JPH0463026B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to products made from carbonaceous friction plates, such as brake and clutch disks of the type used in airplanes, automobiles, and the industrial field.

More particularly, the present invention relates to a refurbished carbonaceous brake or clutch disc and a method for renewing a worn disc.
Rather than discard worn disks, this method uniquely adheres a light weight, long-wear material to the worn portions of the disks, returning them to a safe and usable condition.

BACKGROUND OF THE INVENTION Brake discs and clutch facings made of carbon or graphite materials have been used commercially. Such discs are manufactured in various ways from carbonaceous materials in the form of felt or woven fabrics. Disks are often made by cutting the carbonaceous material into annularly shaped pieces, stacking the shaped pieces on top of each other to form a stack, impregnating the stack with a binder, and then pyrolyzing the stack to form the carbon disk. get. Such a procedure is disclosed in US Pat. No. 3,794,509. A somewhat similar procedure is disclosed in US Pat. No. 3,730,320.

Brake discs and clutch aces made from carbon or graphite materials oxidize during use and are further removed from the friction surfaces, reducing their original condition by 10 to 15 minutes.
% develops into internal porosity. When these worn friction materials are mechanically fabricated into a refurbished core with new porous fiber-reinforced composites, their porosity is on the order of 15-20%, which is quite permeable. Furthermore, it is porous.

The invention describes chemically and mechanically bonding together two porous segments, both of which are carbon fiber reinforced matrix composites.

The most advantageous carbonaceous friction materials that can be used in the manufacture of brake discs, as well as methods of making such materials, are disclosed in US Pat. Bauer's method does not involve impregnating the carbonaceous material with a binder, but rather uses a chemical vapor deposition (CVD) method for internal deposition of the carbonaceous material using pyrolytic carbon to obtain the final brake disc. include.

Various methods have been proposed for refurbishing worn carbon brake discs. For example, Patent No. 3,712,427 to Kutsuk et al. discloses a brake disc coated on both sides with carbon wear plates secured to the core by rivets.

U.S. Patent No. 3,956,548, issued to Kovac et al.
A method of manufacturing a carbon composite brake disc is disclosed in which one or more carbon felt layers are bonded to a reusable carbon composite material using a high carbon wear cement. An important point pointed out by Kovac et al. in that patent is the use of a carbon felt layer. In fact, Kovac et al., in particular, found that carbon cloth layers and the like were not suitable for producing the brake discs of the invention and did not yield a better bond.

The gist of the invention lies in the use of one or more carbon fabric layers to provide the contact material, rather than the use of a carbon felt layer as deemed essential by Kovac et al. According to the present invention, not only a fabric layer is used, but also a novel method of bonding the fabric layer to the reusable core provides a completely new brake disc with exceptional properties and abrasion properties. I will provide a.

In view of the substantial costs involved in manufacturing carbonaceous brake discs, either by impregnation or CVD infiltration methods, the regeneration process of the present invention provides significant cost savings. Furthermore, because of the new method of bonding the carbon cloth lining to the core, the refurbished brake discs have quality characteristics comparable in all respects to the originally manufactured discs, and therefore such brakes The disk is novel in this configuration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a refurbished carbonaceous brake disc and an economically effective replacement of worn carbon discs and pads of the type used in aircraft, automotive and industrial applications. Provide a way to get used to it.

Another object of the invention is to provide a refurbished brake disc having the above-mentioned characteristics, giving high quality characteristics and reliability and parity in all respects with originally manufactured brake discs. be.

Another object of the invention is to replace severely worn and chipped or damaged carbonaceous brake discs with
The objective is to provide a method for renewing, either by resin or pitch impregnation or by CVD infiltration techniques.

Yet another object of the invention is not to use carbon felt lining materials, but rather carbon fabrics or various types such as rayon, PAN,
A method is provided for forming a tie layer between a refurbished core and a new wear lining using a woven carbon cloth material such as pitch, cellulose, or cellulose.

Another object of the invention is to provide the features mentioned in the previous section, whereby the unique combination of carbonizable adhesive and CVD infiltration of pyrolytic carbon converts wear lining materials into carbon composites. It is also used to provide a new integral disc as the first thing after the infiltration process to ensure secure adhesion to the material core.

Another object of the invention is to provide an improved brake disc which is reliable in use and has the property of not chipping, peeling or cracking during use.

A further object of the invention is to provide an improved brake disc as mentioned in the previous section,
This disc exhibits wear characteristics that are equal to or superior to those of the original brake disk.

