O CINHWCI'J :1: F) m r-3 [‘1 :13 m ;> C <1 FL lHl H H IHHIWIHIII P UH ’ .l Hh‘ IJMQ ll camp ' 5““ .- cmNDER WEAR IN INTERNAL COMBUSTION ENGINES, [TS CAUSES AND PREVENTION Thesis for the Degree of M. S. MICHIGAN STATE COLLEGE Edmund Chester Sauvé 1941 v .‘ ~ ‘ 'IA . r-' of. , . . 9". '3' 13“ . . I. o 4 . us“, _ . .1 g . «a; - :3 '5 “‘3, :\ "13‘. "f ‘\ i ‘ "'57:. » I‘ t'v’ . ,_ . .. . . -.¢.'..-.‘.\ .3" _ . - - a ,‘A , . . ' Jr?!“ ; £3} 1“; ‘ ~’ . -.y4-""x._' ,. L. 'b' :3", 5;.“ r» \— * an", ‘n ' m _\ :z' a ‘3 ‘L 3; ‘5 t 3‘. W . . , ’.' . $3.".- .. " :5 .1". . ‘. ' x _ \:’\. .‘é- . ’ ;\_I' ~‘ 'v". '- 1,"ng ‘ u 1-3;, ':’-.~'.,S.J-‘- :4‘ .o'V b \ .fi’ : A. “J ‘ ~ g: ‘zg‘ft'f‘f' n- At ’E“.:.“O~‘ {c ‘ cnmmm mm m mama. COMBUSTION mums, ms cmszs mp PREVENTION By Edmund Chester vae' A TIESIS Submitted to the Graduate School of Michigan State College of Agriculture and Applied. Science in partial fulfilment of the requirements for the degree of MASTER 01' sermon Department of Mechanical Engineering Year 1911]. CONTENTS Introduction...................................................... History........................................................... Statement of the Problem.......................................... Method of Procedure............................................... Analysis and Comments............................................. The General Problem............................................... Lubricating 0119.................................................. Method of Securing................................................ Requirements of a Good LubricatiOn Oil............................ Deterioratim Promcing FactoreOOOOOOOOOOOOO0.0.0.000....00...COO. ”rasionOOOOCOCCOOOOOOCCOCOOOOOCOOO...000......000000000000.0.0... ErosionOOOOIOOOOO...0..0.00.0000...0..0...00...OOOOOOOOOOOOOOOOOOO corrosion.OOOOOOOOOOOOOOOOOOOOOO00....0......OOOOOOOOOOOOOOOOOOOOO Deteriorating Correcting Factors.................................. Improvement of Metallic Structure................................. Coatings for'Piston Rings......................................... Ierrox:Method..................................................... Granosol Coating.................................................. Altinizing........................................................ Feritex Coating................................................... Bonderite D....................................................... Cylinder Bore Structure........................................... Bubrication Oils - Better Refining Methods, Compounded Oils or Mditive80000000000.0.0.000...0.00000000000000000000000...... Refining by Use of Chemicals...................................... compounded Oils-Report Of TeBtSOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ILiquid compoundBOOOOOOOOOOOOOOOOO—OOOOOOOOOOOOOOOOOOOOOOOOOOO0.0... 13¢i~3 9 on mmm gFUUW N 10 12 12 13 13 1!: 1h 15 15 15 Solid Lubricants................................................. Water in Crank Case Oil - Seurces and Control.................... Foreign Material - Control of.................................... Conclusions...................................................... WWOOOOOOOOOOOOO0..OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO... “MOWIGmentBOOOOOOOOOOCOOOOOOOCOOOOOOOOCOOOOOOOOOOOOOOOO00.... Literature CitedOOOOOOOOOOOOOOOOOOOO0.00000000000000000.0.0.0.... BibliongOOOOOOOOOOOOOOOOOOOOOO0......OOOOOOOOOOOOOOOOOOOOOOO. 20 21 23 2M 2M 27 28 3O lr"lll|! .b’ 'I lit I'll! III'I GYLINDEB.WEAB.IH INTERNAL COMBUSTION ENGINES, ITS CAUSES AND PREVENTION Edmund Chester Sauve' INTRODUCTION The subject “cylinder wear“ as applied in particular to internal combustion engines. presents very wide application and interest in the world today. The registration of motor vehicles in the united States alone gives 3l.u68,887 units as of Jan. 1. l9hl. The number of farm tractors may be considered to be in excess of 1,500,000 units. The addition of many thousands of units of stationary engines, aircraft en- gines, industrial and marine engines make a total of gigantic propor- tions. Obviously then. the cost of servicing these units, owing to the single item of cylinder wear. reaches huge sums annually. The need of reducing these costs, by a.program to improve the conditions causing cylinder wear. has long been recognized by the industry as a whole. Much pregress has been made. It is, therefore. the purpose of this thesis to assemble and correlate the material made available through many years of experimentation. HISTORI ”Perfect lubrication“ are the two words which express the final solution to this problem of cylinder wear. The quality of the lubricant is necessarily very important, but owing to other factors. which will be discussed later, it will be recognized that perfect lubrication is as yet unattainable. Internal combustion engine lubricants are obtained essentially from petroleum, in its original form of crude oil, by the process of distillation. _ 2 - History does not record the earliest period when petroleum was first employed by man. It is believed to date back to Abraham's time, when vessels were constructed containing a.hydrocarbon known as bitumen. More than 7.000 years ago the Egyptians made extensive use of bitumen for embalming purposes. As early as 221 3.0. deep well drilling for petroleum was prac- ticed in China. It was at Cuba.Lake, N. Y.. in 1627 that a.missionary priest discovered the first oil pool known to the white man in North America. The use of a.lubricant for internal combustion engine uns doubtedly dates back to the time of’Drt N. A. Otto, a.German. who in 1876 received a patent on the first really successful engine operating on the four-stroke-cycle principle. No mention is made of the kind of lubricant used, but W. L. Nelson in his book Petroleum Refining Engineerb 235'states that mineral lubrication oils gained favor with the public during the period from 1885 to 1900 and continued to the present time. Prior to 1885 vegetable oils were considered the best lubricants. STATEMENT OF THE PROBLEM The problem is an endeavor to assemble, correlate, and analyse existing research.materials on the subject of ”Cylinder Wear in Internal Combustion Engines,“ listing all known contributing causes, with comments by eminent researchers as to the results of their experimentation and suggested methods for prevention of excessive cylinder wear. The expression ”cylinder wear“ is understood to include such parts as pistons and piston rings. for without the consideration of these re- ciprocating parts within the cylinder bore, the problem ceases to exist. The scope of this problem is limited to the