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ASM Handbook, Volume 18: Friction, Lubrication, and Wear Technology Copyright © 1992 ASM International® P.J. Blau, editor, p 785-794 All rights reserved. DOI: 10.1361/asmhba0002331 www.asminternational.org

Friction and Wear of Aluminum- Alloys

Barrie S. Shabel, Douglas A. Granger, and William G. Truckner, Technical Center

ALUMINUM-SILICON ALLOYS are noted provide the bearing surface, resulting in im- resistance of these alloys. The silicon is for their unique combination of desirable charac- proved wear resistance. Jorstad (Ref 6) has sug- cubic with a of --2.6 g/cm 3 teristics, including excellent castability and low gested the use of this for other weight- (0.094 lb/in. 3) and a Vickers hardness of ap- density combined with good mechanical proper- saving applications where good wear resistance proximately 10 GPa (1.5 × l06 psi). Silicon is ties. Interestingly, there is no mention of wear is required (for example, brake drums and disk essentially insoluble in aluminum (Ref 10). Fig- resistance in the many published tabulations of brake rotors). ure 2 illustrates the typical microstructurc of a the attributes of this class of alloys (see, for A powder (P/M) production route common hypoeutectic alloy, A357.0. Hypereu- example, Ref 1 and 2). In a comprehensive re- for the manufacture of cylinder liners from hy- tectic alloys, the most commonly used wear- view of the wear characteristics of aluminum pereutectic aluminum-silicon alloys has also resistant alloys, contain coarse, angular, pri- alloys, Eyre (Ref 3) remarks on the dearth of been explored (Ref 4). Using this method, the mary silicon particles as well as eutectic silicon. published information about the wear resistance size of the primary silicon particles may be opti- These primary silicon particles impart excellent of aluminum-silicon alloys, while acknowledg- mized and can be added to the wear resistance to these alloys. A typical micro- ing their increased application in environments matrix to serve as a . The liners are then structure of an unrefined hypereutectic alloy demanding this physical characteristic. inserted into the engine , which is pro- (A390-type) is shown in Fig 3. in the late 1950s, cast aluminum-silicon duced from conventional aluminum-base alloys. Commercial aluminum-silicon alloys (Table alloy cylinder blocks were manufactured for the While applications for aluminum-silicon al- 1) generally contain other alloying elements to automotive to take advantage of the loys are currently centered in the automotive further enhance or modify the wear resistance or weight and good of_ industry (which accounts for greater than 50% of impart additional properties to these alloys. fered by hypoeutectic alloys such as A356 and the market), other applications in communica- . The most common alh)ying clement is A380 (Ref 4). However, because these alloys tions equipment, instrumentation, and small en- iron, which can be tolerated up to levels of 1.5 to exhibited only modest wear resistance, the early gines appear likely. The hypereutectic alloys are 2.0% Fe. The presence of iron modifies the sili- engine blocks (for example, those produced for likely to dominate because their wear resistance, con phase by introducing several AI-Fe-Si the American Motors Corporation Rambler) had combined with low coefficient of thermal expan- phases. The most common of these are the c~ and a cast-in cylinder liner. In Europe, automo- sion (CTE) and fluidity properties, allows thin- 13 phases. The a phase has a cubic struc- tive engine blocks were also being die cast in ner wall castings to be manufactured. ture and appears in the as a "'Chi- aluminum-silicon alloys (such as LM24 and Both the Aluminum Association (AA) and the nese script" eutectic. The less common [3 phases LM26), but these blocks had liners that were Society of Automotive Engineers (SAE) desig- shrink-fitted in place. A major boost was given nations are commonly used to classify alumi- to the use of lightweight aluminum alloys in num-silicon alloys in the United States. Atomic percent silicon 10 20 30 40 50 60 70 80 90 100 automobiles when the energy crisis in the early 1400 I I I I I I I I I 1970s resulted in the government mandating im- Metallurgy of 1300 proved fuel consumption in automobiles. Be- Aluminum-Silicon Alloys cause fuel consumption can be directly related to 1200 vehicle weight (Ref 5), the use of aluminum in Aluminum alloys for wear resistance applica- 1100 place of in engine components became tions are based on the aluminum-silicon alloy 0 1000 highly desirable. However, the use of die cast system. This binary system is a simple eutectic 900 aluminum engine blocks with a cast iron cylin- alloy system with the eutectic composition at 80o ~60,4 L -25o~ der liner proved to be too costly in production, 12.5% Si (Fig 1). Standard alloys, of course, ~ 700 paving the way for the development of hypereu- contain a number of alloying ingredients. Se- ~ 600 ~/ s.oc tectic aluminum-silicon alloys with greater wear lected commercial alloy compositions are shown 1.65 12.6 resistance that could be used without liners. in Table 1. Table 2 cross references United 5OO 400 One such alloy that has been developed spe- States aluminum-silicon compositions with -- (AI) (Si) -- cifically for its high wear resistance is the hyper- compositions of European and Japanese sources. 300 eutectic aluminum-silicon alloy A390 (A390.0), At room temperature, the hypoeutectic alloys 200 I I I I I I I I I which has been used in engine blocks without a consist of the soft, ductile primary aluminum 10 20 30 40 50 60 70 80 90 100 liner. An electrochemical surface treatment is phase and the very hard, brittle silicon phase AI Weight percent silicon Si used to etch away some of the matrix aluminum associated with eutectic reaction. It is this sili- Aluminum-silicon binary phase diagram. so that the eutectic and primary silicon particles con phase that contributes to the very good wear Fig 1 Source:Ref 7 786 / Materials for Friction and Wear Applications

Table 1 Nominal compositions of selected commercial alloys Al9Fe2Si2-type constituents. The - recommended for wear applications bearing constituents are typically less needlelike or platelike than the manganese-free iron- or Composition, wt% (iron/silicon)-bearing primary constituents. Man- Alloy SI Fe Cu Mg Mn Other ganese additions also improve elevated-temper- ature properties of the aluminum-silicon alloys. Hypereutectic alloys Cumulative Effect of Alloying Elements. In 390.0 16-18 1.3 4-5 0.45 -0.65 0.1 • • • summary, aluminum wear-resistant alloys are A390.0 16-18 0.5 4-5 0.45-0.65 0.1 • • - B390.0 16-18 1.3 4-5 0.45 -0.65 0.5 1.5 Zn based on alloys containing the hard, brittle sili- 392.0 18-20 1.5 0.4-0.8 0.8-1.2 0.2-0.6 0.5 Ni, 0.5 Zn, 0.3 Sn con phase. Alloying element's such as iron, man- 393.0 21-23 1.3 0.7-1.1 0.7-1.3 0.1 2-2.5 Ni ganese, and increase the volume fraction Eutectic alloys of the silicon-bearing phases, con- tributing to increased wear resistance compared 384.0 10.5-12 1.3 3-4.5 0.1 0.5 0.5 Ni, 3 Zn, 0.35 Sn 336.0 11-13 1.2 0.5-1.5 0.7-1.3 0.35 2-3 Ni, 0.35 Zn to binary aluminum-silicon alloys. In addition, 339.0 11-13 1.2 1.5-3 0.5-1.5 0.5 0.5-1.5 Ni, 1 Zn and copper also provide additional 413.0 11-13 2 1 0.1 0.35 0.5 Ni, 0.5 Zn strengthening by producing submicroscopic pre- 4032 11-13.5 1 0.5-1.3 0.8-1.3 • • • 0.5-1.3 Ni cipitates within the matrix through an age-hard- Hypoeutectic alloys ening process. 319.0 5.5-6.5 1 3-4 0.1 0.5 0.35 Ni, 1 Zn 356.0 6.5-7.5 0.6 0.25 0.2-0.45 0.35 0.35 Zn Properties and Structure 364.0 7.5-9.5 1.5 0.2 0.2-0.4 0.1 0.25-0.5 Cr, 0.15 Ni, 0.15 Sn 380.0 7.5-9.5 2 3-4 0.1 0.5 0.5 Ni, 3 Zn, 0.35 Sn Alloying aluminum with silicon at levels be- 333.0 8-10 1 3-4 0.05-0.5 0.5 0.5 Ni, 1 Zn 332.0 8.5-10.5 1.2 2-4 0.5-1.5 0.5 0.5 Ni, 1 Zn tween about 5 and 20% imparts a significant 360.0 9-10 2 0.6 0.4-0.6 0.35 0.5 Ni, 0.5 Zn improvement in the characteristics rela- 383.0 9.5-11.5 1.3 2-3 0.1 0.5 0.3 Ni, 3 Zn, 0.15 Sn tive to other aluminum alloys. As a result, these

