Thermo-structural analysis of sol-gel route based yttria stabilized tetragonal zirconia (YSTZ) powders for thermal barrier applications

Abstract

Yttria stabilized zirconia (YSZ) powders have been synthesized via sol-gel solution route in order to obtain thermal barrier coatings (TBCs) from sol-gel. Conventional method of preparation of sol and gel has been used for coating and thermal analysis respectively. Prepared gel is heated at 150°C for 3h and 250°C for 3 h and thermal analysis of powder is carried out. At this stage two routes are followed to get the sintered powder. Sintered powder-1 is obtained after heat treatment of 800°C for 3 h and sintered powder-2 is obtained by heat treatment at 1300°C for 3 h. Thermal analysis of both gel and dried powder at 150°C for 3 h show the exothermic process of 187.5°C, indicating the start of the nucleation process of crystallization of the tetragonal phase of YSZ powder. Sintered powder obtained after heating the powder at 1300°C for 3 h is found to have more identical grain size distribution of YSZ powder in comparison to powder sintered at 800°C for 3 h. The total mass loss of gel and powder obtained by drying gel at 150°C for 3 h is found to be 31.4% and 31.0% respectively, indicating amorphous behavior at this stage.