Formation of protective coatings by electrolytic codeposition of a nickel- cobalt matrix and ceramic particles

摘要

Alloy steel or nickel based superalloy parts may be given protection against oxidation and frictional wear at temperatures below 600° C. by means of a protective coating applied by electrolyte codeposition of a nickel-cobalt matrix comprising a uniform dispersion of ceramic particles selected from a group of carbides and oxides including SiC, Al. sub.2 O.sub.3, and Cr.sub.2 O.sub.3, the mass content of the ceramic particles being between 3.5% and 10%. The deposition is carried out in a sulfamate bath comprising a metallic salts content (Ni+Co) of from 70 g/l to 100 g/l, a Ni/Co mass ratio of from 5 to 33, and a mass content of the ceramic particles in suspension of from 50 g/l to 300 g/l.