CMAS corrosion behavior of a LaPO4 ceramic prepared by spark plasma sintering

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)center dot 6H(2)O) 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.