Na_2O对MgO-Al_2O_3-B_2O_3-SiO_2体系微晶玻璃结构和性能的影响

利用烧结法制备Na_2O-MgO-Al_2O_3-B_2O_3-SiO_2微晶玻璃。采用FT-IR、DSC、XRD和SEM等分析方法,研究玻璃组成中Na_2O对MgO-Al_2O_3-B_2O_3-SiO_2系统微晶玻璃的结构、析晶性能、热膨胀系数以及化学稳定性的影响。结果表明:随着Na_2O含量的增加,玻璃结构中出现了SiO_4]被破坏和BO_3]转变为BO_4]的现象。Na_2O的添加明显降低了样品的玻璃化转变温度与析晶峰值温度,增强了MgO-Al_2O_3-B_2O_3-SiO_2体系微晶玻璃的析晶能力。未加Na_2O的微晶玻璃主晶相为球状顽辉石,添加后的微晶玻璃析出镁橄榄石颗粒和柱状硼镁钛石,最终A_3、A_4只析出硼镁钛石,并且颗粒逐渐细化。随着Na_2O量的增加,微晶玻璃的热膨胀系数呈逐渐增大的趋势。微晶玻璃的耐酸碱侵蚀能力随Na_2O含量的增加先增强后减弱,其中耐碱腐蚀能力相对较强。

Effect of Na_2O Addition on Structure and Properties of MgO-Al_2O_3-B_2O_3-SiO_2 Glass-Ceramic

Na2O-MgO-Al2O3-B2O3-SiO2 glass-ceramic was prepared by sintering method. The influences of Na2O addition on the structure,crystallization ability,thermal expansion coefficient and chemical stability of the glass-ceramic were investigated by means of FT-IR,DSC,XRD and SEM. The results showed that: with the content of Na2O increasing,the phenomenon of SiO4] being destroyed and BO3] being transformed into BO4] appeared in the glass structure. The addition of Na2O significantly reduced the glass transition temperature and crystallization temperature of the samples,and enhanced the crystallization capacity of MgO-Al2O3-B2O3-SiO2 galss-ceramic. The main crystalline phase of the glass-ceramics without Na2O was spherulitic enstatite. After the addition of Na2O,forsterite particles and columnar warwickite were precipitated. Finally,only warwickite was precipitated out from A3 and A4,and the particles were gradually refined. With the content of Na2O increasing,the thermal expansion coefficient of glass-ceramic was increasing gradually,and the corrosion resistance of glass-ceramic was first enhanced and then weakened,while the alkali resistance was relatively strong.