Source: Ref 8, 9 high-silicon alloys are generally utilized as cast- ing alloys rather than for the manufacture of wrought products. Aluminum-silicon alloys also generally appear as needles and/or platelets in magnesium and copper additions, some sacrifice possess excellent resistance, machin- the structure. Other iron-bearing phases such as in and corrosion resistance occurs. ability, and (Table 3). AI6Fe and FeAI 3 can also be found in these al- Manganese. Many of the important alumi- loys. Aluminum-silicon alloys intended for die num-silicon alloys also contain low (< 1 wt%), castings typically have higher minimum iron but significant, amounts of manganese. The levels to reduce sticking between the mold and presence of manganese can reduce the solubility the casting. of iron and silicon in aluminum and alter the Magnesium is added to provide strengthening composition and morphology of the A1-Fe-Si through of Mg2Si in the matrix. In primary constituent phases. For example, man- an A1-Fe-Si-Mg alloy, the AI-Si-Fe phases will ganese additions can favor the formation of con- not be affected by the addition of magnesium. stituents such as AI]2(Fe,Mn)3Si rather than the However, magnesium can combine with insolu- ble aluminum-iron phases, resulting in a loss of strengthening potential (Ref 12). Copper. The most common aluminum wear- resistant alloys also contain copper. Copper ad- ditions impart additional strengthening of the matrix through the aging or precipitation-hard- ening process (AICu 2 or Q phase) or through modification of the hard, brittle AI-Fe-Si phases (a) by substitution in these intermetallic phases. As the strength of these alloys increases through

Table 2 Cross-reference to equivalent wear-resistant aluminum-silicon alloys Specific composition limits may vary from United States limits. Foreign alloy equivalent United States United alloy Kingdom France Japan Germany

390 LM28 A-SI8UNG ... G-AISiI7Cu4 392 ...... AC9B ' - • 413 ...... G-AISiI2(Cu) 336 LMI3 A-SI2UNG AC8A ... 332 LM26 A-SIOUG AC8C ' ' " 333 LM2 • • • AC8B . ' • (b) 360 • - • A-9G •. - G-AISilOMg(Cu) 380 LM24 ...... G-AISi8Cu3 Microstructure of type A390.0 hypereutectic 356 •. • A-S7G AC4C • • • Fig 3 alloy. (a) Unrefined (Graff-Sargent etch). Dark Typical microstructure of type A357.0 hypoeu- regions contain coarse primary silicon particles in ad- Source: Ref 8, 9 Fig 2 tectic alloy. Source: Ref 11 dition to eutectic silica. (b) Refined (as polished). 120x Friction and Wear of Aluminum-Silicon Alloys / 787