field of published material made available through library sources. No attempt is made on -3... the part of the author of this thesis to incorporate his own views and opinions in its pages or to include any experimental data or conclusions of others not based on sound experimental procedure. METHOD OF BECOME! A bibliography on the subject was first prepared and added to from time to time as new material was published. Many of the articles were read and abstracted followed by the preparation of a card index of authors and subjects. These materials were then in such fom as to make them most useful in their analyses. ANALYSIS AND COWTS The General Problem The focal parts of construction of an internal combustion engine involved in this study are (l) the cylinder, (2) the piston rings and (3) the piston. These are the metallic parts that must resist the nu- merous actions tending to destroy their intended efficiency inopera- tion. It is not difficult to visualize an ideal lubrication system in which the reciprocating parts of an engine are separated by a film of oil of such thickness as to provide no metal-to-metal contact. This would, of course, assume proper mechanical clearances between cylinder and piston for all conditions of operation and a high quality lubricant free from contamination and capable of providing at all times a fluid film of oil between these reciprocating parts. The prime pur- pose of the internal combustion engine is to produce power, and this is accomplished by converting the heat units of a fuel such as gasoline into mechanical power at a pulley, shaft or wheel. The combustion of the fuel in an engine tends to destroy, in many ways, the equilibrium of the ideal system Just described. -14.- The farm tractor, for example, is required at times to perfom its work under extreme dusty conditions. The large quantities of air which the tractor engine requires for combustion of the fuel enters the cylin— ders not entirely free of the contaminants of the outside air. The com- bustion which follows in a normal process produces high temperatures and pressures which tend to destroy the ideal system and usually results in deterioration of cylinder, piston and rings. The crank case oil designed to lubricate these vital reciprocating parts also become contaminated with dust which enters through the breather opening, air moisture to condense as water, blowby gases, which carry water vapor as a product of combustion into the crank case, all of which act in the final analysis to produce cylinder wear. These few factors are mentioned here to indi- cate that a real problem does exist. Lubricating Oils Method of Securing According to refining process, all lubricating oils may be broadly divided into (a) distillates and (b) residuals. A distillate is any oil that has been vaporized and subsequently condensed in the refining process. Distillates comprise the bulk of lubricating oils now on the market. Their viscosity range is from 60 to 600 S.U. S. at 100° F. They are used as straight cut-oils or are blended with residual oils to make finished oils of different viscosities. A residual oil is any oil that has not been vaporized and subsequently condensed in the refining process. Notably in this class of residual oils are steam cylinder oils made from paraffin-base crude and the dark lubricating oils. Lubrication oils are secured from all three base crudes; namely, the paraffin crudes found in the eastern part of the country, the napthenic or asphalt crudes found in the far west and the mixed base -5- crudes found in the mid-west and the Rocky Mountain section of the United States. Most lubrication oils come from the mixed base crudes. Paraffin crudes produce lubrication oils of high quality. These oils are com- posed predominantly of the saturated hydrocarbons probably of the paraffin and naphthene series. The napthene base crudes were not considered desirable in the production of a high quality lubrication oil for internal combustion engines until the solvent extraction method of refining was developed, the reason being, that the oils derived from the refining of these crudes had a low viscosity index which is unsuited generally to mito- mobile and tractor engines. The mixed base crudes as the name suggests are mixed in character, being neither predominantly paraffinic or napthenic. Modern refining methods have made it possible to produce‘high quality lubrication oils from this mixed base crude, oils which are suited for all types of machines. . ' Requirements of a Good Lubrication Oil The term “Oiliness“ has been extensively used to designate the de- sired quality of a lubrication oil. Burwell (3) defines Oiliness as the property which an oil must possess to a sufficient degree to enable the oil to lubricate adequately under all conditions imposed by the machine for which the oil is desiaed. In general, well refined oils, either straight-run or blended, seem to be rather satisfactory as applied to low compression internal combus- tion engines. They should meet the following specifications: 1. Possess low internal friction. -5- 2. Have the ability to withstand rupture under extreme conditions of pressure and temperature. 3. Have a viscosity as low as possible, compatible with the particular use. M. Have the ability to cling to the metal surfaces which it must lubricate. 5. Should be chemically stable to resist oxidation. 6. Possess suitable flash and fire test characteristics. Deterioratingrgroducing Factors Cylinder wear will be found by examination to occur almost entirely in the space known as the ring travel. Therefore, it would appear that an attempt should be made to perfect the design of piston rings and cylinders to minimize this wear. The causes of cylinder wear are numer- ous and complicated and are indicated as (l) abrasion, (2) erosion, and (3) corrosion. Roensch (17) defines these terms as follows: Abrasion is wear due to foreign particles in the oil film. Erosion is wear due to metallic contact between the piston or rings and the cylinder bore. Corrosion is wear occasioned by oxidation or chemical action of the cylinder wall by the products of combustion. Abrasion Abrasives may get into an engine in any one of the following ways: 1. Core sand, cast iron fillings, chips and dirt left in the engine not taken out by the cleaning and washing process. 