Na2O-Al2O3-SiO2-P2O5玻璃的结构和析晶性能研究

采用熔融-淬冷法制备了不同(Al₂O₃+P₂O₅)含量的碱铝硅酸盐玻璃,通过拉曼光谱、X射线衍射光谱、扫描电镜研究了其结构特征和析晶性能。发现随着(Al₂O₃+P₂O₅)含量减少,玻璃中Na₂O含量增加,玻璃化转变温度从685 ℃降低到622 ℃,当减少至摩尔分数为22%时,出现析晶峰且起始析晶温度降低。拉曼光谱表明Q⁴_P对应的拉曼峰强度变低且逐渐向低波数方向移动,说明Na₂O作为网络修饰体使硅酸盐玻璃结构逐步解聚,玻璃的析晶能力逐渐增强。结果表明:当(Al₂O₃+P₂O₅)摩尔分数为22%时热处理后的样品存在晶型转变,700 ℃热处理时以NaAlSiO₄霞石晶体为主,900 ℃时转变为以Na_6.8Al_6.3Si_9.7O₃₂霞石晶体为主。当(Al₂O₃+P₂O₅)的摩尔分数为21%和20%时,热处理后的样品能稳定析出Na₃PO₄和Na_6.8Al_6.3Si_9.7O₃₂晶体。热处理后的样品析出了耐酸侵蚀性较差的富磷相和Na₃PO₄晶体,导致化学稳定性变差。

Structure and Crystallization Behavior of Na2O-Al2O3-SiO2-P2O5 Glasses

Alkali-aluminosilicate glasses with different(Al₂O₃+P₂O₅)concentrations were prepared by the melting-quenching method,and their structural characteristics and crystallization behavior were studied by Raman spectroscopy,X-ray diffraction spectroscopy,and scanning electron microscopy.It is found that as the concentration of(Al₂O₃+P₂O₅)decreases,the concentration of Na₂O increases,resulting in the glass transition temperature decreases from 685℃to 622℃.When the(Al₂O₃+P₂O₅)concentration decreases to 22%(mole fraction),a crystallization peak appears and the onset crystallization temperature gradually decreases.The intensity of the Raman vibration band corresponding to Q_P⁴ becomes lower and gradually shifts towards low frequency,indicating that the Na₂O as a network modifier gradually depolymerizes the structure of silicate glass and enhances the crystallization ability of the glass.The results show that there is a crystalline transformation after heat treatment when the concentration of(Al₂O₃+P₂O₅)is 22%(mole fraction).The main precipitation crystals are NaAlSiO₄ nepheline at 700℃for 2 h while it transforms to Na_6.8Al_6.3Si_9.7O₃₂ nepheline crystals at 900℃for 2 h.When the concentration of(Al₂O₃+P₂O₅)is 21%and 20%(mole fraction),Na₃PO₄ and Na_6.8Al_6.3Si_9.7O₃₂ crystals are precipitated after heat treatment.After heat treatment,phosphorus-rich phase and Na₃PO₄ crystals with poor acid corrosion resistance are precipitated,resulting in poor chemical stability.