The Effect of Carbide Content and Pre-Heat Treatment on the Oxidation Characteristics of Cobalt-Chromium Carbide Electrodeposits in Air at 1,000°C

SummaryThe behaviour of cobalt-chromium carbide composite coatings at elevated temperatures has been shown to be influenced by the breakdown of the carbide particles. A series of deposits were produced with a range of carbide contents and oxidation tests were carried out on as-plated and inert heat treated specimens. The oxidation resistance of the deposits was found to increase with an increase in the carbide content and after an inert heat treatment in argon at 1,000°C. Results compared favourably with cobalt-chromium alloys. An examination of the oxidised specimens revealed that the scales formed on the as-plated specimens were non-adherent, porous and cobalt-rich, whereas the scales formed on the heat treated specimens were mostly adherent, less porous and chromium-rich.