n s ity re g io n s and s o l u t io n s . The c o n c e n t r a t i o n r a t i o s w ere p l o t t e d l o g a r i t h m i c a l l y t o b e t t e r i l l u s t r a t e t h e d i f f e r e n c e s fo u n d i n d i f f e r e n t s o l u t i o n s a n d c u r r e n t d e n s i t y r e g i o n s o v e r th e w id e r a n g e o f r a t i o v a lu e s i n v o l v e d . The c u r r e n t d e n s i t i e s w ere p l o t t e d l o g a r i t h m i c a l l y b e ca u se i t h a s b een e s ta b lis h e d ( 30) t h a t th e r e i s l i n e a r r e la tio n s h ip b e tw e e n c a th o d e p o t e n t i a l a n d t h e l o g a r i t h m o f t h e c u r r e n t d e n s i t y o v e r a ra n g e o f c u r r e n t d e n s i t i e s . Some o f t h e r e s u l t s d e n o te d b y F i g u r e s h th r o u g h 15 w i l l be p r e ­ s e n t e d i n a d e f i n i t e o r d e r t o f a c i l i t a t e c o m p a ris o n s an d re d u c e u n n e c e s ­ s a r y r e p e t i t i o n , a s fo llo w s * E le m e n t a. The g e n e r a l c o n c e n t r a t i o n ra n g e fo u n d i n t h e n i c k e l d e p o s i t s a s com pared t o t h e s o l u t i o n c o n c e n t r a t i o n o f a n i m p u r i t y . b. The e f f e c t o f pH o n t h e d e p o s i t - s o l u t i o n c o n c e n t r a t i o n r a t i o o f a n i m p u r i t y a t lo w , m o d e r a te , an d h ig h c u r r e n t d e n s i t i e s . The a p p a r ­ e n t pH o r d e r assu m ed b y t h e o r g a n ic o r c h l o r i d e ty p e s o l u t i o n s a s r e l a t e d t o t h e two W a tts ty p e s o l u t i o n s due t o t h e p r e s e n c e o f t h e o r g a n ic c o n s t i t u e n t s o r t h e h ig h c h l o r i d e c o n c e n t r a t i o n . 33 c. The e f f e c t on t h e c o n c e n t r a t i o n r a t i o due t o t h e h ig h c h l o r i d e c o n c e n t r a t i o n , o r p r e s e n c e o f o r g a n ic c o n s t i t u e n t s , a s d i f f e r e n t i a t e d fro m pH a n d c u r r e n t d e n s i t y e f f e c t s a s e v id e n c e d b y t h e W a tts ty p e s o l u ­ tio n s . d. The e x i s t e n c e o f a maximum o r minimum r a t i o , and w h e th e r o r n o t t h e r e i s a n i n t e r - r e l a t i o n s h i p among ( l ) th e c u r r e n t d e n s i t y l o c a t i o n o f t h e maxima o r m in im a, ( 2 ) pH , and ( 3 ) t h e m a g n itu d e o f t h e maxima o r m inim a r a t i o v a l u e s . e. The n u m e r ic a l l o c a t i o n o f t h e im p u r ity a c c o r d in g to t h e i n c r e a s ­ i n g o r d e r o f d e p o s i t - s o l u t i o n c o n c e n t r a t i o n r a t i o v a lu e s o f t h e im p u r i­ t i e s a t v a r i o u s c u r r e n t d e n s i t i e s i n th e f o u r s o l u t i o n s . 1. A lum inum . a. The d e p o s i t c o n c e n t r a t i o n v a r i e d from a b o u t o n e - f o u r t h t o n e a r l y tw ic e t h e s o l u t i o n c o n e e n t r a t i o n j t h e lo w e s t r a t i o w as o b t a i n e d from t h e lo w pH W a tts ty p e s o l u t i o n , t h e h i g h e s t from t h e low c u r r e n t d e n s i t y r e g i o n o f t h e o r g a n ic ty p e s o l u t i o n . I n g e n e r a l t h e r a t i o s w ere n e a r l y c o n s t a n t f o r t h e r e s p e c t i v e s o l u t i o n s , i n c r e a s i n g s l i g h t l y a t h ig h c u r ­ re n t d e n s itie s . b. The c o n c e n t r a t i o n r a t i o s i n c r e a s e d w ith an i n c r e a s e i n pH a t a.11 c u r r e n t d e n s i t i e s . The c h l o r i d e ty p e s o l u t i o n r a t i o s b e h av e d a s th o u g h t h e pH w e re b e tw e e n t h a t o f t h e low pH W a tts and th e o r g a n ic ty p e s o l u t i o n s a t low c u r r e n t d e n s i t i e s , an d b e tw e e n t h e o r g a n ic and t h e h ig h pH W a tts ty p e s o l u t i o n s a t h i g h e r c u r r e n t d e n s i t i e s . 3k jT c. The r a t i o s o f t h e o r g a n ic ty p e s o l u t i o n i n c r e a s e d m a rk e d ly w i t h a d e c r e a s e i n c u r r e n t d e n s i t y a t low c u r r e n t d e n s i t i e s a s com pared t o t h e n e a r l y c o n s t a n t r a t i o s fo u n d w i t h t h e o t h e r s o l u t i o n s . d. A minimum r a t i o o c c u r r e d f o r t h e o r g a n ic an d t h e h ig h pH W a tts ty p e s o lu tio n s . The h ig h e r minimum r a t i o o c c u r r e d a t th e h ig h e r pH and a t a lo w e r c u r r e n t d e n s i t y . e. A c c o rd in g t o t h e i n c r e a s i n g o r d e r o f d e p o s i t - s o l u t i o n c o n c e n ­ t r a t i o n r a t i o s o f t h e i m p u r i t i e s a t v a r io u s c u r r e n t d e n s i t i e s i n t h e f o u r s o l u t i o n s , alum inum r a t e d a f i f t h p o s i t i o n e x c e p t a t low c u r r e n t d e n s i t i e s a n d t h e h i g h e r c u r r e n t d e n s i t y r e g i o n o f t h e h ig h pH W a tts ty p e s o l u t i o n . A t low c u r r e n t d e n s i t i e s i t was i n s i x t h p o s i t i o n e x c e p t i n t h e b l a c k d e p o s i t o f t h e h ig h pH W a tts ty p e s o l u t i o n w here i t ra n k e d fo u rth . I n t h e h ig h pH W a tts ty p e s o l u t i o n i t o c c u p ie d t h e s i x t h p o s i t i o n a t c u r r e n t d e n s i t i e s o f tw o and f o u r a m p ./d m .^ , t h e t h i r d p o s i t i o n a t a c u r r e n t d e n s i t y o f e i g h t am p./dm . ^ 2. B o ro n . a. The c o n c e n t r a t i o n o f b o ro n i n t h e d e p o s i t s v a r i e d fro m f o u r t e n - t h o u s a n d t h s t o one o n e -h u n d re d th o f t h e s o l u t i o n c o n c e n t r a t i o n . The c o n c e n t r a t i o n r a t i o w h ic h was n e a r l y c o n s t a n t w ith i n c r e a s e d c u r r e n t d e n s i t y f o r t h e low pH W a tts ty p e s o l u t i o n , i n c r e a s e d w ith a n i n c r e a s e i n c u r r e n t d e n s i t y a t t h e h i g h e r c u r r e n t d e n s i t i e s , and i n c r e a s e d w ith d e c r e a s e d c u r r e n t d e n s i t y f o r t h e o r g a n ic and t h e h ig h pH W a tts ty p e s o l u t i o n s . a t lo w e r c u r r e n t d e n s i t i e s . b. W ith t h e c h l o r i d e t y p e b a th o c c u p y in g a n a p p a r e n t pH p o s i t i o n b e tw e e n t h e low pH W a tts and t h e o r g a n ic ty p e s o l u t i o n s , t h e c o n c e n t r a t i o n 35 r a t i o s i n c r e a s e d w i t h an i n c r e a s e i n pH, t h e d i f f e r e n c e s b etw een t h e v a lu e s b e in g more n o t i c e a b l e a t h ig h and low c u r r e n t d e n s i t i e s . A t low c u r r e n t d e n s i t i e s t h e o r g a n ic c o n s t i t u e n t s te n d e d to i n c r e a s e th e r a t i o . ^d. A minimum r a t i o was o b s e rv e d i n th e o r g a n ic and h ig h pH W a tts ty p e s o l u t i o n s ; th e h i g h e r minimum r a t i o o c c u r re d a t th e h ig h e r pH and a t a lo w e r c u r r e n t d e n s i t y . 