Abstract: A method of producing an overlay coating on a substrate such as a turbine blade which comprises: (1) plating a protection layer comprising a metal matrix M.sub.1 containing particles of CrAlM.sub.2, (2) plating an anchoring layer comprising a metal layer containing larger particles, and (3) spray coating a thermal barrier of a refractory material.

Abstract: A substrate such as a single crystal gas turbine blade is given a protective coating by composite electrodeposition of a metal matrix M.sub.1 containing particles of CrAlM.sub.2, where M.sub.1 is Ni or Co or Fe and M.sub.2 is Y, Si, Ti, or a rare earth element. The preferred matrix is Ni or Co or NiCo and the preferred particles are CrAlY. The particle size is important and preferably 75% by weight are between 3.9 and 10.5 .mu.m. The coating is heat treated to produce interdiffusion between the constituents of the matrix and the particles.

Abstract: A process of and apparatus for coating an article with a layer of metal incorporating particles. The article is placed in a barrel together with the particles and the barrel is placed in a plating bath and rotated therein. The barrel has an opening covered by a cover which is pervious to the solution but impervious to the particles. The article is thus flowed over by solution within the barrel which can have a high concentration of particles but there are no particles in the part of the bath outside the barrel. The process may be electroless or electrolytic. In the latter case, the anode is preferably outside the barrel.