Cobalt is a hard metal in silver color which looks very similar to nickel and iron in terms of behavior and properties.
When cobalt added to iron it prevents softening at high temperatures, therefore it is the most important alloy element of air steels. Cobalt is used especially for the coating of other metals by electrolysis.
Because cobalt coating is very bright and hard it is better than nickel plating. Air steel contains the cobalt from 5% to 12%. Cobalt improves magnetisation feature when added to steels up to 40%. For this reason, cobalt is an indispensable alloy element of magnets.