DEFINITIONS OF TERMS 1 "Carbon fibers" are fibers made by heat treating natural and synthetic fiber materials such as wool, rayon, polyacrylonitrile, cellulose and pitch at temperatures on the order of 100°C.

2 "Graphite fiber" is a fiber obtained by heat treating carbon fiber at a temperature on the order of 200°C or higher.

3. The "pyrolytic carbon" used in the present invention is a material that pyrolyzes hydrocarbons, such as natural gas, onto carbon fibers, into the open pores of a prefabricated core, and at the interface between the core and core overlay. refers to the carbon material deposited by

4. Deposition into crevices refers to depositing pyrolyzed carbon into the crevices of carbon fiber materials by chemical vapor deposition.

5 "Carbonaceous binder" is a material that is used separately or in addition to the pyrolytic carbon material to bond the carbon and graphite fiber materials together and to bond the core overlay to the core. Coal tar pitch, oil pitch,
Various pitch and resin materials have been found to be satisfactorily used as binder materials, including furan resins, phenolic resins, polysaccharides such as corn starch, epoxy resins, polyimide resins, furfural alcohol, and binder materials and mixtures thereof. .

6. “Woven fabric” is a fabric obtained by interweaving warp and weft yarns on a loom or the like.

7 "Friction disks and pads" are disks or pads that can be used as friction members in brake and clutch assemblies having properties used in dry and wet applications in aircraft and automobiles.

This will be explained with reference to the drawings. FIG. 1 is a cross-section of a carbon composite disk 10 of the present invention, which disk is used as a friction member in clutch or brake assemblies having properties used in aircraft, automobiles, and other industrial machinery fields. is appropriate. The carbon composite disk 10 has a reusable carbon composite core 12.
and a friction facing core overlay 14 secured to at least one side of the core 12.

Overlay 14 comprises at least one layer of woven carbon fabric material, the individual fibers of which are bonded together at their cross-overlap points by pyrolytic carbon already deposited in the interstices of the fabric material.

The reusable carbon composite core 12 is preferably a carbon fiber reinforced composite product obtained according to the following method, i.e. a high strength carbon or graphite fiber material is ,
The method is such that the amount of fibers and degree of internal fiber alignment are precisely controlled to form a substrate optimized for the final product application. In the manufacture of composite products, the optimized substrate is infiltrated with pyrolytic carbon in a manner that structurally bonds together the fibrous materials that make up the substrate. The product formed in this way is
It is strengthened by further infiltration in a limited manner with pyrolytic material to the extent necessary to achieve the desired final product density. Details regarding methods of manufacturing composite products are described in the above-identified patent No. 3,895,084 issued to Bauer.

Composite core 12 also comprises a resin bonded structure made from carbon-based material and fibrous layers. Preferably, the carbon-based material is furfural alcohol, coal tar pitch, furan resins, epoxy resins, polyimide resins, phenolic resins, and mixtures thereof. These materials have fairly high coking values which allow them to pyrolyze to essentially give carbon material.

According to the method of the invention, the core overlay 14
is uniquely bonded to carbon composite core 12 by a combination of pyrolytic carbon and a suitable adhesive. A satisfactory adhesive for carrying out the method of the invention is manufactured by Union Carbide under the trade name "C-
Furfural alcohol is manufactured and sold under the name ``34''. However, any suitable mixture of certain fillers and furfural alcohol or similar materials can be used as long as the adhesive has a sufficiently high carbon content to bond adjacent solids during the curing and CVD steps of the process. Furthermore, the adhesive material must be capable of being converted by heat into a porous carbon intermediate bonding framework, which in turn can be bonded by chemical vapor deposited carbon.

The friction facing core overlay 14 is
Preferably manufactured by stacking multiple layers of carbon fabric or woven carbon fabric material already cut to the appropriate size and shape, but if a layer of woven material is used between the core and the overlay. It can also be made from impregnated non-woven carbon fiber molding compounds. The assembly thus formed is then debulked and placed in a suitable vacuum deposition furnace where pyrolytic carbon is deposited between the fibers of the substrate. This deposition process is
By depositing pyrolytic carbon from carbonaceous gases, e.g. methane, which decompose under the influence of heat, e.g.
It can be carried out. Deposition is 1-760mmHg in the furnace
It is preferably carried out under a pressure within the range of 1 to about 50 mmHg. The temperature of the furnace is 1400〓～
Temperature within the range of 2300㎓, preferably around 1800㎓
It is 〓. Penetration time during the deposition process varies from 10 to 10, depending on the desired end product application and furnace size
Changes to 200 hours.

