Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1990-03-23
1992-05-19
Hunt, Brooks H.
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
75235, C22C 2912
Patent
active
051144689
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a Cu-based sintered alloy which excels particularly in wear resistance in air at temperatures ranging from the ordinary temperature to 400.degree. C., is of high strength and high toughness, and further has superior uniform temporal change characteristics with respect to associated members, as measured by the coefficient of friction; and to parts for automotive equipment of this Cu-based sintered alloy, such as synchronizer rings for transmissions, valve guides for engines, bearings for turbochargers, and the like.
BACKGROUND ART
Hitherto, for manufacture of the parts of the various automotive equipment mentioned above, it has been proposed to use Cu-based sintered alloy having the representative composition of Cu--28% Zn--6% Al by weight % (hereafter, the symbol % represents weight %).
The above conventional Cu-based alloy has superior uniform temporal change chracteristics with respect to associated members because it is a sintered one, but it does not possess sufficient wear resistance, strength and toughness. The alloy, therefore, cannot meet the design requirements of compactness, light-weightness and increase of output power for the various equipment of recent years, and it has been keenly desired to develop a Cu-based sintered alloy having better wear resistance, strength and toughness.
DISCLOSURE OF THE INVENTION
Therefore, in light of the facts described above, the present inventors have directed their attention particularly to the above conventional Cu-based sintered alloy and have conducted research to develop a Cu-based sintered alloy which possesses better wear resistance, strength and toughness. As a result, they have learned that a certain Cu-based sintered alloy has excellent wear resistance in air at temperatures ranging from the ordinary temperature to 400.degree. C., high strength and high toughness, and therefore, is usable for manufacturing parts which can meet the design requirements of compactness, light-weightness and increase of output power for the various equipment. The alloy has a composition containing:
Zn 10-40%, Al: 0.3-6%, oxygen: 0.03-1%,
at least one additional element selected from the group including at least one of Fe, Ni and Co: 0.1-5%; Mn: 0.1-5%; Si: 0.1-3%; and at least one of W and Mo: 0.1-3%, and the remainder consisting of Cu and inevitable impurities. The sintered alloy has a structure wherein fine oxides including aluminum oxide (Al.sub.2 O.sub.3) as the main constituent and intermetallic compounds are uniformly dispersed in a matrix.
This invention has been carried out on the basis of the above knowledge. The Cu-based sintered alloy according to the invention, with the above composition, comes to have a structure in the matrix of which the oxides mainly consisting of Al.sub.2 O.sub.3 are distributed with a granule size ranging from 1 to 40 um so as to comprise 0.5-15% of surface area ratio. The intermetallic compounds are distributed with a granule size from 1 to 25 um and are uniformly dispersed comprising 1-10% of the surface area ratio. These oxides and intermetallic compounds cause the wear resistance to be remarkably improved, and particularly by the uniform dispersion of the oxides, the resistance to heat damage is improved in addition to the improvement in the heat resistance of contacting surfaces. Hence, the alloy of the present invention exhibits excellent wear resistance, even under high loads. Accordingly, the parts for automotive equipment made of the above Cu-based sintered alloy excel likewise in wear resistance and so forth, and can sufficiently meet the design requirements of compactness, light-weightness and increase of output power for the equipment.
Subsequently, description will be made concerning the reasons for limiting the component constitution in the Cu-based sintered alloy of the invention as described above.
(a) Zn
The Zn component has the function of forming, together with Cu and Al, the matrix to enhance the strength and toughness of the alloy. When its content is less than 10%, how
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Akutsu Hidetoshi
Kohno Tohru
Otsuki Masato
Hunt Brooks H.
Jenkins Daniel J.
Mitsubishi Materials Corporation
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