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:Lu_2O_3·SiO_2、Lu_2O_3·2SiO_2和Lu_2O_3·2.26SiO_2.在1400℃、50%H_2O-50%O_2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:Lu_2SiO_5+Lu_2Si_2O_7、Lu_2Si_2O_7+SiO_2和Lu_2Si_2o_7+SiO_2.在水蒸气作用下,Lu_2SiO_5相与Al_2O_3反应生成新相Lu_3Al_5O_(12)而Lu_2Si_2O_7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 Lu_2O_3·SiO_2 , Lu_2O_3·2SiO_2 and Lu_2O_3·2.26SiO_2 , respectively. Their corrosion behavior in water vapor was investigated in 50% H_2O-50% O_2 steam environment with a total pressure of 1.01 × 10~5 Pa 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 Lu_2SiO_5 + Lu_2Si_2O_7, Lu_2Si_2O_7 + SiO_2 and Lu_2Si_2O_7 + SiO_2, respectively. Lu_2SiO_5, instead of Lu_2Si_2O_7 , reacts with Al_2O_3 to form garnet phase (Lu_3Al_5O_(12)) in the water vapor environment. This indicates that Lu_2Si_2O_7 exhibits more excellent chemical stability than Lu_2SiO_5.
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