US3869259A

US3869259A - Composite sliding member

Info

Publication number: US3869259A
Application number: US356611A
Authority: US
Inventors: David M Lindsey
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1973-05-02
Filing date: 1973-05-02
Publication date: 1975-03-04
Anticipated expiration: 1992-03-04
Also published as: IT1011295B; GB1440867A; FR2228155A1; JPS50123504A; CA1018965A; DE2415035B2; FR2228155B1; DE2415035C3; AU6731774A; DE2415035A1

Abstract

In a preferred embodiment a sliding member, such as an apex seal in a rotary internal combustion engine, is formed of particulate carbon interdispersed with, and metallurgically bonded to, a copper base alloy containing, by weight, 3% to 22% lead,, and titanium and optionally tin in amounts providing effective wetting and bonding of the metallic phase to the carbon and yet not substantially detracting from the physical strength of the composite, the carbon phase making up 20% to 80% by volume of the composite seal member. In various sliding members that have been evaluated as apex seals 5% to 20% of titanium and up to 15% tin in the copper base alloy have been successfully employed. Seal members of this composition are wear resistant and can be employed to particular advantage in combination with a rotor housing having a hard chrome wear surface.

Description

United States Patent [191 Lindsey 1 Mar. 4, 1975 1 1 COMPOSITE SLIDING MEMBER David M. Lindsey, Taylor, Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: May 2, 1973 [21] Appl. No.: 356,611

[75] Inventor:

[52] U.S. Cl 29/I82.8, 75/156, 75/163, 75/164 [51] Int. Cl. C22c 1/04 [58] Field of Search 75/156, 163, 164; 29/1825, 182.8; 418/179 [56] References Cited UNITED STATES PATENTS 3,114,197 12/1963 Du Bois 29/1825 X 3,177,564 4/1965 Reynolds et al.. 29/1825 3.191.278 6/1965 Kendall et a1 29/182 5 3,545,901 12/1970 Belzner 418/179 3,782,930 l/1974 Shibata 29/1828 X 3.795.493 3/1974 Merth 29/1825 Primary E.\'aminerL. Dewayne Rutledge Assistant E.raminerArthur J. Steiner Attorney, Agent, or FirnzGeorge A. Grove [57] ABSTRACT In a preferred embodiment a sliding member, such as an apex seal in a rotary internal combustion engine, is formed of particulate carbon interdispersed with, and metallurgically bonded to, a copper base alloy containing, by weight, 3% to 22% lead., and titanium and optionally tin in amounts providing effective wetting and bonding of the metallic phase to the carbon and yet not substantially detracting from the physical strength of the composite, the carbon phase making up 20% to 80% by volume of the composite seal member. In various sliding members that have been evaluated as apex seals 5% to 20% of titanium and up to 15% tin in the copper base alloy have been successfully employed. Seal members of this composition are wear resistant and can be employed to particular advantage in combination with a rotor housing having a hard chrome wear surface.

4 Claims, 3 Drawing Figures PMENTEUHAR 413.;

till-ill!!! COMPOSITE SLIDING MEMBER This invention relates to metal-carbon composite compositions for use in forming sliding machine elements such as seals. More particularly, this invention relates to titanium-containing, copper base alloycarbon compositions suitable for forming rotary internal combustion engine apex seals.

Rotary mechanisms, such as internal combustion engines, pumps and compressors, are known and now being developed for many different applications. In general, such rotary mechanisms comprise an outer peripheral wall body, interconnected by a pair of parallel end walls to define a cavity whose peripheral shape is basically an epitrochoid. A rotatably mounted rotor is supported on a shaft within the cavity. The outer surface of the rotor defines a plurality of circumferentially spaced apex portions having radially movable seal strips mounted therein for sealing engagement with the inner surface of the peripheral wall. Thus, working chambers are formed between the rotor and peripheral wall which vary in volume upon relative rotation of the rotor and the outer body. An intake port is provided which, in the case of an internal combustion engine, admits air or an air-fuel mixture for supplying the combustion zone of the engine. An exhaust port is provided for expelling the working fluid, such as the burnt gases in the case of the engine. In an engine ignition means may be provided for ignition of the fuel-air mixture so that the stages of intake, compression, expansion and exhaust may be carried out.

