M 1 4 WIN” ff“! EFFW OF TRACE AMOUNTS {I}? COPQfiI QPON SOME fiHYSKlAL iflGPERTIES 0F ELECT RODEPOSH'EQ NICKEL -I_‘;'=_‘ I40.) CD—t\l Thai: for flu: begun cf M. S. MimiGAN STATE COLLEGE Raé'sw? gsmas Roménsficé E9149. This is to certifr] that the thesis entitled 'The Effects of Trace Amounts of Copper Upon Some Physical Properties of Electrodepcsited Nickel.‘ presented In] Robert James Romineki has been accepted towards fullillment of the requirements for degree in __ Physical Chemistry ' I II' | ‘4___ — — — —— - l‘vlajur l‘v1‘1)l€§51_vr Date May 224: 12242- M-Tt-S “Pu .OI' THE EFFECTS OF TRACE AMOUNTS OF COPPER UPON SOME PHYSICAL PROPERTIES OF ELECTRODEPOSITED NICKEL By Robert James Rominski A THESIS Submitted to the School of Graduate Studies of Michigan State College of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Chemistry 1949 MEMBTHY new T54 / ,3 R 76 5 Acknowledgement I wish to express my sincere appreciation to Dr. D.T.Ewing for his guidance and assistance during the course of this research. I would like to extend my thanks to the American.Electroplater's Society for the fellowship grant that made this research possible, and to the project committee, Mr. B.C.Case, Chairman, Hanson-VanWinkle-Munning Company; Mr. L.B.Sperry, Doehler-Jarvis Corporation: and.Dr. R.C.Olsen, later succeeded by Mr. G.M.Cole, both of Fisher Body-Tern- stedt Division, General Motors Corporation, for their contributions. , r gi?910 TABLE OF CONTENTS: I. Introduction II. Experimental Preparation and purification of solutions Preparation of nickel plated panels Curves for; Depletion of Copper from nickel solutions at 40 amperes per square foot. III Effects of cOpper as an impurity in nickel solutions. Appearance .Adherence Ductility Hardness Corrosion resistance (salt Spray) Throwing power and efficiency IV The removal of cepper from.nickel plating solutions. Technique Evaluation of results Curves for: Rate of removal at low current density Rate of removal by high pH treatment V Conclusion. VI Bibliography Page Page Page Page Page Page Page Page Page Page Page Page Page 1. 10 12 12 15 15 19 21 24 50 55 55 INTRODUCTION This investigation is the first of a series of the effects and removal of known amounts of impurities in four typical nickel plating solutions. This research was undertaken at the request of, and under a grant from the American Electroplater's Society. The material in this thesis consists of the effects of c0pper on electro- deposited nickel and its removal from nickel plating solutions. The first study of the effects of cepper in nickel plating solutions was carried out by the laboratories of Brass World in 1911 (1). In general they observed a darkening of the deposit upon the addition of small amounts of cepper to the nickel solution. Later investi- gation carried out at the Bureau of Standards by Thompson and Thomas (2) and.Haring (3) reported the permissable limits of cepper in the nickel salts for nickel plating solutions, and its effects on the deposit, resulting in dark spongy deposits. The limits of copper as an impurity in nickel solu- tions has been reported by Diggen (4) to be up to 0.5 oz./ gal. (0.38 g./1.) in the gray nickel solutions and 0.001 oz./ga1. (0.0075 g./l.) for the bright nickel solutions. From.this observation, the bright nickel solutions have considerably lowered the upper limits of copper as an imp purity. Eckelmann (5), Johnson (6), and Francis-Carter (7) -1- stated that the effects of copper in the bright nickel solutions will cause dull dark deposits in the low current density regions and a fogging or milky deposit in the other areas. Several methods have been preposed for the removal of cepper from nickel plating solutions. Among these is that set forth by Thompson and Thomas (2) in 1922. By making the bath slightly acid, scrap nickel is suspended in the nickel solution; the nickel precipitates the