MgO/Al2O3比对MgO-Al2O3-SiO2系统玻璃分相与析晶的影响

Effect of MgO/Al2O3 Ratio on Phase-separation and Crystallizationof MgO-Al2O3-SiO2 Glass

中文关键词: 镁铝比 分相 析晶 堇青石

英文关键词: MgO/Al₂O₃ ratio, phase-separation, crystallization, cordierite

中文摘要:

      采用高温熔融法制备了具有不同MgO/Al₂O₃比的堇青石微晶玻璃。采用差热分析仪(DTA)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)等测试技术研究了MgO/Al₂O₃比对该系统玻璃分相和析晶的影响。结果表明:当SiO₂含量不变时,随着MgO/Al₂O₃比的减小,分相形貌由连通的蠕虫状逐渐变为孤立的球形结构,且分相粒子尺寸逐渐减小,从200~300 nm减小至30~50 nm。当MgO/Al₂O₃比从3降到1,析晶峰温度由997 ℃升至1 105 ℃,析晶的难度逐渐提高。当MgO/Al₂O₃比为3时,MgO-Al₂O₃-SiO₂系统玻璃经950 ℃热处理后即产生大量分相,经1 050 ℃热处理后在分相液滴中析出大量堇青石晶体,且堇青石优先在富Mg相中析出。提高MgO/Al₂O₃比有利于MgO-Al₂O₃-SiO₂系统玻璃在分相中析晶,反之,则会降低系统的分相和析晶能力。

英文摘要:

      Cordierite-based glass-ceramics with diverse MgO/Al₂O₃ ratios were prepared by high temperature melting met-hod. The impact of MgO/Al₂O₃ ratio on the phase separation and crystallization behavior of the MgO-Al₂O₃-SiO₂ glass were investigated by means of differential thermal analyzer (DTA), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicated that with the constant content of SiO₂, the decrease of MgO/Al₂O₃ ratios leaded to the morphology change of phase separation droplets from worm-like shape to isolated sphere,and the gradual size reduce of phase separation droplets from 200—300 nm to 30—50 nm. The increase of crystallization peak temperature (Tp) from 997 ℃ to 1 105 ℃could be observed as the MgO/Al₂O₃ ratio decreased from 3 to 1, which made the crystallization become more difficult. When the MgO/Al₂O₃ ratio is 3, the MgO-Al₂O₃-SiO₂ glass would produce a large amount of phase separation droplets after heat treatment at 950 ℃. After heat treatment at 1 050 ℃, substantial cordierite crystals were precipitated in phase separation droplets, which were preferentially precipitated in Mg-rich phase. Increasing MgO/Al₂O₃ ratio was highly beneficial to the phase separation and crystallization in MgO-Al₂O₃-SiO₂ glass. Conversely, reducing the MgO/Al₂O₃ ratio would weaken the the ability of phase separation and crystallization of the glass.