Table 3 Relative ratings of aluminum-silicon casting and num-silicon and AI-Si-X alloys to improve their alloys in terms of castability, corrosion-resistance, machinability, and weldability properties ductility. These thermal treatments modify the angular primary silicon particles to a more Property(a) Aluminum rounded shape. This rounded shape reduces the Association Resistance Resistance tendency for crack initiation beginning at the number to hot Pressure Shrinkage to sharp edges of the particles. Such treatments are of alloy (b) tightness Fluidity(c) tendency(d) corrosion(e) Machinahility(f) Weldabltity(g) particularly effective on the hypereutectic al- alloys loys. Other means of modifying the shape for improved ductility are discussed in the sections 319.0 2 2 2 2 3 3 2 354.0 1 1 1 1 3 3 2 "Modification" and "Refinement" in this article. 355.0 1 1 1 1 3 3 2 Principles of Microstructural Control. The A356.0 1 1 1 1 2 3 2 three categories of aluminum-silicon alloys are 357.0 1 1 1 1 2 3 2 based on the silicon level (Table 1). These alloy 359.0 1 1 1 1 2 3 1 A390.0 3 3 3 3 2 4 2 categories are hypoeutectic, eutectic, and hyper- A443.0 I I I 1 2 4 4 eutectic. The hypoeutectic alloys solidify with 444.0 1 I I 1 2 4 1 a-aluminum as the primary phase followed by Permanent mold casting alloys aluminum-siliconeutectic. Other solutes (for ex- 308.0 2 2 2 4 3 3 ample, iron, magnesium, and copper) form 319.0 2 2 2 3 3 2 phases that separate in the freezing range of the 332.0 2 1 2 3 4 2 alloy in the interdendritic locations (Fig 2). 333.0 1 2 2 3 3 3 Hypereutectic alloys solidify in a similar man- 3 3 4 2 336.0 2 ner, but in these alloys silicon is the primary 354.0 1 3 3 2 355.0 2 3 3 2 phase rather than a-aluminum (Fig 3a). The eu- C355.0 2 3 3 2 tectic alloys solidify principally with an alumi- 356.0 1 2 3 2 num-silicon eutectic structure; either aluminum A356.0 1 2 3 2 or silicon is present as a primary phase depend- 357.0 1 2 3 2 A357.0 1 2 3 2 ing on which side of the eutectic composition 359.0 1 2 3 I (12.7% Si) the alloy lies. A brief description of A390.0 3 2 4 2 microstructural control is given below; addi- 443.0 1 2 5 1 tional information is available in Ref 2 and 12. 1 2 3 1 A444.0 Grain Structure. The grain size of the primary (a) For ratings of characteristics I s the bes and 5 s he poorest of the alloys listed. Individual alloys may have different ratings for other castin~ processes. (b) Ability of alloy to withstand stresses from cuntracfi,,m while cooling through hot-short or brittle temperature range. (c) Ability or aluminum is controlled through the addition of molten alloy to flow readily in motd and fill thin sections. (d) Decrease in wdume accompanying freezing of alluy and measure of amount nf heterogeneous nuclei to the melt in the form of compensa ing feed required in form of risers. (e) Based on resistance of alloy in standard spray test. (f) Composite rati ng, based on ease of cat ng chip characteristics quality of finish and t(ml life. In the case of heat-treatable alloys, rating is based on T6 temper. Other tempers. master alloy inoculants such as A1-6Ti or AI- particularly the annealed temper, may have lower ratings. (g) Based on ability of material to be fusion welded with filler rod ol same alloy. Source: Ti-B (in the latter, the can range from 3 Ref 13 to 5% and the Ti:B ratio from 3:1 to 25:1 ). Grain sizes vary from -100 to 500 }xm (-0.004 to 0.020 in.). An example of the effect of grain refinement by an AI-Ti-B refiner is shown in Binary hypoeutectic alloys are too soft to have Heat Treatment. Depending on the applica- Fig 4. a good machinability rating. However, the ma- tion, thermal treatments can be employed to: Cell Size. The interdendritic arm spacing (or chinability of aluminum-silicon alloys is gener- cell size) is controlled by the cooling rate (Ref ally very good in terms of surface finish and chip • Increase strength 19), which is in turn a function of the casting characteristics. Tool life can be short with con- • Control thermal growth process and section thickness. The smallest cell ventional tools, particularly in the case • Improve ductility size is achieved with thin-wall high-pressure die of the hypereutectic alloys. With the recent in- casting. At the other extreme, thick-wall sand troduction of diamond cutting tools, tool life has Aluminum-silicon alloys containing copper and castings exhibit the largest dendrite cell size. been significantly increased, making the ma- magnesium can be heat treated and aged in the Casting processes such as low-pressure die cast- chining of the hypereutectic alloys practical. same manner as wrought precipitation-hardened ing and permanent mold casting provide inter- Corrosion resistance of these alloys is gener- alloys. Depending on the strength level re- mediate solidification rates and consequently ally considered excellent. Alloys containing in- quired, room-temperature aging (T4 temper) or cell sizes that lie between the two extremes. In a creasing amounts of copper have a somewhat elevated-temperature aging (<205 °C, or 400 lower corrosion resistance than the copper-free °F) (T6 temper) may be required after heat treat- alloys as measured in standard salt spray tests. ment to obtain the necessary properties. As the Because of their high fluidity and good cast- strength of the alloy increases from the T4 to T6 ing characteristics, these alloys are highly weld- temper, reductions in ductility will occur as the able with conventional techniques. For strength increases. joining purposes, alloys and filler wire In addition, aluminum-silicon and AI-Si-X al- alloys (for example, alloys 4043 and 4047) (Ref loys can be given a higher temperature (205 to 14) are also based on the aluminum-silicon alloy 260 °C, or 400 to 500 °F) aging treatment from system. the as-cast condition to improve their strength For wear applications, the important physical and thermal stability. This is particularly impor- properties of these alloys include thermal expan- tant for applications where dimensional toler- sion, thermal conductivity, electrical conductiv- ances are critical (for example, when the alloy is ity, and Young's modulus. Data for these prop- operated at elevated temperatures as a (a) (b) component in an engine). Generally, such an erties are available in standard references (Ref Effect of grain refinement by the addition of an 13-18). Because silicon is generally in precipi- aging practice is designated by the T5 temper. Fig 4 AI-5Ti-0.2B master alloy to type A356.0. (a) tate form, the rule of mixtures is applicable High-temperature (480 to 540 °C, or 900 to Without titanium addition. (b) With 0.04% Ti addition. when calculating the properties. 1000 °F) treatments can also be given to alumi- Etched with Poulton's reagent. 0.85x 788 / Materials for Friction and Wear Applications: similar to the cell size, the constituent through the addition of a master alloy such as are "abrasive" and "sliding" wear. These have phase size is largely controlled by the freezing Cu-10P. The combines with alumi- also been identified by Eyre (Ref 3) as the most rate. num to form aluminum phosphide, AlP, which common types of wear. Wear mechanisms, Modification• The term modification refers to provides effective nuclei for the silicon phase though, can be thought of as involving more the change in morphology and spacing of the much the same as TiB2-type particles are effec- specific descriptions of local processes occur- aluminum-silicon eutectic phase induced by the tive nuclei for o~-aluminum (Fig 3b). However, ring in the metal and countersurface of the wear addition of a chemical agent such as or phosphorus also negates the effectiveness of so- system during the wear process. Wear mecha- . There is a change from large divorced dium and strontium• It does so by combining nisms are discussed in detail in this Volume in silicon particles to a fine coupled aluminum- with them to form phosphides, which do not the Sections "Wear by Particles or Fluids," silicon eutectic structure with an addition of ap- modify the eutectic structure. Similarly, sodium "Wear by Rolling, Sliding, or Impact," and proximately 0.001% Na or 0.005% Sr to the and strontium reduce the effectiveness of phos- "Chemically Assisted Wear." The purpose of melt. Varying degrees of modification (Fig 5) phorus additions by the primary silicon this discussion is to focus on the interaction be- are obtained with lower levels of addition. For phase. tween microstructure and wear mechanisms. details of the mechanism and practice of modifi- Gas Porosity. porosity can be con- This is important for aluminum-silicon alloys cation, see Granger and Elliott (Ref 12). trolled by maintaining gas levels at <0.10 cm3/ because of the variety of microstructures that is also used to modify (more accu- 100 g. This is not readily accomplished, particu- can be achieved as the alloys are processed for rately, refine) the eutectic structure in hypoeu- larly when modification of the melt is being particular applications. The relative effects of tectic and eutectic alloys, particularly in Europe sought with the addition of sodium or strontium• silicon particles, matrix hardness, and interme- and Japan. Like sodium and strontium, it in- However, gas fluxing methods are available tallic constituents on the wear resistance of alu- creases the fluidity of the alloys and improves (Ref 20) that provide the means of reducing hy- minum-silicon alloys are summarized below. mechanical properties. Furthermore, it is perma- drogen levels to the desired range• Silicon Particles. Under relatively light load nent, allowing melts to be more effectively de- Also deleterious to casting soundness is the conditions, which are normally associated with gassed, which, in turn, provides sounder cast- presence of nonmetallic inclusions that act as low (< 10- ii m3/m) losses, wear resistance is ings. The great disadvantage of antimony is that nuclei for gas pores. Various molten metal filtra- not a strong function of silicon content (Ref 22- it poisons (or negates) the effect of sodium and tion systems are available for inclusion removal 25). In general, however, silicon additions to strontium, and it also creates a problem in recy- (Ref 20). aluminum will increase the wear resistance. The cling. An additional serious drawback is the po- Sludge. A problem experienced with alumi- principal mechanism appears to be the influence tential for the formation of stibine gas, which is num-silicon alloys is the formation of hard inter- of the hard silicon panicles, which to higher highly toxic. Unlike sodium and strontium, metallic phases of the Al(FeM)Si-type, which overall levels of hardness. The fact that the hard which can be used to effectively modify eutectic settle out under gravity from the melt (Fig 6). silicon particles are surrounded by a softer and structures over a wide range of freezing rates, The conditions that favor the formation of these relatively tough matrix improves the overall antimony provides eutectic refinement only at phases arc low holding temperaturcs (which are toughness of the material and can contribute to the relatively high rates experienced in die cast- often employed in the die-casting industry); a wear resistance by favoring more behav- ings and some thin-wall permanent mold cast- quiescent melt; and relatively high lcvels of ior. The eutectic and hypereutectic silicon al- ings. iron, manganese, and . The relative loys, with increased volume fractions of hard Refinement. In hypereutectic alloys, the pri- tendency to form sludge in the holding furnace is primary silicon particles relative to the hypoeu- mary phase is silicon. In order to provide the given by a segregation factor (SF): tectic alloys, might be expected to have the best desired small well-dispersed silicon particles, wear resistance of the aluminum-silicon alloys. SF = (%Fe) + 2 (%Mn) + 3 (%Cr) (Eq 1) phosphorus is added to the level of about 0. 1% P Andrews et al. (Ref 26, 27), for example, found The relationship among the segregation factor, that increasing the silicon content in hypereutec- holding temperature, and sludging tendency is tic alloys reduced wear. However, binary alloy given for alloy AA 339 and several other alumi- data (Ref 22, 28) indicate that the hypereutectic - i "'% num-silicon alloys in Ref 21. alloys are not necessarily the most wear resis- tant. Clarke and Sarkar (Ref 28) found that there Wear Behavior was a relative minimum in wear for binary alu- .~iI " %, .'~' " ~ t'"'.:":,l"'t';~'.~,~" s'' " . ~" minum-silicon alloys at about the eutectic level, The two major types of wear relevant to in- as did Jasim et al. (Ref 22), especially at applied dustrial applications of aluminum-silicon alloys pressures <100 kPa (<15 psi). Clarke and

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Variation m microstructure as a function of the (a) (b) Fig 5 degree of modification. The modification level increases from A to F; thus microstructure F is highly Coarse intermetallic AI12(Fe,Mn,Cr)3Si 2 phase constituent generated by entrapped sludge in alloy 339. (a) modified. Source: Ref 2, 12 Fig 6 130x. (b)265x Friction and Wear of Aluminum-Silicon Alloys / 789

