烧结法制备负膨胀β-锂霞石微晶玻璃

Preparation of the β-eucryptite Glass-ceramics with Negative Thermal Expansion by Sintering Method

采用化学纯原料,利用烧结法制备了Li_2O-Al_2O_3-SiO_2系负膨胀微晶玻璃。利用DTA、XRD、SEM和EDS等测试方法,研究了微晶玻璃基础成分配比(Al_2O_3/Li_2O)和添加剂(Bi_2O_3)用量对微晶玻璃物相组成、显微结构、热学性能和力学性能的影响。随着Al_2O_3/Li_2O不断增大,样品的主晶相始终为β-锂霞石,样品的吸水率逐渐减小,热膨胀系数与抗折强度则不断增大。随着Bi_2O_3添加量的增加,微晶玻璃中次晶相Bi_2SiO_5的析出量也随之增加。由于Bi_2SiO_5晶相的热膨胀系数远大于β-锂霞石晶相,故微晶玻璃的热膨胀系数逐渐增大。

The negative expansion glass-ceramics of Li2O-Al2O3-SiO2 system was successfully produced by sintering method using pure chemical raw materials. The effect of Al2O3/Li2O and amount of Bi2O3 on the phase composition, microstructure, thermal and mechanical properties of the glass-ceramics was studied. The results shows that with the increase of Al2O3/Li2O, the main crystalline phases of the samples are β-eucryptite, the water absorption of the sample decreases, the thermal expansion coefficient and the bending strength increases. With the increase in the amount of Bi203, the precipitation amount of the secondary crystalline phase Bi2SiO5 increases. Because the thermal expansion coefficient of Bi2SiO5 crystal phase is much larger than that of the β-eucryptite, so the thermal expansion coefficient of glass-ceramics increases gradually.