Anti-stick coating for internal passages of turbine components

A gas turbine engine component having internal cooling passages, the internal cooling passages having surfaces on which there is a diffusion aluminide coating, an alumina scale layer on the diffusion aluminide coating, and an outer coating on the alumina scale layer, the outer layer being uniformly deposited throughout the internal cooling passages to have a thickness of at least one micrometer and not more than three micrometers, the outer layer being resistant to adhesion by silica and calcium compounds as a result of consisting of Ta2O5 and/or SiO2.

A method of inhibiting the adhesion of dirt contaminants to surfaces of internal cooling passages within a gas turbine engine component, the method comprising the steps of:

• depositing an aluminide-containing environmental coating so that the surfaces of the internal cooling passages;
• and then
• uniformly depositing an outer coating throughout the internal cooling passages, the outing coating being resistant to adhesion by the dirt contaminants, the outer coating being deposited to have a thickness of not greater than three micrometers and to comprise at least one layer of at least one coating material selected from the group consisting of Ta2O5, TiO2, HfO2, Nb2O5, Y2O3, SiO2 and Al2O3.

A method of inhibiting the adhesion of silica and calcium compounds to surfaces of internal cooling passages within a gas turbine engine component the method comprising the steps of:

• depositing a diffusion aluminide coating by vapor phase aluminizing the surfaces of the internal cooling passages;
• and then
• depositing an outer coating by chemical vapor deposition at a temperature of less than 790° C., the outing coating being resistant to adhesion by the silica and calcium compounds, the outer coating being uniformly deposited throughout the internal cooling passages to have a thickness of at least one micrometer and not greater than three micrometers, the outer coating consisting of Ta2O5 and/or SiO2.