Process for applying coatings of zirconium and/or titantuim and a less noble metal to metal substrates and for converting the zirconium and/or titanium to an oxide, nitride, carbide, boride or silicide

摘要

Protective coatings are applied to substrate metals by coating the metal surface, e.g. by dipping the substrate metal in a molten alloy of the coating metals, and then exposing the coating at an elevated temperature to an atmosphere containing a reactive gaseous species which forms an oxide, a nitride, a carbide, a boride or a silicide. The coating material is a mixture of the metals M1 and M2, M1 being zirconium and/or titanium, which forms a stable oxide, nitride, carbide, boride or silicide under the prevailing conditions. The metal M2 does not form a stable oxide, nitride, carbide, boride or silicide. M2 serves to bond the oxide, etc. of M1 to the substrate metal. Mixtures of M1 and/or M2 metals may be employed. This method is much easier to carry out than prior methods and forms superior coatings. Eutectic alloys of M1 and M2 which melt substantially lower than the melting point of the substrate metal are preferred.