Thermal shock behavior of mixed ytterbium disilicates and ytterbium monosilicates composite environmental barrier coatings.

Abstract The thermal shock properties of mixed Yb 2 Si 2 O 7 and Yb 2 SiO 5 composite environmental barrier coating (EBC) topcoat, with various Yb 2 Si 2 O 7 -to-Yb 2 SiO 5 ratios, are investigated between room temperature and 1500 °C. The results show that, with more Yb 2 Si 2 O 7 introduced, the mixed Yb 2 Si 2 O 7 and Yb 2 SiO 5 composite topcoats exhibit an increasing thermal shock property. This may be attributed to that, while Yb 2 Si 2 O 7 mole fraction increases, the thermal expansion coefficient of the mixed Yb 2 Si 2 O 7 and Yb 2 SiO 5 composite ceramics becomes smaller, more matched to substrates and the fracture toughness of the mixed Yb 2 Si 2 O 7 and Yb 2 SiO 5 composite ceramics becomes larger, both of which are favoring the improvement of thermal shock resistance. Highlights • Yb 2 Si 2 O 7 and 3Yb 2 Si 2 O 7 •Yb 2 SiO 5 exhibit better durability compared with other EBC samples. • TEC and fracture toughness for five compositions of ytterbium silicates have been studied. • The failure mechanisms are probably unveiled as TEC and TGO. [ABSTRACT FROM AUTHOR]