Patent ID: 6933062

Claim:
An article protected by a protective coating, comprising: a substrate having a substrate surface; and a protective coating comprising an outer layer deposited upon the substrate surface and having a protective-coating outer surface, and a diffusion zone formed by interdiffusion of the outer layer and the substrate, wherein the outer layer comprises platinum, aluminum, no more than about 2 weight percent hafnium, elements diffused into the protective coating from the substrate, and substantially no added silicon, and wherein the protective coating has an average hafnium composition profile comprising a relatively small first concentration of hafnium in a first depth range adjacent to the protective-coating outer surface, a relatively large second concentration of hafnium, but not exceeding about 9 weight percent, in a second depth range at greater depths than the first depth range below the protective-coating outer surface, and a relatively small third concentration of hafnium In a third depth range at yet greater depths than the second depth range below the protective-coating outer surface.