A comprehensive study on the mechanical properties of Yb2SiO5 as a potential environmental barrier coating

Yb2SiO5 is a promising damage tolerant material to be used as an environmental barrier coating (EBC) for silicon-based ceramic substrates. However limited research is available on its mechanical properties, thus hindering the detailed evaluation of its performance as a possible EBC candidate. In this work, dense Yb2SiO5 is synthesized from Yb2O3 and SiO2 and sintered at 1580 degrees C. The mechanical properties of the material, including Young's modulus, Vickers hardness and fracture toughness are comprehensively studied to better understand the reliability of Yb2SiO5 as an EBC. Yb2SiO5 has a low Young's modulus of 119 GPa leading to low thermal stresses when deposited on a SiC/SiC substrate. It also has a low hardness value of 6.4 GPa, but a comparatively high fracture toughness value of 1.97 GPa. The effect of different loads on hardness was also investigated and it was noted that Yb2SiO5 exhibits reverse indentation size effect (ISE). This suggests that Yb2SiO5 undergoes relaxation when loaded. These promising results show that Yb2SiO5 could be used as a potential candidate for EBC applications.