The Frictional Properties of Some White Metal Bearing Alloys: The Role of the Matrix and the Hard Particles

Abstract

A previous paper has described an investigation of the frictional properties of alloys of the copper-lead type which consist of a hard matrix (copper) in which are dispersed particles of a soft material (lead). It was shown that these alloys function by the extrusion and smearing of the soft phase over the hard matrix, so providing metallic-film lubrication. This paper describes experiments on a typical lead-base bearing alloy which consists of a soft matrix in which are dispersed numerous hard crystallites. Measurements of the friction were made at room temperature and at elevated temperatures for clean and for lubricated surfaces. Comparison with a special alloy consisting of the matrix material alone, showed that the hard particles played no appreciable part in the basic frictional and wear properties of the bearing alloy. It is suggested that the frictional behaviour of the bearing alloy is determined essentially by the properties of the matrix material itself although in practical running operations there may be other properties which determine the suitability of the alloy for use in bearings. Similar experiments are described on a typical tin-base bearing alloy and a corresponding tin-base ``matrix'' alloy.