Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Patent
1997-07-23
2000-03-28
Copenheaver, Blaine
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
156329, 156335, 192107M, 228121, 228175, 228176, 2282627, 26099813, 4234472, 427228, 4273837, 4282934, 4283177, 4283179, 4283191, C04B 35573, C04B 3580, F16D 6902
Patent
active
060429356
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a friction unit for frictional engagement with a counter-body, especially a brake or clutch body, having at least one freely accessible friction surface which is formed of a carbon fiber-reinforced, porous carbon body whose pores are at least partially filled with silicon and silicon carbide.
The invention furthermore relates to a method for manufacturing a friction unit for frictional engagement with a counter-body, especially brake or clutch bodies, wherein a carbon fiber reinforced, porous carbon body is prepared and infiltrated with fluid silicon at a temperature in the range from 1410.degree. C. to 1700.degree. C. in a controlled atmosphere.
Such friction units and method for their manufacture were presented by a work group of the DLR (Deutsche Forschungsanstalt fur Luft- und Raumfahrt e.V.), Stuttgart, Institut fur Bauweisen- und Konstruktionsforschung, at the 1994 VDI Materials Convention in Duisburg on Mar. 9-10, 1994, the theme of which was lightweight structures and lightweight components, in the framework of the lecture entitled "Development of integral lightweight structures of ceramic fiber." In this lecture, a technology for manufacturing carbon fiber-reinforced carbons was presented. The carbon fiber-reinforced carbons are infiltrated with fluid silicon by a so-called "fluid silicification method" and subjected to a heat treatment, wherein the silicon is converted with carbon to SiC. One possible application of these C/C--SiC materials is, among others, brake disks.
Increasingly severe requirements are being made of brakes, especially in motor vehicle and aircraft construction. The speeds which are attained nowadays by such vehicles are constantly increasing. When brakes are applied, the kinetic energy is converted by friction to heat, which is absorbed by the brake disk and the brake linings. A brake system of this kind is accordingly limited by the friction characteristics of the brake material and its ability to store and remove heat. In general, brake materials must have very good thermomechanical properties, high and constant friction characteristics and good resistance to abrasion. Ordinary brake disks of cast iron or steel, which are today used in ordinary automobile construction, permit temperatures of approximately 650.degree. C. Brakes of carbon fiber-reinforced carbon materials (C/C) developed in recent years, such as those described for example in DE-A1 3 24 200, allow temperatures up to 100.degree. C., combined with a weight reduction in comparison with cast-iron brake disks.
Such carbon brake disks have in the meantime been adopted and established in race car construction and aircraft construction. What is problematic in this case is, in addition to a number of tribological properties, the high cost factor involved in the brake disks, which presently is accepted in the field of race car and aircraft construction, but cannot be accepted for general vehicle construction.
At the above-described VDI presentation, a C/C--SiC material was exhibited, as stated above, which shows decided advantages over a C/C material, especially in regard to thermal shock resistance, oxidation resistance, moisture absorption and frictional performance.
Setting out from the state of the art described above, the present invention is addressed to the problem of devising a friction unit as well as a method for the manufacture of such a friction unit, in conjunction with which the advantages are achieved which are associated with C/C--SiC materials, which can be manufactured at a reasonable cost, so that such friction units are economically feasible especially for general vehicle construction.
The above-stated object is obtained by a friction unit formed of at least a core body and at least a friction body fixedly joined thereto, the friction body being joined to the core body on its side facing away from the friction surface, and both bodies being joined together as intimately as possible by a refractory bonding layer.
In another aspect, the in
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patent: 3759353 (1973-09-01), Marin
patent: 3859160 (1975-01-01), Marin
patent: 3867491 (1975-02-01), Marin
patent: 4742948 (1988-05-01), Fisher et al.
Entwicklung Integraler Leichtbaustrukturen Aus Faserkeramik, by Walter Krenkel, Volkmar Dollhopf und Frank Kocian, DLR-Stuttgart, published at the VDI Werkstofftag '94, Leichtbau-Strukturen und Leichtebauteile, in Duisburg, 9./10.3.1994.
Patents Abstracts of Japan, M-1354 Jan. 19, 1993, vol. 17/No. 26, Frictional Member, JP 4-249627 (a), Sep. 4, 1992, Sumitomo Electric Ind. Ltd., Masatake Sakagami.
Kochendorfer Richard
Krenkel Walter
Copenheaver Blaine
Deutsche Forschungsanstalt fuer Luft-ung Raumfahrt e.V.
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