Effect of platinum on the durability of thermal barrier systems with a γ + γ′ bond coat

The effect of the Pt content on the durability of thermal barrier coatings (TBCs) with a Pt-enriched γ + γ′ bond coat was investigated. It was found that the TBCs with a higher Pt content exhibit a significantly longer isothermal life than those with a lower Pt content. The subsequent analysis indicated that the Pt content has only a negligible effect both on the stresses in the thermally-grown oxide (TGO) and the elastic properties of the bond coat, but has a significant effect on the interfacial chemistry. During oxidation, impurities such as S, C and refractory elements segregating to the interface would degrade the TGO adherence to the bond coat. However, a higher content of Pt can inhibit this segregation, and thus improve the TBCs life.