Sarkar attribute the effects of silicon in part to its Table 4 Typical hardness values of Table 5 Automotive engine effect on metal transfer mechanisms between the selected intermetallic constituents of applications of aluminum-silicon alloys pin and countersurface (Ref 29). There is also aluminum-silicon alloys Type of evidence for increased wear resistance with re- Hardness SAE alloy casting(a) Typical application finement of the silicon particle morphology (Ref 319.0 S General purpose alloy 30, 31). Phase MPa kgf/mm2 Ref" 332.0 PM Compressor It is clear, therefore, that microstructure- CuAI 2 3900 400 36, 37 333.0 PM General purpose based explanations are needed to account for the 3800-7600 390-780 36 336.0 PM Piston alloy (low expansion) 36, 37 339.0 PM Piston alloy variation in wear rates with silicon content. FeAI 3 7200 730 6400-9400 650-960 37 355.0 S, PM Pump bodies, cylinder heads Moreover, there is a need to account for the 5160-7110 526-725 36 390.0 D Cylinder blocks, transmission pump reduction in strength that occurs with increased 3500 360 38 and air compressor housings, silicon content (Ref 32, 33). The complex ef- NiAI 3 6000-7600 610-770 36 small engine crankcase, air con- 37 ditioner pistons fects of composition on wear behavior suggest 7100 720 4500 460 38 A390.0 S, PM Cylinder blocks, transmission pump that wear resistance depends on other material Ni2AI3 9800-11,000 1000-1120 36, 37 and air compressor housings, properties (for example, fracture toughness) Si 7000-14,200 715-1450 36 small engine crankcase, air con- (Ref 34). Thus lower fracture toughness at 11,880 1211 37 ditioner pistons higher levels of silicon could lead to higher wear Mg2Si 4480 457 37 (a) S, sand cast; D, die cast; PM, permanent mold. Source: Ref43 AI2CuMg 3700-3900 380-400 37 rates if larger pieces of debris are created during AIgFeNi 8400-9680 860-987 37 the wear process. Variations in toughness and AII2Fe3Si 10,760 1097 37 strength with composition might also account for the apparent ability of the near-eutectic com- haps the most widely used. Equivalent versions positions to have a greater load-bearing capabil- tance can be modeled in terms of their volume of these alloys are used for similar applications ity at a given wear rate than either higher or fraction and morphology. This composite ap- by European and Japanese automakers (Ref 45- lower silicon levels. proach has been effectively used to develop new 47). Matrix Hardness. Increased matrix hardness piston materials (see the section "Metal-Matrix Pistons. Typical applications for aluminum- is typically achieved through the heat treatment Composites" in this article). silicon alloys in the French response produced by copper and magnesium Finally, the use of "softer" constituents (for are shown in Table 6 (Ref 45). In addition to additions. Most commercial applications of alu- example, graphite) should also be noted as an being cast, the A-S12UN (eutectic) alloy can minum-silicon alloys, in fact, depend on the in- active area for development of wear-resistant also be forged (Ref 48). Similarly, AA 4032, creased strength achieved by heat treatment. The aluminum-silicon MMC materials (Ref 32, 39, somewhat similar in composition to 336, is also improved wear resistance of precipitation- 42). In these materials, ranking may depend on widely used as a piston alloy (for example, for strengthened material compared to solid solution whether volumetric wear rates (in units of m~/m) high-performance forged pistons). Hypereutec- strengthened material under low wear conditions or seizure resistance is being considered. The tic alloys are also used for cast pistons, espe- was also noted by Soderberg et al. (Ref 35) presence of the softer phase may lead to greater cially in diesel engines (Ref 45, 49). The poten- using aluminum alloy 6061, which is strength- volumetric wear in some cases but greater resis- tial benefit from composites that combine the ened primarily by Mg2Si precipitates. This is tance to seizure (higher load at seizure) in other strength reinforcement of with an alu- also the strengthening mechanism in the heat- cases. minum-silicon alloy matrix has also been evalu- treatable magnesium-bearing aluminum-silicon To summarize, the results of wear studies us- ated (Ref 45, 47, 48). alloys. Although heat treatment has a beneficial ing aluminum-silicon alloys illustrate a variety Engine Blocks and Cylinder Liners. The ev- effect (Ref 26, 27, 32), variations in matrix of mechanisms. The effect of variations in sili- olution of lightweight power plants has de- hardness may be less important than the effects con particle morphology is often not clear cut, pended not only on lightweight pistons but also of silicon content (Ref 27). although heat treatment is beneficial to the slid- on the availability of wear-resistant cylinder lin- Intermetallic Constituents. In addition, ing wear resistance. Therefore, selection of an ers and engine blocks. Hypereutectic liners were there are important "other" hard phases present optimum microstructure is often difficult in described by Mazodier (Ref 50) and El Haik in commercial aluminum-silicon alloys that pro- practical situations where several wear types or (Ref 51). It was also known that hypereutectic vide enhanced wear resistance. These constitu- mechanisms could occur. In general, either eu- aluminum-silicon alloys had excellent properties ents (for example, AI-Fe-Si, AI-Fe-Mn, AI-Ni, tectic or hypereutectic alloys offer the greatest for engine blocks (Ref 52-54). This led to the AI-Ni-Fe, AI-Cu-Mg) have varying degrees of wear resistance under a wide range of wear con- development and application, in both the United hardness (Ref 36-38). Despite the apparent scat- ditions. Selection may then hinge on the depen- States and Europe, of the A390 (A-SI7U4) al- ter, these constituents are all much harder than dence of in-service performance on other alloy loys for die cast engines (Ref 55-60). An impor- the aluminum matrix. Some examples of the characteristics or cost. Overall, the aluminum- tant aspect of the A390 success is the use of a hardness values of these intermetallic com- silicon alloy system provides a good basis for "system" (Ref 60) that includes the engine alloy, pounds are shown in "Fable 4. developing lightweight, strong, wear-resistant the piston materials (electroplated cast F332[AA Typical room-temperature hardness values for materials. Examples of these applications will 332.0] alloy), and the cylinder bore finishing the aluminum alloy matrices would be <1000 be discussed in the following sections. process. Fine honing to a 0.075 to 0.15 ~m (3 to MPa (< 100 kgf/mm2). The hardness values of 6 p, in.) surface finish, followed by controlled the decrease with increasing tem- Aluminum-Silicon etching/polishing to leave silicon particles stand- perature (Ref 36), albeit at slower rates than the Alloy Applications ing slightly above the alloy surface, was deemed matrix hardness. necessary for optimum wear resistance. The addition of "hard" phases in the form of Aluminum-silicon alloys are used in a variety Efforts to simplify the 390-type technology by particles or fibers to reduce wear is also utilized of automotive, aerospace, and consumer product a more wear-resistant alloy for the cylin- to create metal-matrix composites (MMC) mate- applications. der or reducing the difficulties of finishing the rials (Ref 39). These materials utilize hard inter- bore have led to substitute alloys. One approach metallic, , or phases to provide Automotive Components has been the use of a lower silicon alloy contain- the high hardness material for wear resistance. Table 5 lists typical automotive components ing more and manganese (for example, Hornbogen (Ref 40) and Zum Gahr (Ref 41) made from aluminum-silicon casting alloys (Ref the Australian-3HA alloy, with a nominal com- have described in quantitative terms how the 43). The eutectic or nearly eutectic alloys (for position of Al-13.5Si-0.5Fe-0.45Mn-0.5Mg- contribution of these hard phases to wear resis- example, 332, 336, and 339) (Ref 44), are per- 2Ni) (Ref 61). 790 / Materials for Friction and Wear Applications

