Improvements in or relating to the formation of cobalt oxide layers

摘要

A protective coating of Co3O4 is formed on the surface of a Co or a Co-based alloy member by placing the member in an oxidizing atmosphere having a temperature between 40 DEG and 150 DEG C. (preferably between 40 DEG and 70 DEG C.) and a relative humidity of between 50 and 100% (preferably between 50 and 92%). The alloy may include nickel or phosphorus. A scratch in the Co3O4 coating is self-healing.