Patent GB-704761-A (GB)
Title: Improvements in or relating to anti-friction bodies and materials, and to methods ofproducing the same
Inventor: TAIT WILLIAM HENRY
IPC: C23C8/08
Filed: 1950-07-31
Abstract: Bearings, having bearing surfaces consisting of or comprising molybdenum with a film of molybdenum disulphide on them, are packed with oil or grease containing a sulphidizing agent, e.g. sulphurized oleic acid, sulphurized ketene, cetyl sulphonic acid or mercaptans. Specification 677,240, [Group II], is referred to.ALSO:Metallic elements or components, e.g. plain bearings, bearing liners, thrust washers, lathe centres, gear wheels, cross-head slides, and agricultural cutter bars, having a bearing surface comprising or consisting of molybdenum of porous, pitted or like discontinuous formation, are subjected to chemical treatment so that the exposed molybdenum is converted to molybdenum disulphide which fills or partially fills the pores, pits or the like.  The porous or pitted surface may be formed by etching, or an electro-chemical or chemical treatment, e.g. phosphating, or by spraying the component with molybdenum to form an adherent coating having a creviced surface and then machining the coating, as by grinding, rolling or pressing, to smooth the surface whilst leaving a network of crevices.  The chemical treatment is followed by compacting to ensure that the crevices are filled with molybdenum disulphide.  Alternatively the component may be formed by compacting and sintering a metal powder, with or without a steel backing, coating the compact electrolytically with molybdenum and converting the coating to molybdenum disulphide by chemical treatment.  In all cases, the chemical treatment is preferably with H2S at 800-850 DEG  C.  A plain bearing may be made (a) by spraying strip backing, e.g. steel, with molybdenum and then treating chemically, (b) pressing and sintering a molybdenum powder compact and treating with H2S, or (c) pressing and sintering a compact formed of molybdenum powder mixed with other metal powder and treating with a reagent which sulphides only the molybdenum powder. These treatments may take place before or after the bearing has been formed.  Bearing liners may be formed by spreading molybdenum powder or a powder mixture of 90 per cent. Mo, 10 per cent. Ni loosely on to the backing strip and alternately sintering and compacting, or the molybdenum powder or powder mixture may be compacted and sintered and attached to the backing by pressing.  In the latter case impurities may be removed from the backing strip and/or it may be coated with copper, nickel or tin or an interlayer which alloys with both the molybdenum and the backing strip may be used. Roller, ball or needle bearings may be made of solid molybdenum or sintered molybdenum compacts and treated as above.  In use, the bearings may have a sulphidizing agent in contact with them to renew the molybdenum disulphide film.  Up to 200 DEG  C. the sulphidizing agent, e.g. sulphurized oleic acid, sulphurized ketene, cetyl sulphonic acid or mercaptans, is contained in the oil or grease and above this temperature a sulphidizing gas, e.g. H2S, carbon disulphide or mercaptan vapours, alone or in admixture with hydrogen or nitrogen is preferably used. Specification 677,240 is referred to.