烧结法制备LAS系低膨胀微晶玻璃的研究
发布时间：2018-08-22 14:27
【摘要】： 本研究以化学纯Li_2CO_3、Al_2O_3、SiO_2为主要原料,添加TiO_2、ZrO_2、P_2O_5晶核剂,采用烧结法制备了LAS系微晶玻璃。借助正交试验并采用DTA、XRD、TEM、SEM等分析测试方法,研究玻璃组成、热处理制度、显微结构和性能四者之间的相互联系和影响。确定了合理的微晶玻璃组成和热处理制度,制备出具有较高力学性能和合理晶相组成的低膨胀微晶玻璃。在此基础上,进一步研究了TiO_2、ZrO_2、P_2O_5晶核剂对微晶玻璃结构及性能的影响。 结果表明:当SiO_2/ Al_2O_3摩尔比为5∶1时,微晶玻璃中只存在颗粒状的晶体,随SiO_2/Al_2O_3的减小,有纤维状的晶体析出。在烧结温度较高,晶化较充分的情况下,微晶玻璃的热膨胀系数随着SiO_2/Al_2O_3的减小而增大,其抗折强度则先增加后减小。初步探讨了烧成温度对性能的影响,当烧成温度为1000℃时,微晶玻璃的主晶相为β-石英固溶体,此时微晶玻璃热膨胀系数低,但制品致密度低,力学性能差;随着烧成温度升高,β-石英固溶体开始向β-锂辉石固溶体转变,膨胀系数有所增大。当烧成温度提高到1200℃时,强度大于70MPa。 研究LAS微晶玻璃热处理制度对热膨胀系数及力学性能的影响,确定较佳的热处理制度为:核化温度780℃、核化时间1h,晶化温度860℃、晶化时间1.5h,升温至1200℃烧结。此时微晶玻璃的热膨胀系数为0.67×10-6/℃,强度达到80.48MPa。LAS系统微晶玻璃的析晶过程是一个分相促进析晶的过程,并且整个过程受成核-长大机理控制。当核化温度为760℃时,晶核数量少,而当核化温度为820℃时,晶核长大粗化,只有在780℃下进行核化处理时,晶核数量多而粒径小。 烧结法制备LAS系微晶玻璃时,晶核剂种类及含量只会影响晶体的形貌,并不会改变其主晶相,即使不添加任何晶核剂,依然能获得具有一定结晶度的制品。P_2O_5有利于析出纤维状的β-锂辉石固溶体,而TiO_2、ZrO_2则有利于析出颗粒状的β-锂辉石固溶体,且随着TiO_2、ZrO_2总量的增大,晶体颗粒减小。当TiO_2、ZrO_2及P_2O_5的比为1∶1∶3时,微晶玻璃的热膨胀系数为0.61×10-6/℃,强度达到85.71MPa。
[Abstract]:In this study, the LAS system glass-ceramics were prepared by sintering method with the chemical pure Li2COS _ 3Al2O-Al _ 2O _ 2 as the main raw material and adding TiO2ZR _ 2O _ 2P _ 2O _ 5 as the nucleating agent. The relationship and influence of glass composition, heat treatment system, microstructure and properties of glass were studied by means of orthogonal test and SEM. The reasonable composition and heat treatment system of glass-ceramics were determined and a low expansion glass-ceramics with high mechanical properties and reasonable crystalline phase composition was prepared. On this basis, the effect of tio _ 2o _ 2o _ 2O _ 5 nucleating agent on the structure and properties of glass ceramics was further studied. The results show that when the molar ratio of SiO_2/ Al_2O_3 is 5:1, there are only granular crystals in the glass-ceramics, and with the decrease of SiO_2/Al_2O_3, there are fibrous crystals precipitated. When the sintering temperature is high and the crystallization is sufficient, the thermal expansion coefficient of glass-ceramics increases with the decrease of SiO_2/Al_2O_3, and the flexural strength of glass-ceramics increases first and then decreases. The effect of sintering temperature on the properties was discussed. When the sintering temperature was 1000 鈩，
本文编号：2197372
[Abstract]:In this study, the LAS system glass-ceramics were prepared by sintering method with the chemical pure Li2COS _ 3Al2O-Al _ 2O _ 2 as the main raw material and adding TiO2ZR _ 2O _ 2P _ 2O _ 5 as the nucleating agent. The relationship and influence of glass composition, heat treatment system, microstructure and properties of glass were studied by means of orthogonal test and SEM. The reasonable composition and heat treatment system of glass-ceramics were determined and a low expansion glass-ceramics with high mechanical properties and reasonable crystalline phase composition was prepared. On this basis, the effect of tio _ 2o _ 2o _ 2O _ 5 nucleating agent on the structure and properties of glass ceramics was further studied. The results show that when the molar ratio of SiO_2/ Al_2O_3 is 5:1, there are only granular crystals in the glass-ceramics, and with the decrease of SiO_2/Al_2O_3, there are fibrous crystals precipitated. When the sintering temperature is high and the crystallization is sufficient, the thermal expansion coefficient of glass-ceramics increases with the decrease of SiO_2/Al_2O_3, and the flexural strength of glass-ceramics increases first and then decreases. The effect of sintering temperature on the properties was discussed. When the sintering temperature was 1000 鈩，
本文编号：2197372
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