Preparation of YSZ coatings by thermal pressure and filtration of sol-gel paint (TPFSP) for thermal barrier application

Thick YSZ ceramic coatings were prepared by thermal pressure and filtration of sol-gel paint (TPFSP), a modified sol-gel composite coating technique. SEM results show that the coatings were dense and crack-free by using paints of high mass ratios of YSZ powder to Zr-Y oxide in sol and high pressures. And the cross-sectional detail of coatings exhibited that the microstructure was consisted of micro/nano-size ceramic particles and micro-pores. The thermal insulation tests indicated that mass ratio of YSZ powder to Zr-Y oxide in sol was in inversely linear relationship with temperature drop per micron thickness. The coating showed good adherence with alloy substrate and maintained structural integrity when exposed at 1050 °C for 200 h. The cyclic oxidation test also indicated that both of oxidation resistance and spallation resistance for YSZ coated specimens were greatly improved. The TPFSP process could be a promising method to prepare TBCs for wide applications.