Patent ID: 7368164

Claim:
A combustor component of a gas turbine, the component having a thermal barrier coating overlying a surface thereof and a multilayer outer coating overlying the thermal barrier coating, the outer coating comprising an inner layer and an outer layer, the inner layer consisting essentially of about 5 to about 85 weight percent of alumina comprising first and second alumina particles and the balance being a first silica-containing matrix material, the silica-containing matrix material being free of zinc titanate and consisting essentially of at least one of silica, silicate and mullite, the first and second alumina particles defining a bimodal size distribution in which the first alumina particles have a particle size range of about 3.0 to about 6.0 micrometers and the second alumina particles have a particle size range of about 0.05 to about 0.8 micrometer, the outer layer consisting essentially of about 5 to about 85 weight percent of third alumina particles, about 0 to about 35 weight percent of a glass material, about 0 to about 35 weight percent zinc titanate, and the balance being a second silica-containing matrix material consisting essentially of at least one of silica, silicate and mullite, the third alumina particles of the outer layer having a particle size distribution that is finer than the particle size distribution of the first alumina particles and finer than the particle size distribution of the second alumina particles of the inner layer, the outer layer defining an outermost surface of the component, the outermost surface having a surface roughness of not greater than 3 micrometers Ra.