2. Valve grinding compound or cylinder honing residue due to improper cleaning. -7- 3. Road dust may enter the crank case with the ventilating air. 14. Road dust that comes into the engine through the intake system. These abrasive particles under engine operation soon find their way to the lubrication oil in the crankcase where they may be circu- lated through the engine in their path of metal destruction. This bad condition is made worse by the entrance of water into the crankcase oil, either by condensation due to cold weather or by water vapor accompanying the blowby gases as a result of combustion of the fuel. The lubrication oil on the cylinder walls, because of the intense heat of combustion, oxidizes forming asphaltenes. These as- phaltenes are subsequently deposited into an already contaminated oil system forming sludge. Clower (6) states that there is no doubt that oils having high oxidation numbers are readily susceptible to oxidation and produce soluble pitch-like materials commonly called asphaltenes. The presence of asphaltenes is accepted rather generally as being the cause of ring sticking in internal combustion engines. The importance of oil oxidation is expressed by Spitzglass and Zucrow (20) as follows: “Sludge is, however, largely the deteriora- tion products of the oil due to oxidation acting in conjunction with other impurities.‘I In general, sludge formation is usually associated with winter driving for Larson (11‘) states that 'Very little direct lubrication difficulty with any high quality products in farm equip- ment during the summer is experienced. This is especially true in regard to sludge.“ Blackwood (2) confirms the above citation when he states "Sludge is more dangerous in cold weather operation than in warm weather oper- ation. The cold weather operation results in condensation of water vapor inside of the engine. The oxidized materials and used oil readily -8... emulsified in this water to form.pasty'masses of semi-solid sludge.I The problem of sludge in lubrication oil was also recognized by Wagner (2h) who comments as follows: ”As some percentage of moisture or water will always be present in used crank case oil, emulsification may occur, causing the formation of soapy matter or sludge. A properly refined oil will have a.high degree of resistance to emulsification in.the presence of moisture, but the presence of other foreign materials, such as carbon and road dust, will increase the tendency to emulsify and cause the formation of objectionable deposits.II Since the circulation of an emulsified crank case oil is so imporb tant in producing abrasion of the cylinder and piston parts, it may be of interest to know the analysis of an average sludge deposit. Marshal (15) states that “most of these are high in oil; the lowest is 56 percent and most are above 70 percent. Asphaltic material is in all but two cases less than 10 percent, but carbonacemus solids lie between 10 and 20 per— cent for more than.half the cases. On an oil free basis the bulk of the solids are carbonaceous, partically all being above 50 percent and.most above 60 percent. The remainder is divided between asphaltic and inorh ganic material.“ Erosion Since erosion has been previously defined as a.metallic contact between pistons or rings and the cylinder bores.it is obvious that the oil film.between these parts has not functioned properly. Assuming that oil was present, erosion can take place as a result of a breaking down of the oil film to cause in its initial stage “scuffing“ and in its final stage “scoring”. Roensch (17) states that this metal-to-metal contact may be due to any one or all of the following: -9... 1. High spots on cylinder wall caused by mechanical and thermal dis- tortion. 2. High temperature of the cylinder wall which burns off the oil film. 3. Piston rings not giving uniform wall pressure or excessive wall pressure. h. High-spots on the piston that create high pressures and dry up sections of the cylinder wall. 5. Lubricating oils of low film strength that break down under load. 6. Oil not present at all, or washed off with gasoline or water as during cold starting and warming up. Roensch (17) says ”The worse condition for scuffing piston rings and bores during normal owner driving is present during the warm up period after a cold start at low temperature. The piston warms up much faster than the cylinder bore which is surrounded by cold water, with the result that the piston tends to get larger than the bore. This con- dition creates tremendous pressure during the time when the lubrication is very apt to be deficient.“ It is reasonable to conclude that, if erosion is to be prevented, the surface of the piston ring contacting the cylinder wall must be adequately lubricated. Sufficient oil must be present to give a continuous film capable of withstanding the bearing pressure. This applied to the compression rings as well as to the oil control ring. Sparrow and Scherger (l9) writes: “The experiment emphasizes the fact that the lubrication of the compression rings is dependent on the oil left on the walls by the oil control ring and that compression rings which receive insufficient oil because of a too effective oil control ring may be a.major cause of wear.“ Excess cylinder wall temperatures will cause a.breakdown of the oil permitting metal contact. Teetor (21) in this connection says: “When the surface temperature exceeds N00O F., a breakdown in lubrica- tion may be expected permitting metal-to-metal contact between the rings and the cylinder walls. If the operation under these conditions is of short duration, the scuffed surfaces may smooth.up under less strenuous operating conditions. The operation of some engines is a constant process of scuffing and smoothing up accompanied by high oil consump- tion, blowby and excessive wear.” Corrosion It has been known fer many years that corrosion takes place in internal combustion engines. The older as well as the more recent studies on this subject traced the cause of corrosion to the conden- sation of water vapor in the gases of combustion and in the air upon the cold metallic surfaces of the engine. In approximate terms, if all of this water vapor is condensed, it would amount to about 1 1/8 times the volume of the fuel burned. Ob- viously the greater amount of this water vapor passes out with the exhaust gases and does no harm. However, some of the condensed water vapor gets by the piston with the blowby gases, causing a deposition of water with.the crank case oil. In this connection Jardine (12) states that ”Ideal conditions for condensation exist when starting a cold engine, namely, hot moisture- laden products of combustion in contact with cold metallic cylinder walls. The water thus formed literally runs down into the crank case until the temperature of the cylinder walls rises above 110° 3., when condensation ceases. The period of condensation in an engine that is started at a.temperature of 10° F. has been shown to vary between 2 and -11- 10 minutes, the time depending upon the design of the engine and par- ticularly upon the size and type of the cooling system used.