8. B oron h ad t h e lo w e s t r a t i o o f a l l o f t h e i m p u r i t i e s e x c e p t i n t h e b l a c k d e p o s i t from t h e o r g a n ic ty p e s o l u t i o n w here i t had a r a n k o f fo u r. 3. Cadmium. a. The c o n c e n t r a t i o n r a t i o s o f cadmium d e c re a s e d from a v a lu e o f a b o u t s i x t o a v a lu e o f a b o u t one w ith a n i n c r e a s e i n c u r r e n t d e n s i t y . b. A t low c u r r e n t d e n s i t i e s t h e c o n c e n t r a t i o n r a t i o in c r e a s e d w i t h a d e c r e a s e i n pH; a t m o d era te c u r r e n t d e n s i t i e s , th e c h l o r i d e ty p e s o l u t i o n r a t i o s w ere s t i l l t h e h i g h e s t , w ith t h e o r g a n i c , th e h ig h pH W a t t s , and t h e low pH W a tts ty p e s o l u t i o n s h a v i n g ,r e s p e c t i v e l y , s m a lle r r a t i o s ; a t h ig h c u r r e n t d e n s i t i e s t h e r a t i o in c r e a s e d w ith a n i n c r e a s e i n pH , t h e c h l o r i d e ty p e s o l u t i o n o c c u p y in g an a p p a r e n t pH l o c a t i o n b e tw e e n t h e o r g a n ic and t h e h ig h pH W a tts ty p e s o l u t i o n s . c. The i n c r e a s e d c o n c e n tr a ti o n o f c h l o r i d e i n t h e s o l u t i o n f a v o r e d a h i g h e r r a t e o f d e p o s i t i o n o f cadmium. e. Cadmium had a ra n k w hich v a r i e d from n in e t o e le v e n , t h e ra n k b e in g g e n e r a l l y h ig h e r w ith a h ig h e r pH. 36 U. C alcium . a. The d e p o s i t c o n c e n t r a t i o n s o f c a lc iu m v a r i e d from a b o u t o n e - t e n t h t o s l i g h t l y m ore th a n t h e s o l u t i o n c o n c e n t r a t i o n s . The g e n e r a l t r e n d showed a c o n s t a n t r a t i o f o r m o st o f t h e c u r r e n t d e n s i t y ra n g e w ith a d e c id e d i n c r e a s e i n r a t i o w ith an i n c r e a s e i n c u r r e n t d e n s i t y a t h ig h c u r r e n t d e n s i t i e s . b. C o n s id e r in g o n ly th e W a tts ty p e s o l u t i o n s th e c o n c e n tr a ti o n r a t i o w as h i g h e r i n t h e h ig h e r pH s o l u t i o n . The a p p a r e n t pH p o s i t i o n o f t h e c h l o r i d e ty p e s o l u t i o n was b e tw ee n t h e two W a tts ty p e s o l u t i o n s , an d t h e a p p a r e n t pH l o c a t i o n o f t h e o r g a n ic ty p e s o l u t i o n was below t h a t o f t h e low pH W a tts ty p e s o l u t i o n . c. The h i g h e r c o n c e n t r a t i o n o f c h l o r i d e i n c r e a s e d th e c a lc iu m r a t i o , w h e re a s t h e p r e s e n c e o f th e o r g a n ic c o n s t i t u e n t s d e c r e a s e d i t . e. C alcium h ad a ra n k o f one and two i n t h e o r g a n ic and t h e h ig h pH W a tts ty p e b a th s when low c u r r e n t d e n s i t y , b la c k d e p o s i t s w ere o b ­ ta in e d . I t h ad a r a n k o f t h r e e f o r th e r e s t o f th e c u r r e n t d e n s i t i e s f o r t h e o r g a n ic s o l u t i o n , a r a n k o f s i x a t v e r y h ig h c u r r e n t d e n s i t i e s f o r t h e c h l o r i d e and t h e h ig h pH W a tts ty p e s o l u t i o n s , and a r a n k o f f o u r a t t h e o t h e r c u r r e n t d e n s i t i e s and f o r th e o th e r s o l u t i o n s . 5. C o b a lt. a. The c o n c e n t r a t i o n o f c o b a l t i n t h e d e p o s i t s v a r i e d from o n e - t h i r d t o t h i r t e e n tim e s itf^ s c o n c e n t r a t i o n i n t h e s o l u t i o n s , w ith a maximum o c c u r r i n g f o r a l l t h e s o l u t i o n s . b. A t low and m o d era te c u r r e n t d e n s i t i e s th e c o n c e n tr a ti o n r a t i o d e c r e a s e d w i t h a n i n c r e a s e i n pHj a t h ig h e r c u r r e n t d e n s i t i e s th e r a t i o s 37 f o r t h e c h l o r i d e s o l u t i o n w ere lo w e r t h a n t h o s e f o r t h e o t h e r s o l u t i o n s whose r a t i o s had p r a c t i c a l l y t h e same v a l u e . c. A h i g h e r c h l o r i d e c o n c e n t r a t i o n te n d e d t o d e c r e a s e th e co n cen ­ tr a tio n r a t i o fo r c o b a lt. d. F o r t h e s o l u t i o n s o t h e r t h a n t h e c h l o r i d e t y p e , a s t h e pH d e ­ c r e a s e d t h e maximum c o n c e n t r a t i o n r a t i o v a lu e i n c r e a s e d and th e c u r r e n t d e n s i t y l o c a t i o n o f t h e maximum d e c r e a s e d . The maximum f o r th e c h l o r i d e ty p e s o l u t i o n h a d a lo w e r v a lu e and was l o c a t e d a t a h ig h e r c u r r e n t d e n s i t y t h a n t h e maximum f o r a n y o f t h e o t h e r s o l u t i o n s . e. C o b a lt had a r a n k o f f i v e a t v e ry low c u r r e n t d e n s i t i e s f o r t h e c h l o r i d e s o l u t i o n ; t h e r a n k i n c r e a s e d w ith an i n c r e a s e o f c u r r e n t d e n s i t y u p t o tw e lv e a t two am p ./d m .^ I t had t h e h ig h e s t c o n c e n tr a ti o n r a t i o ( r a n k o f tw e lv e ) o f any o f t h e i m p u r i t i e s a t a l l c u r r e n t d e n s i t i e s i n t h e lo w pH W a tts ty p e s o l u t i o n . F o r t h e o r g a n ic ty p e s o l u t i o n th e r a n k i n c r e a s e d r a p i d l y from se v e n i n th e low c u r r e n t d e n s i t y , b la c k d e p o s i t t o tw e lv e a t two a m p . / d m a n d th e n d e c r e a s e d t o e le v e n a t v e ry h ig h c u r r e n t d e n s i t i e s . I n th e h ig h pH W a tts ty p e s o l u t i o n t h e ra n k o f c o b a l t i n c r e a s e d r a p i d l y w ith i n c r e a s i n g c u r r e n t d e n s i t y from se v en i n t h e low c u r r e n t d e n s i t y b la c k d e p o s i t t o e le v e n . 