Fiber materials used in the manufacture of friction facing core overlays include carbonized wool, rayon,
selected from the group consisting of pitch, cellulose, polyacrylonitrile and mixtures thereof. However, in all cases, carbon cloth in single or multilayer form is used for fabricating a friction facing core overlay to be affixed to a reusable carbon composite core.

For some applications, it may be preferable to use a small amount of a suitable carbonaceous binder to bond together the fibers of the layers of carbon fabric that make up the core overlay. In carrying out this process, for example, a phenolic resin, furan resin, epoxy resin, polyimide resin or the like is applied to each layer of the carbon cloth. next,
The carbon fabric layer is assembled onto a substrate or starting substrate having a greater than desired amount of core overlay. This substrate is then subjected to controlled temperature and pressure in a hydraulic press or fixture to obtain a debulked shaped substrate with a high degree of open porosity;
The known quantity and shape substantially correspond to the shape of the final product core overlay. During this press bonding or debulking process, the individual fibers of the carbon fiber material are selectively bonded together by a binder material at multiple locations. These bonds or "sticks" stiffen the substrate so that it can be easily handled during the hardening process. Finally, the shaped substrate is partially or fully work hardened by depositing the selected pyrolytic carbon onto the substrate in an interval manner by chemical vapor deposition.
On the other hand, in the practice of the present invention, pyrolytic carbon is usually deposited in the interstices of the substrate, such as pyrolytic graphite, boron nitride, silicon nitride, titanium, tantalum, tungsten, molybdenum, columbium, tantalum carbide,
Other pyrolytic materials such as niobium carbide, zirconium carbide, hafnium carbide, titanium carbide and silicon carbide can be used for other specific applications. Chemical vapor deposition of these materials is well known to those skilled in the art and is further described in the Bauer patents cited above.
Discussed in 3895084.

In the practice of the present invention, after the friction facing core overlay is made according to any of the methods described in the previous section, the renewable carbon composite core is machined to the desired size and shape.
The carbon composite core can be made from a newly manufactured material with a predetermined open porosity, or it can already be used in either the brake disc or the clutch disc and undergo further wear and damage. and carbon composite cores exhibiting a degree of open porosity that would otherwise be unsuitable for further use.

After the carbon composite core is machined to size,
One or both sides of the core may be grooved or roughened either mechanically or by mechanical processes. Roughening of the carbon composite core surface is preferably accomplished by machining continuous helically shaped grooves extending to a constant depth across the core surface. An enlarged cross-section of such a helical groove is shown in FIG. 2 and designated at 16.

After grooving or roughening one or both sides of the composite core, a thin layer of "C-34" or coal tar pitch, furfural alcohol, petroleum pitch, furan resin, epoxy resin, polyimide resin, phenolic resin or mixtures thereof. (approx. 0.010 inch)
is applied to the roughened surface of the composite core 12 and also to the mating surface of the friction facing core overlay 14. The assembled or temporary substrate thus formed is heated to an elevated temperature on the order of about 200 to about 400 °C, with or without pressure applied to engage the core overlay to the reusable core. harden with. If pressure is applied during the curing process,
The resin comprising the core, core overlay and temporary substrate is compressed at a pressure of about 100-5000 psi. Subsequently, the resin is post-cured at a temperature of about 300 to about 500 °C without applying pressure. The cured assembly is then placed in a chemical vapor deposition furnace and infiltrated with a pyrolytic material such as pyrolytic carbon. The infiltration process is from 1 to
At pressures below atmospheric pressure in the range of 760mmHg, typically about 1~
It is carried out in a vacuum furnace at a pressure of 50 mmHg. The furnace temperature is maintained within the range of about 1400° to about 2300°, preferably about 1800°. Penetration time is approximately 10 to approx.
The range is 200 hours.

During the infiltration step, pyrolytic carbon is deposited uniformly over and around the fibers of the porous core and core overlay and at the intermediate or interface between the core material and core overlay material.

As a result of the curing and CVD process, the adhesive previously applied to the core and core surface is transformed from organic to inorganic form.

According to the method described in the previous section, friction facing core overlay 14 is tightly and stably bonded to carbon composite core 12 by a combination of carbonizable adhesive material and pyrolytic carbon.

