Protective coating

PCT No. PCT/GB95/01746 Sec. 371 Date Jul. 16, 1996 Sec. 102(e) Date Jul. 16, 1996 PCT Filed Jul. 24, 1995 PCT Pub. No. WO96/03536 PCT Pub. Date Feb. 8, 1996A method of producing a coating on a substrate by electrolytically co-depositing a metal matrix M1 and particles of CrAlM2, where M1 is Ni, Co or Fe or two or all of these elements and M2 is Y, Si, Ti, Hf, Ga, Nb, Mn, Pt, a rare earth element or two or more of these elements. The co-deposition is carried out at a current density of less than 5mA per square centimeter. Preferably, the co-deposition forms a layer less than 50 microns thick, and occurs at a bath loading of less than 40 grams per liter of the particles. In a preferred embodiment, the particle size distribution in the plating bath is 25 percent between 15 and 12 microns, 45 percent between 12 and 10 microns and 30 percent less than 10 microns. The method is particularly useful for coating a gas turbine part.