Table 6 Selected aluminum-silicon alloy applications in automobiles produced num-silicon or AI-Sn-Cu alloys, whereas in France according to engine type and specific automobile manufacturer wrought bearing alloys have included the 8xxx Manufacturer types (for example, AA 8081 and AA 8020) (Ref 66, 67). Compositions of various alumi- Engine type Citroen Peugot Talbot num bearing alloys are listed in Table 8. Gas A-SI2UN A-S10UN(F)(a) A-SI 2UN A-S10.5UN Improved strength and performance, . • • A-S 12 UN(A)(b) - - - A-S 11 UN as well as some increased wear resistance, has ...... A-SI2UN been achieved with silicon additions. Thus, al- Diesel A-SI 8UN A-SI 2UN A-SI 8UN . - - • •. A-S13UN ...... loys SAE 780 and SAE 781 have become widely used for automotive applications such as main (a) F, cast iron liner. (b) A, aluminum block. Source: Ref 45 and connecting rod bearings (Ref 68, 69). The higher silicon alloy, 781, is also used in bush- ings and thrust bearings. Its improved wear per- Continuing interest in the use of more highly Typical examples from a more detailed com- formance has been attributed to the increased wear-resistant materials in other engine-related pilation of aluminum alloys used in wear-resis- silicon content of the wear surface (Ref 70). parts has led to recent applications such as roller- tant applications in U.S. autos are shown in Ta- These aluminum-silicon alloys are readily used type valve rocker arms (Ref 62) and valve lifters ble 7. with steel backing in high-load situations. for the Toyota Lexus (Ref 63-64). The rocker Bearing Alloy Components. Aluminum al- Advanced Aluminum Bearing Alloys. The arm alloy used in the Mazda 929 is a nominal loys have been utilized for bearing applications nominal compositions of improved bearing al- Al-10Si-2.7Cu-0.8Mg-0.45Mn alloy somewhat for many years. The many uses range from die- loys with silicon additions are listed in Table 9. similar to the AA 383 alloy. The valve lifter, on sel and internal combustion engines to a variety Although a soft phase (for example, ) is the other hand, is a strontium-modified AI-Si-Cu of tooling applications (for example, presses, normally considered desirable for avoiding sei- alloy designated 4T 12 (composition, AI- 10.5Si- lathes, and machines) (Ref 66). Impor- zure, the compatibility of an AI-11Si-lCu alloy 4.5Cu-0.6Mg-0.2Mn). tant cast bearing alloys were based on alumi- was better than that of the traditional aluminum- tin alloy (SAE 783) (Ref 71). The silicon-copper alloy also had much better fatigue resistance. Table 7 Wear-resistant aluminum-silicon alloys used in automotive piston components The improved properties resulted in applications produced for United States automotive manufacturers in 1978 to 1985 model years such as diesel crankshaft and connecting rod bearings. Nevertheless, in line with the concerns Application Manufacturer Model/make Model year(s) expressed by Davies (Ref 72), the harder sili- Internal combustion engine components con-containing alloy was more sensitive to mis- alignment-induced seizure. Pistons American Motors All 1978-85 Ford 1978-81, 83-85 The addition of silicon to aluminum-tin alloys General Motors Buick 1978-81, 84-85 containing lower tin levels than that of the 783 Others 1978-81, 83-85 alloy provided a compromise between the con- Brake system components formability of the soft-phase material and the benefits of the harder silicon phase for improved cylinder pistons American Motors All 1983-85 Chrysler All 1983-85 wear and fatigue resistance (Ref 73). This alloy Ford All 1978-85 could apparently be used without the common General Motors All (except for 1984-85 lead alloy overlays employed for seizure resis- Cadillac) tance. The importance of fatigue resistance was Cadillac 1985 Master cylinder pistons American Motors All 1984-85 also emphasized in the improved A1-Sn-Si alloys Chrysler All 1984-85 reported by Ogita et al. (Ref 74). As shown in Ford All 1983 -85 Table 9, these alloys are somewhat similar to Ford Mercury 1978-81, 84-85 those of Fukuoka et al. (Ref 73). General Motors All 1984-85 As another alternative to the lead- or tin-con- Transmission components taining alloys, a graphite-containing AI-12Si al- Intermediate band servo pistons Ford Some 1983-85 loy has been successfully evaluated for bearings Rear band servo pistons Chrysler Some 1984-85 (Ref 75). The use of a modified lead plus Ford Some 1983-85 addition to an AI-I lSi-Pb bearing alloy has also Source: Ref 65 been reported (Ref 76).

Table 8 Nominal compositions of standard Table 9 Nominal compositions aluminum-silicon alloys used in bearing applications of advanced aluminum-silicon alloys used in bearing applications Alloy Composition, wt% Aluminum Composition, wt% Association SAE Alloy(a) Si Sn Cu Mg Pb Other Ref designation designation Si Sn Cu Fe Ni Cd 11 --- 1 ...... ''" 6 850 770 0.7 5.5-7 0.7-1.3 0.7 0.7- t .3 ' " " 3 10 0.4 • • - 1.8 0.3 Cr 8 8280 780 1-2 5.5-7 0.7-1.3 0.7 0.2-0.7 . . . 12 ' " • 1 1.5 . • - 3C, 851 " " " 2-3 5.5-7 0.7-1.3 0.7 0.3-0.7 " " - 1 Ni 9 852 ' ' ' 0.4 5.5-7 1.7-2.3 0.7 0.9-1.5 . . - D ...... 4.5 ...... 3C -.. " " " 781 3.5-4.5 " ' ' 0.05-0.15 0.35 " - - 0.8-1.4 E 11 ...... 20 1.4 In 10 8081 "" 0.7 18-22 0.7-1.3 0.7 ...... F 2.5 12 1 ...... 0.25 Mn 11 • " " 782 0.3 - ' - 0.7-1.3 0.3 0.7-1.3 2.7-3.5 G 6 • • • 1.2 0.5 1 4 Zn 12 " . " 783 0.5 17.5-22.5 0.7-1.3 0.5 0.1 • • . H 4 0.5 0.1 0.1 6 0.3 Mn 13 Source: Ref 66-68 (a) Arbitrary designations Friction and Wear of Aluminum-Silicon Alloys / 791

