In situ hot pressing/reaction synthesis, mechanical and thermal properties of Lu2SiO5

Lu2SiO5 is a promising candidate of environmental barrier coatings (EBC) for silicon based ceramics due to its excellent high temperature stability. However, little information is available for the mechanical and thermal properties of Lu2SiO5, which frustrated evaluation of its performances for EBC applications. In this paper, dense Lu2SiO5 ceramic is successfully fabricated from Lu2O3 and SiO2 powders by in situ hot pressing/reaction sintering at 1500 °C. Mechanical properties, including Young's modulus, bulk modulus, shear modulus, Poisson's ratio, fracture toughness, Vickers hardness, and bending strength are reported for the first time. Lu2SiO5 possesses excellent high temperature mechanical properties up to at least 1300 °C. Thermal stress for the case of Lu2SiO5 or Y2SiO5 coating on silicon bond coat and thermal stress resistance parameter are also estimated based on the experimental mechanical and thermal properties. The present results suggest that Lu2SiO5 has better reliability than Y2SiO5 in harsh thermal environment.