Microstructure and Thermal Properties of Double Rare-earth Co-doped SrZrO3 Coating Prepared by Solution Precursor Plasma Spray

SrZrO3 is an alternative material for thermal barrier coating (TBC) application, which has the advantage of low thermal conductivity and similar thermal expansion coefficient to YSZ. However, the phase transitions of SrZrO3 below 1200oC seem to be a disvantage for TBC application. The rare-earth elements doping has been approved to be an effective way to reduce the thermal conductivity and suppress the phase transitions of SrZrO3. In this study, a double rare-earth (Yb/Gd) co-doped SrZrO3 coating was prepared by solution precursor plasma spray (SPPS) using an aqueous solution precursor, and its microstructure and thermophysical properties were studied. The coating has a typical microstructure of SPPS coating observed by a scanning electron microscopy (SEM). The thermal stability of the coating calcined at high temperatures was studied by XRD. It was found that the SrZrO3 phase has good thermal stability after 360 hours heat treatment at 1400oC, and the thermal conductivity of the as-sprayed coating is ~0.9 W/(m K). The thermal cycle life of the (Yb/Gd) co-doped SrZrO3 coating reached 650 times.