cop- per from.the solution. The efficiency of this cementa- tion process depends upon the surface area of the nickel exposed. Pink and Rohrman (8), Raub and Bihlmaier (9), Diggin (4), and Waite (10) and others preposed the electrolytic removal of copper from.nicke1 solutions by the use of low current densities. The four typical nickel plating solutions used in this study consisted of a 2.2 pH and a 5.2 pH Watts type gray nickel solutions, a nickel cobalt alloy type bright nickel solution as per Weisberg Stoddard papent, and an organic type bright nickel solution as per Schlbtter pa- tent. To study the general effect of cepper as an impurity in nickel plating solutions and to set up limits of con- tamination, a series of panels were produced from.the nickel solutions containing up to 500 milligrams of copper per liter of solution. The upper limit of 100 milligrams was established, as the deposits obtained from the nickel solutions containing an excess of this amount were con- sidered unusuable. Panels were produced from.the four nickel solutions. In this investigation, special attention has been given to the following preperties:- appearance, adherence, salt-fog corrosion resistance, ductility, and hardness. In addition, the throwing power and current efficiency was studied. The removal of c0pper from.nickel solutions was studied using the methods of electrolytic purification and high.pH treatment. No attempt has been made to evaluate these properties in exacting physical units. Rather, the trend of the change in the property under consideration was noted as the concentration of the impurity was changed. The results were reported in relative rather than absolute values us- ing a deposit from.a pure plating solution as a standard. The methods of testing were not the most precise, nor did they require expensive apparatus, but were designed for the layman operator to determine quickly whether or not impuri- ties may be present. To better study these effects of impurities, it was necessary to prepare nickel solutions free from impurities. Two methods have been used, chemical precipitation and electrolysis. EXPERIMENTAL A. Technique: 1. Preparation and_purification of solutions. The plating solutions used in this investigation are listed in the following tables: Table No. 1. Watts type nickel plating solution. Nickel sulfate 240 grams/liter 32 oz./gallon Nickel chloride 45 " " 6 " " Boric acid 50 " " 4 " " Temperature 50°C. 122°F. pH (electrometric) 2.2 and 5.2 Current density 40 amperes per square foot. Table No . 2 . Nickel cobalt (18%) alloy type solution. Nickel sulfate 240 grams/liter 52 oz./ga110n Nickel chloride 45 " " 6 " " Boric acid 50 ” " 4 " " Nickel formate 45 " " 6 " " Cobalt Sulfate 15 " " 2 " “ Ammonium.sulfate 0.75 " " 0.10 " " Formaldehyde 2.50 " " 0.55 " “ Temperature 55°C. 152°F. pH (electrometric) 5.75 Current density 40 amperes per square foot. Table NO. 5 o Organic type nickel solution 1 Nickel sulfate 262.5 grams/liter 55 oz./ga1. Nickel chloride 60 " " 8 " " Boric acid 54 " " 4.5 " " Nickel benzene disulfonate 7.5 " " 1 " " Triaminotolyldiphenylmethane 0.14 m1./1iter ' Temperature 55°C. 152°F. pH (electrometric) 5.2 Current density 40 amperes per square foot. The plating solutions were made up in twenty liter stock solutions. The purification of these was accomplished by the high pH precipitation of 5.5 to 6.0 (electrometric) with.nickel carbonate and electrolysis at a current density of 2-7 amperes per square foot on a corrugated, cathode. .It has been found that about 100 ampere hours per gallor of solution will remove the heavy metal ion concentration to SpectroscOpic traces. Any organic im- purities present were removed after electrolysis had been completed by the addition of about 7.5 grams per liter of activated carbon of a good commercial grade. After 24 hours of agitation and a solution temperature of 70-7530. the solution was filtered and ready for use. King (11) has described the proceedure in greater detail. 