In the successful operation of a rotary mechanism of the type described there must be effective sealing contact between the apex seal strips and the inner surface of the peripheral wall over the useful life of the mechanism. In fact, the level of performance of the mechanism depends upon there being minimal or no leakage between a seal and the peripheral surface so that the several working chambers are effectively isolated from each other. In the case of the rotary engine many different materials have been evaluated for the manufacture of the apex seals and the peripheral rotor housing. For example, a rotor housing construction that has been used commercially is formed of an aluminum alloy. The aluminum alloy is employed because of its relatively low weight and high thermal conductivity. An intermediate layer of iron is formed on the inner peripheral surface of the light alloy housing. Iron bonds well with the aluminum alloy and provides a relatively harder surface. This intermediate layer is relatively thin, typically about 0.025 inch to 0.050 inch so that it will not be subject to large thermal stresses. After the bonding of the iron layer to the housing, a relatively thin inner layer of hard chrome is applied, typically by electroplating. The chrome layer is the wear surface of the peripheral housing against which the apex seals slide.

Various mixtures of materials have been proposed for the manufacture of apex seals, including those which are intended to run against a hard chrome surface. For example, various types of carbon and mixtures of carbon with tin, lead, zinc, antimony and aluminum have been considered. Of these, at least the aluminum alloy-carbon seals have been employed commercially. Examples of such seal materials are described in British Pat. No. 1,234,634 and German Offenlegungsschrift No. 2,034,896. The aluminumcarbon seals have been used in relatively small (120 in.

and 14 0 in. swept volume 2 rotors) or low performance rotary engines. However, they have been found to fail in larger engines (e.g., 200 in. and 266 in. swept volume 2 rotors) where the seal strip must be longer and subject to more flexing, and in higher performance engines where the seal is subjected to more severe loads and temperatures.

For optimum results in a rotary mechanism it is recognized that the material of the apex seal and the wear surface of the peripheral housing must both be considered and selected so that they operate well together. For example, a very hard seal material may be chosen which resists seal wear but produces excessive wear of the housing. Conversely, hard housing surfaces may be chosen which produce excessive :seal wear or failure.

It is an object of the present invention to provide a sliding member having particular utility as an apex seal member in a rotary internal combustion engine. The sliding member is a composite of carbon particles dispersed in a copper base alloy matrix. The copper base alloy is characterized by the presence of titanium, lead and optionally tin. The composition is especially advantageous as a rotary engine apex seal member characterized by strength at high engine temperatures and/or in larger engines, and minimal wear of both the seal itself and the housing against which it slides.

In accordance with a preferred embodiment of my invention, these and other objects are accomplished by providing a composite sliding element or sea] member which is characterized by the presence of small carbon particles interdispersed in a suitable copper base alloy. The copper base alloy contains, by weight, 5% to 20% titanium, 3% to 22% lead and 0% to 15% tin. A particularly preferred copper base alloy for use in this composite composition in rotary engine apex seals consists essentially, by weight, of 9% to 18% titanium, 4% to 10% lead, 4% to 13% tin and the balance copper excluding impurities. Since this copper base alloy contains both titanium and lead in significant amounts it may be generally characterized as a titanium bronze. The composite carbon-titanium bronze sliding members of my invention may be prepared by any of a number of known techniques which will be described such that the carbon particles and copper alloy are generally uniformly interdispersed and there is a metallurgical bond at the interface of the carbon particles and the metallic phase. The carbon may make up 20% to by volume of the subject seal composition, but preferably the composition consists of 40% to 65% by volume carbon and the balance metal phase. The composition of my invention provides high flexural strength even at temperatures as high as 900 F. It is chemically stable in the hot water containing environment of an internal combustion engine. The copper base alloy employed in accordance with my invention provides good wetting of the particulate carbon phase, resulting in higher strength seals and yet requires less expensive manufacturing techniques because of the improved wetting.