The fact that the pyrolytic material is deposited both in the middle of the material and on and around the fibers that make up the core and core overlay makes the formed composite assembly extremely robust for both brake and clutch applications. and very well suited. In fact, the combined adhesive action of the pyrolytic carbon and carbonaceous binder materials results in a composite disc having a strength very close to that of the base material of the core itself. Accordingly, composite disks formed according to the method of the present invention will readily withstand broad spectrum energy outages typically found in brake and clutch type applications.

The tight bonding of the core overlay and core material is clearly shown in Figure 3, which is a 40x photograph of the intermediate layer. As is clear from FIG. 3, the material at the interface is quite uniform. The pyrolytic material appearing in white surrounding the fibers of both the composite core and core overlay and bonding the overlay and core at the bonding surface or interlayer is readily visible in FIG.

In typical brake and clutch applications, the structure depicted in FIG. It comprises a circular structure with a notch. When the disk is used for either a rotor or a stator, both sides of the carbon composite core must be roughened or grooved and the friction facing core overlay material must be affixed to both sides of the composite core. .

It should be understood that the composite friction disc of the present invention can be specially finished for a variety of applications. By controlling the amount of resin used and the amount of pyrolytic material deposited into the interstices of the core overlay, the density and porosity of the overlay can be precisely and controllably varied. Similarly, bond the core overlay to the core
The processing conditions used during the CVD or infiltration process are:
Precise control is possible to specifically finish the disc for various target product applications.

As previously mentioned, pyrolytic materials other than pyrolytic carbon may be used for application specific applications for friction disks. Furthermore, the following content is extremely important. That is, Applicants have found that for some applications, boron can be added to the intermediate surface of the core and core overlay prior to the infiltration step. On the other hand, although not absolutely necessary, the use of boron at the intermediate surface substantially improves the bonding of the core to the core overlay, increases the oxidation resistance as well as the functionality of the adhesive layer, and increases the performance of either the brake or the clutch. Provides an extremely strong carbon composite friction disc for use in applications.

Furthermore, in order to control the thickness of the adhesive layer, which is essential in the manufacturing process, techniques have been developed for saturating a single layer of carbon cloth with one of the aforementioned binders. The thus "prepregged" fabric layer is then applied between the roughened core and core overlay as previously described. About 2-20% by weight of boron powder can also be mixed with the binder impregnated into a single fabric layer. After debulking, it has been found that the presence of the fabric layer allows precise regulation of the thickness of the adhesive layer, which can vary within the range of 0.010 to 0.040 inches. Maintaining the thickness of the adhesive layer will ensure the quality of the adhesive layer with high strength.

As explained in the previous section, according to the method of the present invention,
A unique and extremely useful carbon composite disc is obtained. The disc can be specifically finished to meet the objectives of the invention and for various uses as a friction member in clutches, brakes, or other industrial applications. The composite obtained by the method of the invention comprises a reusable carbon composite core and a friction facing core overlay affixed to at least one side of the core. The overlay comprises at least one layer of woven carbon fibers, the individual fibers being bonded together at their cross-overlap points by pyrolytic carbon that has been deposited intermediary on the fibrous material. According to the method of the present invention, a friction facing core overlay is uniquely bonded to a carbon composite core by a combination of a carbonaceous binder and a pyrolytic material, such as pyrolytic carbon.

(Example) The following example illustrates the basic method of the invention.

Example 1 After selecting an already used core for refurbishment, the core was machined to the desired size and shape. One side of the core was then machined to obtain elongated helical shaped groups of substantially uniform depth across the entire surface of the core.

A friction facing core overlay was then fabricated by first cutting a panel of fully carbonized rayon fabric into discs having a diameter that substantially corresponded to the diameter of the machined core. Next, the thus formed disks (20 in this example) were stacked on another top surface to form a temporary base material. The temporary substrate was then debulked and placed into a vacuum deposition furnace where pyrolytic carbon was deposited between the fibers of the substrate. The technique for accomplishing this infiltration step is fully described in Bauer US Pat. No. 3,895,084.

After the core overlay was completed, a thin layer of "C-34" was applied to the surface of the overlay and the grooved surface of the core. The core overlay was then combined with the core while pressing the "C-34" coated surfaces into intimate contact. The thus formed assembly was cured at about 300° C. for about 1 hour.