2. Preparation of nickel plated panels. The steel used for the bent cathodes was low-car- bon, cold rolled tin can stock of 0.01" thickness, with an R.M.S. value of 10 and supplied through the courtesy of Dr. Richard Wick of the Bethlehem Steel Corporation. -5- The strip steel was cut to a standard size of 2"x 8"; A lip of 1.25" was formed by bending the lower edge of a 2"x 8" panel 90°. A line was scribed 5.5'? from the bend across the panel. This gave an area of 0.08 square feet of surface to be plated. .The panel was degreased with carbon tetrachloride, numbered, and given an electrocleaning prior to plating. The composition of the electrocleaner is given in Table 4. Table No. 4. Electrocleaner composition T Sodium.hydroxide 21 grams/liter 2.81 oz./ga110n Sodium metasilicate 15 " " 2.01 " " Tri-sodium.ph03phate 18 " " 2.41 " " Temperature 80°C. 167°F. " Current density 75 amperes per square foot. The steel panel to be cleaned was made the anode in the electrocleaner and current was passed for two minutes. It was rinsed in running water, checked for water breaks, and then dipped in a 20% hydrochloric acid solution for two minutes. This was followed by two running water rinses, the latter being distilled water. The panel was then ready for plating. The panels were plated in 1 liter glass battery jars with a current density of 40 amperes per square foot, 1 operating temperature of the bath in use, and at an agita- tion rate of 4 feet of solution past the cathode per minute. The concentration of cepper was maintained by -5- reference to depletion curves of the impurity from.the nickel bath.in use. The depletion rate data was obtain- ed for each of the four nickel solutions by electrolysis at a current density of 40 amperes per square foot from.the bath containing the upper limit 03 contamination. The electrolysis was maintained until the lower limits of con- tamination had been passed. Samples were taken at inter- vals and analysed for capper concentration usingthe color- imetric method of analysis as set forward.by Serfass and Levine (12). Figure 1. illustrates the rate of depletion of capper from.the four nickel solutions at 40 amperes per square foot. Figure 2. is the calibration curve for the deter- mination of capper in.nickel solutions as capper diethyl dithiocarbamate in a mixture of amyl acetate and ethyl alcohol. The impurity concentrations were maintained within 10% throughout the plating runs by timed additions. The solutions were analyzed for capper each.hour of plating time as a further check. The pH of the solution was ad- justed.to the operating range before plating, and this pH was maintained.by frequent checks. A Beckman electrometric pH meter was used for this purpose. The temperature of the solutions was maintained.by means of a water bath. All the plating solutions were filtered before use daily, and in the case of the organic bright nickel bath, filtration -7- was necessary after each plated panel. A wetting agent, sodium.lauryl sulfate, in sufficient amount to lower the surface tension to 35 dynes per square centimeter, was re- quired to relieve the pitting encountered in this bath. After plating was completed, the panel was removed from.the solution, rinsed in running tap water and dis- tilled water, and wiped dry with a clean cheese cloth. The dry panels were stored in a large dessicator contain- ing calcium chloride. The chemicals and anodes necessary for this project‘ were furnished through the courtesy of the Hansoanan Winkle-Munning Co. and the Udylite Corp. 100 U) C) \ Cepper concentration, ‘g./l. CD <3 .