Microstructure and nanomechanical properties of plasma-sprayed nanostructured Yb₂SiO₅ environmental barrier coatings

In this study, nanostructured and conventional Yb₂SiO₅ coatings were prepared by atmospheric plasma. The microstructure and nanomechanical properties of these coatings were compared before and after heat treatment. The results show that the nanostructured Yb₂SiO₅ coatings have a mono-modal distribution, and the conventional Yb₂SiO₅ coatings have a bimodal distribution. Both types of coatings had improved nanomechanical properties after heat treatment. However, the increased elastic modulus and nanohardness of the nanostructured Yb₂SiO₅ coating were more apparent than those of the conventional Yb₂SiO₅ coatings. The nanostructured Yb₂SiO₅ coating had a higher elastic modulus than the conventional Yb₂SiO₅ coating, reflecting its high density. Subsequently, the microscopic morphology and micromechanical properties of the coatings were analyzed after heat treatment. Defects in the coatings, including pores, and microcracks, were significantly reduced with grain growth after thermal treatment, and the nanostructured Yb₂SiO₅ coatings had improved healing ability and micro-mechanical properties.