Effects of Y doping on phase structure, mechanical properties and sintering behavior of (Yb1-xYx)2SiO5 environmental barrier coating materials

Yb2SiO5 is one of the most widely studied environmental barrier coating materials due to its excellent high-temperature phase stability and resistance to water oxygen corrosion. In this paper, a series of (Yb1-xYx)(2)SiO5 (x = 0, 0.1, 0.2, 0.3, 0.4) ceramics were fabricated by high-temperature solid state sintering at 1550 degrees C. The effects of Y doping concentration on phase composition, mechanical properties, thermal conductivity and high-temperature sintering behavior of Yb2SiO5 ceramics were investigated in detail. The results show that all the (Yb1-xYx)(2)SiO5 ceramic specimens are composed of single X2-Yb2SiO5 phase with relative high compactness. The introduction of Y gives rise to the reduction of the thermal conductivity of Yb2SiO5 and the value of cell parameters and volume of (Yb1-xYx)(2)SiO5 is proportional to the Y3+ doping concentration. Among the five (Yb1-xYx)(2)SiO5 ceramics, (Yb0.9Y0.1)(2)SiO5 possesses the lowest brittleness index and its average fracture toughness is 2.85 MPa m(1/2), which is about 10 % higher than pure Yb2SiO5. In addition, (Yb0.9Y0.1)(2)SiO5 has good high temperature phase stability from room temperature to 1450 degrees C and the grain size of (Yb0.9Y0.1)(2)SiO5 is basically unchanged after sintering at 1400 degrees C for 100 h. We believe that (Yb0.9Y0.1)(2)SiO5 is one of the most promising candidate materials for environmental barrier coatings.