GB807909A - Improved porous sintered metal friction element - Google Patents

Abstract

807,909. Powder metallurgy. GENERAL MOTORS CORPORATION. May 31, 1957 [July 6, 1956], No. 17329/57. Addition. to 807,776. Class 82(1) [Also in Groups XXIV and XXXIV] A composite porous sintered metal friction element, e.g. for use as brake and clutch linings, consists of a compacted powder mixture in two layers, the one layer (the friction layer( comprising 20 to 25 per cent graphite, 2 to 6 per cent molybdenum disulphide, and at least 60 per cent iron, whilst the other layer being more ductile and strong comprises 1 to 4 per cent graphite and at least 76 per cent iron. The first layer may also include up to 5 per cent copper, up to 3 per cent lead and up to 2 per cent ceramic, e.g. powdered clay; the ductile layer may contain wp to 9.09 per cent of other metals, e.g. copper, lead. The powders preferably pass 150 to 250 mesh; the iron may be reduced ovide, or electrolytic or sponge iron. A layer 30 of Fe powder with 2 per cent graphite is levelled off in a die cavity 24 (Fig. 2), retracted on the punch 26, and covered with the layer 34 of powdered Fe, graphite and MoS 2 in the specified proportions (Fig. 4). Upper punch 28 is lowered to briquette the composite at 60,000-100,000 1b./sq. inch into a self-sustaining mass which is removed from the die and sintered at 1800‹ to 2000‹F. for 30-60 minutes in a non-oxidizing atmosphere which is in equilibrium with the carbon content of the mass. The composite is riveted at 48 to a steel brake shoe 46 (Fig. 6) where the more ductile layer 44 is at its thickest and the frictional layer 42 at its thinnest. The average thickness of the frictional layer is preferably about three times that of the inner layer.