‘l Spitzglass and Zucrow (20) call attention to the fact that "The mechanism by which this condensed water caused corrosion has been little understood until recently. The earlier investigations attrib- uted the increased engine deterioration accompanying cold weather operation to the rusting of engine parts and mainly to the action of sulphuric acid upon the bearing surfaces; the sulphuric acid being formed by the combustion of the sulphur in the fuel to sulphur dioxide and the oxidation of this gas to sulphur trioxide and finally its solution in the condensed water. This explanation was widely accepted even though the sulphur content of gasolines is low and the analysis of the water in crank case oil showed no strong acid reaction. While the sulphur in the fuel may contribute to the corrosion of the engine to a slight extent, modern investigations tend to discount the theory that sulphuric acid is the main cause of corrosion.“ It is now gener- ally accepted that organic acids are responsible for most of the corro- sion caused in engines, for Williams (25) reports that: "The operation of an engine on hydrogen fuel effected a.very considerable wear at low temperatures, thereby suggesting that organic acids in the products of combustion are largely responsible for corrosion, water alone being insufficient." Furthermore, Blackwood (2) states that: “It is popu- larly believed and.has been frequently stated that high sulphur fuels cause rapid wear. Present knowledge on this point does not permit of making any such broad statement, even for low temperature operation. Some of the west coast gasolines are high in sulphur, and yet have given excellent performance for many years in areas experiencing bitter cold weather. On the other hand, there have been evidences of poorly -12- refined gasolines from low sulphur crudes giving excessive corrosion." In further evidence of the affect that organic acids play in producing corrosion, Spitzglass and Zucrow (20) said that available data show that "with low cylinder wall temperatures a blend of ethyl alcohol amounting to 15 to 20 percent in the gasoline produced practically twice the wear obtained using the same gasoline alone. In this case the sulphur content was less than normal and yet the wear was considerably increased." Thus Williams (25) concludes that since water alone or traces of sulphur in the presence of water are not the main causes of corrosion, the prinp cipal cause of corrosion has been attributed to the carbon-dioxide pro- duced by the combustion of the fuel forming carbonic acid in the presence of moisture. Deteriorating»Correctinggractors The causes of cylinder wear are definitely known by the researchers who have studied this problem. In recent years many investigators have studied the various factors which would be at least partially successful in minimizing cylinder wear. Some of these most important factors are discussed in the following pages. Improvement of Metallic Structure In the prevention of cylinder bore wear due to erosion or corrosion, the design of the cylinder block and piston rings are of great importance. Much improvement has been made with piston rings using alloys, but only slight progress has been made in cylinder block design according to Roensch (17) for he states: “Some tests have shown that a 50 percent reduction in wear has been affected by the use of small additions of cOpper to the cylinder block. Nickle, chrome and molybdenum have con- tributed some improvement, but very little actual performance data has been reported.’I It is generally believed that regardless of the material - 13 - used, ideal bore wear is accompanied by steady operation. Intermittent driving gives from two to five times the wear compared with steady driv- ing according to Roensch (17). He continues, ”If the material in the cylinder bore scuffs easily the bore wear is apt to be excessive, because for low rates of wear it is absolutely essential that the bore and ring face become smooth. If ring alloys polish in readily, long life will result. The worst condition for scuffing of piston rings and horse come during the starting period in cold weather. Heat of combustion reaches the piston rings causing expansion, whereas cylinder walls remain cool due to the cold cooling water. Tremendous pressures are created on the cylinder walls when lubrication is usually deficient, causing scuffing. Anodizing or coating of pistons to make them hard yet porous to hold oil is a.great improvement to cut down scuffing. Tin plating also helps, by producing in the plating a lubricant at these high pressures.” Lane (13), in commenting on Roensch's (17) discussion, offers the following conclusions as a result of tests that cylinders should be finished co-directionally with ring travel and suggests the use of alloy rings that will be non-seizing or self-lubricated during the dry period. An iron-bronze piston ring has been used successfully in diesel engines, increasing life of moving parts by minimizing scuffing. Coatings for Piston Ringg: A.great number of piston ring manufac- turers are now using some process to provide a coating on the rings to minimize scuffing and wear. Several methods will be indicated here. Ierrox Method: This method produced by one manufacture is derived from ferroso - ferric oxide (F930h)' the magnetic oxide of iron, also known as magnetite. In this process the parts to be coated are subjected to a temperature of approximately l,OOO° I. in the presence of a suitable gaseous oxidizing agent in a closed chamber. - 1h - The iron will form a number of different oxides, and to produce a proper compound with the desired physical attributes, with a gradual transition from the surface layer to the core, calls for accurate temperature control, uniform heating and correct introduction, dis- tribution and maintenance of the oxidizing medium. The formation of the oxide hematite (3e303) must be guarded against, as this forms a soft film lacking adherence and presenting an unsightly reddish color. Since oxygen combines with.the iron during the process, there is a slight growth which must be allowed for in machining. Granosol Coating: This coating consists of an iron phosphate with a high percentage of manganese phosphate. It is softer than gray iron and is sufficiently porous to absorb an appreciable amount of oil. The material is a.dielectric and has anti-welding