These and other objects and advantages of my invention will become more apparent from a detailed description thereof which follows. In the description reference will be had to the drawings, in which:

FIG. 1 is an elevational view partly in section of the rotor housing and rotor assembly of a rotary engine;

FIG. 2 depicts a rotary engine apex seal; and

FIG. 3 is a photomicrograph at 200X magnification showing the microstructure of a composite seal composition of my invention.

With reference to FIG. 1, there is shown a side view partly in section of the rotor assembly and peripheral housing of a rotary engine. The rotary combustion engine comprises a stationary outer body formed by a peripheral wall or rotor housing 12. The rotor housing is interconnected with end housings 14 (only one shown) to form a rotor cavity 16. As viewed in FIG. I the inner surface 13 of the peripheral wall 12 has a multilobed (two-lobe) profile which is basically a twolobed epitrochoid or a curve parallel thereto whose center is indicated at 20. A crankshaft 22 is rotatably supported within the end housings 14 by bearing means, not shown, so that the shaft axis is coincident with a line through the center 20 parallel to the peripheral wall 12. The crankshaft 22 has an eccentric 24 in the rotor cavity 16. Rotatably supported on the eccentric 24 is a rotor 26 having three circumferentially spaced apex portions 28, in each of which there is a spring biased, radially movable apex seal strip 30. Each seal strip 30 (see also FIG. 2) extends completely across the rotor cavity 16 from one end housing 14-to the opposite one.

An annular externally toothed gear 32 is received about and is concentric with the crankshaft 22 and is rigidly secured to an engine housing 14. The gear 32 meshes with an internally toothed gear 34 that is concentric with and fixed to one side of the rotor 26. The gear 34 has one and one-half times the number of teeth as the gear 32, with the result that this gearing enforces a fixed cyclic relation between the rotor and the crankshaft such that the crankshaft, which is the engines output shaft, makes three complete revolutions for every one complete revolution of the rotor. The rotor faces 36 cooperate with the peripheral wall 12 and with the side walls 14 to define three variable volume working chambers 44 that are spaced around and move with the rotor within the housing as the rotor orbits within the rotor cavity.

Side seals 38 are provided within each of the side faces 40 of the rotor for sealing engagement with the inner surfaces of the end housings. These seals mate with corner seal bodies 42 which also aid in supporting the apex seal strips 30 in each of the apex portions. Thus, a continuous seal is provided for each of the working chambers 44 defined between the faces 36 and apex portions 28 of the rotor and inner surface 13 of the peripheral wall 12. As the rotor and outer body rotate relative to one another, the working chambers being defined between the apex portions of the rotor and the inner surface of the peripheral wall vary in volume as is known.

As depicted in FIG. I, an intake port 46 is provided in end housing 14 for admitting air or a fuel-air mixture to supply the combustion zone of the engine. An exhaust port 48 is provided in the peripheral wall 12 for expelling the combustion products. An ignition means 50 may be provided for ignition of the fuel-air mixture. It may be eliminated if the engine is run on a diesel cycle.

In accordance with a preferred application of the apex seal member embodiment'of my invention the rotor housing 12 is preferably formed from a lightweight alloy material (indicated at 52), such as aluminum, aluminum alloy, magnesium or magnesium alloy,

and the inner surface 13 of the peripheral wall is provided with a liner 54 to increase the wear life of the inner surface and of the apex seal strips. The light alloy housing has an intermediate layer 56 bonded to its 5 inner surface which may be formed of molybdenum, iron or steel, or a combination thereof. These materials bond well with the light alloy housing and provide a relatively hard surface. As is now known, the intermediate layer may be formed by a known transplant casting method. In accordance with this method, a mandrel is designed so that its outer surface substantially defines the shape of the housing cavity. A suitable parting compound is applied to the surface of the mandrel and the material of the intermediate layer is sprayed onto the mandrel in a layer 0.025 inch to 0.050 inch in thickness. The light alloy housing is then cast around the preformed intermediate layer and the mandrel is removed, leaving the intermediate layer 56 securely bonded to the housing.