The cured assembly was then placed in a vacuum oven for infiltration with pyrolytic carbon. Penetration is about 1800〓 and approx.
It was performed at a pressure of 50 mmHg. Penetration time was approximately 100 hours. The assembly was then machined to final size. During the infiltration process, pyrolytic carbon was deposited within the porous core and core overlay and at the interface between the core and core overlay.

Example 2 In this example, a core and core overlay were processed substantially as described in Example 1, except that one side of the overlay was also grooved to form a continuous helix across that side. The grooved surfaces of the core and overlay were then coated with a layer of furan resin with boron powder already mixed in, and the single layer of carbonized rayon fabric was saturated with the furan resin-boron powder mixture. It has been found that the addition of boron effectively increases the thermal conductivity of the adhesive layer, while also suppressing oxidation. Although varying amounts of boron powder can be added to the particular carbonaceous binder used in this case, the boron is present at about 15% by weight. A fabric layer is then positioned between the grooved surface of the core and the core overlay, and the assembly thus formed is then placed in a press and subjected to a pressure of 100 psi. The compressed assembly was cured at a temperature of about 500°C for about 20 hours.

Following the curing step, the assembly was infiltrated in the manner described in Example 1. The use of boron tended to substantially improve the properties of the adhesive layer between the core and core overlay.

Having thus described the invention in detail, those skilled in the art will have no difficulty in making changes and modifications in the relative assemblies or individual parts thereof to meet particular needs or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention as set forth in the claims.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of one embodiment of the invention showing a core overlay secured to a carbon composite core, and FIG. 2 is a general view of the area illustrated by numeral 2 in FIG. FIG. 3 is a partially enlarged cross-sectional view of the intermediate layer between the core overlay and the core at the desired location; FIG. This is a photo of the substance (40x magnification). 10... Carbon composite disk, 12... Core, 14... Core overlay.

Claims (1)