properties, which together with its oil-absorbing properties make it an excellent scuff preventative. The coating is produced by immersing the part in an aqueous solution of phosphoric acid saturated with iron and.manganese phosphates at a tame perature of 2100 F. The surface of the iron is attacked by the acid, iron phosphate being formed, hydrogen freed and manganese phosphate deposited. After coating to a depth of 0.00025 inch. the action slows down to a low rate. The etching action of the acid ordinarily would re- duce the dimensions of the part, but since the phosphoric acid already is saturated with iron phosphate, the coating does not dissolve, but remains integral with.the piece treated. There is a slight volume ins crease owing to the process not exceeding 0.00015 inch. Altinizing: This process consists of the electro deposition of tin on the ring surfaces. Before the plating process is started the surfaces must be cleaned chemically and then acid-etched to insure adv hesion and prevent blistering of the coating. The plating ordinarily - 15 - is effected in a bath of sodium stannate solution, but it can be accom- plished also in an acid bath of a tin salt. Ieritex Coating: This coating is produced by immersing the cleaned rings in a bath of sodium hydroxide, sulphur and water, which removes certain constituents of the cast iron and produces a slightly porous surface covered with a very thin film of iron sulfide. Bonderite D: This process produces a.coating of zinc and iron phosphates in a bath containing phosphoric acid and zinc phosphate. An activator is always used and a very fine grained soft and porous coat— ing is produced. After coating, the rings are dipped in an emulsion of soluble oil and water, holding Acheson colloidal graphite in suspension. The chemical coatings such.as iron manganese and zinc iron phos- phates are softer than the raw iron, which also makes possible a quick initial seating. However, while the coating as a whole is soft the individual crystals are harder than the iron, so if they are scuffed off they aid in lapping in the parts. The metallic coating is the softest of all and, therefore, facilitate rapid seating. This material is also rather plastic which causes the load to be distributed over the face of the ring, thus preventing high local pressures that might break the oil film and cause scuffing. The metallic coating also retains a consider- able amount of oil which may help under conditibns of boundary lubri- cation. Cylinder Bore Structure: Cylinder bore wear has been very definitely related to the presence of ferrite in the metal. Smith (21) stated that in his study he examined.many specimens from cylinder bores at a point about % inch from the top of the bore. The examination of specimens from five different sources appeared to indicate that there was a re- lation between the amount of ferrite present in the structure and wear, - 16 - the more ferrite present the greater the wear, provided normal thin flakes of graphite were present. He concluded that the best cylinder bore structure at position of maximum wear should consist of an entirely pearlitic matrix, with long thin flakes of normal graphite, no ferrite and sufficient small particles of iron chromium carbide to increase re— sistance to wear, Dierker, Tried and Dawson (9) declared that the results of their tests indicated no correlation between seizure, resistance and micro- structure. Large amounts of carbides or ferrite are not desirable in specimens, also since no relationship between Brinell hardness and the tendency of the material to seize has been found, seizure is not likely to be avoided by using harder materials. Teetor (22) in discussing the subject of structure says ”Structure of the cylinder material is far more important than hardness or analysis. Ierrous materials having the same hardness and analysis can have entirely different structures. The structure of cast iron is affected by the rate of cooling. Iron from one ladle poured into molds of different dimensions will have different structures. At certain critical temperatures during the cooling period definite changes in structure take place. Alloys change these critical temperatures thus affecting the structure. Heat treatment can take advantage of these critical temperatures and rearrange structure. Therefore, in studying wear characteristics, structure in addition to analysis, hardness and physical characteristics should be considered.“ Jackson (11) in discussing the sulfide process in connection with cylinder liners for diesel engines says: "The liners after finish honing are cleaned and then immersed in a concentrated water solution of sodium hydroxide and a small amount of sulfur. The process is one of etching - 17 - and literally might be called a controlled pitting process. Any free ferrite at the bore surface (and free ferrite should not be in any bore surface) is etched from the matrix. The carbide constituent of a pearl- itic matrix is also reacted upon by the solution and fine lamellar pearlite is etched away leaving small pits filled with etching and products.I Jackson (11) remarks that chemical surfacing treatment of cylinder liners is not the complete answer to the problem. The choice of both lubricating oil and liner material is subject to no less rigid specifications. The methods by which chemical treatment makes the liner bore surface more susceptible to safe run in are, according to Jackson (11), (1) by removal of the undesirable components of surface composition, (2) the deposition of certain chemical and products upon the surface and (3) by change in the surface configuration. The important surface metal to be removed by etching is the strain— hardened metal formed on the surface by honing. When the layer by honing is removed in etching, the running-in process begins with non-strained metal, insofar as the transformation is concerned. Jackson (11) concurs with other investigators when he says nThe most readily welded constituent of the cast iron of either piston rings or liners is free ferrite. For this reason the presence of free ferrite in either ring or liner bearing surface is undesirable. The removal of this free ferrite in the process of chemical surfacing is a definite aid toward the administration of a safe run in." The advantage of etching the surface of the liner is mentioned by Jackson (11) when he says: “When free ferrite and small grains of fine pearlite are etched by the caustic sulfur solution, pits are formed which will be filled partially by the sulfide-oxide end products. - 13 - These pits serve as reservoirs to hold a supply of lubricating