//::;// / N O \(s\ 4) 0 2 4 6 8 10 Time in hours Fl gure l Depletion rate of copper at 40 amperes per square foot. loo(1) Organic bath (2) Watts 5.2pR (5) watts 2.2pH (4) Ni-Co. //.z /' . so / H \. / 39 a / a“ 60 O I: / s a .p a 8 I g: 40 O O H /////l 0 o. $4 20 / L) /// 0 0 50 100 150 200 250 300 350 400 Colorimeter units Figure 2 The calibration curve for the determination of copper in nickel solutions. B. EFFECTS OF COPPER AS AN INPURITY ON SOME PHYSICAL PROPERTIES OF NICKEL DEPOSITS l. ‘éppearance: It has been generally known that small amounts of cepper in nickel plating solutions effects the appearance or brightness of the deposits, eSpecially in the recessed areas receiving low current densities. This physical prop- erty has been thecriterion for the necessity of removal of copper because it is the most easily recognized as a source of rejection in the plating industry. Without a doubt the cathodic current density can change the numer- ical limits of cepper contamination at which appearance may be effected. The limits stated hold true for the cur- rent densities found and the copper concentrations tested. Two tests were used to describe the effects of cepper on the appearance of 0.001" deposit thickness panels. First, for the gray nickel deposits, the panel was comp pared to the Eastman Gray Scale and assigned a value. Second, for the bright nickel deposits, the panels were classified in a range from.mirror bright to a dull matte. Table 5 summarizes the effect of copper on appearance for the four nickel solutions. -10- Table 5 o Effect of cepper as an impurity on the appearance of nickel deposits. Cu. conc. Watts Watts Ni-Co Organic Mg. /1. 2.2pH 5.2pH 5.75pH s .2pH 0 2 2 mirror'bright dull luster 10 2 2 milky dull luster 25 2 2 milky dull luster 50 2 2-5 milky milky 75 2 2-5 dull luster milky 100 2 2-5 dull luster milky In general, brightness of deposits is effected when the copper concentration reaches 10 mg./1. in the solution, the effects being noticed in areas which received from.6-8 amperes per square foot. At 50 mg./1. practically all current densities are adversely effected. As appearance is the most easily evaluated physical prOperty, it was not deemed necessary to give results in extreme detail. The deposits from all four baths were ultimately effected by increasing copper contents, with the Watts type deposit changing somewhat later than the bright deposits. Rough- ness of all the deposits, starting at the edges, became noticeable when the copper reached 50 mg./l. extending into other areas as the copper increased to 100 mg./1. 2. Adherence: To evaluate the adherence of the nickel coating to the steel base, a simple test was devised which was the most adaptable and the nearest to the most satisfactory methods used in industry at this date. This test consist- ed of bending the lip of a 0,001" deposit thickness panel 180° around a 5/16" mandrel along the middle and across the short dimension. The deposit was observed for non- adherence along the bend with the aid of a magnifying glass. This allowed observation of non-adherence at a range of deposit thicknesses. . With increasing copper contents up to 100 mg./1., the adherence of the nickel coating to the steel base showed no discernible change in any deposit, at any cur- rent density area from the four nickel solutions. 5. Ductility: It has been found that a nickel deposit on steel is not sensitive enough for a ductility test, and, there- fore a stripped deposit was prepared for testing. This stripped deposit was made by plating a 0,001" deposit of nickel on a slightly oxidized surface. The deposit will cover the prepared surface completely but may still be readily peeled from.the surface. The oxidized surface was prepared by repeating the cleaning and acid dip cycle on a steel panel plated with 0.0005" thickness of nickel ' ~12- The stripped deposit was cut into 1"x2" strips and creased between the fingers across the short dimension. By alternately creasing and straightening, rupture will soon occur. By this method, the results were reported as an increase, a