In situ reaction–based synthesis of a novel nanostructured Lu₂SiO₅-based environmental barrier coating with controllable Lu₂O₃ content

Poor fracture toughness and calcium–magnesium–aluminum–silicate (CMAS) corrosion resistance adversely affect environmental barrier coatings (EBCs) during prolonged service. Herein, an in-situ nanostructured Lu₂O₃/Lu₂SiO₅ composite EBC was successfully prepared using nanostructured Lu₂SiO₅ feedstocks. The morphologies and phase structures of the Lu₂SiO₅ feedstocks and the corresponding coating were thoroughly characterized. Additionally, the mechanism of the in suit reaction of the Lu₂O₃/Lu₂SiO₅ composite EBC was examined. The results indicate that the nanostructured as-deposited EBC exhibits a bimodal and dual-phase structure. The nanostructured Lu₂SiO₅ coating comprises melted lamellae and unmelted or partially melted particles. The phase structure of these unmelted or partially melted particles includes Lu₂O₃ and X2-Lu₂SiO₅. The Lu₂O₃ nanoparticles are formed by the decomposition of Lu₂SiO₅ during spraying, and their content can be controlled to <15 %, which can enhance the fracture toughness and CMAS corrosion resistance of the EBCs to some extent.