6. C o p p e r. a. The c o p p e r c o n c e n tr a ti o n s i n t h e d e p o s i t s v a r i e d from a b o u t o n e - h a l f t o o v e r s i x tim e s t h e s o l u t i o n c o n c e n t r a t i o n s . In g e n e ra l, th e c o n c e n tra tio n r a t i o d e c re a se d a s th e c u rre n t d e n s ity in c re a s e d . b. s o lu tio n . The c o n c e n t r a t i o n r a t i o s w ere h ig h e r t h e h ig h e r t h e pH o f t h e The a p p a r e n t pH o f th e c h lo r i d e ty p e s o l u t i o n was h ig h e r 38 t h a n t h a t o f t h e o r g a n ic ty p e s o l u t i o n a t low an d m o d era te c u r r e n t d e n s i t i e s ; a t " h i g h c u r r e n t d e n s i t i e s t h e c h l o r i d e ty p e s o l u t i o n had th e lo w e s t r a t i o s i n a c c o rd a n c e w ith t h e g e n e r a l t r e n d w ith r e s p e c t to pH. c. The h i g h e r c h l o r i d e c o n c e n tr a ti o n i n c r e a s e d t h e r a t e o f c o p p e r d e p o s i t i o n a t low an d m o d e ra te c u r r e n t d e n s i t i e s . d. A minimum o c c u r r e d i n t h e h ig h pH W a tts ty p e s o l u t i o n r a t i o s i n t h e h ig h c u r r e n t d e n s i t y r e g i o n . e. The r a n k o f c o p p e r d e c re a s e d w ith i n c r e a s i n g c u r r e n t d e n s i t y a n d , a t v e r y h ig h c u r r e n t d e n s i t i e s , i t s r a n k i n c r e a s e d w ith a n i n c r e a s e i n pH. The r a n k d e c r e a s e d from tw e lv e a t v e ry low c u r r e n t d e n s i t i e s , from e le v e n i n t h e low pH W a tts ty p e s o l u t i o n , to s e v e n a t a c u r r e n t d e n s i t y o f a b o u t f o u r amp ./d m .2 A t a c u rre n t d e n s ity o f abo ut e ig h t amp ./d m .2 i t s r a n k in c r e a s e d w ith an i n c r e a s e i n pH from a v a lu e o f f o u r i n th e c h l o r i d e ty p e s o l u t i o n t o e i g h t i n th e h ig h pH W a tts ty p e s o lu tio n . 7. Iro n . a. The d e p o s i t c o n c e n tr a ti o n s o f i r o n v a r i e d from a b o u t o n e - h a l f t o o v e r t h r e e h u n d re d tim e s t h e s o l u t i o n c o n c e n t r a t i o n s . The t h r e e h i g h e s t pH s o l u t i o n s had a minimum, th e two lo w e s t a maximum c o n c e n tr a ­ tio n r a t i o . b. A t low and a t h ig h c u r r e n t d e n s i t i e s th e r a t i o i n c r e a s e d w ith a n i n c r e a s e i n pH; a t a c u r r e n t d e n s i t y o f a p p ro x im a te ly t h r e e - f o u r t h s o f a n am p./dm . 2 t h i s r e l a t i o n s h i p was r e v e r s e d w ith t h e e x c e p tio n t h a t t h e r a t i o s f o r t h e c h l o r i d e ty p e s o l u t i o n w ere lo w e r a t a l l c u r r e n t d e n s itie s . 39 c. The h ig h c h l o r i d e c o n c e n t r a t i o n te n d e d t o d e c r e a s e t h e r a t e o f iro n d e p o s itio n . A t low c u r r e n t d e n s i t i e s t h e o r g a n ic c o n s t i t u e n t s seem ed t o en h an ce t h e d e p o s i t i o n r a t e . d. The maximum c o n c e n t r a t i o n r a t i o was a t a h ig h e r c u r r e n t d e n s i t y an d h ad a lo w e r r a t i o v a lu e f o r t h e lo w e r pH s o l u t i o n , th e c h l o r i d e ty p e s o l u t i o n , t h a n t h a t o f t h e low pH W a tts ty p e s o l u t i o n . The minimum r a t i o v a lu e s i n c r e a s e d w i t h th e pH o f t h e s o l u t i o n an d d e c r e a s e d w ith an i n c r e a s e d c u r r e n t d e n s i t y l o c a t i o n . e. I n g e n e r a l , i r o n ' s r a n k , w h ich v a r i e d from se v e n a t a v e r y low c u r r e n t d e n s i t y i n t h e c li l o r i d e ty p e s o l u t i o n t o tw e lv e a t h ig h c u r r e n t d e n s i t i e s i n t h e h i g h pH W a tts ty p e s o l u t i o n , i n c r e a s e d w i t h a n i n c r e a s e i n pH . The c u r r e n t d e n s i t y l o c a t i o n o f t h e h i g h e s t r a n k f o r a p a r t i c u ­ l a r s o l u t i o n was h i g h e r t h e h i g h e r t h e pH o f t h e s o l u t i o n . I r o n 's r a n k f o r t h e c h l o r i d e ty p e s o l u t i o n i n c r e a s e d r a p i d l y from s e v e n t o e le v e n w ith a s m a ll i n c r e a s e i n c u r r e n t d e n s i t y , an d t h e n d e c r e a s e d w ith c o n ­ t i n u e d i n c r e a s e i n c u r r e n t d e n s i t y u n t i l a r a n k o f e i g h t was r e a c h e d . I n t h e lo w pH W a tts ty p e s o l u t i o n i r o n 's r a n k i n c r e a s e d r a p i d l y from n in e t o e le v e n w i t h a n i n c r e a s e i n c u r r e n t d e n s i t y . As t h e c u r r e n t d e n s i t y i n c r e a s e d i n t h e o r g a n ic ty p e s o l u t i o n th e ra n k in c r e a s e d r a p i d l y from a b l a c k d e p o s i t r a n k o f n in e t o a ra n k o f t w e lv e , t h e n d e c r e a s e d t o e le v e n u n t i l v e ry h ig h c u r r e n t d e n s i t i e s w ere re a c h e d w hen i t s r a n k c h an g ed b a c k t o tw e lv e a g a i n . W ith in c r e a s e d c u r r e n t d e n s i t y i n t h e h ig h pH W a tts ty p e s o l u t i o n t h e ra n k o f i r o n i n c r e a s e d from t e n i n t h e low c u r r e n t d e n s i t y , b l a c k d e p o s i t r e g i o n t o tw e lv e a t h ig h e r c u rre n t d e n s itie s . ko 8. L ead. a. The c o n c e n t r a t i o n r a t i o s f o r l e a d d e c re a s e d a s th e c u r r e n t d e n s i t y i n c r e a s e d ; t h e d e p o s i t 's c o n c e n tr a ti o n v a r ie d from one to t h r e e tim e s t h e s o l u t i o n c o n c e n t r a t i o n . b. I n g e n e r a l , t h e c o n c e n t r a t i o n r a t i o was h ig h e r th e h ig h e r th e pH o f t h e s o l u t i o n ; t h e c h l o r i d e ty p e s o l u t i o n had a n a p p a r e n t pH v a lu e b e tw e e n th e v a lu e s o f