decrease, or no change in ductility in relation to the pure deposit. Discernible changes in the. ductility of the nickel deposits appeared with a copper content of the solution from.10 to 25 mg./1. Bending a plated steel panel or a stripped deposit showed definite and serious loss of ductility. As the copper content of the solution in-' creased the ductility of the deposits decreased. No units for reporting this test are available and it is not possible to state where a deposit is useless because limits vary with the end use.. 4. Hardness: . The vertical portion of the bent cathodes de- posited to a thickness of 0.002" nickel was tested for hardness by means of a Knoop hardness tester.' Table 6 gives the gain or loss in hardness of deposits from.the four solutions. -13- Table No.0 60 Effect of cOpper as an impurity on the hardness of nickel deposits. * Cu. cone. Watts Watts Ni-Co Organic Mg./1. 2.2pH 5.2pH 3.75pH 5.2pH lO . 2.8% + 27.2% - 15.8% +19.1% 25 + 17.2 + 22.6 ~22.6 412.5 50 4.77.8 + 15.6 +15.2 *18.2 75 +86.0 +10.l +12.2 +20.5 100 +15.l $14.5 ’19.1 t 7.8 * Expressed in percentage change from the pure deposit. The deposits from the Watts bath showed an increase in hardness with the first addition of copper. The bright deposits followed this pattern but were slightly delayed. A degree of inconsistency was evidenced between hardness figures on the same type of deposit with various amounts of copper present in the plating solution. As the depo- sition of copper present with nickel is subject to great variations as a result of plating variables, it is not difficult to attribute the variations in hardness measure- ments to locals variations ochpper content in the deposit. The above test was conducted at the National Bureau of Standards, Washington D.C., through the courtesy ofADr. William.Blum, Director of the Electrochemical Division. -14- 5. Salt spray corrosion resistance: The effects of the presence of cepper in varying amounts upon the self fog corrosion resistance of nickel coatings upon steel were determined using three thicknesses of nickel deposits, 0.0005", 0.001", & 0.0015". These panels were prepared in triplicate for each pure bath and each concentration of impurity, this enables observation of the effect of impurity upon increasing deposit thick- ness. The vertical portions were tested for corrosion resistance in a commercial type salt spray (fog) cabinet. The conditions followed are as described in the A.S.T.M. standards (15). ‘ The breakdown was recorded after a condition was reached comparable to that of a set of standards previously prepared as a standard breakdown point. . Testing the deposit as plated produced results sur- prisingly consistent except for one or two of the 0.0015" deposits. Results were tabulated and recorded percentage- wise using the hours of resistance to a salt fog atmos- phere to a standard.breakdown of a deposit from.a clean plating bath as 100% performance. For all practical pur- poses, the results from.the performance of the two thick- nesses of nickel deposits, 0.001" and 0.0015" can be come bined into one curve for each of the plating solutions. The 0.0005" deposits failed in less than one hour but re- vealed substantially the same trend as the heavier deposits. -15.. 100 90 ‘4— l . l I 80 o t; i o H l 4’ \ in a). 60 \ 0 £1 a K\\\\‘\ .p l U) I 'g 50 i $.40 .p T? «5: 30 2O “ '- 10 Q ~ . O 10 20 3O 40 50 60 O 80 90 C H l Copper concentration, Hg./l. figure 5 Percent salt spray resistance of 0.001" & 0.0015" nickel coating on steel vs. copper concentration in a latte type nickel bath of pH 2.2 and 5.2 electrometric c"A‘l’c. spray resistance, Percent “Na-f 100 90 80 70 6O 50 4O 30 20. 