oil to meet local surface needs during any period of boundary lubrication. The superficial sulfide-oxide coating is removed during the run in, but the pits, on the other hand, last for many hours after the run in.” Lubrication Oils - Better Refining Methods, Compounded Oils or Additives Refining_by'Use of Chemicals: Chemicals are used in petroleum re- fining processes for two purposes according to Clower (6), (l) to remove objectionable foreign substances such as sulphur compounds, tars, gums, resins and carbon and (2) to separate the hydrocarbons on the basis of their chemical activity and structure. The distillation process separates the molecules according to their size only, but petroleum contains many molecules which are approximately of the same size but which chemically are quite different. For example, Clower (6) continues, an oil may and usually does contain paraffin, olefin, napthenic, aromatic and other hydrocarbons. Although the molecules of the various hydrocarbons may be of the same size, yet their chemical activity and structures are widely different. Improvements in the quality and suitability of petroleum prod- ucts may be accomplished not only by removing undesirable constituents and impurities and by changing the chemical structure of others, but also by adding to them various agents. These agents or inhibitors were first used in gasolines, but more recently were added to lubricating oils, for the purpose of not only to retard oxidation while in service, but also to improve_viscosity inder, pour point, oiliness, load carrying capacity or film strength. The use of animal and vegetable oils and fatty acids to improve oiliness of mineral oils has been practiced from the very beginning of the lubricating oil industry. At the present time several addition agents are used, designed to improve oil. They are Exanol (or Paratone) to improve viscosity index; benzyl chloride, aluminum stearate, - 19 - zinc and magnesium hydrostearate. and esters of cholesterin acting as pour point depressants. Lead soaps, sulphur and chlorides have been used alone and in various combinations for increasing the film strength of lubrication oils. Compounds of phosphorus, arsenic and antimony and organic compounds of chromium, bismuth, mercury and other metals are employed as corrosion inhibitors. Oxidation inhibitors include phenolic derivatives, naphthols, naphthylamines, aniline derivatives, elementary sulphur, disulfides, chlorine, phosphorus, arsenic, antimony, selenium and tellurium. Compounded Oils - Report of Tests: Research workers in this field of lubrication oils containing additives haye expressed themselves pro and con. Liquid Compounds: Neely (16) points out that the great majority of oil soluble compounds will reduce coefficient of friction for some operating conditions, therefore, improving oiliness, but the effective- ness of such compounds on wear reducing value of the lubricants often may be considered different in degree and sometimes in direction from the effect on friction. His conclusion is that friction and wear do not correlate and that high oiliness of compounded oils does not nec- essarily result in low wear. Carton (10) states in confirmation of Neely's experiments, “That under high load conditions, oils of the same viscosity and viscosity index may show closely similar friction characteristics, but measurable differences in wear.“ Barnard (l) in commenting on Neely's paper states “That a reduction of friction between heavily loaded rubbing surfaces is frequently attended by increased wear. In fact, this occurancs appears to be the rule rather than the exception." - 20 - Not all investigators agree with the above mentioned comments, for Rurwell (h) maintains that his company possesses considerable evidence that a "proper degree of oiliness in lubricating oils of the most various kinds contributes infallibly to the reduction of wear.“ He continues, ”Our corporation believes it is possible to select addition compounds that will lower friction, greatly decrease wear and in many cases prevent corrosion due to chemical changes in the lubricant.“ It may be said at this point that Neely's (16) experimental work did not involve the use of an actual engine under test, and, therefore, Davis (7) comments, ”That considering the dissimularity of his (Neely's) appara- tus compared to the operating parts of automotive engines, and the ques- tion as to whether his apparatus shows the effects of viscosity, film thickness, extreme pressure characteristics or oiliness, I fear it is difficult to feel much nearer to a solution of the problem of oiliness and wear.“ He concludes, ”Mr. Neely has emphasized clearly a point that we should always bear in mind, that all materials which may be added to oils to reduce their frictional characteristics do not necessarily re- duce wear. By the same token extreme care must be used in drawing con- clusions from tests on one particular apparatus and applying them to an entirely different test.” Solid Lubricants: Graphite is considered to be the most important of the solid lubricants and is often mixed in colloidal form with the lubrication oil. In the Acheson process graphite is produced in the electric furnace from anthracite coal and petroleum coke. The product is of a soft, greasy, noncoalescing nature and is almost chemically pure with not less than 99 percent of pure carbon. It is ground to 200 mesh and deflocculated by treatment with a.water solution of tannin. As a result of this treatment, colloidal graphite is produced. This colloidal -21... graphite is obtained for commercial use dispersed in liquids such as distilled water, mineral lubricating oil and glycerin. According to Clower (6) the chief advantage of graphited oil and greases is to form films of graphite on the bearing surfaces of mechanical devices. These films are closely bonded to the metal and possess a low coefficient of friction. Also at ordinary temperatures graphite is not affected by acids, alkalies or halogens. Tests conducted by Diakoff (8) indicated rather satisfactory results from the use of a colloidal graphite known as "Pyroil". His conclusions of tests conducted on a semi-diesel engine were as follows: The presence of Pyroil in lubrication oil in the quantity prescribed by the company reduces fuel consumption in the range of 11.5 percent, reduces frictional losses in the range of h6.6 percent. It also reduces the temperature of the cylinder walls of the engine and of the exhaust gases. Its presence in fuel does not make a noticeable improvement in the performance of the tested engine. Diakoff continues by saying, "The consequences of its usage may be the formation of hard, highly polished, wear resisting, graphitized surfaces with low coefficient of friction, permitting bear- ing surfaces to run at higher temperatures or carry higher loads, to use less oil, or use inferior oils and to improve starting.I There is not enough available published material on this subject for complete acceptance of these results. Water in Crank Case Oil - Sources and Control Water enters the crankcase of internal combustion engines from three principal sources: 1. The blowby of the combustion gases past the piston. 