t h e low pH W a tts and th e o r g a n ic ty p e s o l u ­ t i o n s i n t h e low and medium c u r r e n t d e n s i t y r e g i o n s , and b e tw ee n th o s e o f t h e o r g a n ic an d t h e h ig h pH W a tts ty p e s o l u t i o n s a t h ig h c u r r e n t d e n s itie s . c. The h ig h e r c h l o r i d e c o n c e n t r a t i o n and t h e p re s e n c e o f th e o r g a n ic c o n s t i t u e n t s te n d e d t o i n c r e a s e t h e r a t e o f d e p o s i t i o n o f l e a d . a. I n g e n e r a l l e a d 's r a n k h a d a minimum v a lu e o f e i g h t a t m o d era te l y low c u r r e n t d e n s i t i e s , th e r a t i n g in c r e a s e d from t h i s v a lu e w ith e i t h e r a n i n c r e a s e o r a d e c re a s e i n c u r r e n t d e n s i t y , e x c e p t i n t h e low pH W a tts ty p e s o l u t i o n w here i t re m a in e d c o n s t a n t w ith a d e c r e a s e i n c u rre n t d e n s ity . L ead h ad a maximum ra n k o f e le v e n a t a v e ry h ig h c u r ­ r e n t d e n s i t y i n t h e c h l o r i d e ty p e s o l u t i o n and a t a v e ry low c u r r e n t d e n s i t y i n t h e two h i g h e s t pH s o l u t i o n s . 9. M agnesium . a. The c o n c e n t r a t i o n o f magnesium i n t h e d e p o s i ts v a r i e d from o n e - t o f o u r t e e n - h u n d r e d t h s o f i t s c o n c e n tr a ti o n i n s o l u t i o n . The r a t i o s w ere n e a r l y c o n s t a n t a t low an d m o d erate c u r r e n t d e n s i t i e s , b u t te n d e d t o i n c r e a s e w ith a n i n c r e a s e i n c u r r e n t d e n s i t y , th e r a t e o f i n c r e a s e b e in g g r e a t e r , t h e h ig h e r th e pH . ia b. The c o n c e n t r a t i o n r a t i o s i n c r e a s e d w ith an i n c r e a s e i n pHj th e c h l o r i d e ty p e s o l u t i o n h a d a n a p p a r e n t pH l o c a t e d betw een th o s e o f th e o r g a n i c an d t h e h ig h pH W a tts ty p e s o l u t i o n s . c. The h ig h c h l o r i d e c o n c e n t r a t i o n f a v o r e d a m ore r a p i d d e p o s i t i o n r a t e f o r m agnesium . e . M agnesium had a r a n k o f two a t a l l c u r r e n t d e n s i t i e s and f o r a l l s o l u t i o n s e x c e p t f o r a r a n k o f t h r e e i n t h e h ig h pH W a tts ty p e s o l u ­ t i o n a t v e r y low c u r r e n t d e n s i t i e s w here a b l a c k d e p o s i t w as o b t a i n e d . 10. M an g an ese. a. The c o n c e n t r a t i o n o f m anganese i n th e d e p o s i t v a r i e d from t h r e e - to s ix ty -h u n d re d th s o f i t s ; s o lu tio n c o n c e n tr a tio n . The r a t i o s w ere p r a c t i c a l l y c o n s t a n t i n t h e low and m o d e ra te c u r r e n t d e n s i t y r e g io n s i n t h e h ig h c u r r e n t d e n s i t y r e g i o n t h e r a t i o in c r e a s e d w ith a n i n c r e a s e i n c u r r e n t d e n s i t y , t h e r a t e o f i n c r e a s e w as g r e a t e r t h e h ig h e r t h e pH o f th e s o lu tio n . b. The h ig h pH W a tts ty p e s o l u t i o n had h i g h e r c o n c e n t r a t i o n r a t i o s t h a n t h e low pH W a tts ty p e s o l u t i o n . c. A t low an d m o d e ra te c u r r e n t d e n s i t i e s t h e o r g a n ic c o n s t i t u e n t s i n c r e a s e d t h e r a t e o f d e p o s i t i o n o f m anganese s u f f i c i e n t l y to g iv e t h e s o l u t i o n an a p p a r e n t pH h i g h e r th a n t h a t o f th e h ig h pH W a tts ty p e s o l u ­ tio n . The h i g h c h l o r i d e c o n c e n t r a t i o n im proved t h e d e p o s i t i o n r a t e o f m anganese, s u f f i c i e n t l y t o y i e l d h ig h e r r a t i o s th a n t h o s e fo u n d f o r th e low pH W a tts ty p e s o l u t i o n . e. The r a n k o f m anganese w h ic h v a r i e d from t h r e e t o f i v e was t h r e e i n t h e two lo w e s t pH s o l u t i o n s . I n t h e o r g a n ic ty p e s o l u t i o n t h e ra n k k2 i n c r e a s e d fro m t h r e e a t v e ry low c u r r e n t d e n s i t i e s t o f o u r a t h ig h e r c u rre n t d e n s itie s . I t s r a n k w as t h r e e e x c e p t a t v e ry h ig h and v e ry low c u r r e n t d e n s i t i e s i n t h e h ig h pH W a tts ty p e s o l u t i o n w here i t s ra n k was fiv e . T h u s , a t v e ry low and v e ry h ig h c u r r e n t d e n s i t i e s , m a n g a n e s e 's r a n k i n c r e a s e d w ith a n i n c r e a s e i n pHj a t c u r r e n t d e n s i t i e s i n th e r e g i o n b e tw e e n , i t s r a n k w as t h r e e e x c e p t f o r t h e o r g a n ic ty p e s o l u t i o n w here i t s r a n k w as f o u r . 11. S ilic o n . a. The c o n c e n t r a t i o n o f s i l i c o n i n t h e d e p o s i t s v a r i e d from tw o - t e n t h s t o tw ic e i t s s o l u t i o n c o n c e n t r a t i o n . The r a t i o s i n c r e a s e d w ith a n i n c r e a s e i n c u r r e n t d e n s i t y f o r t h e W a tts ty p e s o l u t i o n s . The c h l o r i d e an d t h e o r g a n ic ty p e s o l u t i o n r a t i o s d e c r e a s e d w ith an i n c r e a s e i n c u r r e n t d e n s i t y up t o one a m p ./d m .2 ; above t h i s c u r r e n t d e n s i t y th e c h l o r i d e ty p e s o l u t i o n 's r a t i o s c o n tin u e d t o d e c r e a s e s l i g h t l y , w h ile t h e o r g a n ic ty p e s o l u t i o n 's r a t i o s i n c r e a s e d w ith i n c r e a s e d c u r r e n t d e n s­ ity . b. An i n c r e a s e i n pH y i e l d e d a h ig h e r c o n c e n tr a ti o n r a t i o f o r t h e W a tts t y p e s o l u t i o n s . The a p p a r e n t pH o r d e r p la c e d t h e o r g a n ic ty p e s o l u t i o n t h e h i g h e s t , t h e c h l o r i d e ty p e s o l u t i o n n e x t fo llo w e d b y t h e h ig h pH an d th e n t h e low pH W a tts ty p e s o l u t i o n s . c. The h ig h c h l o r i d e c o n c e n t r a t i o n and th e o r g a n ic c o n s t i t u e n t s i n c r e a s e d t h e r e l a t i v e am ounts o f s i l i c o n i n th e d e p o s i t s , e s p e c i a l l y a t lo w e r c u r r e n t d e n s i t i e s . d. The o r g a n ic ty p e s o l u t i o n had a minimum c o n c e n tr a ti o n r a t i o a t m o d e ra te c u r r e n t d e n s i t i e s . h3 ®» S i l i c o n * s r a n k w as s i x i n t h e m edium c u r r e n t d e n s i t y r e g i o n s e x c e p t i n t h e h ig h pH W a tts t y p e s o l u t i o n w h e re i t had a r a n k o f f i v e i n t h e m o d e r a te a n d h i g h c u r r e n t d e n s i t y r e g i o n s . I t h ad a low r a n k o f f o u r a t v e r y h i g h c u r r e n t d e n s i t i e s i n t h e h ig h pH W a tts ty p e s o l u ­ t i o n a n d i t h a d a h i g h r a n k o f n i n e a t a v e r y lo w c u r r e n t d e n s i t y i n t h e c h lo r id e ty p e s o l u t i o n . 