GB510871A - Improvements in or relating to the manufacture of iron or steel articles having protective coatings - Google Patents

Abstract

510,871. Coating with metals. BOLTON, C. A. Jan. 4, 1938, No. 238. [Class 82 (ii)] One or more surfaces of an iron or steel article are coated or impregnated with chromium or an alloy of chromium with one or more non-ferrous metals by passing a salt or salts of the coating or impregnating metal or metals in gaseous form over said surface or surfaces, the latter being then subjected to a consolidation under pressure and to a heat treatment to render the surfaces hard and very resistant to corrosion and to improve their appearance. The coating or impregnation may be carried out as described in Specification 492,521. The consolidation is preferably carried out in the cold, e.g. by cold rolling, the article being then heated to an elevated temperature, e.g. about 600‹C., and then quickly cooled, e.g. by quenching in water or oil. Alternatively the heat treatment and consolidation may be combined by carrying out the latter at an elevated temperature, the article being then quenched immediately after the rolling or the like. The treated surfaces may be polished. The coating or impregnating substance may be, for example, a combination of chromium with one or more of molybdenum, tantalum, vanadium, or nickel, e.g. 80 per cent. chromium with 20 per cent. nickel. The article may be brought to its finished shape, e.g. by stamping or pressing, either before or after the coating, consolidating, and heat treatment. Reference is made to the treatment of articles such as sheets : bars, rods, strips, tubes, bolts, and nuts. The Provisional Specification describes broadly the subjection of iron or steel articles which have been coated or impregnated with one or more non-ferrous metals, such as chromium, nickel, or manganese, to a mechanical after-working and a heat treatment.