Thermal properties and anti-corrosion behavior of multicomponent (Dy1/5Er1/5Tm1/5Yb1/5Y1/5)2SiO5 monosilicate against water vapor attack at high temperature

Abstract

Materials with a thermal expansion coefficient compatible with silicon carbide based ceramic matrix composites and low thermal conductivity at higher temperatures are crucial for developing environmental barrier coatings (EBCs) for aero-engines. Lately, high entropy silicate engineering has been a promising approach to develop optimized EBC materials. The solid solution reaction method was adopted for the fabrication of high entropy multicomponent (Dy1/5Er1/5Tm1/5Yb1/5Y1/5)2SiO5 or (5RE1/5)2SiO5 monosilicate. Scanning electron microscopy and X-ray diffraction show the homogenous distribution and a single-phase solution of (5RE1/5)2SiO5 monosilicate. Differential scanning calorimetry testing was done at 1450 °C which shows no exo/endothermic reaction has occurred. The value of the coefficient of thermal expansion (6 ppm/°C) up to temperature 1500 °C and low thermal conductivity values for (5RE1/5)2SiO5 monosilicate were observed (1.1–1.4 W/m°C) in the temperature range between 25 and 1500 °C. The water vapor corrosion resistance of (5RE1/5)2SiO5 monosilicate further confirms that the material is suitable for EBC applications due to the synergistic effect of different rare earth radii and stable crystal structure with a negligible weight loss value of 0.0005 mg/cm2 after 150 h corrosion time under 90 % H2O and 10 % O2 at 1300 °C. The results of this work suggest that (5RE1/5)2SiO5 monosilicate can be used as a promising candidate for environmental barrier coatings.