Long lifespan thermal barrier coatings overview: Materials, manufacturing, failure mechanisms, and multiscale structural design

A long lifespan is a basic support for the thermal protection of thermal barrier coatings (TBCs). Plasma-sprayed TBCs provide high thermal insulation and cost-effective advantages; thus, they are used in cutting-edge areas, such as land-based gas turbines. However, following thermal exposure, sintering causes structural changes and significant degradation in thermal insulation and strain tolerance. Thus, plasma-sprayed TBCs often show poor performance in thermal cycling tests. Therefore, extending the lifespan of plasma-sprayed TBCs is crucial. This study reviews the structural design of TBCs for a long lifespan. The main contents reviewed include the following aspects: (1) the basic structural features of plasma-sprayed TBCs with high thermal insulation and strain tolerance in an as-deposited state; (2) the dynamic structural evolution during thermal exposure to reveal the degradation mechanism in thermal and mechanical properties; and (3) multiscale structural design of TBCs to achieve a long lifespan. This review aims to contribute to the development of advanced gas turbines.