Influence of Yb2Si2O7 doping concentration on mechanical properties and thermal conductivity of Yb2SiO5-Yb2Si2O7 composite ceramics

Ytterbium silicate is one of the most promising candidate materials for environmental barrier coatings. (1-x)Yb2SiO5-xYb2Si2O7 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, mol. %) composite ceramics were prepared by high-temperature sintering method at 1500 degrees C. The microstructure, phase composition, mechanical properties, thermal conductivity and high-temperature sintering behavior of Yb2SiO5-Yb2Si2O7 composite ceramics were investigated. The results showed that the (1-x)Yb2SiO5-xYb(2)Si(2)O(7) composite ceramics were composed of X2-Yb2SiO5 and beta-Yb2Si2O7 phases, and no other phases were formed. The hardness (3.93 +/- 0.11 GPa) and fracture toughness (1.53 +/- 0.03 MPa.m(1/2)) of 0.5Yb(2)SiO(5)-0.5Yb(2)Si(2)O(7) ceramic were about 50% higher than those of pure Yb2SiO5 ceramic. The thermal conductivity of 0.5Yb(2)SiO(5)-0.5Yb(2)Si(2)O(7) ceramic was 1.39 W.m(-1).k(-1) at 1073 K, and maintained at a lower level. The microstructure and phase composition of 0.5Yb(2)SiO(5)-0.5Yb(2)Si(2)O(7) ceramic were still stable after sintered at 1400 degrees C for 100 h, exhibiting excellent high-temperature structural stability. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Ytterbium silicate is a promising candidate material for environmental barrier coatings. Composite ceramics of (1-x)Yb2SiO5-xYb2Si2O7 were prepared by high-temperature sintering, showing improved mechanical properties and thermal stability compared to pure Yb2SiO5 ceramics.