Alloys or metallic compositions – Aluminum base – Copper containing
Patent
1992-06-18
1994-02-15
Roy, Upendra
Alloys or metallic compositions
Aluminum base
Copper containing
420535, 420536, 420554, C22C 2100
Patent
active
052864456
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to aluminium bearing alloy, and more particularly, to aluminium bearing alloy which is intended to exhibit increased seizure resistance and fatigue strength.
BACKGROUND OF THE PRIOR ART
Aluminium bearing alloy finds its application in sliding or plain bearing of an internal combustion engine, but there is an increasing demand on improving the seizure resistance and fatigue strength thereof recently as higher load and temperature requirements are imposed upon the plain bearing with an increase in the speed of operation and the output of such engine. An improvement in the seizure resistance or fatigue strength requires an improved surface characteristics of the plain bearing, for which the use of a low melting metal, such as Sn, Pb, Bi or the like, for example, is essential.
The use of Sn as a low melting point metal in an aluminium bearing alloy is known in the prior art, as exemplified by Japanese Patent Publication No. 14,990/1989, and another aluminium bearing alloy using Bi as a low melting point metal is also known (see Japanese Laid-Open Patent Application No. 235,436/1987).
Generally, the use of a low melting point metal contributes to improving the seizure resistance and fatigue strength, but if the amount of low melting metal used is excessive, its grains are too large, or a melting point is too low with respect to an environment in which the bearing is to be used, there is an adverse effect in that the fatigue is likely to occur. By way of example, Bi has a higher melting point than Sn, and is effective generally in achieving a higher melting point for Al matrix, but this is influenced by the kind of other elements added as well as the amount of such addition, with consequence that a simple addition of Bi cannot assure an excellent seizure resistance or fatigue strength.
DISCLOSURE OF THE INVENTION
Accordingly, the present invention provides aluminium bearing alloy which exhibits an excellent fatigue strength and seizure resistance over conventional aluminium bearing alloy containing Bi, by using Bi having a higher melting point than Sn as a low melting point metal while simultaneously choosing a particular element(s) added as well as the amount of such addition.
Specifically, a composition according to the invention comprises 2 to 15% by weight of Bi, 0.05 to 1% by weight of Zr, 0.1 to less than 1.5% by weight of Cu and/or Mg and the remainder of Al.
In accordance with the invention, one or more of elements Si, M, V, Sb, Nb, Mo, Co, Fe, Ti and Cr may be added to the above composition with the amount of addition being limited in a range from 0.05 to 5% by weight in total. In addition, one or more of elements Sn, Pb and In may be added separately or in combination with the above addition so that a total of such addition remains in a range from 0.05 to less than 2% by weight.
In accordance with the invention, by using Bi having a higher melting point than Sn as a low melting point metal, a higher melting point of Al matrix can be achieved. During the rolling operation, Bi will be extended in the direction of rolling operation, and then remains as extended without being divided into finer grains during a subsequent annealing operation which usually takes place at a temperature from 250.degree. to 350.degree. C.
On the other hand, Zr which is added simultaneously with Bi is effective in improving the strength of Al matrix and in achieving a fine dispersion of Bi. A precipitation treatment at elevated temperatures of Zr is preferred for its marked effect in raising its recrystallizing temperature. A raised recrystallizing temperature is effective in maintaining a stabilized mechanical properties at an elevated temperature range to which the bearing of an internal combustion engine is subjected to, and as far as the hardness is concerned, it reduces a decrease in the hardness under elevated temperatures to improve the strength of the bearing in such an elevated temperature range.
In consideration of these aspects, during the manufacturing of a plain bearing b
REFERENCES:
patent: 3753695 (1973-08-01), Lloyd
patent: 4375499 (1983-03-01), Nara et al.
patent: 4590133 (1986-05-01), Lloyd
patent: 4806308 (1989-02-01), Kamiya et al.
Roy Upendra
Taiho Kogyo Co. Ltd.
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