Effect of deposition temperature on the corrosion behavior of CVD SiC coatings on SiC_f/SiC composites under simulated PWR conditions

摘要

To improve the hydrothermal corrosion resistance of SiCf/SiC composites, SiC coatings were chemical vapor deposited at 1000, 1150 and 1200 degrees C. Their corrosion behaviors were investigated using immersion tests and various analytical methods. The intergranular corrosion phenomenon was observed at all three coatings. It caused the delamination on the surface of 1000 and 1150 degrees C coatings, whereas only the local fall-off of large grains occurred on the 1200 degrees C coating. The large grain size and high crystallinity of coating deposited at 1200 degrees C contributed to the excellent corrosion resistance compared with coatings deposited at other two temperatures.