Effect of Yb₂SiO₅ addition on the physical and mechanical properties of sintered mullite ceramic as an environmental barrier coating material

다국어 초록 (Multilingual Abstract)

In this study, ytterbium monosilicate (Yb<SUB>2</SUB>SiO<SUB>5</SUB>)-added sintered mullite ceramics are prepared as candidate materials for environmental barrier coatings (EBCs). The effect of adding Yb<SUB>2</SUB>SiO<SUB>5</SUB> on the physical and mechanical properties of the sintered mullite ceramics is investigated. The Yb<SUB>2</SUB>O<SUB>3</SUB>-SiO<SUB>2</SUB>-Al<SUB>2</SUB>O<SUB>3</SUB> ternary phase diagram indicates that adding Yb<SUB>2</SUB>SiO<SUB>5</SUB> to the mullite goes beyond simply mixing; instead, liquid sintering occurs. Therefore, when we add Yb<SUB>2</SUB>SiO<SUB>5</SUB> to the mullite, the sintered body possesses a denser microstructure and faster densification rate than does pure mullite. The density rapidly increases with the addition of 6wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB> in the mullite, and almost full densifications are achieved with the addition of 12wt% and 18wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB>. In this study, mullite ceramic that contains 12wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB> exhibits the smallest plastic deformation and the highest elastic modulus among ceramics containing 6, 12, and 18wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB>, according to Hertzian indentation results. The results suggest that 12wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB>-doped mullite may be expected to act as a potential EBC material based on its excellent elastic properties, dense microstructure, and appropriate coefficient of thermal expansion.