After bonding of the intermediate layer 56 to the housing 12 a relatively thin layer 58 of high wear resistant metal, preferably chromium or chromium alloy, is deposited onto the intermediate layer to form a hard, smooth, wear resistant, relatively low friction surface for engagement by the apex seal strips. The chromium layer may be electrodeposited onto the intermediate layer. The chromium layer 58 after finish grinding is quite thin, typically 0.002 inch to 0.010 inch in thickness.

The subject apex seals (depicted at 30 in FIGS. 1 and- 2) have also been employed with a cast iron rotor housing having a chrome plated inner surface.

The seals and other sliding members of my invention are formed of a metal-carbon composite which is durable and wear resistant, e.g., under the dynamic conditions experienced in the apex position of the Wankel type rotary engines. In a preferred embodiment a composite apex seal consists of finely divided, particulate carbon dispersed 'in and metallurgically bonded to a continuous interconnecting phase of a copper-titanium alloy containing some lead. The metal portion and the carbon portion of the seal complement each other insofar as wear, strength and frictional characteristics are concerned. It is believed that a significant factor in the performance of my seal composition is the bonding of the titanium bronze alloy to the carbon due to wetting enhanced by the lead and the formation of interfacial titanium carbides. chromplated,

The titanium bronze alloy used in my sliding member compositions contains, by weight, 3% to 22% lead, optionally up to about 15% tin, titanium in an amount providing effective wetting and bonding of the metal phase to the carbon without substantially detracting from the strength and toughness of the composite, and the balance copper. As indicated above, I employ titanium and lead to cause the copper base alloy to wet the carbon particles. I prefer to employ at least about 5% by weight titanium in the copper base alloy. A titanium content in excess of 20% by weight of the alloy does not appear to further contribute to the useful strength of my composite and can cause detrimental embrittlement. Lead contents in excess of 22% by weight of the alloy may unduly soften the composite seal. Tin contributes to the desirable friction properties of the composite seal. Preferably, the alloy portion of my composite seal consists essentially, by weight, of 9% to l8% titanium, 4% to 13% lead, 4% to tin and the balance copper excluding impurities.

Sliding members of the subject composition may be formed by the employment of standard power metallurgy processes. When such techniques are employed the carbon and copper base alloys, of course, must be in finely divided, particulate form. The carbonaceous particles employed in accordance with the invention are hard, wear resistant grades of carbon (amorphous or crystalline), such as anthracite coal, vitreous carbon and synthetic carbons containing crystalline carbon. In an apex seal application amorphous carbon-graphite mixtures (containing up to 15% to graphite) may also be employed, but graphite alone is too soft. In less stringent wear situations graphite alone may be used as the carbon constituent.

The carbon is preferably 325 mesh size although somewhat larger particles (200+325 mesh) have been used. I have found, however, that pitting of the composite is more likely to occur in apex seal applications if the carbon mesh size is larger than 3 mesh. Carbon particles of 325 mesh size are prepared by known comminuting procedures, such as ball or rod milling. In the subject metal-carbon composites 20 to 80 volume percent of carbon is present. The subject titanium bronze alloy may be prepared in particulate form by atomizing molten alloy in an argon atmosphere. A 325 mesh alloy powder of high purity is thus formed. It is not necessary to use prealloyed powder. A powder mixture of the individual constituents can suitably be employed.

Carbon powder 325 mesh and copper base alloy powder 325 mesh are measured out by weight or by volume in the desired proportions. They are thoroughly blended together by standard blending techniques and equipment. The powder blend is then consolidated into a unitary composite member.

One technique of accomplishing this is by vacuum hot pressing. The powder blend is placed in a carbon die of suitable predetermined configuration. Individual seal members can be formed, or a large block of composite material may be formed from which seals are cut or machined. Pressure is applied through the carbon dies to the powder blend in an apparatus arranged and constructed so that all air can be evacuated from around the powder mixture and replaced with argon or other suitable inert gas. A pressure of 1,000 psi is maintained on the powder as it is heated from room temperature to l,800 F. The pressure is then increased to 6,000 psi while the l,800 F. temperature is maintained for minutes. The composite material is then permitted to cool to room temperature, the pressure being relieved when the temperature has fallen below about l,400 F. Under the high temperature and pressure conditions the copper base alloy melts and wets the carbon particles forming an interfacial metallurgical bond therewith. The wetting is enhanced by the pressure of the lead and titanium, and titanium carbide is formed.

