Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1996-12-18
1998-02-03
Mai, Ngoclan
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
75247, 419 33, 419 36, 419 39, 419 60, C22C 906
Patent
active
057147000
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a self-lubricating composite material which is excellent in strength and in high temperature oxidation resistance, and which can be used in the atmosphere and in vacuum, and a production method of the same.
BACKGROUND ART
A large number of researches have been made since 1950th, mainly in U.S.A., for self-lubricating composite materials containing solid lubricants dispersed in a metal. Among them, composite materials using a Cu alloy as the matrix have been examined, and have been put into practical application, in Japan, too, as typified by a Cu--Sn type composite material. For example, Japanese Unexamined Patent Publication (Kokai) No. 62-196351 describes a technology relating to a self-lubricating composite material which comprises 10 to 80% of a bulk phase consisting of a lubricating material as a principal component and a bonding phase of a metal, wherein the bulk phase comprises a plurality of crystal grains of not greater than 30.mu., which has a gain size of 30 to 1,000 .mu.m. This prior art technology avoids the simultaneous addition of raw material powder of a lubricating material and powder as the metallic bonding phase, adds in advance a bonding adjuvant to the lubricating material and forms the bulk.
Japanese Unexamined Patent Publication (Kokai) No. 4-99834 discloses a technology which improves seizure resistance, wear resistance, etc, by adding graphite, molybdenum disulfide, WS.sub.2, etc, to a Cu--Sn alloy. This prior art technology is directed to increase corrosion resistance by a lubricating oil by adding Pb.
However, the materials according to the prior art are all decomposed or oxidized at a high temperature, and the upper limit of their practical continuous use is 300.degree. C. They also involve the problem that the mechanical strength and the yield strength are inferior.
Recently, needs have been increasing for high strength mechanical sliding members which are required to keep an excellent lubricating property in an oxidizing atmosphere in a high temperature zone of higher than 300.degree. C., at which the lubricating oil cannot be used, and for high strength sliding members in a high vacuum atmosphere. In other words, technical development of a composite material capable of producing as economically as possible those self-lubricating composite materials which can exhibit the sliding characteristics irrespective of the atmosphere of use and the load condition as the solid lubricant, and a production method thereof, have been desired from the aspect of the lubrication property and safety, by examining the metal components of heat-resistant alloy systems for the matrix metal.
SUMMARY OF THE INVENTION
As described above, the self-lubricating composite material using the conventional Cu type alloy for the matrix cannot be applied in the high temperature atmosphere for which lubrication-free sliding members are originally required. The self-lubricating composite material has low mechanical characteristics and for this reason, too, its application to structural materials is also limited.
As a result of examinations of the kinds and quantities of solid lubricants, optimization of matrix metals and production methods so as to obtain a self-lubricating composite material which can withstand the use at a high temperature and which has improved high temperature sliding characteristics, the present invention aims at providing a self-lubricating composite material excellent in mechanical and frictional characteristics up to 700.degree. C. in vacuum and up to 500.degree. C. in the atmosphere, and a production method of such a self-lubricating composite material. The gist of the present invention for accomplishing the object described above resides in the following points.
(1) A high strength self-lubricating composite material for a high temperature characterized in that the composite material is a Cu--Ni--Sn type composite sintered body containing 20 to 70 vol % of mixed particles of graphite and WS.sub.2 particles as solid lubricant components,
REFERENCES:
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patent: 4505987 (1985-03-01), Yamada et al.
patent: 5256494 (1993-10-01), Tanaka et al.
patent: 5288457 (1994-02-01), Boegel
patent: 5326384 (1994-07-01), Asada et al.
Nishida Tokuhiko
Ono Toru
Sekiguchi Shoichi
Tsuya Yuko
Mai Ngoclan
Nippon Steel Corporation
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