Corrosion Behavior of Lu-Si-O System in Water Vapor

Three kinds of lutetium silicates powders were prepared by solgel method, marked by Lu2O3·SiO2, Lu2O3·2SiO2 and Lu2O3·2.26SiO2, respectively. Their corrosion behavior in water vapor was investigated in 50%H2O-50%O2 steam environment with a total pressure of 1.01×105Pa at 1400℃. The specific weight change as a function of corrosion time was recorded. The phase evolution of lutetium silicate at different corrosion stages was observed by X-ray diffraction. The bonds of samples after corroded for different times were characterized by fourier transform infrared spectroscope(FTIR). The composition of corroded samples was analyzed by EDS. The results show that the main crystal phases of the as-prepared samples are Lu2SiO5+Lu2Si2O7, Lu2Si2O7+SiO2 and Lu2Si2O7+SiO2, respectively. Lu2SiO5, instead of Lu2Si2O7, reacts with Al2O3 to form garnet phase (Lu3Al5O12) in the water vapor environment. This indicates that Lu2Si2O7 exhibits more excellent chemical stability than Lu2SiO5.