Japanese concerns with the pollution and tox- of the preferred fabrication routes for composite minimize wear problems (Ref 100). The selec- icity aspects of -containingalloys have pistons. tive fiber strengthening noted above is related to led to improved aluminum- bearing alloys The property improvements at elevated tem- this problem also. One widely used treatmentqs (Ref 77). These have also been improved with peratures have encouraged ongoing develop- the so-called Nikasil treatment (Ref 101), an silicon additions. The additional matrix wear be- ment of the MMC technology for automotive electrochemical treatment utilizing a dispersion tween the silicon particles is believed to create engine applications, including engine blocks. of particles, preferably <4 txm lubricant reservoirs that enhance seizure resis- The ability of the MMC approach to allow selec- (<160 txin.) in size, in a nickel matrix. tance. However, overlays (lead-tin alloys) are tive strengthening of the cylinder region was Efforts to take advantage of both the P/M and still required for best conformability. taken advantage of by Honda engineers (Ref surface treatment approach are exemplified by Finally, the combined effect of silicon and 89), who utilized composite reinforcement of the emerging surface treatment technologies of refinement of the silicon- and lead-bearing alloy ADC 12 (a Japanese alloy similar to 383) in surface alloying via implantation (Ref 102- phases by rapid solidification processing has re- the manufacture of a die cast engine block. 105), thermal spraying (Ref 106-108), and sur- sulted in an improved AI-6Pb-4Si bearing alloy . The combined benefits face treating or alloying using treatments (Ref 78). This alloy has grown in usage recently of high silicon content and refined silicon parti- (Ref 109-111). is recognized and is projected to be used in 78% of the cle size on wear resistance are strong driving for its ability to impart wear-resistant surfaces, built in the United States during 1991. lbrces behind the use of P/M techniques for but principal applications have been to protect Because of the increasing understanding of making aluminum-silicon alloy parts. The P/M tool surfaces in critical processing operations. the balance among wear, fatigue, and seizure approach has been of special benefit to the hy- Laser hardening can be achieved through laser resistance of bearing materials, silicon alloys pereutectic silicon alloys. One example of this is cladding to produce a chemically different sur- have been used to develop new and improved the use of P/M A-SI7U4 alloy to make cylinder face or through the effective heat treatment (or bearing materials. Further improvements will liners (Ref 90, 91). The properties of these al- remelting and rapid solidification) brought about undoubtedly be necessary as engine operating loys exceed those of standard alloys (Ref 92). In by laser heating. The work by Blank et al. (Ref conditions evolve toward higher temperatures addition, high levels of additional elements can 111) using 7 and 12% Si alloys, however, indi- and operating speeds. be utilized to obtain good strength and wear- cated that surface alloying (for example, with resistant properties at elevated temperatures (Ref iron or iron plus ) was more effective Consumer Components 93-95). for increased wear than surface heat treatment The growth of this market, which encom- The refined available from effects alone. In any case, the ability to tailor passes video cassette recorders (VCRs), video the P/M fabrication of hypereutectic alloys have surface properties to a technological need will tape recorders (VTRs), digital audio tape (DAT) a beneficial effect on fatigue characteristics as enable engineers to obtain further enhancement applications, and other devices (for example, well. This attribute has been utilized in the pro- of the wear resistance of the aluminum-silicon personal ), has created numerous op- duction of rotors and vanes for rotary automo- base alloys without sacrificing their other advan- portunities for the use of lightweight, relatively tive air conditioners (Ref 96). For this applica- tages. tion, P/M alloys with high levels of iron or corrosion-resistant and wear-resistant alumi- REFERENCES num-silicon alloys. VTR cylinders arc specifi- nickel are blended with P/M 2024-type alloys to cally cited by various Japanese authors (Ref 79- create alloys containing 17 to 20% Si and 5 to 1. J.P. Lyle and D.A. Granger, Ulhnan's 81) because the eutectic-type silicon alloys have 8% Fe or Ni. Emych~pedia o[ Industrial Chemisto', low coefficients of friction against the tape. Spray casting, as exemplified by Osprey proc- Vol I A, VCH Publishers, 1985, p 481-528 essing, has been shown to offer benefits similar 2. E.L. Rooy, Aluminum and Aluminum Al- Aerospace Components to powder metallurgy (Rcf 97, 98). This has the loys, Casting, Vol 15, 9th ed., potential for even greater cost savings, which is Handbook, ASM International, 1988, p A nonautomotive engine application of alumi- an important factor if the aluminum industry is 743-770 num-silicon alloys is the use of the 390-type to compete successfully in the automotive mar- 3. T.S. Eyre, Wear Resistance of Metals, alloys in an aircraft engine (the Thunder engine) ket. In a comparison of the structure in an AI- Treatise on and Tech- (Ref 82). 20Si alloy, Kahl and Leupp (Ref 97) showed nology, Vol 13, Douglas Scott, Ed., that there was practically no difference in silicon Wear, Academic Press, 1979, p 363-442 Breakthroughs in Aluminum- particle size between the P/M and Osprey proc- 4. A. Kaye and A. Street, Met- Silicon Wear-Resistant Materials essing routes. Furthermore, they claimed that allurgy, Butterworths Scientific, London, the fine and uniform silicon particle size resulted 1982, p 32 Metal-Matrix Composites. Composite pis- in improved wear behavior compared with that 5. S. Rabinowitz, The Expanding Role of tons were recognized early as a potentially via- of conventionally produced material, although Aluminum in the Automotive Industry, ble application of MMC technology. While details of their test procedure are not known. Die Cast. Eng., Sept-Oct 1, 1977 some composite approaches, especially for the Earlier work at Delft University (Ref 99) com- 6. J.L. Jorstad, "Aluminum Lightweight severe operating conditions of diesel pistons, pared the rate of loss of an AI-20Si-3Cu- Castings--Some Cost Saving Ideas," Pa- recommended the addition of specific metallic 1.3Mg alloy rubbing against cast iron at a pres- per No. 770322, SAE Automotive Engi- inserts to achieve improved performance (Ref sure level of 5.5 MPa (800 psi). In this test, the neering Congress, Society of Automotive 83), the bulk of development efforts have gone Osprey material showed better resistance to Engineers, 1977 into the incorporation of ceramic fibers. wear than e~ther the ingot metallurgy (I/M) or 7. J.L. Murray and A.J. McAlister, The Alu- The use of ceramic fiber aluminum-silicon P/M samples. The reason for the better perform- minum-Silicon System, Bull. Alloy Phase MMC materials for pistons is described in a va- ance of the Osprey product compared with the Diagrams, Vol 5 (No. 1), 1984, p 74-84, riety of publications (Ref 47, 48, 84-88). There P/M material was not clear, but it was hypothe- 89-90 are clear benefits to strength at elevated temper- sized that the slightly larger silicon particles of 8. Registration Record of Aluminum Associ- atures and reduction of the the Osprey product helped reduce the fretting ation, Alloy Designations and Chemical coefficient. These materials appear to be espe- wear. Composition Limits for Aluminum Alloys cially applicable in critical areas such as the top Coatings/Surface Treatments. Other ap- in the Form of Castings and Ingot, 1987- piston rings and top land (a high-temperature proaches to the wear (adhesion) problems of alu- 09-01, Aluminum Association area). The castability of the aluminum-silicon minum pistons moving in aluminum cylinders 9. Registration Record of Aluminum Associ- alloys is a favorable factor in their use as matri- have taken the path of coating or surface treat- ation, Limits for Wrought Aluminum and ces, particularly because squeeze casting is one ment of the piston rings and cylinder bore to Wrought Aluminum Alloys, 1987-04-01, 792 / Materials for Friction and Wear Applications

