GB707048A - Improvements in or relating to plain bearings - Google Patents

Abstract

A bearing element, (see Group XXXIV), has a matrix or body of any suitable material in which at least the bearing surface or bearing surface layer consists of, or comprises, boron nitride (BN). The BN which is an effective solid lubricant may be compacted into a porous sintered metal matrix or metallic wool body or into a plastic sponge structure. The BN may be incorporated in the matrix in the form of powder, with or without a binder, or in suspension, e.g. alcohol as described in Specification 707,065, [Group XXXIV]. If a binder such as corn syrup or fish glue is used the BN must be baked at 150-200 DEG C. The BN may, however, be produced in situ by gaseous or other chemical treatment of boron incorporated in the matrix or forming the bearing surface or layer, and in a further modification the BN may be mixed with metallic powder such as 89/11 Cu-Sn and the whole sintered and compacted, the proportion of BN being 5-30 per cent. In yet a further modification, the BN may be mixed with a synthetic plastic powder and pressed to form the bearing element.ALSO:A plain bearing or liner &c. has its bearing surface or surface layer consisting of or comprising boron nitride. Where the bearing is required to conduct heat the supporting matrix is metallic and may consist of a porous structure produced as described in Specification 701,690, [Group XXXIV], by sintering metallic powders, the boron nitride being applied to or formed in the structure afterwards. Alternatively, the matrix is formed with surface pits which are filled with boron nitride. The bearing may however consist of a layer of metallic wool compacted with boron nitride. The boron nitride may be applied or incorporated in the form of a powder, with or without a binder, or in an alcohol suspension as described in Specification 707,065, [Group XXXIV], or may be produced in situ in the matrix or by gaseous or chemical treatment of boron previously incorporated in the matrix. In all the above embodiments, as the bearing wears the surface remains a composite structure, in part nitride and in part matrix smeared with nitride. In a further modification a porous matrix in a layer 0.005 inches thick is produced on a steel backing 0.050 inches thick, boron nitride being compacted into the pores. In yet a further modification 5-30 per cent. boron nitride is mixed with 89/11 copper/tin powder and is sintered and compacted, or boron nitride mixed with a binder such as corn syrup or fish glue may be applied to a surface and then baked at 150-200 DEG C. The matrix may however consist of a combination of metallic and non-metallic materials. Composite strip material for use in the production of liners &c. comprises a metallic matrix having boron nitride incorporated in at least the bearing surface or bearing surface layer.