Patent ID: 7833586

Claim:
A process for depositing an alumina-based coating onto a thermal barrier coating, the process comprising providing an article with a thermal barrier coating disposed thereon; heating an alumina powder, wherein the alumina powder has a composition of at least 60 weight percent alumina with a balance comprising titania, zirconia, and gadolinia based on a total weight of the alumina-based coating; and thermally spraying the alumina powder onto the thermal barrier coating to form the alumina-based coating, wherein the alumina-based coating increases a melting point of a contaminant composition comprising mixed calcium-magnesium-aluminum-silicon-oxides relative to the contaminant composition in the absence of the alumina-based coating, and the alumina-based coating has an average surface roughness of less than 4.0 micrometers to 0.75 micrometers.