MgO含量对RSCAF体系微晶玻璃析晶行为的影响

采用MgO取代R₂O-SiO₂-CaO-Al₂O₃-F(RSCAF)体系中的部分CaO制备了微晶玻璃,系统研究了MgO含量对该微晶玻璃析晶行为的影响。结果表明,RSCAF体系中不含MgO时(CaO含量为16.5%,质量分数,下同),经过热处理后微晶玻璃的主晶相为硅碱钙石,微观形貌中结晶相呈犬牙交错状,微晶玻璃的密度小于基础玻璃。当RSCAF体系中MgO的含量为0%~3%时,微晶玻璃的结晶度随着CaO含量的减少而降低;随着体系中MgO含量的进一步增加以及CaO含量的减少,微晶玻璃的主晶相由硅碱钙石逐渐向透辉石转变,微观形貌中呈柱状、片状的透辉石相增多,密度也逐渐增加;当体系中MgO的含量增加到4%(CaO含量降低至12.5%)时,微晶玻璃的主晶相完全转变为透辉石,且透辉石的结晶度相对主晶相为硅碱钙石时有所增加,微晶玻璃的密度大于基础玻璃。

Effect of MgO Content on Crystallization Behavior of RSCAF System Glass-Ceramics

The glass-ceramics were prepared by using MgO to replace part of CaO in the R₂O-SiO₂-CaO-Al₂O₃-F (RSCAF) system, and the effect of MgO content on the crystallization behavior of the glass-ceramics was investigated systematically. The results show that the main crystalline phase of the glass-ceramics is canasite after heat treatment when the RSCAF system without MgO (CaO content is 16.5%, mass fraction, the same below). Then, the crystalline phase in the microscopic morphology of the glass-ceramics presents a indented appearance and the density of the glass-ceramics is less than that of the basic glass. As the content of MgO in the RSCAF system is in the range of 0% to 3%, the crystallinity of the glass-ceramics reduces with the decrease of CaO content. Along with the further increase of MgO content and the decrease of CaO content in the system, the main crystalline phase of the glass-ceramics transforms gradually from canasite into diopside, and the crystalline diopside phase with columnar and flake-shaped appearance increases in the microscopic morphology and the density of glass-ceramics increases gradually. When the content of MgO in the system increases to 4% (CaO content decreases to 12.5%), the main crystalline phase of the glass-ceramics completely changes to diopside, and the crystallinity of diopside increases compared with that of the main crystalline canasite phase glass-ceramics, and the density of the glass-ceramics is higher than that of the basic glass.