Lu-Si-O体系在高温水蒸气环境中的腐蚀行为

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

采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料.以氧化物的摩尔比来表示此三种粉体,分别为:Lu2O3.SiO2、Lu2O3.2SiO2和Lu2O3.2.26SiO2.在1400℃、50%H2O-50%O2静态常压气氛下,研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能,结合X射线衍射(XRD)、傅里叶红外光谱(FTIR)和扫描电镜能谱分析(SEM-EDS)等分析手段,揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理.结果表明:三种原始粉体主要物相依次为:Lu2SiO5+Lu2Si2O7、Lu2Si2O7+SiO2和Lu2Si2O7+SiO2.在水蒸气作用下,Lu2SiO5相与Al2O3反应生成新相Lu3Al5O12,而Lu2Si2O7相并未受到水蒸气的作用而发生任何反应,表现出优异的化学稳定性.

Three kinds of lutetium silicates powders were prepared by sol-gel 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.