1 2 . Z in c . a. T he c o n c e n t r a t i o n o f z in c i n t h e d e p o s i t v a r i e d from t h r e e - f o u r t h s t o tw i c e i t s s o lu tio n c o n c e n tra tio n . The c o n c e n t r a t i o n r a t i o s w e re c o n s t a n t o r te n d e d to w a rd a maximum i n t h e low c u r r e n t d e n s i t y r e g i o n s ; h o w e v er t h e r a t i o s d e c r e a s e d w i t h i n c r e a s e d c u r r e n t d e n s i t y i n m o d e ra te a n d h i g h c u r r e n t d e n s i t y r e g i o n s . b. E x c lu d in g t h e c h l o r i d e ty p e s o l u t i o n , t h e r a t i o s i n c r e a s e d w ith a n i n c r e a s e i n pH . The a p p a r e n t pH l o c a t i o n o f t h e c h l o r i d e ty p e s o l u ­ t i o n r a t i o s v a r i e d fro m t h e l o w e s t pH l o c a t i o n a t v e r y lo w c u r r e n t d e n s i t i e s t o a l o c a t i o n b e tw e e n t h e low pH W a tts ty p e s o l u t i o n an d t h e o r g a n i c t y p e s o l u t i o n a t low a n d m o d e ra te c u r r e n t d e n s i t i e s . A t h ig h c u r r e n t d e n s i t i e s i t s r a t i o s w e re b e tw e e n t h o s e o f t h e o r g a n ic a n d t h e h ig h pH W a tts t y p e s o l u t i o n s . c. T he h i g h c h l o r i d e c o n t e n t i n c r e a s e d t h e r a t e o f d e p o s i t i o n o f z in c a s th e c u r r e n t d e n s ity in c r e a s e d . *- * d. The z in c r a t i o h a d a maximum v a lu e i n t h e o r g a n i c and i n t h e c h l o r i d e ty p e s o l u t i o n ; t h e maximum v a lu e w as h i g h e r a n d t h e c u r r e n t d e n s i t y l o c a t i o n o f t h e maximum w as lo w e r i n t h e h i g h e r pH s o l u t i o n . kk e. Z in c had r a n k s o f s e v e n o r e i g h t a t a l l c u r r e n t d e n s i t i e s an d f o r a l l s o lu tio n s e x c e p t i n th e h ig h c u r r e n t d e n s ity r e g io n o f th e c h l o r i d e t y p e s o l u t i o n w h ere i t s r£ n k was n i n e . I n t h e h i g h pH W a tts t y p e s o l u t i o n t h e r e l a t i v e am ount o f a n im p u r­ i t y fo u n d i n t h e b l a c k d e p o s i t d e c r e a s e d w i t h i n c r e a s e d c u r r e n t d e n s i t y f o r a lu m in u m , i r o n , l e a d , m a n g a n e se , and s i l i c o n ; re m a in e d c o n s t a n t f o r c o p p e r , m ag n esiu m , a n d z i n c ; an d i n c r e a s e d f o r b o r o n , cadm ium , c a lc iu m , an d c o b a l t . C o p p e r , l e a d , b o r o n , cadm ium , and z in c w e re fo u n d i n l a r g e r r e l a t i v e am ounts i n t h e b l a c k d e p o s i t s t h a n i n t h e a d j a c e n t n o n - b la c k o r r e g u l a r d e p o s i t s • alu m in u m , c o b a l t , m ag n esiu m , m a n g a n e se , i r o n , a n d c a lc iu m w ere fo u n d i n s m a l l e r a m o u n ts. The o r d e r o f i m p u r i t i e s a r r a n g e d a c c o r d in g t o t h e i r i n c r e a s i n g d e p o s i t - s o l u t i o n c o n c e n t r a t i o n r a t i o v a lu e s i n t h e b l a c k d e p o s i t o b t a i n e d a t a c u r r e n t d e n s i t y o f 0 .1 1 am p ./d m . 2 from t h e h ig h pH W a tts ty p e s o l u ­ t i o n w as b o r o n , c a lc iu m , m agnesium , alu m in u m , m a n g a n e se , s i l i c o n , c o b a l t , z i n c , cadm ium , i r o n , l e a d , a n d c o p p e r ; f o r t h e b l a c k d e p o s i t o b t a i n e d a t a c u r r e n t d e n s i t y o f 0 .1 2 amp ./d m . 2 from t h e o r g a n i c ty p e s o l u t i o n t h e o r d e r w as c h an g e d so t h a t b o r o n f o llo w e d m a n g a n e se , alum inum f o llo w e d s i l i c o n , a n d cadmium f o llo w e d i r o n . The p e r c e n t c o n c e n t r a t i o n v a lu e s l i s t e d - i n T a b le s lU an d 17 f o r t h e b l a c k d e p o s i t s r e f e r t o t h e am ount o f i m p u r i t y d e p o s i te d p e r c o u lo m b ic e q u i v a l e n t o f one- h u n d re d gram s o f n i c k e l d e p o s i t . S in c e t h e am ount o f n i c k e l p r e s e n t i n t h e d e p o s i t w as c o n s i d e r a b l y lo w e r t h a n t h a t h$ i n t h e a d j a c e n t r e g u l a r d e p o s i t s , a c o m p a ris o n o f t h e o r d e r s o f t h e i m p u r i t i e s , a r r a n g e d a c c o r d i n g t o t h e i n c r e a s i n g d e p o s i t - s o l u t i o n co n ­ c e n t r a t i o n r a t i o v a l u e s , b e tw e e n a r e g u l a r d e p o s i t and a n a d j a c e n t b l a c k d e p o s i t s h o u ld show how t h e v a r i o u s i m p u r i t y d e p o s i t i o n s w ere a f f e c t e d b y t h e c o d e p o s i t i o n o f n i c k e l , a ssu m in g t h a t t h e d e p o s i t i o n p o t e n t i a l o f t h e i m p u r i t i e s w as e x c e e d e d i n t h e a d j a c e n t d e p o s i t s and t h a t t h e c h a n g e i n p o t e n t i a l e x i s t i n g a t t h e tim e o f d e p o s i t i o n b e tw ee n t h e tw o a r e a s w as n o t s u f f i c i e n t t o c a u s e a c h an g e i n t h e i r o r d e r . On t h i s b a s i s , we c a n s a y t h a t t h e r e l a t i v e am ount o f alu m in u m , c a lc iu m , c o b a l t , i r o n , a n d m anganese ( i n t h e o r g a n i c ty p e s o l u t i o n ) d e p o s i t i n g w as i n c r e a s e d b y t h e c o - d e p o s i t i o n o f n i c k e l . As h a s b e e n m e n tio n e d p r e v i o u s l y , t h e r e i s a l i n e a r r e l a t i o n s h i p b e tw e e n t h e d e p o s i t