My favorite use of cobalt is in magnets (Alnico and
Alloys, such as Superalloys, for parts in gas turbine aircraft engines.
Corrosion- and wear-resistant alloys.
High speed steels.
Cemented carbides (also called hard metals) and diamond tools.
Catalysts for the petroleum and chemical industries, e.g. for hydroformylation and oxidation.
Electroplating because of its appearance, hardness, and resistance to oxidation.
Drying agents for paints, varnishes, and inks.
Ground coats for porcelain enamels.
Pigments (cobalt blue and cobalt green).