10 ’ n _ rs_____ T 5 i ’”—T i 7 + 4 - — E 1 4 ‘fi 1 \ 1 \\ O 10 20 30 4O 50 60 70 80 90 100 Copper concentration, Eg./l. Hgme4 Percent salt spray resistance of 0.001” 0.0015” nirkel coating on steel vs. copper concentration in a nickel-cebalt bath of pH 3.75 electrometrié tance, Te .a stray resis + 'v Sal 100 so r H ~ 40 ~—-— so ---—w 20 E4} - — -—+H-—r. .. -4; \l 1.4 ‘) 0 13 20 30 40fl 50 60 7O 80 90 10 r cancentrstlon, lg./l. .7 J '(J F') Firure 5 Percent salt stray resis ance of 0.001” & 0.0ClS" n1 Rel costing on steel vs. cogger ccncentratisn in an organic type hright nickel hath r r L L ;H 3.8 electrmxetric. O The Watts type gray nickel deposits (Figure 5) were identical for both pH's and showed less loss in corrosion resistance, eofi/loo mg./l. of cOpper, than either of the bright nickel deposits. In the case of the nickel cobalt alloy type bright nickel deposits (Figure 4), and the organic type nickel deposits (Figure 5), these suffered the greatest loss in corrosion resistance, 80-85%/lOO mg. of copper per liter. 6. Throwinggpower and efficiency: Panels of 0.002" thickness were prepared from the four solutions covering the range of impurity con- centrations. The lips of these panels were cut off and microsc0pic thickness tests were made on each series and were compared with the deposit from the corresponding pure baths. The lips cut from the panels were carefully cut in half across the short dimension. These pieces were then clamped together, polished, etched with "nital", and ex- amined on a Banach and.Lomb Research Metallographic micro- scope. The distance from.the front edge of the steel to a deposit thickness of nickel of 0.002" was recorded for the four pure baths. On the succeeding panels the same distance was measured from the front edge of the steel, and the thicknesses of the deposits on the top of the lips were recorded. -19... Differences were reported as the net change in effi- ciency and throwing power. If no change in gassing is noted the change in thickness may be assumed to be due to a difference in throwing power. The effects of varying amounts of COpper in the four types of nickel solution did not disclose to the eye any change of gassing at the cathode, indicating little if any effect upon the cathode efficiency of that bath. In checking deposit thicknesses under controlled conditions and in pro-determined locations, any changes in thicknesses were therefore deemed the result of changes in the throwing power rather than in the cathode efficiency. Table V gives the gain or loss in throwing power and efficiency of the four nickel solutions. Table 7. Effect of c0pper as an impurity on the throwing power and efficiency of nickel plating solutions.* Cu. conc. Watts Watts Ni-Co Organic Mg./l. 2.2pH 5.2pH 5.75pH 3.2pH 10 + 2.7% ~5.0% 47.0% +1.57. 25 -0.8 ~5.5 +8.6 +1.0 50 +7.5 ~6.5 +7.0 +0.5 '75 -2.0 ~5.0 +2.5 +4.0 100 -2.7 ~11.5 +1.5 +5.0 * Expressed in percentage change from.the pure deposit. -20- The Watts type type of baths showed slight losses in deposit thicknesses indicating adverse effects upon the throwing power with increasing c0pper contents of the solution. The bright nickel deposits showed no substantial change in thickness at definite points of measurement, with.increasing copper content indicating little effect from.the presence of capper. C. The removal of copper from nickel plating solutiong: 1. Technique: The laboratory investigation consisted of two methods for the removal of cepper from.nickel solutions: ie., the electrolytic method and the high pH treatment using nickel carbonate. The procedure for the preparation and plating of the panels and apparatus used was as described previously. The current densities employed were l,2,5,and 4 amperes per square foot, at the Operating temperatures of the nickel baths. The agitation rate of four feet per minute of solution past the cathode. Flat lipless cathodes, 2" wide and 3%" long were used. Initial study indicated that in all cases the copper was rapidly lowered from 100 mg./l. to 25 mg./l., but for smaller concentrations the plating variables must be