Preparing dense Yb₂SiO₅ sintered bodies from Yb–Si–O powder synthesized by the polymerizable complex method and appropriate calcination

Abstract

SiC fiber-reinforced SiC matrix composite (SiC_f/SiC_m) is one of the most promising materials for application in hot section components of gas turbine engines. However, due to the insufficient chemical durability of SiC_f/SiC_m under combustion environment, environmental barrier coating (EBC) is required as a protective coating on SiC_f/SiC_m surfaces. To determine the suitable materials for EBC, a synthetic process of ceramic powders with excellent compositional controllability should be established, and its calcination and sintering conditions should be determined to allow the preparation of a dense sintered body. Since ytterbium silicates are promising materials as an EBC, in this study, we investigated the synthesis of a precursor polyester containing Yb and Si components through the polymerizable complex (PC) method, which could achieve compositional homogeneity of the obtained oxide powder, as well as the dependence of the densification behavior of Yb–Si–O powder prepared by the calcination of the precursor polyester on calcination temperatures and periods. We successfully obtained a single-phase Yb₂SiO₅ sintered body using the Yb–Si–O powder prepared by the calcination of the precursor polyester synthesized using the PC method. In terms of calcination conditions, calcination at 800–1100 °C for 24 h and at 1100–1400 °C for 1 h were considered appropriate to obtain dense Yb₂SiO₅ sintered body with a relative density of >95 % at the sintering condition with 1700 °C for 5 h.