2. The condensation of water vapor from the air in the engine, on the walls of the cylinders and crankcase. - 22 - 3. The condensation of the moisture in the air used for ventilating the crank case. I The largest potential source of water is the moisture in the products of the combustion of the fuel when they enter a cold engine. Obviously only a small part of the water vapor produced enters the crank case since most of it passes out with the exhaust. The ideal conditions for the deposition of water are present when a cold engine is first started. The hot moisture laden gases formed by the combustion of the fuel come in contact with the cold metallic walls and deposit a part of this moisture. The crank case of an engine, until it becomes heated up, acts as a conden- ser for all of the exhaust gases that pass downward by the pistons. when the crank case becomes thoroughly warm, the greater portion of such exhaust gases passes on out through the breather. A.hot, running engine allows much less water accumulation in the oil pan than a cold one. Clayden (5) says "No water is deposited if the cylinder wall tempera, ture exceeds 110° F. Furthermore, tests indicated that the rate of de- position increased in direct proportion to the drop in cylinder wall temper- ature below 110° F. The explanation of this action undoubtedly is that 110° F. represented the dew point for the water vapor present for the average conditions of pressure existing where the cylinder walls are exposed." Thus it is evident that if abrasion is to be minimized, water must be kept out of the crank case, because of its relationship in the former tion of emulsion sludge. Thorns (23) says, “The thermostatic control of jacket water temperap ture serves to shorten the warming-up period and maintain a.higher operating temperature.' Either manually or thermostatically controlled radiator shut- ters serves a similar purpose.I - 23 - Foreign Material - Control of Road dust is undoubtedly the principal cause of cylinder wear if not controlled, for road dust, because of its character, is highly abrasive when mixed with lubrication oil. The sources of dust accumulation are in the combustion air and in the air used for ventilating the crank case. Roensch (17) states, ”Road dust has been the cause of more engine repair and replacement in service than almost any other single factor. Even with the improved air cleaners now generally used, dust entering the engine still causes more wear than most peOple suspect.'I The accumulation of road dust is a serious problem in tractor operation and is given considerable thought in tractor design. In this connection Spitzglass and Zucrow (20) have indicated several means to combat the in- fluence of dust in reducing cylinder wear as follows: 1. Cylinderbblock hardness and alloy content: Soft or porous cylinder block.will cause abnormal wear irrespective of the presence of dust. Until the iron is made very hard there is, however, very little dif- ference in the range of wear normally encountered in present day pro- duction practice of 180 - 220 Brinnell. With centrifugally cast iron liners having a hardness of 500 Brinnell, Operation under dusty condi- tions will give less bore wear than with the normal cylinder block iron of 200 Brinnell. 2. Piston-ring line-up and ring design: Wider piston rings having less unit pressure show a lower rate of wear. 3. Piston-ring material and design: With abnormal amounts of dust enter- ing the engine, cast iron pistons show less piston and cylinder-bore wear than do aluminum pistons. 5. 1. 2. 1. 2. - 2h - Improvement in air cleaners: Recent developments in air cleaner con- struction and experience with these devices in tractor service lead one to believe that air cleaners which are 100 percent efficient are within the realm of possibility. Improvement of oil filters: There is great activity in improving the effectiveness of oil filters and the future, no doubt, will see great advancement in the effectiveness of these devices. CONCLUSIONS The result of this study has emphasized the fact that there are still ' many problems unsolved with reference to this subject of cylinder wear. Much progress has been made as most users of automotive equipment know. It is obvious that the perfect lubrication system in all its ramifica- tions is unattainable. There is a vital need for the education of users of automotive equip- ment to enable them to better understand the importance of the many factors presented in this thesis. SUMMARY The cost of servicing approximately 33,000,000 motor vehicles and farm tractors annually due to cylinder wear reaches sums of huge proportions. Engineering research during the past seventeen years has aided greatly in reducing cylinder wear cost. Cylinder, piston and piston ring wear are caused from (a) abrasion, (b) erosion and (c) corrosion. Abrasion is wear due to foreign particles in the oil film. Erosion is wear due to metallic contact between the piston or rings and the cylinder bore. Corrosion is wear occasioned by oxidization or chemical action of the cylinder wall by the products of combustion. - 25 - 5. Abrasion represents in normal operation the greatest source of cylinder wear. 6. Crank case sludge is formed as a result of foreign impurities such as road dust mixed with water of combustion and condensation, and the material formed due to oxidation of the oil film. 7. Piston ring sticking is attributed to the oxidation of the lubricating oil film forming pitchelike materials called asphaltenes. 8. Sludge formation is generally associated with winter driving at a time when condensed water vapors of combustion more readily reach the crank case and the lubrication oil. 9. A.highly refined lubrication oil is a deterrent to the formation of sludge. lO. Erosion may occur as a result of high spots on piston and cylinder walls, high cylinder wall temperatures, lack of uniform piston ring pressure, lubrication oil of low film strength and absence of oil, that is oil which is not present at all or oil that has been washed away by the unburned fuel or by the water of combustion. ll. Teetor (21) remarks that a surface temperature in excess of uoo° F. may cause a breakdown of the oil, permitting metal-to-metal contact. 