an d s o l u t i o n c o n c e n t r a t i o n s f o r s e v e r a l i m p u r i t i e s . From t h i s i t w ould seem t h a t t h e tim e r a t e o f change o f c o n c e n t r a t i o n o f a n i m p u r i t y i n s o l u t i o n due t o e l e c t r o d e p o s i t i o n s h o u ld be d i r e c t l y p ro p o r tio n a l to th e c o n c e n tra tio n . A lth o u g h no e l e c t r o d e p o s i t i o n r a t e s w ere c a r r i e d o u t a s su a h i n t h i s r e s e a r c h p r o j e c t , d a t a p u b l is h e d b y R o m in sk i (U) , C l a r k ( 5 ) , E w in g , B ro u w e r, C l a r k , Owen, R o m in s k i, and W e rn e r (3 2 ) w e re fo u n d t o c o n fo rm to t h i s c o n c e p t when th e i m p u r i t i e s had a s o l u t i o n c o n c e n t r a t i o n o f m ore t h a n t e n m il l ig r a m s p e r l i t e r . As a d e p o s i t i o n r a t e c o n s t a n t c o u ld b e e x p e c te d t o b e a d e f i n i t e v a lu e o n ly f o r a c e r t a i n s e t o f e l e c t r o d e p o s i t i o n c o n d i t i o n s , we w i l l d i s c u s s o n ly t h e g e n e r a l t r e n d s e s t a b l i s h e d b y o u r w ork r a t h e r t h a n s t a t e s p e c i f i c v a lu e s . 1*6 I n g e n e r a l t h e tim e r a t e s o f d e p o s i t i o n f o r t h e i m p u r i t i e s i n c r e a s e d a s th e c u rre n t d e n s ity in c re a s e d . S e v e ra l e x c e p tio n s to t h i s g e n e ra l t r e n d o c c u r r e d i n t h a t t h e r e w as a maximum o r a n e a r l y c o n s t a n t r a t e a t lo w o r m o d e r a te c u r r e n t d e n s i t i e s w i t h t h e r a t e i n c r e a s i n g a g a i n a t wi h i g h e r c u r r e n t d e n s i t i e s , t h u s o b t a i n i n g a t y p e o f i n v e r t e d S -s h a p e d c u r v e , i f t h e r a t e s w e re p l o t t e d w i t h r e s p e c t t o c u r r e n t d e n s i t y . A m in i ­ mum d e p o s i t i o n r a t e a l s o o c c u r r e d . C o p p e r h ad a maximum r a t e o f d e p o s i t i o n i n t h e lo w e r c u r r e n t d e n s i t y r e g i o n s ; t h e maximum w as l o c a t e d a t a h i g h e r c u r r e n t d e n s i t y w i t h a lo w e r pH o f t h e s o l u t i o n . I t w as a l s o o b s e r v e d t h a t t h e c o p p e r d e p o s i ­ t i o n r a t e w as t h e h i g h e s t a t t h e c u r r e n t d e n s i t y w h e re no n i c k e l , com­ p a r a t i v e l y s p e a k i n g , d e p o s i t e d from t h e tw o h i g h e s t pH s o l u t i o n s . T h is f o l l o w s a n o b s e r v a t i o n b y F in k a n d Rohrman (1 5 ) t h a t t h e maximum re m o v a l o f c o p p e r o c c u r s b e tw e e n t h e p o i n t w h ere n i c k e l d e p o s i t i o n s t o p s a n d t h e p o i n t w h ere t h e c o n c e n t r a t i o n e f f e c t o f h y d ro g e n i o n s comes i n t o p la y . The sam e g e n e r a l t y p e o f d e p o s i t i o n r a t e c u rv e i s fo u n d f o r i r o n a s f o r c o p p e r, e x c e p t t h a t th e r a t e s a re h ig h e r th a n th o s e f o r c o p p er i n th e h ig h c u r r e n t d e n s ity r e g io n s . As i n t h e c a s e o f c o p p e r , t h e l o c a t i o n o f t h e wiaTrimnTn w i t h r e s p e c t t o c u r r e n t d e n s i t y d e c r e a s e d w i t h a n i n c r e a s e i n pH; h o w e v e r, t h e m axim a f o r t h e two lo w e s t pH s o l u t i o n s w e re a t som e­ w h a t h i g h e r c u r r e n t d e n s i t i e s t h a n t h o s e f o r c o p p e r , w h ile t h e maxima f o r t h e tw o h i g h e s t pH s o l u t i o n s w e re a t som ew hat lo w e r c u r r e n t d e n s i ­ tie s . I r o n , a s co m p ared w i t h c o p p e r , d e p o s i t e d a t a l o w e r , r a t h e r t h a n h i g h e r r a t e w hen n i c k e l d e p o s i t i o n e f f e c t i v e l y s to p p e d . U7 T h e re was a n o t i c e a b l e i n c r e a s e i n t h e r a t e o f d e p o s i t i o n o f l e a d , s i m i l a r t o t h e c a s e o f c o p p e r , when n i c k e l e f f e c t i v e l y s to p p e d d e p o s i t ­ in g . H ow ever, no maximum w as p r e s e n t i n t h e r a t e - c u r r e n t d e n s i t y c u rv e w hen r e g u l a r n i c k e l d e p o s i t s w ere o b t a i n e d . B o ro n an d alum inum h a d a minimum d e p o s i t i o n r a t e f o r t h e o r g a n ic s o l u t i o n o n ly a t a c u r r e n t d e n s i t y o f a b o u t f o u r - t e n t h s a m p ./d m . 2 C o b a lt h ad no maximum r a t e b u t t h e r e was a l e v e l i n g o f f i n t h e d e p o s i t i o n r a t e s a t a c u r r e n t d e n s i t y som ew hat h i g h e r t h a n w here t h e m axim a o c c u r r e d i n t h e i r o n d e p o s i t i o n r a t e s . R e l a t i v e e n e rg y e f f i c i e n c y c a l c u l a t i o n s , a ssu m in g t h e r e s i s t a n c e o f t h e c e l l t o be c o n s t a n t o v e r t h e c u r r e n t d e n s i t y ra n g e c o n c e rn e d , i n d i c a t e d t h a t , i n g e n e r a l , t h e r e was a d e c r e a s e i n e n e rg y e f f i c i e n c y o f im p u rity d e p o s itio n w ith an in c r e a s e i n c u r r e n t d e n s ity . C o b a lt an d i r o n had maximum e n e rg y e f f i c i e n c i e s i n t h e low c u r r e n t d e n s i t y r e g i o n o f t h e tw o l o w e s t pH s o l u t i o n s , and i r o n h ad a minimum e f f i c i e n c y a t a m o d e ra te t o a h ig h c u r r e n t d e n s i t y i n t h e two h i g h e s t pH s o l u t i o n s . The m axim a o f c o b a l t an d i r o n , an d t h e m inim a o f i r o n d e c r e a s e d i n t h e i r c u r r e n t d e n s i t y l o c a t i o n w i t h a n i n c r e a s e i n t h e pH o f th e s o lu tio n . I t i s known t h a t t h e e f f e c t i v e r e s i s t a n c e t o t h e p a s s a g e o f c u r r e n t th r o u g h t h e b a t h i n c r e a s e s w i t h i n c r e a s e d d u r r e n t d e n s i t y ( 1 ,3 3 ) . T h is w o u ld a l t e r t h e r e l a t i v e e n e r g y e f f i c i e n c y v a lu e s so t h a t th e r a t e o f d e c r e a s e i n t h e e n e r g y e f f i c i e n c y f o r i m p u r i t y d e p o s i t i o n w