Crystal growth behavior and sintering-resistance property of nano-sized β-Yb2Si2O7 for environmental barrier coatings

Abstract

In this article, as an attractive candidate of EBCs for SiC-based ceramic matrix composites, nano-sized β-Yb2Si2O7 was synthesized by hydrothermal method. The sintering-resistance property and crystal growth behavior of β-Yb2Si2O7 powders and compacted bodies were evaluated via various techniques. Quantity analyses demonstrate that β-Yb2Si2O7 was formed at about 1100 °C, and possessed well thermal stability at even higher temperatures. The determined coefficient of thermal expansion and thermal conductivity are 4.63 × 10-6 K-1 and 1.72 W m-1 K-1, respectively. The microstructures of compacted bodies under different temperatures reveal the critical temperature of anti-sintering is about 1400 °C. Based on different growth mechanisms, the activation energy of crystal growth (Q) can be segmented into two sections with a turning point of 1076 °C. Furthermore, the relative relationship between activation energy and sintering was bridged.