Cobalt and Its Alloys

Cobalt and cobalt-based alloys are very similar to nickel and nickel-based alloys in terms of corrosion resistance, but typically they are slightly more susceptible to corrosion compared to their nickel counterparts. Cobalt-based alloys have an inherent wear and corrosion resistance. Cobalt is not considered an oxidation resistant metal, especially since the oxidation rate is generally about 25 times that of nickel. Cobalt-based superalloys, however, are resistant to oxidation and hot corrosion. Furthermore, the cobalt superalloys are more resistant to hot corrosion than are the nickel superalloys. Nickel and cobalt superalloys have a similar resistance to aqueous corrosion at lower temperatures.