Plasma sprayed thermal bond coat system

Abstract

A method for forming a thermal barrier coating system on an article subjected to a hostile thermal environment, such as the hot gas path components of a gas turbine engine. The coating system is generally comprised of a ceramic layer and an environmentally resistant beta phase nickel aluminum intermetallic (β-NiAl) bond coat that adheres the ceramic layer to the component surface. A thin aluminum oxide scale forms on the surface of the β-NiAl during heat treatment. The β-NiAl may contain alloying elements in addition to nickel and aluminum in order to increase the environmental resistance of the β-NiAl. The β-NiAl powder having a size in the range of 20-50 microns is applied using air plasma spray techniques to produce a surface having a roughness of 400 microinches or rougher. The ceramic top coat can be applied using inexpensive thermal spray techniques to greater thicknesses than achievable otherwise because of the rough surface finish of the underlying β-NiAl bond coat.

Dependencies are inferred from the claim text.