THERMAL BARRIER COATING RESISTANT TO DEPOSITS AND COATING METHOD THEREFOR

摘要

A protective coating system and method for protecting a thermal barrier coating from CMAS infiltration. The coating system comprises inner and outer alumina layers and a platinum-group metal layer therebetween. The outer alumina layer is intended as a sacrificial layer that reacts with molten CMAS, forming a compound with a melting temperature significantly higher than CMAS. As a result, the reaction product of the outer alumina layer and CMAS resolidifies before it can infiltrate the TBC. The platinum-group metal layer is believed to serve as a barrier to infiltration of CMAS into the TBC, while the inner alumina layer appears to enhance the ability of the platinum-group metal layer to prevent CMAS infiltration.