Aluminum Association bricated Sliding, Mater. Sci. Eng., Vol Microstructure, Wear of Metals--1985, 10. L.F. Mondolfo, Aluminum Alloys: Struc- 93, 1987, p 57-72 K. Ludema, Ed., American Society of ture and Properties, Butterworths, 1976 26. J.B. Andrews, M.V. Seneviratne, K.P. Mechanical Engineers, p 477-484 11. D.A. Granger, RR. Sawtell, and M.M. Zier, and T.R. Jett, The Influence of Sili- 41. K.-H. Zum Gahr, Abrasive Wear of Two Kersker, Effect of on the Prop- con Content on the Wear Characteristics Phase Metallic Material with a Coarse Mi- erties of A357.0 Castings, Trans. AFS, of Hypereutectic AI-Si Alloys, Wear of crostructure, Wear of Metal--1985, K. 1984, p 579-586 Metals--1985, K. Ludema, Ed., Ameri- Ludema, Ed., American Society of Me- 12. D.A. Granger and R. Elliott, Aluminum- can Society of Mechanical Engineers, p chanical Engineers, p 45-57 Silicon Alloys, Casting, Vol 15, 9th ed., 180-184 42. B.N. Pramila Bai, E.S. Dwarakadasa, and Metals Handbook, ASM International, 27. J.B. Andrews, M.V. Seneviratne, and S.K. Biswas, Scanning Micros- 1988, p 159-168 T.R. Jett, The Influence of Si and Other copy Studies of Wear in LM 13 and LM 13- 13. J.E. Hatch, Aluminum: Properties and Alloying Additions on the Wear Charac- Graphite Particulate Composite, Wear, Physical Metallurgy, American Society teristics of Hypereutectic AI-Si Alloys, Vol 76, 1982, p 211-220 for Metals, 1984, p 344-345 4th European Tribology Congress (EU- 43. General lnformation~hemical Compo- 14. Source Book on Selection and Fabrication ROTRIB 85), Vol III, 1985 sitions, Mechanical and Physical Proper- of Aluminum Alloys, American Society for 28. J. Clarke and A.D. Sarkar, Wear Charac- ties of SAE Aluminum Casting Alloys, Metals, 1978 terization of As-Cast Binary Aluminum- SAE Handbook, J452, June 1983, Society 15. A.L. Kearney and E.L. Rooy, Aluminum Silicon Alloys, Wear, Vol 54, 1979, p of Automotive Engineers Products, Properties and Selec- 7-16 44. R. Wilson, Piston Improvement Relies on tion: Nonferrous Alloys and Special-Pur- 29. J. Clarke and A.D. Sarkar, The Role of Material Science, Diesel Prog. North pose Materials, Vol 2, ASM Handbook, Transfer and Back Transfer of Metals in Am., Vol 52 (No. 2), Feb 1986, p 18-20 ASM International, 1990, p 123-151 the Wear of Binary A1-Si Alloys, Wear, 45. J. Ayel, The Influence of Metallurgical 16. A.L. Kearney, Properties of Cast Alumi- Vol 82, 1982, p 179-185 and Geometric Parameters on the Wear of num Alloys, Properties and Selection: 30. T.K.A. Jaleel, N. Raman, S.K. Biswas, Recent Engines, Ing. Automob., Sept-Oct Nonferrous Alloys and Special-Purpose and K.K. Murthy, Effect of Structural 1980, p 82-98 Materials, Vol 2, ASM Handbook, ASM Modification and Load on the Wear of a 46. M. Coulondre and J. Travaille, New International, 1990, p 152-177 Hypereutectic Aluminum-Silicon Alloy, Trends in the Design and Manufacture of 17. J.E. Hatch, Chapters 8 and 9, Aluminum: , Vol 60 (No. 12), 1984, p 932- Pistons and Cylinders for Automobile En- Properties and Physical Metallurgy, 933 gines, Ing. Automob., Sept-Oct 1980, p American Society for Metals, 1984, p 31. Y. Odani, K. Akechi, and N. Kuroishi, 68-72 152-177 High Strength and High Wear Resistance 47. A.R. Baker and S. Gazzard, Develop- 18. General Information--Chemical Compo- AI-Si P/M Alloys, Modern Developments ments in Materials for Pistons, Mater. sitions, Mechanical and Physical Proper- in Powder Metallurgy, Vol 16, 1984, p Des., Vol 9 (No. 1), Jan-Feb 1988, p ties of SAE Aluminum Casting Alloys-- 493-505 28-33 SAE J452, June 1983, SAE Handbook, 32. S. Das, S.V. Prasad, and T.R. Ramachan- 48. J.C. Avezou and A. Parker, Evolution of Society of Automotive Engineers, 1989, p dran, Microstructure and Wear of Cast Materials for Pistons, Segments and Valve 10.5-10.13 (A1-Si Alloy) Graphite Composites, Seatings for Petrol and Diesel Engines of 19. R.E. Spear and G.R. Gardner, Dendrite Wear, Vol 133, 1989, p 173-187 Automobiles, Ing. Automob., Oct 1983, p Cell Size, Trans. AFS, Vol 71, 1963, p 33. B.N. Pramila Bai, S.K. Biswas, and N.N. 73-80 209-215 Kumtekar, Scanning Electron Microscopy 49. J.P. Whitacre, "Hypereutectic Alumi- 20. D.V. Neff, Non-Ferrous Molten Metal Study of Worn AI-Si Alloy Surfaces, num--A Piston Material for Modern High Processes, Casting, Vol 15, 9th ed., Met- Wear, Vol 87, 1983, p 237-249 Specific Output Gasoline Engines," TP als Handbook, ASM International, 1988 34. K.-H. Zum Gahr, Microstructure and 871944, Society of Automotive Engi- 21. J. Gobrecht, Gravity-Segregation of Iron, Wear of Materials, Tribology Series, Vol neers, 1987 Manganese and Chromium in an Alumi- 10, Elsevier, 1987 50. M. Mazodier, Aluminum Engine Blocks num-Silicon Casting Alloy, Part I, 35. S. Soderberg, U. Bryggman, and A. with Thin Hypersilicon Alloy Liners, lng. Giesserei, Vol 62 (No. 10), 1975, p 263- Canales, Influence of Precipitation and Automob., No. 10, Oct 1977, p 586-590 266; and D.A. Granger, Investigation of a Solution Strengthening on Abrasive Wear 51. R. El Haik, The Possibilities of Using AI -Like Intermetallic Phase Occurring in Resistance, Wear of Metals--1985, K. Cylinder Blocks--Hypersiliconized Cyl- Alloy 339, Trans. AFS, Vol 91, 1991, p Ludema, Ed., American Society of Me- inder Liner Tests, Ing. Automob., No. 10, 379-383 chanical Engineers, p 645-653 Oct 1977, p 569-577 22. K. Mohammed Jasim and E.S. Dwaraka- 36. E.R. Petty, Hot Hardness and Other Prop- 52. J.L. Jorstad, "Development of the Hyper- dasa, Wear in A1-Si Alloys under Dry erties of Some Binary Intermetallic Com- eutectic AI-Si Die Casting Alloy Used in Sliding Conditions, Wear, Vol 119, 1987, pounds of AI, J. Inst. Met., Vol 89, 1960- the Vega Engine Block," TP No. 105, 6th p 119-130 1961, p 343-349 International Society of Die Casting Engi- 23. B.N. Pramila Bai and S.K. Biswas, Effect 37. A.A. Ivanko and G.V. Samsonov, Hand- neers Congress (Cleveland, OH), Nov of Load on Dry Sliding Wear of Alumi- book of Hardness Data, Translation from 1970 num-Silicon Alloys, ASLE Trans., Vol 29 Russian, National Bureau of Standards- 53. J.L. Jorstad, The Hypereutectic Alumi- (No. 1), 1986, p 116-120 National Science Foundation, 1968 num-Silicon Alloy Used to Cast the Vega 24. R. Shivanath, P.K. Sengupta, and T.S. 38. H.E.N. Stone, The Oxidation Resistance, Engine Block, Mod. Cast., Vol 60 (No. Eyre, Wear of Aluminum-SiliconAlloys, Hardness and Constitution of Metallic 4), Oct 1971, p 59-64 Wear of Materials--1977, International Aluminides, J. Mater. Sci., Vol 10, 1975, 54. J. Ayel, Frictional Behavior of the Alumi- Conference on Wear of Materials, W. p 923-934 num Hypersilicon Alloys Used as Engine Glaeser, K. Ludema, and S. Rhee, Ed., 39. S.V. Prasad and P.K. Rohatgi, Tribologi- Liners, Rev. ., Apr 1978, p 186-191 American Society of Mechanical Engi- cal Properties of AI Alloy Particle Com- 55. H.H. Hofmann and K. Schellmann, "Alu- neers, p 120-126 posites, J. Met., Nov 1987, p 22-26 minum 390 Alloy Engine Blocks: Design 25. R. Antoniou and D.W. Borland, Mild 40. E. Hornbogen, Description of Wear of and ," TP 830007, Society Wear of A1-Si Binary Alloys during Unlu- Materials with Isotropic and Anisotropic of Automotive Engineers, 1983 Friction and Wear of Aluminum-Silicon Alloys / 793

