Formation of hard intermetallic coatings from electro-deposited layers of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten

摘要

788,804. Electrodeposition of refractory metals to form intermetallic compounds thereof. HORIZONS, Inc. April 22, 1955 [April 29, 1954], No. 11695/55. Class 41. A layer of a hard intermetallic compound of one of the refractory metals of the Periodic Groups IVa, Va and VIa and one of the metalhardening elements boron, carbon, nitrogen and silicon is formed electrolytically on a basis metal by immersing said metal containing one of the specified metal-hardening elements as cathode in a fused salt bath composed of a halide of the refractory metal and a diluent alkali metal halide, and heating the cathode bearing the deposited refractory metal so as to effect thermal diffusion of the metal hardening element from the basis metal into the refractory metal. The basis metal may be steel or iron, copper, brass, bronze, nickel or a refractory metal treated to have a suitable content of a metalhardening element, and the refractory metal halide may be a simple or double halide. The refractory metal may be deposited at a temperature above 800‹ C. by the cladding method of Specification 775,585 or by that of Specification 788,295. Alternatively the refractory metal may be deposited at 500-600‹ C. with an electrolysing voltage of 5-8. volts, followed by subsequent heating at 800-1000‹ C. to effect diffusion, thicker layers being obtained with higher temperatures.