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Ceramic thermal barrier coatings (TBCs) are widely used on the gas turbine engine. As one of the candidate TBC materials, LaPO4 has attracted much attention. In the present study, the bulk LaPO4 was prepared by spark plasma sintering (SPS). The effect of different preparation conditions on the properties of the obtained LaPO4 ceramic was studied. The phase composition, microstructure, thermal expansion and thermal conductivity of the LaPO4 ceramic with heat treatment at 1450°C for different time were studied by XRD and SEM.

At high temperatures in gas turbines, traditional yttria stabilized zirconia materials fail prematurely owing to CMAS (calcium–magnesium–alumina–silicate) corrosion. Thus, new materials need to be developed urgently. In this study, LaPO4 powder was synthesized by chemical coprecipitation and heat treatment using lanthanum nitrate (La(NO3)3∙6H2O) and ammonium dihydrogen phosphate (NH4H2PO4) as starting materials, and LaPO4 bulk was prepared by spark plasma sintering. The surface of the LaPO4 bulk was coated with CMAS (CaO–MgO–Al2O3–SiO2) powder, and the CMAS interaction with the LaPO4 bulk at different temperatures was investigated. The phase and microstructure of the LaPO4 powder and bulk, as well as the CMAS corrosion products, were characterized using X‐ray diffraction and scanning electron microscope. The superior CMAS resistance of the LaPO4 bulk was attributed to the low wettability of LaPO4 by the CMAS melt and the development of dense layers of new corrosion products, which effectively protected the LaPO4 bulk from CMAS infiltration.