As seen in FIG. 3, the microstructure (shown at 200X) consists of carbon particles 60, each surrounded by the copper alloy metallic phase 62. The copper phase is strengthened by the presence of tin and titanium. The lead is present as discrete particles, randomly distributed in the metallic phase (not visible at 200X). There is a metallurgical bond between the metallic phase and the carbon. Titanium from the metallic phase reacts with the carbon to form titanium carbide. Evidence for this is seen in an X-ray diffraction pattern and in an electron microprobe analysis for titanium. This carbide provides the bond between the metallic matrix and the carbon particle.

The carbon-titanium bronze mixture may also be consolidated into my composite seal member by other known powder metallurgical techniques, such as isostatic hot pressing (wherein the powder mixture is placed in a glass or metal can and subjected to high fluid pressure); atmospheric hot pressing (using additives such as titanium hydride which decompose to provide a protective atmosphere); cold pressing and sintering; cold pressing, presinter and hot forming; or extrusion.

My composite seal members may also be formed by a warm forming method utilizing an inert atmosphere. A suitable mixture of 325 mesh titanium bronze alloy and carbon powders (for example, 5050 by volume) are purged with argon and heated in an argon atmosphere to l,800 F. In the meantime, forging dies having a cavity adapted to receive the hot powder mixture are heated to 500 F. Preheated powder is placed in the die and a pressure of twenty tons per square inch imposed for about a minute. The pressure is released and a formed composite block is removed from the die. Individual seal members, such as that depicted in FIG. 2, are machined from the block.

In order that a finished seal will better hold its dimensions when experiencing the elevated temperatures of a rotary engine, the block from which individual seals A few specific examples will further illustrate my in- I vention. A 325 mesh prealloyed powder (designated AM-l consisting essentially, by weight, of 9.9% titanium, 9.1% lead, 9.2% tin and the balance copper, was obtained. This metal alloy powder was thoroughly mixed with 325 mesh anthracite coal powder. The amorphous carbon powder made up 20% by weight of the mixture. The mixture was hot pressed in a vacuum to form a composite block consisting of approximately equal proportions by volume of carbon particles and copper base alloy matrix. Apex seals were machined from the blanks and placed in a commercial rotary combustion engine. The epitrochoidal housing of the engine had a hard chrome surface against which the subject seals ran. The engine was run driving a dynamometer for hours. At the end of that time the engine was dismantled and the seals examined. The average Wear of the three seals (from one rotor) was found to be 6.5 mils during the 100 hours. In a companion test of seals formed of the above alloy, but a different carbon (U.S. Graphite Co. Graphitar 34), in a similar engine the average seal wear was found to be 2.9 mils over the 100 hour test. These seals were considered to have operated in a wholly satisfactory manner.

For purposes of comparison, commercial aluminum alloy-carbon composite seals of the type described above were also run in commercial rotary engines of the same design as those employed in the abovedescribed tests. In two different dynamometer runs identical to those employed above the average wear of the aluminum-carbon composite seals was found to be 9.3 mils per 100 hours and 7.4 mils per 100 hours, respectively.

Another set of composite apex seal members were prepared as described above in accordance with my invention, except that in this instance the copper base alloy (designated J) consisted essentially, by weight, of 16.3% titanium, 8.8% lead, 7.7% tin and the balance copper. Furthermore, a quantity of amorphous carbon particles was employed such that the carbon made up about 65% by volume of the composite seal member. As above, the carbon particles were initially 325 mesh. A set of these seals was also tested in a commercial rotary internal combustion engine driving a dynamometer over a 100 hour test. The average wear of the seals was 8.9 mils. These seals also were considered to have performed satisfactorily; A'number of other carbon-titanium bronze alloy composite seals have been produced and tested in commercial rotary engines as described above. in each instance an essentially amorphous 325 mesh carbon was employed in amounts such as to make up 50% to 65% by volume of the alloy.