more carefully determined. Removal studies were therefore started at a copper concentration of 25 mg./l. m’ 0. '21- For the high pH removal of copper, nickel carbonate was added to a series of nickel sclutions containing about 100 mg./l. of copper. The amounts of nickel carbonate added were such as were necessary to give a series of pH values ranging from.2.2 to 6.0. The pH values were taken only after equilibrium.was established. The time of standing was a function of rate of agitation and tempera- ture. 2. Evaluation of results: In all cases studied of the electrolytic removal of capper, the current density of two amperes per square foot was the most effective for the fastest rate. If time is not a factor involved, a current density of one ampere per square foot can be utilized to remove the c0p- per more economically from.the standpoint of nickel de- posited, at least up to 8000 ampere minutes per gallon. Figures 6-13 shows the rate of removal of cOpper from.the four nickel solutions as removed electrolytically at the Specified conditions. A study of the effect of temperature upon the elec- trolytic removal of copper was investigated, whereby a run was made on the Watts 5.2 pH bath at room temperature. The rate of removal was less as illustrated in.Figures 14- 15. An increase in the rate of agitation from four to twenty feet of solution past the cathode per minute -22- brought about an increased rate of removal of the copper impurity. This is shown in Figures 16-17. To determine the effectiveness of removing c0pper by raising the pH, a measured.volume of the Watts type . gray nickel bath, at a pH of 2.5 and containing 87 mg./l. of cOpper was treated with nickel carbonate. The pH of the solution was raised slightly, sampled, and analyzed. This procedure was repeated until no further change in pH was observed. This treatment removed all but 15 mg./l. of copper. The solution was allowed to come to equilibriwm before pH readings were taken. Figure 18 shows the curve obtained for this high pH treatment for the removal of cepper. . In the case of the nickel-cobalt alloy bath and the crganic bath, the above procedure was followed. The treatment reduced the cOpper content of the nickel-cobalt bath from.92 to 31 mg./l. at a pH of 5.85. The organic bath was treated at a pH of 5.95 and the copper content reduced from.92 to 15 mg./l. Figures 19-20. _ ‘Nickel is also lost in this treatment as in the elec- trolytic method. In no case was the c0pper content re- duced through high pH treatment to as low values as ob- tained through electrolysis at low current density. -25- 30 25 15 1, w o "'3: , J—t- "‘ J- . ~ . .. _ 1 . . l , ',“.‘. O 1“- V r- f {t 'r 11‘. n“ _ §+ s H .,‘ ' _‘. 1.1 w,“ a .— "4 I.“ a; l- ‘ y - C-s : "I ’ 5 ‘- . y, ’\.4‘ .‘Q L ,. ,,- ’1) p...) a-) H I 3 p-.. ”-5 J L I .1‘1‘3‘ .' ‘ ‘ L- .. 1‘ .. V: :_, (44» r ’3‘, “7‘ g. -. ‘. : L . -. ,A v. '- . — l. V . A, i I ‘ - \. 5 vv ,- ‘ ”J. W ‘ ‘0 r . ‘1 - .’_¢ a ‘H' g - ,..n e o ,, a. ’ :a '.,,.l ‘1' c. ‘ a; 3‘ d -\. n ‘J 0 1000 9,90 3;” 13"“ .451. --‘ "-—i: ' . f ‘P 217:1 ("fl {‘ff’ nna o ' ++ ‘- ‘v‘\ .‘ . ‘. . * . . -- f, r )\ 5-7 fl (“AA ”’1 ‘2.“ c or» M‘Ctg )g (,«LJ 'br~’- p. .1 r- 1:.” 'n.j\,1 1 .591 . ' i v‘ , _,-._. L Q! “7. '7 a ‘1- ‘ 1., :, r. 1. I 1“ V, a, ‘ ‘ co.-.— ... a.» .t: A _, . . '1 “A xv f‘ I“ ‘ .34.)”. 4; ‘5 1 ‘1 A -. ‘I ‘K 5,, . A ./1. ~ V ‘ o C)n ’ #:‘3 concentrati ‘~./l. V -‘4 ~ncentration, .- d Capper c- 30 25 H U! 10 O H U" 3...: O 5 _._. 1.____. ___,._ _..___—_‘ .mn1__nlnpl_____, 1 _n,_ -_4,_.. _ L.._______ ( c —-—H .mmefHH-HHH 111 I0 1___ 4 6 8 lO )2 14 18 Time in hours. 3-71 gin-e .1‘; refers] of ef*j*r by electrolysis at low current dcfifiltl “flint? t;je bright nickel bath of p3 5.? 9190t?0“5tfiif- exec. nggtatinn rate of 4 feet/min- 4h ———————4 F—H- .—-_1—— a or V‘ I 2300 3300 4000 5000 6000 7000 ETQO ~ . pf c.’ , A“. . ., 3 _ _. i 1 ectrclysis at 10; currrrt Lennity ., - 4 ..