SiO2-Al2O3-MgO-K2O-(F)系玻璃陶瓷的分相和析晶

应用差热分析、X射线衍射分析、扫描电子显微镜等技术，研究了氟含量在SiO2—Al2O3—MgO—K2O系玻璃陶瓷分相及析晶中的作用。结果表明：当玻璃中不含氟时，试样在高温发生整体析晶，析出晶相为堇青石(Mg2Al4Si5O18)。当玻璃中含有质量分数为1．0％的氟时，玻璃的玻璃转变温度及析晶温度都有所降低，但首先在玻璃表面析出云母晶体，玻璃内部发生分相。随着析晶温度的升高，试样内部析出相互交错条状云母晶体。当玻璃中氟的质量分数达到4．0％时，云母晶体呈针片状整体析出，而且析晶温度进一步降低。

PHASE-SEPARATION AND CRYSTALLIZATION OF SiO2-MgO-Al2O3-K2O-(F) GLASS-CERAMICS

Phase-separation and crystallization of SiO2- MgO - Al2O3- K2O glass with and without fluorine were investigated. XRD, SEM and DTA results show that in this glass system fluorine contents have influence not only on the nucleation and phase-separation of glass, but also on the microstructure and the variety of crystalline. The crystalline is cordierite (Mg2 Al4Si5O18) in the fluorine-free glass. When fluorine content is 1. 0 % in mass the interlocking crystalline precipitated is mica, after a surface-induced mica crystallization and phase-separation in the interior of glass hody. When fluorine content is at-tained at 4. 0 % in mass, it is suggested that the crystalline of mica phase appears dominantly to be a needle-like layered prod-ucts following the bulk-activated crystallization mechanism. Fluorine also decreases the transition temperature of glass.