engine, more or less of the type described having hard chromeplated, layered rotor housings. A number ofthe seals were also placed in a 120 in. swept volume engine, also of the general type described having a hard chrome plated layer on the rotor housing. Purchased prior art aluminum-carbon seals were placed in both a 206 in. engine and a l20 in. engine. Titanium bronzecarbon seals of the above composition, but formed by the warm forming process described above, were also placed in a 206 in. engine and a 120 in. engine. All of the 206 in. engines containing the respective seal members were operated steadily for a prolonged period of time under the same predetermined engine durability schedule. The 120 in. enginescontaining the same respective seals were likewise steadily operated for a prolonged period of time but under a different durability schedule. At the end of the tests the engines were disassembled and all of the seals examined. The wear rate and other properties for the various seals in the re- Finely divided, prealloyed, titanium bronze powders 2O spective engines were as follows:

206 in. Engine 120 in. Engine Seal How Wear Rate Wear Rate Pitting Modulus of Rupture (PSI) Material Obtained (Mils/lOO hrs.) (Mils/l00 hrs.) Resistance 75 F. 700 F. 900 F.

Aluminum- Carbon Purchased 13.0 3.0 Fair 38,400 28,200 21,000 Titanium Vacuum Bronze- Hot Carbon Pressing 5.5 2.0 Good 43,200 37, I00 31,000 Titanium Bronze- Warm v Carbon Forming 8.5 1.5 Good 44,800 38,000 32,000

were employed having compositions as tabulated below.

Composite apex seals, wherein the above alloys were employed as the metal phase, all were tested in commercial engines and found to operate generally satisfactorily. It was felt, however, that the alloy designated AM-2" was probably at about the upper limit for suitable lead content since the wear of these seals was relatively higher than other seals in accordance with this invention and some lead was observed to have sweated out of the composite during heat treatment at 850 F.

In another example of the performance of a composite seal member in accordance with my invention, a titanium bronze alloy powder (325 mesh) of the following composition, by weight, was obtained: 71% copper, titanium, 4.5% lead and 9.5% tin. Anthracite coal powder (325 mesh) was also obtained and a powder blend of the alloy and carbon consisting of by weight calcined anthracite and 80% by weight titanium bronze alloy was prepared. This powder blend was consolidated into a number of apex seal members, such as depicted in FIG. 2, by the vacuum hot pressing technique described above. This mixture resulted in a composite seal which consisted of about 50% metallic phase and 50% anthracite by volume. These seals were placed in a 206 in. swept volume rotary combustion It is seen that the wear rates for the sliding members of my invention are lower than for the most directly comparable known prior art seals. In addition, the modulus of rupture of my sliding members is significantly greater both at room temperature and at temperatures of 700 F. and 900 F.

It is recognized that, in general, metal alloy-carbon composites may be formed more or less in accordance with the procedure outlined in Hucke, US. Pat. Nos. 3,235,346 and 3,348,967. In accordance with Hucke a permeable framework of carbon is provided and the framework is infiltrated with a suitable molten metal alloy. Depending upon the composition of the infiltrating alloy, the conditions under which infiltration is accomplished, or subsequent conditions, the alloy may or may not form a metallurgical bond with the continuous framework of carbon. However, structures produced in this manner have thus far experienced substantial chipping when employed as apex seal members in rotary engines. Chipping from the surface of the seal member in such an application is, of course, undesirable because the effectiveness of the seal is thereby diminished and engine performance decreases. The structure of the present invention differs from Hucke as a result of the use of a particulate mixture of carbon and the copper base alloy, the composition of the alloy and in the avoidance of such chipping due to the coaction of all of the initially particulate ingredients.

While my invention has been described in terms of some preferred embodiments thereof, it will be appreciated that other forms thereof could readily be adapted by one skilled in the art. Accordingly, it is to be understood that the scope of my invention is to be limited only by the following claims.

