GB1032833A - Composite bearing material - Google Patents

Abstract

In a composite bearing material, a hard metal backing strip 10, Fig. 3 (not shown), has a porous sintered metallic matrix 12 bonded thereto and the latter has a film of polyamide plastic 14 (nylon), which incorporates finely particulated molybdenum disulphide particles, impregnated therein. The amount of molybdenum disulphide particles present is from 0.25 to 5 per cent by weight and preferably from 1.5 to 2.5 per cent by weight. The matrix has a porosity ranging from 10-50 per cent by volume and the polyamide plastic effects a filling of at least 75 per cent and preferably at least 90 per cent of the porosity of the porous matrix. Finely particulated p.t.f.e. particles from 10 to 20 per cent by weight may be present in the polyamide plastic and the average particle size of the p.t.f.e., may be between 6 and 12 microns. A film 96 of p.t.f.e., Fig. 7 (not shown) may be provided at the bearing surface, the thickness of the film being from 0.0002 to 0.001 in. but preferably from 0.0003 to 0.0006 inch. The metal backing strips may be steel and may be plated prior to bonding on the matrix, which may be bronze. In a method of making the composite bearing material a metallic powder 22 for forming the sintered porous matrix, Fig. 1 (not shown), is distributed uniformly across the backing strip 10 by means of a doctor-blade 24 and the strip is advanced into a sintering chamber 25 of a furnace 26 and is then passed into a cooling chamber 30. The strip may then be wound on to a take-up reel 32 or may be advanced directly into a pre-heat section 36, Fig. 2 (not shown) of a furnace 38, after which it is passed beneath an extrusion assembly 42, comprising a hopper 46 containing particulated or pelletized nylon plastic 48 incorporating molybdenum disulphide particles therein. The mixture is heated in a heating-section 50 and is extruded through a die 52 to form a film 44 which passes beneath a roll 56 and between impregnating rolls 60, having gaps which progressively decrease towards the right. The resulting composite bearing material 62 is passed to a cooling section 64, is passed through sizing rolls 66, 661 and on to a take-up-reel 68. In a modification, the molten plastic and molybdenum disulphide is applied to the matrix directly from a die 72, Fig. 4 (not shown), having a cavity 74 therein.