[Claims] 1. A method for producing a reusable carbon composite friction disk, which comprises: (a) coal tar pitch, petroleum pitch, furfural alcohol, furan resin, epoxy resin,
fabricating a porous carbon composite core comprised of carbon fiber materials bonded together by a polymeric material selected from the group consisting of polysaccharides such as corn starch, polyimide resins, phenolic resins, and mixtures thereof; (b) ) The process of fabricating a porous core overlay comprised of at least one layer of carbon woven material, in which the individual fibers of the material are oxidized by pyrolytic carbon deposited into the interstices of the fibrous material by chemical vapor deposition. bonded together at fiber cross-over points; (c) coal tar pitch, petroleum pitch, furan resin, furfural alcohol, epoxy resin;
(d) applying a thin layer of a carbonaceous binder selected from the group consisting of polysaccharides such as corn starch, polyimide resins, phenolic resins and mixtures thereof to at least one side of said carbon composite core; fabricating a temporary support by engaging a core overlay with a thin layer of said binder; (e) placing said temporary support in a carbon-containing gas at subatmospheric pressure and from about 1800 〓 to about 2300㎓ and depositing pyrolytic carbon into the porous core overlay and interstices between the porous core overlay and the porous core to form an integral carbon composite friction brake, thereby forming the overlay. substantially coating the fibers of and permanently bonding them together with the pyrolytic carbon, and permanently bonding the overlay to the core with the pyrolytic carbon to form an integral carbon composite friction brake. The method comprising: 2. The method of claim 1, wherein the porous carbon composite core further comprises pyrolytic carbon deposited in the interstices of the carbon fiber material to bind individual fibers together. 3. The porous core overlay is also fabricated using a small amount of carbonaceous binder to bond individual fibers of carbon fiber material together at spaced apart locations along the fiber length. 1st
The method described in section. 4. The method of claim 1, wherein the fibers of the carbon textile material are selected from carbonized wool, rayon, pitch, polyacrylonitrile, cellulose and mixtures thereof. 5. The method of claim 1, wherein boron is added to the temporary porous support at a location intermediate the core and the core overlay. 6. The method of claim 1, including the step of scoring at least one surface of the porous core and its mating surface with a porous core overlay before applying the carbonaceous binder. 7. The method of claim 6, wherein the scoring is in the form of a spiral provided in the plane of the mating surface. 8. The method of claim 1, wherein a single layer of fabric is saturated with a carbonaceous binder and further introduced between the core and the core overlay to control the thickness of the adhesive layer. 9. The method of claim 1, comprising the step of compressing the temporary support under a pressure of about 100 to 5000 psi while exposing the temporary support to a temperature of about 200 psi. 10. The method of claim 9, wherein the carbonaceous binder comprises about 2-20% by weight boron. 11 A method for manufacturing a reusable carbon composite friction disc, comprising: (a) a step of manufacturing a porous carbon composite core made of carbon fiber material, in which pyrolytic carbon deposited in the gaps between the fibers causes the fibers to (b) fabricating a porous core overlay comprised of at least one layer of carbon woven material selected from the group consisting of wool, rayon, pitch, polyacrylonitrile, cellulose and mixtures thereof; the individual fibers are bonded at regularly spaced locations by a carbonaceous binder and at their intersection points by pyrolytic carbon already deposited in the interstices of the fiber material by chemical vapor deposition. (c) scoring at many points on at least one side of the core; (d) adding coal tar pitch, petroleum pitch, furan resin, furfural alcohol, epoxy resin, applying a thin layer of a carbonaceous binder selected from the group consisting of polysaccharides such as corn starch, polyimide resins, phenolic resins and mixtures thereof; (e) applying said porous core overlay to a layer of said binder material; (f) holding the porous temporary support under pressure at an elevated temperature for a time sufficient to cure the carbonaceous binder; The process of;
and (g) subsequent to said curing step, said temporary support is held below atmospheric pressure and at a temperature of about 1800° to about 2300° to pyrolyze the core overlay and intermediate core overlay and core gaps. forming a monolithic carbon composite friction plate by depositing carbon, thereby substantially coating and permanently bonding the fibers and core of the overlay together with the pyrolytic carbon; and pyrolyzing the overlay. The method comprises the step of permanently bonding carbon to the core to form an integral carbon composite friction plate. 12. A carbon composite disc for use as a friction member, such as a brake disc or clutch disc, comprising: (a) a porous reusable carbon composite core; and (b) fixed to at least one side of the porous carbon composite core. a porous friction facing core overlay, the porous overlay comprising at least one layer of carbon fiber material, wherein the individual fibers are bonded together by pyrolytic carbon already deposited in the interstices of the carbon material. said carbon composite disks being joined together at intersection points of said carbon composite disks. 13. The disk of claim 12, wherein the porous friction core facing core overlay is affixed to the carbon composite core by a combination of carbonaceous and pyrolytic carbon. 14. The carbonaceous binder is selected from the group consisting of coal tar pitch, petroleum pitch, furfural alcohol, furan resins, epoxy resins, polysaccharides such as corn starch, polyimide resins, phenolic resins, and mixtures thereof. A disk according to scope item 13. 15. The disk of claim 12, wherein the fibers of the friction facing overlay are selected from carbonized wool, rayon, pitch, polyacrylonitrile, cellulose and mixtures thereof. 16. The disk of claim 12, wherein boron is applied intermediate the core and the overlay. 17. A carbon composite disc for use as a friction member, such as a brake disc or clutch disc, comprising: (a) a porous reusable carbon composite core having grooves formed on at least one side thereof; and (b) a porous friction facing core overlay comprising at least one layer of carbon fiber material;
the individual fibers of the carbon fiber material are bonded together at their cross-overlap points by pyrolytic carbon already deposited in the interstices of the carbon fiber material; and (c) the grooved side of the core. and a single layer of carbon fiber material deposited intermediate the core overlay, the carbon fiber material being carbonized and further comprising coal tar pitch, petroleum pitch,
filled with a binder selected from the group consisting of furfural alcohol, furan resins, epoxy resins, polysaccharides such as corn starch, polyimide resins, phenolic resins and mixtures thereof; the composite materials being compressed together at a temperature sufficient to cure the binder and further bond together the core, the core overlay, and a single layer of carbon fiber material to form the carbon composite disk. , the composite disk. 18 The resulting composite material is exposed to a carbon-containing gas at an elevated temperature, thereby securing the overlay and the monolayer to the carbon composite core by a combination of a carbonaceous binder and pyrolytic carbon. 17. The disk according to item 17. 19 The carbonaceous binder is coal tar pitch,
18. The disk of claim 17, which is selected from the group consisting of petroleum pitch, furfural alcohol, furan resin, epoxy resin, polysaccharide such as corn starch, polyimide resin, phenolic resin and mixtures thereof. 20. The disk of claim 17, wherein the fibers of the friction facing overlay are selected from carbonized wool, rayon, pitch, polyacrylonitrile, cellulose and mixtures thereof. 21. The disk of claim 17, wherein boron is applied intermediate the core and the overlay.