Mechanical evaluation of thermal barrier coatings by indentation: A review

Thermal barrier coatings (TBCs) play an important role in the thermal protection of alloy components in high temperature industries. Accurately characterizing and extracting mechanical properties of TBCs are crucial for structural design, performance optimization, failure prediction and lifespan assessment. Indentation test is an effective method for experimentally obtaining the mechanical properties and provides valuable insights into the elastic, plastic and fracture behaviors of TBCs at elevated temperatures. This paper aims to provide an overview of indentation mechanical evaluation of TBCs, including the mechanical properties at different temperatures, the mechanical property anisotropy, the microstructural and mechanical behavior under thermal exposure and/or thermal cycling, as well as the comparison of functional performance between conventional and nanostructured TBCs. Furthermore, this paper points out the main challenges and future directions from indentation investigations of TBCs. Finally, this paper is summarized and prospected.