添加Li_2O对BAS玻璃陶瓷相变和性能的影响

Effect of Lin_2O on Phase Transition and Properties of BAS (BaO- Al_2O_3-SiO_2 System)Glass-Ceramics

研究了溶胶─凝胶法合成的含Ｌｉ２Ｏ的ＢＡＳ凝胶玻璃的晶化行为及Ｌｉ２Ｏ加入量对ＢＡＳ玻璃陶瓷性能的影响规律。结果表明，不含Ｌｉ２Ｏ的ＢＡＳ凝胶玻璃晶化处理后获得主晶相为六方钡长石的ＢＡＳ玻璃陶瓷，加入Ｌｉ２Ｏ后，促进六方钡长石向单斜钡长石转变。

The research results presented here are believed to be first such results published in China, if not in the world. We have done research on ceramics since 1985 and since 1991, we have concentrated on BAS (BaO-Al2O3- SiO2 system) 81ass- ceramics as matrix of composites for use in aircraft engines. Here we report on how to achieve the optimum is transforming hexacelsian into celsian during crystallization of BAS gel glasses.The optimum is reached by preparing BAS glass-ceramic containing 1 wt % of Li2O:such BAS glass - ceramic possesses the fOllowing good properties: room temperature flexural strength of =139MPa, 1200℃ ne-cural strength σ= 148 MPa and linear expansion coefficient α=4.9 ×10-6/℃. Our selection of 1 wt % of Li2O as optimum is based on the consideration that, while keeping the above three properties satisfactory, we can transform as much hexacelsian into celsian as possible.Fin. 5 shows the variation of σ and σ with the amount of Li2O. Clearly, of peaks at about 1 wt % of Li2O. Table 1 shows α(last column) to be decreasing with increasing amount of Li2O (second column). Fig. 3 shows variation of percentage of hexacelsian transformed under suitable heat treatment into celsian with amount of Li2O. At Li2O≈1 wt %, this percentage is about 60%.