What is claimed is:

l. A liquid phase sintered metal-carbon composite sliding member formed of carbon uniformly dispersed in and metallurgically bonded to a phase of a copper base alloy, said copper base alloy consisting essentially, by weight, of 5% to 20% titanium, 3% to 22% lead, to 15% tin and the balance copper, said carbon making up about 20% to 80% by volume of said composite member, said metallurgical bond comprising titanium carbide.

2. A liquid phase sintered metal-carbon composite sliding member consisting essentially of particulate carbon dispersed in and metallurgically bonded to a continuous interconnecting phase of a copper base alloy, said carbon particles being initially about 200 mesh or smaller and collectively making up 20 to 80 volume percent of said composite member, said copper base alloy consisting essentially, by weight, of to 20% titanium, 3% to 22% lead, 0% to tin and the balance copper, said metallurgical bond comprising titanium carbide.

3. A liquid phase sintered metal-carbon composite sliding member particularly suitable for use as a rotary engine apex seal member consisting essentially of particulate carbon dispersed in and metallurgically bonded to a continuous interconnecting phase of a copper base alloy, said carbon particles being initially 325 mesh and collectively making up about 40 to 65 volume percent of said composite member, said copper base alloy consisting essentially, by weight, of 5% to 20% titanium, 3% to 22% lead, 4% to 15% tin and the balance copper, said metallurgical bond comprising titanium carbide.

4. A liquid phase sintered metal-carbon composite sliding member particularly suitable for use as a rotary engine apex seal member formed of carbon particles dispersed in and metallurgically bonded to an interconnecting phase of a copper base alloy, said carbon particles being initially --325 mesh and collectively making up about 40 to 65 volume percent of said composite member, said copper base alloy consisting essentially, by weight, of 9% to 18% titanium, 4% to 10% lead, 4% to 13% tin and the balance copper, said metallurgical bond comprising titanium carbide.

Claims

1. A LIQUID PHASE SINTERED METAL-CARBON COMPOSITE SLIDING MEMBER FORMED OF CARBON UNIFORMLY DISPERSED IN AND METALLURGICALLY BONDED TO A PHASE OF A COPPER BASE ALLOY, SAID COPPER BASE ALLOY CONSISTING ESSENTIALLY , BY WEIGHT, OF 5% TO 20% TITAIUM, 3% TO 22% LEAD, 0% TO 15% TIN AND THE BALANCE COPPER, SAID CARBON MAKING UP ABOUT 20% TO 80% BY VOLUME OF SAID COMPOSITE MEMBER, SAID METALLURGICAL BOND COMPRISING TITANIUM CARBIDE.

2. A liquid phase sintered metal-carbon composite sliding member consisting essentially of particulate carbon dispersed in and metallurgically bonded to a continuous interconnecting phase of a copper base alloy, said carbon particles being initially about 200 mesh or smaller and collectively making up 20 to 80 volume percent of said composite member, said copper base alloy consisting essentially, by weight, of 5% to 20% titanium, 3% to 22% lead, 0% to 15% tin and the balance copper, said metallurgical bond comprising titanium carbide.

3. A liquid phase sintered metal-carbon composite sliding member particularly suitable for use as a rotary engine apex seal member consisting essentially of particulate carbon dispersed in and metallurgically bonded to a continuous interconnecting phase of a copper base alloy, said carbon particles being initially -325 mesh and collectively making up about 40 to 65 volume percent of said composite member, said copper base alloy consisting essentially, by weight, of 5% to 20% titanium, 3% to 22% lead, 4% to 15% tin and the balance copper, said metallurgical bond comprising titanium carbide.

4. A liquid phase sintered metal-carbon composite sliding member particularly suitable for use as a rotary engine apex seal member formed of carbon particles dispersed in and metallurgically bonded to an interconnecting phase of a copper base alloy, said carbon particles being initially -325 mesh and collectively making up about 40 to 65 volume percent of said composite member, said copper base alloy consisting essentially, by weight, of 9% to 18% titanium, 4% to 10% lead, 4% to 13% tin and the balance copper, said metallurgical bond comprising titanium carbide.