56. W. Dahm and R.G. Putter, "Light Alloy Aluminum Alloy Bearings Containing Fiber Matrix Reinforcement in Aluminum Engines--Experience Gained from Re- Hard Particles Fitted for Use with Nodular Diesel Pistons," TP 900536, Society of search and Development," TP 830005, Iron Shaft, Studies of Engine Bearings and Automotive Engineers, 1990 Society of Automotive Engineers, 1983 Lubrication, SP-539, Society of Automo- 89. T. Hayashi, H. Ushio, and M. Ebisawa, 57. G. Renninger, D. Abendroth, and M. Bo- tive Engineers, 1983, p 33-44 (TP "The Properties of Hybrid Fiber Rein- lien, "Casting Engine Blocks in GK AI Si 830308) forced Metal and Its Application for En- 17 Cu 4 Mg," TP 830003, Society of Au- 74. Y. Ogita, K. Niwa, and Y. Kondo, "New gine Block," TP 890557, Society of Auto- tomotive Engineers, 1983 Engine Type Fatigue Phenomenon of AI- motive Engineers, 1989 58. E.G. Jacobsen, "General Motors 390 Alu- Based Engine Bearings," TP 890556, So- 90. R. Perrot, Engine Sleeves Made in a Hy- minum Alloy 60 degree V6 Engine," TP ciety of Automotive Engineers, 1989 pereutectic Aluminium-Silicon Alloy by 830006, Society of Automotive Engi- 75. B.P. Krishnan, N. Raman, K. Naray- Powder Metallurgy, European Symposium neers, 1983 anaswamy, and P.K. Rohatgi, Perform- on Powder Metallurgy (Stockholm), Vol 59. H.M. Ward, III, " Control for ance of Aluminum Alloy Graphite Bear- 2, 1978, p 212-217 High Volume 390 Die Casting," TP ings in a Diesel Engine, Tribol. Int., Vol 91. R. Perrot, Engine Cylinder Liners in High 830009, Society of Automotive Engi- 16 (No. 5), 1983, p 239-244 Silicon Aluminum Alloy Produced by neers, 1983 76. D.P. Howe and J.D. Williams, An AI-Si- Powder Metallurgy, Rev. Alum., Mar 60. J.L. Jorstad, "Reynolds 390 Engine Tech- Pb-In Plain Bearing Material, Proceed- 1979, p 129-135 nology," TP 830010, Society of Automo- ings Fourth Conference of lrish Durability 92. N. Kuroishi, Y. Odani, and Y. Takeda, tive Engineers, 1983 and Fracture Committee (IDFC4), 1986, High Strength High Wear Resistance Alu- 61. J. Barresi, R. Giannini, and B.J. Clarsen, p 183-191 minum-Silicon P/M Alloys, Met. Powder "Cold Scuff Evaluation of 3HA--The En- 77. M. Sakamoto, Y. Ogita, Y. Sato, and T. Rep., Vol 40 (No. 11), Nov 1985, p 642- gine Alloy Developed in Australia," TP Tanaka, "Development of New A1-Zn-Si 645 871203, Society of Automotive Engi- Bearings for Heavy Load Applications in 93. J.L. Estrada and J. Duszczyk, Character- neers, 1987 Uprated Engines," TP 900124, Society of istics of Rapidly Solidified A1-Si-X Pow- 62. S. Komatsu, S, Yahata, K. Fukui, and T. Automotive Engineers, 1990 ders for High Performance Applications, Tokoshima, "Development of Aluminum 78. Automot. Eng., Vol 97 (No. 12), 1989, p J. Mater. Sci., Vol 25 (No. 2A), Feb Alloy Roller Type Valve Rocker Arm by 21-25 1990, p 886-904 Casting and Technique," TP 79. S. Kitaoka, H. Kamio, and S. Kobayashi, 94. K. Hummert and V. Arnhold, Possibilities 890554, Society of Automotive Engi- Material Properties of AI-Si Alloys for of Powder Metallurgy Aluminum Materi- neers, 1989 Forging and Their Application, translation als in Motor Construction, 3rd Interna- 63. S. Ezaki, M. Masuda, H. Fujita, S. Ha- from Alutopia (Jpn.), Vol 17 (No. 10), tional Symposium on Aluminium + Auto- yashi, Y. Terashima, and K. Motosugi, 1987, p 9-18 mobile, 1988, p 171-175 "Aluminum Valve Lifter for Toyota New 80. S. Kitaoka, C. Fujikura, and A. Kamio, 95. "High Strength Powder V-8 Engine," TP 900450, Society of Au- Aluminium-Silicon Alloys, translation of Having Heat and Wear Resistance: Con- tomotive Engineers, 1990 J. Jpn. Inst. Light Metals, Vol 38 (No. 7), tains Silicon, Nickel, Iron and Manga- 64. H. Baker, The Road Ahead for Metals in 1988, p 426-446 nese, and is Used for Cylinder Liners," Autos, Adv. Mater. Proc., May 1990, p 81. O. Takezoe and Y. Yasuda, Technical U.S. patent 4,938,810 27-34 Trends of Highly Wear Resistant Alumi- 96. T. Hayashi, Y. Takeda, K. Akechi, and 65. Aluminum Association Guide to Alumi- num Alloy, Kobe Res. Dev., Vol 38 (No. T. Fujiwara, "Rotary Air Conditioner num Parts 1978-1984, Reynolds Alumi- 4), Oct 1988, p 23-26 Made with P/M AI-Si Wrought Alloys," num 1985 Aluminum Automotive Appli- 82. R.P. MacCoon and R.P. Ernst, "The TP900407, Society of Automotive Engi- cations Thunder Aluminum 390 Alloy Aircraft neers, 1990 66. Chapter 20, Aluminum--Vol H: Design Engine," TP 830008, Society of Automo- 97. W. Kahl and J. Leupp, "High Perform- and Application, K.R. Van Horn, Ed., tive Engineers, 1983 ance Aluminum Produced by Spray Depo- American Society lot Metals, 1967 83. Automot. Eng. (London), Vol 7 (No. 3), sition," BNF 7th International Conference 67. Chapters 8 and 9, Aluminum--Vol I: Prop- June-July 1982, p 25-27 Material Revolution through the 90s erties, Physical Metallurgy and Phase Di- 84. M.W. Toaz and M.D. Smalc, Clevite's 98. F. Hehemann et al., "Comparison of Proc- agrams, K.R. Van Horn, Ed., American Advanced Technology for the Diesel Pis- essing Atomized and Spray-Deposited Diesel Prog. North Am., Society for Metals, 1967 ton, Vol 51 (No. AI-20 Si-5 Fe-2 Ni (wt.%) Aimed at Auto- 68. "Bearing and Bushing Alloys," J460e, 6), June 1985, p 56 motive Applications," PM90, Institute of SAE Handbook, Society of Automotive 85. R.R. Bowles, D.L. Mancini, and M.W. Metals, London Engineers Toaz, Design of Advanced Diesel Engine et al., 69. "Bearing and Bushing Alloys," J459c (In- Pistons Employing Ceramic Fiber Rein- 99. J. Duszczyk The Osprey Preform Process and the Application to Aluminum formation Report), SAE Handbook, Soci- forcement, Seminar Advanced Compos- ety of Automotive Engineers ites: The Latest Developments, Nov 1986, Alloys Including Wear and High Temper- 70. M. Gallerneaut and C. Fulton, "Score Re- American Society for Metals, p 21-27 ature Resistance AI-20 Si-Cu Alloys, Modern Developments in Powder Metal- sistance of SAE 781 Automotive Journal 86. T. Donomoto, K. Funatani, N. Miura, and lurgy, Bearing Alloy-A Metallographic Analy- N. Miyake, "Ceramic Fiber Reinforced Vol 18-21, Metal Powder Industries sis," TP 860062, Society of Automotive Piston for High Performance Diesel En- Federation, 1988, p 441-453 Engineers, 1986 gines," TP 830252, Society of Automo- 100. D.A. Parker, Material and Its 71. G.C. Pratt, "Aluminum Based Crankshaft tive Engineers, 1983 Impact on the Development of Compo- Bearings for the High Speed Diesel En- 87. T. Suganuma and A. Tanaka, Applica- nents for Reciprocating Engines, Int. J. gine," TP810199, Society of Automotive tions of Metal Matrix Composites to Die- Veh. Des., IAVD Congress on Vehicle Engineers, 1981 sel Engine Pistons, J. Iron Steel Inst. Design and Components, 1985, Inter- 72. F.A. Davis, Plain Bearing Wear in Inter- Jpn., Vol 75 (No. 9), Sept 1989, p 1790- science Enterprises, Ltd., United King- nal Combustion Engines, Automot. Eng. 1797 dom, p B35.1-30 (UK), Vol 6 (No. 4), 1981, p 31-33, 37-38 88. R. Keribar, T. Morel, and M.W. Toaz, 101. A.E. Ostermann, "Experiences with 73. T. Fukuoka, H. Kato, and S. Kamiya, "An Investigation of Structural Effects of Nickel-Silicon Carbide Coatings in Cylin- 794 / Materials for Friction and Wear Applications

der Bores of Small Aluminum Engines," 105. J.H. Hirvonen, Industrial Applications of 109. C.W. Draper, Laser Surface Alloying: TP 790843, Society of Automotive Engi- Ion Implantation, Ion Implantation and The State of the Art, J. Met., June 1982, p neers, 1979 Ion Beam Processing of Materials, MRS 24 102. J.D. Destefani, Ion Implantation Update, Symposia Proceedings, Materials Re- 110. J.M. Rigsbee, Surface Engineering by La- Adv. Mater. Proc., Oct 1988, p 39-43 search Society, Vol 27, 1983, p 621-629 ser and Physical Vapor Deposition Tech- 103. C.M. Preece and J.K. Hirvonen, Ion Im- 106. G.L. Kutner, Thermal Spray by Design, niques, J. Met., Aug 1984, p 31 plantation Metallurgy, TMS-AIME, 1980 Adv. Mater. Proc., Oct 1988, p 63 111. E. Blank, M. Pierantoni, and M. Carrard, 104. I.L. Singer, Tribomechanical Properties 107. M.L. Thorpe, Thermal Spray Applica- Laser Surface Modification of A1-Si Cast of Ion Implanted Metals, Ion Implantation tions Grow, Adv. Mater. Proc., Oct 1988, Alloys for Wear Resistance and Surface and Ion Beam Processing of Materials, p 69 Toughness, Surface Modification Tech- MRS Symposia Proceedings, Materials 108. E.J. Kubel, Jr., Thermal Spraying Tech- nologies II1, 1990, T.S. Sudarshan and Research Society, Vol 27, 1983, p 585- nology: From Art to Science, Adv. Mater. D.G. Bhat, Ed., TMS-AIME, 1990, p 595 Proc., Dec 1987, p 69 493-510