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.