Corrosion Behavior of AlPO_4 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.