Corrosion Behavior of AlPO4 as Environmental Barrier Coating in Water Vapor Enviroment

AlPO4 was synthesized by a Sol-Gel method. Its coefficient of thermal expansion (CTE) was measured by dilatometer. Its corrosion behavior was tested in an environment of 50vol%H2O/50vol%O2 with a flow rate of 0.085cm/s at 1350 The phases and composition of the samples were analyzed by X-ray diffraction and Energy Dispersive Spectroscope. The microstructures of AlPO4 were characterized by Scanning Electron Microscope. The results indicate that the CTE of AlPO4 matches with that of C/SiC composites and its corrosion resistance is much better than that of SiC. However, the decomposition of AlPO4 at high temperatures is the main problem in the water vapor enviroment￡ which will be accelerated in combination with silica.