ith i n c r e a s e d c u r r e n t d e n s i t y w o u ld be i n c r e a s e d , o r i n o t h e r w o rd s , h ig h e r r e l a t i v e e n e r g y e f f i c i e n c i e s w ould be o b t a i n e d a t lo w e r c u r r e n t d e n s i t i e s t h a n t h e p r e v i o u s d i s c u s s i o n m ig h t i n d i c a t e . U8 SUMMARY T he c a t h o d ic c u r r e n t e f f i c i e n c y d e c r e a s e d a s t h e pH o f t h e s o l u t i o n i n c r e a s e d due t o t h e p r e s e n c e o f t h e i m p u r i t i e s i n t h e s o l u t i o n s . T h is t r e n d i s t h e r e v e r s e o f w h a t i s g e n e r a l l y fo u n d w i t h l e s s c o n ta m in a te d s o lu tio n s . I n t h e lo w e r c u r r e n t d e n s i t y r e g i o n t h e n i c k e l d e p o s i t i o n e f f i c i e n c y d e c re a se d a s th e c u r r e n t d e n s ity d e c re a s e d . The c o m p o s itio n o f t h e p r e c i p i t a t e fo rm ed i n t h e h i g h e r pH c a th o d e l a y e r i s a b o u t w h a t one m ig h t e x p e c t from s o l u b i l i t y m e a su re m e n ts made i n s i m i l a r s o l u t i o n s a t v a r i o u s pH v a l u e s . The i s o - c u r r e n t d e n s i t y c u r v e s on a n i n c l i n e d c a th o d e showed t h a t t h e r e g i o n s o f t h e c a th o d e w h ic h w ere m ore d i s t a n t l y l o c a t e d from t h e a n o d e h ad lo w e r c u r r e n t d e n s i t i e s , e x c e p t when p r o x im ity to a n ed g e o r c o r n e r p a r t i a l l y c o u n te r a c te d t h e d i s t a n c e r e l a t i o n s h i p . I t was f o u n d t h a t w i t h i n c r e a s i n g c u r r e n t d e n s i t y t h e d e p o s i t s o l u t i o n c o n c e n t r a t i o n r a t i o v a lu e s w e re g e n e r a l l y n e a r l y c o n s t a n t o r i n c r e a s i n g f o r alu m in u m , c a lc iu m , m ag n esiu m , a n d m an g a n ese ; f o r cadm ium , c o p p e r , an d l e a d t h e r a t i o v a lu e s e i t h e r w ere n e a r l y c o n s t a n t o r d e ­ c re a s in g . A maximum c o n c e n t r a t i o n r a t i o was fo u n d f o r c o b a l t , i r o n , a n d z i n c ; a minimum r a t i o f o r alum inum , b o r o n , a n d i r o n . I n g e n e r a l th e l a r g e r v a lu e f o r t h e maximum o r minimum w as o b t a i n e d from t h e h i g h e r pH s o l u t i o n a n d was a t a lo w e r c u r r e n t d e n s i t y , c o b a l t b e in g a n e x c e p t i o n . F o r t h e W a tts ty p e s o l u t i o n s a n i n c r e a s e i n pH r e s u l t e d i n a n i n ­ c r e a s e d c o n c e n t r a t i o n r a t i o f o r alu m in u m , b o r o n , cadmium ( h i g h c u r r e n t d e n s i t i e s ) , c a l c i u m , c o p p e r , i r o n (lo w a n d h ig h c u r r e n t d e n s i t i e s ) , l e a d , m ag n e siu m , m a n g a n e s e , s i l i c o n , an d z i n c ; a d e c r e a s e d r a t i o f o r cadm ium (lo w c u r r e n t d e n s i t i e s ) , c o b a l t , a n d i r o n (a ro u n d 0 .7 5 amp ./d m . 2 The h i g h c h l o r i d e c o n c e n t r a t i o n r e s u l t e d i n a n i n c r e a s e i n t h e c o n ­ c e n t r a t i o n r a t i o f o r a lu m in u m , b o r o n , cadm ium , c a l c i u m , c o p p e r (lo w c u r r e n t d e n s i t i e s ) , l e a d , m ag n e siu m , m a n g a n e s e , s i l i c o n , a n d z i n c ; a d e c re a se i n th e r a t i o s f o r c o b a lt and ir o n . T he p r e s e n c e o f t h e o r g a n i c c o n s t i t u e n t s r e s u l t e d i n a n i n c r e a s e d r a t i o f o r a lu m in u m , b o r o n , i r o n (lo w c u r r e n t d e n s i t i e s ) , l e a d , m an g an ese and s i l i c o n ; a d e c re a s e d r a t i o f o r c a lc iu m . The c o d e p o s i t i o n o f n i c k e l i n c r e a s e d t h e c o n c e n t r a t i o n r a t i o f o r a lu m in u m , c o b a l t , m ag n e siu m , m a n g a n e se , i r o n , a n d c a lc iu m ; i t h a d no • e f f e c t o r d e c r e a s e d t h e r a t i o f o r c o p p e r , l e a d , b o r o n , cadm ium , an d z in c . I n g e n e r a l t h e r e w as a c o n tin u o u s i n c r e a s e i n t h e d e p o s i t i o n r a t e s o f th e im p u r itie s w ith in c r e a s in g c u r r e n t d e n s ity . C o p p er and i r o n h a d maximum r a t e s i n t h e low o r m o d e ra te c u r r e n t d e n s i t y r e g i o n , a n d t h e n i n t h e h i g h c u r r e n t d e n s i t y r e g i o n t h e r a t e i n c r e a s e d w i t h •i n c r e a s ­ in g c u rre n t d e n s ity . C o b a lt * s r a t e s w e re s i m i l a r e x c e p t t h a t a n e a r l y c o n s t a n t r a t e r a t h e r t h a n a maximum w as o b t a i n e d a t s l i g h t l y h i g h e r c u r r e n t d e n s i t i e s t h a n t h e maxim a i n t h e i r o n c u r v e s . A minimum d e p o s i ­ t i o n r a t e o c c u r r e d f o r alum inum a n d b o r o n fro m t h e o r g a n i c ty p e s o l u t i o n T he c u r r e n t d e n s i t y l o c a t i o n f o r t h e maximum i n t h e r a t e c u r v e s f o r c o p p e r a n d i r o n d e c r e a s e d w i t h a n i n c r e a s e i n t h e pH o f t h e s o l u t i o n . I n g e n e r a l i t w as fo u n d t h a t t h e e n e r g y e f f i c i e n c y o f i m p u r i t y d e p o s itio n d e c re a se d w ith an in c re a s e in c u rr e n t d e n s ity . C o b a lt a n d iripSi h a d a maximum e n e r g y e f f i c i e n c y i n t h e lo w c u r r e n t d e n s i t y r e g i o n o f t h e two l o w e s t pH s o l u t i o n s , i r o n h a d a minimum e f f i c i e n c y i n t h e two h i g h e s t pH s o l u t i o n s . T he c u r r e n t d e n s i t y l o c a t i o n o f t h e m axim a a n d m in im a d e c r e a s e d w i t h a n i n c r e a s e i n t h e pH o f t h e s o l u t i o n . 51 i) BIBLIOGRAPHY (1 ) W. Blum a n d G . B . Hogaboom , " P r i n c i p l e s o f E l e c t r o p l a t i n g an d E le c tr o f o r m in g ," M c G ra w -K ill B ook C o ., I n c . , New Y o rk , 1 9 4 9 . (2 ) J . W. M. Du Mond a n d E . R . C o h e n , A m e ric a n S c i e n t i s t . 