‘- ' 1 A ., ‘ ' "f .‘ - .-. -~ - 3 t f“ bl”: ELLU Ill""“1 bq+; wf 5.. v.40: {slit-fl" ‘-' whim". I ,p. [‘0 \o 40 60 Ffifi‘\‘%gj” fir-‘Wfaravq‘fi‘q‘i «IA '.-a. .z.- 4"..'I.‘A.1U .,'1 V- a. 1... ""1"Q 1 5., | .‘ 4.. ‘ .4 (,-_- “.2“ ”an”... arena.“ L--.» , ' A ~ I_.\ I9~N '., \. LN- ' .44-1~ : -' 't m .- t *4} HA VAL n “I" L A \l 3 x. h.;“ l? fl‘ ' 56 49-.” ,. l-Lc ( yes Lo ‘9‘ A (*0 . 1’: __4p— he. 0 Q '3 V.) “ 20 4.0 '--~- em. A yr, 1:,_—.,n+:w t: A ‘v Ur'r \1" v \-¢L(J ';. 3.1. ‘9‘ 11." ..n, .'"~‘ ‘ hi."- 1 Q v a; — 1 O ___4y. To C) 20 40 60 90 100 - raising the pH with ni ckal carbonate. of rerofcl o“ 0?? 9? ”row fin organic tyre bricht niekfil bath by CONCLUSIONS: The results of this investigation of the effects and removal of copper from nickel solutions can be summarized as follows: A. Effects: 1. 3. 5. Appearance - Amounts of cepper in excess of 50 mg./l. produces a deposit tending to become rough and dark. I Adherence — Adherence of the nickel deposit on steel is not appreciably effected by concentrations of copper up to 100 mg./1. Ductility - A loss in ductility results with an increase in cOpper concentration of the nickel solution in excess of 10-25 mg./l. Hardness - In most cases the presence of c0pper as a contaminant increases the hardness of the nickel deposit over that of a pure bath. Corrosion resistance - The corrosion resistance of nickel plated steel is decreased by increasing amounts of copper as an impurity in the plating bath, in concentrations usually considered to be traces. Throwing_power and efficiency - The nickel deposits from.the Watts type nickel solution shows an ad- verse effect on the throwing power with increasing copper contents of the solution. The bright nickel deposits show no substantial change indicating little effects from.the presence of c0pper. 3. Removal: 1. COpper can be removed electrolytically, at the Optimum current densities of 1-2 amperes per square foot. This method permits reductions to the lowest concentrations. 2. Copper can also be removed by a high pH treat- ment to a minimum value of 15 mg./l. by means of nickel carbonate. %**&*%%%%% assesses erases-a:- *aa* aa -54.. BIBLIOGRAPHY: l. 2. 3. 4. Anon. "The Effect of COpper on Nickel-Plating Solutions." Brass World,z, 45-46 (1911). Thompson, M.R. and Thomas, C.T. "The Purity of Nickel Salts." Monthly Rev. Am, ElectrOplaters' Soc..g§, 79-94 (1922). Haring, H.E. "Throwing Powers of Nickel Solutions." Monthly Rev. Am. Electr0platers' Soc. 11, 4-15 (1924). Diggin, Myron B. "The Purification of Electroplating Solutions." Paper before Detroit Branch, Am. Elector- Platers' Soc. Nov. 2, 1945. Eckelmann, L.E. "Bright Nickel." Monthly Rev. Am. Electroplaters' Soc. 2;, 18-35 (1954). Johnson, L.?. "Bright Nickel Plating. Resume of Technical Literature.“ Metal Ind. (London) pp, 281-6 (1957). Francis-Carter, C. "Recent Developments in British Plating Practice." Proc. Amt ElectrOplaters' Soc., _2_'_7_, 9-16 (1959). Fink, 0.0. and Rohrman, F.A. "The Preparation of Pure Electrolytic Nickel. l The Elimination of 00pper from Nickel-Copper Electrolytes." Trans. Am. Electrochem. Soc. 51, 525-558 (1950). Raub, E. and Bihlmaier, K. "The Control of Nickel- Plating Baths." Mitt. Forschungs-Inst. Brobierant Edelmetalle‘g, 61-8 (1955). -55... I'I 10, ll. Waite, V.H. "Bright Nickel Plating." 'l‘lonthly ReV. Am. Electroplaters' Soc.,gg, 467-9 (1945). King, William.M. "Purification of Solutions, Methods of Operation, and Testing of Deposits." M.S. Thesis. Michigan State College. (1949). . Serfass, Earl J. and Levine, W.S. "The Determination of Trace Amounts of Copper in Nickel Plating Baths." Monthly Rev. A111. Electroplaters' 500. gig, 520-7 (1947). men's: MAY15'58' ('13 217915 tflva" tn cnia Rominski T54l.3 217915 R765 Rominski The effects of trace amounts of copper upon some physical properties of electrodeposited nickel 31293 02446 7189