12. Corrosion has been definitely attributed to the formation of carbonic acid produced by the combustion of fuel in the presence of moisture. 13. The use of alloy metals such as copper, nickle, chrome and molybdenum have contributed in some measure in the reduction of wear due to erosion and corrosion. 1h. Ideal bore wear, regardless of the materials used, is generally associ- with steady rather than intermittent operation. 15. Coatings of piston rings and pistons have been employed with the result that scuffing and wear have been minimized. Several methods are discussed. 16. 17. 18. 19. 20. 21. 22. 23. - 26 - Ferrite in the cylinder bore structure is very undesirable. Smith (27) implies from his study that there is a direct relation between wear and the presence of ferrite. The ideal structure should consist of a pearlitic matrix with long, thin flakes of normal graphite, not ferrite, and sufficient small particles of iron chromium carbide to increase resistance to wear. Structure of the cylinder material is far more important than hardness or analysis according to Teetor (22). The surfide process developed to improve diesel engine cylinder liners is a controlled pitting process in which the undesirable ferrite is etched away. The pits formed contain sulfide-oxide end products and also serve as reservoirs to hold a supply of lubrication oil. The use of chemicals in the refining process has contributed greatly to the improvement of lubrication oils for they may retard oxidation, improve viscosity index, pour point, oiliness and load carrying capacity or film strength. Compounded oils are said to improve the friction characteristic of the oil and in some cases to reduce wear. However, Neely (l6) remarks that all materials which may be added to oils to reduce their friction characteristics do not necessarily reduce wear. Colloidal graphite as produced from the Acheson process has been satis- factory in improving engine operating conditions in general. Water deposition in the crank case oil as a result of the combustion gases, is stopped for cylinder wall temperatures in excess of 110° F. according to Clayden (5). Either manually or thermostatically controlled radiator shutters serve to shorten the time necessary to bring cylinder wall temperatures to normal, thus reducing water accumulation in crank case. - 27 - 25. Continued improvement of cylinder, piston and ring materials, along with improved air cleaners and oil filters will aid considerably in reducing cylinder wear. ACKNOWLEDGMENTS The writer wishes to express his appreciation to the following individuals and companies whom they represent, for special assistance in making this report possible: Arthur W. Burwell, Technical Director of the Alex Chemical Corporation; Professor A. J. Diakoff of the Mechanical Engineering Department, University of North Dakota; G. L. Neely, Research Engineer, Standrad Oil Company of California; Dr. M. J. Zucrow, Consulting Engineer, Chicago, Illinois and the Pines Winterfront Company, Chicago, Illinois. 9. 10. 11. 12. 13.. 1h. 15. 16. 17. 18. -25.. LITERATURE CITED Barnard, E. R. High Oiliness - Low Wear - Discussion, S.A.E. Trans. 1937. pp. 5&8-552. Blackwood, A. J. The Performance of Engines at Low Operating Tem- peratures. S.A.E. Trans. 1935 pp. 70 and 76. Bur-well, A. W. Oiliness. Alox Chemical Corporation. 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Larsen, G. M. Lubricants. S.A.E. National Tractor Meeting. Milwaukee, wisconsin. @r. 15, 1938. Marshal, A. G. A Report on Chemical and Physical Changes of Oil During Use. American Society of Testing Materials. bl Annual Meeting 1938. Neely, G. L. High Oiliness - Low Wear? S.A.E. Trans. 1937. pp. 5&6-552. Roensch, Max M. Observations on Cylinder Bore Wear. S.A.E. Jnl. Mar. 1937. PP. 89-98. Smith, E. K. Cast Iron Cylinder Bores, Observation on Microstructure, Composition, Hardness and Wear. Trans. American Foundrymens' Assoc. Vol. us. lguo. pp. 667-772. 190 20. 22. 23. 2h. 25. - 29 - Sparrow, 3. W. and Scherger, T. A. Cylinder Wear - Where and Why? S.A.E. Trans. 1936. p. 121. Spitzglass and Zucrow Engine Lubrication and Deterioration. Bulletin Prepared for Pines Winterfront Company, Chicago, Ill. Teetor, M. 0. Cylinder Temperature. S.A.E. Trans. 1936. p. 330. The Reduction of Piston Ring and Cylinder Wear. S.A.E. Trans. 1938. p. 137.. Thorns, M. A. Thermostatic Control of Jacket Water Temperatures. 3. LE. Trans. 1923. Wagner, L. T. The effects of Engine Operation on Lubricating Oil. 5.1.3. Trans. 1925. Part II. pp. 263-267. Williams, C. G. Cylinder Wear in Gasoline Engines. S.A.E. Trans. 1936. p. 192. -30.. BIBLIOGRAPHY Anon - Additives in Diesel Fuels. Bul. 394. Alex Chemical Corporation, Niagra Falls. Additives in Lubricating Oils. Bul. 391. Alex Chemical Corpora- tion, Niagra Falls. Coating for Piston Rings and their Effect on Ring and Bore Wear. Automotive Industries. Mar. 15, 19%. pp. 288-289. Effect of Oiliness in Hydro-dynamic Lubrication. Bul. 138. Max Chemical Corporation, Niagra Falls. Effects of "Oily" Lubricants in Engines. Form 2-8. Alox Chemical Corporation, Niagra Falls. New Coatings for Pre-lubricating Surfaces. mtomotive Industries. 9. 55“. New "RPM“ Delo (The Correct Lubricant for all Diesel Engines.) Standard Oil Co. of California. Oxidation of Oils in Service and Its Relation to Bearing Corrosion. Bul. 238. 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Templin, E. W. Crank Case Oil Temperature Control. S.A.E. Trans. 1937. pp. 325-3h2. Wagner, Lawrence T. The Effect of Engine Operation on Lubrication Oil. 5.1.n. Trans. 1925. pp. 32-9u. Williams, C. G. Cylinder Wear in Gasoline Engines. S.A.E. Trans. 1936. pp. 191-199. R0 «v- m Ubt ONLY - In. -.I *‘I ~ l.)" '0 5' “fin v . J :..'Iv"‘ . ‘f . -.- : 'k I‘ . , J?- (”1.1. :03; 1" 3‘ u. ‘ " ‘ K‘k I ," ‘r r. .5 -j“)!" \ w -- ~ I E! .i‘ w . ' 5. 51'}, k 1" ¥.$‘-) “.7 .-. {“1 a. «s r.§§°v.' ‘22. x 1..“ . -. .ai‘r been .4 - ’ . .6 . ‘ ‘ u‘ ‘ is 8&3: 1 , ' ‘ ' . ‘. .... .(l‘fl; (“f-2 It . 7.31153 _ ,g-‘r. ’ . ' -'.:.)3"$J"1",J%1)¢: 'fl‘kfi‘r i; '. its {3" xiii =~$J£I§€LTTIWN {(4 first , 41 Wt“? M‘fiA" r M “a: .1..?‘J:.- r- . 1 ".k/ PJ':$.:§ 55.2.? 1. ' 5" ‘2“. \"lh'fg‘nf‘kfi‘ '3" ."~ .W- to? . 5 J . Lily". . .1. I w .7 ‘ .0.“ 7’} ;.. X: . . 0' . . .‘ .. . .I .' . ‘ ‘ o . ‘ .‘a 'h i ." J- .1‘.‘ l ' . «1‘ a " ‘.‘_'4 '7. . i. p . “4.4%. .1 7-. , ‘j a“ ‘ O 7 7‘ .. The _ n ’ wv'w _iR5t . 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