4 0 , 4 4 7 ( 1 9 5 2 ) . (3 ) M. B . D i g g i n , ’’T he P u r i f i c a t i o n o f E l e c t r o p l a t i n g S o l u t i o n s , ” H an so n -V a n W in k le -M u n n in g C o ., M ataw an, New J e r s e y , 1 9 4 5 . ( T a l k b e f o r e t h e D e t r o i t B ra n c h o f t h e A m e ric a n E l e c t r o ­ p la te r s 1 S o c ie ty .) A . F . B r o c k in g t o n , M e ta l I n d . . 6£ , 4 8 6 , 513 ( 1 9 4 6 ) . W. D. G o rd o n , "T h e E f f e c t s o f I m p u r i t i e s a n d T h e i r R em oval fro m N i c k e l P la tin g S o lu tio n s ," M .S . T h e s i s , M ic h ig a n S t a t e C o l l e g e , 1 9 4 6 . D. T . E w ing a n d W. D. G o rd o n , P r o c . Am. E l e c t r o p l a t e r s 1 S o c . , 3 4 , 213 (1 9 4 7 )* G. E . Gardam, J . E le c t r o d e p o s i to r s 1 T e c h . S o c. , 2 2 . 8 (1 9 4 7 )• D. T . E w in g , R . R o m in s k i, a n d W. M. K in g , P r o c . Am. E l e c t r o p l a t e r s 1 S o c . , 3 5 , 119 ( 1 9 4 8 ) . (4 ) R . J . R o m in s k i, "T h e E f f e c t s o f T r a c e A m ounts o f C o p p e r Upon Some P h y s i c a l P r o p e r t ie s o f E le c tr o d e p o s ite d N ic k e l," M .S . T h e s i s , M ic h ig a n S t a t e C o l l e g e , 1949* ( 5) D. D. C l a r k , "T h e E f f e c t s o f T r a c e A m ounts o f Z in c Upon Some P h y s i c a l P r o p e r tie s o f E le c tr o d e p o s ite d N ic k e l," M .S . T h e s i s , M ic h ig a n S t a t e C o l l e g e , 1949* 52 (6 ) D . T . E w in g , R . J . R o m in s k i, a n d W. M. K in g , P l a t i n g , 2 1 , 1157 ( 1 9 5 0 ) . (7 ) A . B r e n n e r , V. Z e n t n e r , a n d C. W. J e n n i n g s , P l a t i n g , 2 9 , 865 ( 1 9 5 2 ) . ( 8) 0 . B usse, Z . E le k tr o c h e m . . 5 8 , 783 ( 1 9 3 2 ) . C. K a sp e r, T r a n s . E le c tr o c h e m . S o c . . 7 7 , 353 ( 1 9 4 0 ) . (. > (9 ) C . G . F i n k an*1. F . A . R ohrm an, T r a n s . Am. E le c tr o c h e m . S o c . , 5 9 . 359 ( 1 9 3 1 ) . ( 10) E . Raub a n d M. W ittu m , K o r r o s io n u . M e t a l l s c h u t z . 1 5 . 127 ( 1 9 3 9 )• 0 . A . , 2 1 l 720V / ( 1 9 3 9 ) . ( 11) F . F o e rs te r, Z . E le k tr o c h e m . . j t , 160 ( 1 8 9 7 ) . ( 12) V. L.- K h e i f e t s a n d A . L . R o tin y a n , D o k la d y A k ad . Nauk S . S . S . R ., 8 2 ,* 4 2 3 ( 1 9 5 2 ) . C. A ., 4 ^ 7 ^ 5 2 ig T l9 5 2 7 . W' (1 3 ) C . G . F i n k a n d F . A . R ohrm an, T r a n s . Am. E le c tr o c h e m . S o c . , 5 8 , 403 ( 1 9 3 0 ) . ( 1*) C . G . F i n k a n d K. H. L ah , T r a n s . Am. E le c t r o c h e m . S o c . , 5 8 , 373 ( 1 9 3 0 ) . (1 5 ) C . G . F i n k a n d F . A . Rohrm an, T r a n s . Am. E le c tr o c h e m . S o c . , 5 7 , 325 (1 9 3 0 ) • ( 16 ) M. I . M orkhov a n d L . P . A t c h i , K o r r o z iy a i B o rb a s Ne)C, 6 , 10 ( 1 9 4 0 ) . c .” a . , M ," 6 5 W C i9 4 ¥ T : (1 7 ) M. R . Thom pson, T r a n s . Am. E le c tr o c h e m . S o c . , 4 4 , 359 ( 1 9 2 3 ) . S . G l a s s t o n e a n d T . E* Syraes, T r a n s . F a r a d a y S o c . , 2 5 , 213 ( 1 9 2 7 ) . T r a n s . F a r a d a y S o c . , 2 ? , 370 ( 1 9 2 8 ) . ( 18 ) K. E ngem ann, Z . E le k tr o c h e m . , 1 7 , 910 ( 1 9 1 1 ) . 53 (1 9 ) E , R aub a n d M. W ittu m , K o r r o a lo n u . M e t a l l s c h u t z . 1 3 , 2.61 ( 1 9 3 7 ) . C . A ., 21^. 7 7 6 5 9 ( 1 9 3 7 ) . B• C• C a se y P r o c . Am. E l e c t r o p l a t e r s 1 S o c . 9 3 4 , 2 2 8 ( 1 9 4 7 ) . (2 0 ) A . N. C a m p b e ll, J . Chem. S o c . , 1 2 3 , 1713 ( 1 9 2 4 ). (2 1 ) D. N . G r l t s a n a n d N. S . T s v e tk o v , Z h u r . P r l k l a d . K him . , 2 2 , 600 ( 1 9 4 9 ) . C. A ., 4 £ , 2 3 3 8 n i 9 5 l T (2 2 ) H. D. C a r t e r , M e ta l I n d . , 2 2 , 170 (1 9 4 8 ). (2 3 ) D. T . E w in g , R . J . R o m in sk i, a n d W. M. K in g , P l a t i n g , 3 6 , 1137 ( 1 9 4 9 ) . (2 4 ) A. B re n n e r, J . R e s e a r c h N a t *1. B u r . S t a n d a r d s , 1 3 , 565 ( 1 9 3 7 ) . G. B . Bowman, M o n th ly R e v . Am. E l e c t r o p l a t e r s 1 S o c . , 3 4 , 1149 ( 1 9 4 7 ) . (2 5 ) W. R . B ro d e , " C h e m ic a l S p e c tr o s c o p y ," J o h n W ile y a n d S o n s , I n c . , New Y o rk 1, 1943* R . A . S aw y er,. " E x p e r im e n ta l S p e c tr o s c o p y ," P r e n t i c e - H a l l , I n c . , New Y ork, 1 9 4 4 . G. R . H a r r i s o n , R . C . L o rd , a n d J . R . L o o fb o u ro w , " P r a c t i c a l S p e c tr o s c o p y ," P r e n t i c e - H A l l , I n c . , New Y o rk , 1 9 4 8 . (2 6 ) G. R . H a r r i s o n , "M. I . T . W a v e le n g th T a b le s o f IO C ,0 0 0 S p e c tru m L i n e s ," J o h n W ile y a n d S o n s , I n c . , New Y o rk , 1939* (2 7 ) M. R . T hom pson, T r a n s . Am. E le c t r o c h e m . S o c . , 4 l , 333 ( 1 9 2 2 ) . A. B re n n e r, P r o c . Am. E l e c t r o p l a t e r s * S o c . , 2 8 , ( l 9 4 l ) . P r o c . Am. E l e c t r o p l a t e r s 1 S o c . , 3 5 , 31 ( 1 9 4 8 ) . G . K orttim a n d J . O'M . B o c k r is , " T e x tb o o k o f E l e c t r o c h e m i s t r y , " E l s e v i e r P u b l i s h i n g H ouse, New Y o rk , 1951* (2 8 ) H. J . W ie s n e r , "T h e C o l l o i d a l S t a t e a n d P r e c i p i t a t i o n o f C e r t a i n M e t a l l i c H y d r o x id e s i n C o n c e n t r a t e d S o l u t i o n s o f N i c k e l S u l f a .t e ," P h .D . T h e s i s , M ic h ig a n S t a t e C o l l e g e , 1 9 4 3 . 5H (2 9 ) R . T . B irg e , R e v . Mod. P h y s . . 1 3 , 233 (192*1). (3 0 ) G. E . Gardam , T r a n s . F a ra d a y S o c . . 3U, 698 ( 1 9 3 8 ) . W. A . W esle y an d E . J . R o e h l, T r a n s . E le c tr o c h e m . S o c . , 8 6 , Ul9 (191*1*). (3 1 ) R . L . N y q u is t, , "The E l e c t r o l y t i c B e h a v io r 4I r o n i n a B u f f e r e d N ic k e l S u l f a t e S o l u t i o n ," M ic h ig a n S t a t e C o l l e g e , 1 9 5 1 . (3 2 ) D. T . E w in g , A . A . B ro u w e r, D . D . C l a r k , C . J . Owen, R . J . R o m in s k i, J . K. W e rn e r, P l a t i n g . 3 9 , 1033 ( 1 9 5 2 ) . (3 3 ) H. E . H a r in g , T r a n s . Am. E le c tr o c h e m . S o c ., 1*9, Ul7 ( 1 9 2 6 ) . E . M a n tz e ll, Z . E le k tro c h e m . . 1*3. 17l* ( 1 9 3 7 ) .