锌镁替换铝硅酸盐玻璃的玻璃转变和晶化行为探索

Exploration on Glass Transition and Crystallization Behavior in Aluminosilicate Glasses with Substitution of MgO by ZnO

作为重要的透明微晶玻璃体系,含镁锌的铝硅酸盐玻璃展现了优异的力学、光学特性。大量研究关注该体系的核化和晶体生长过程,但锌镁替换对铝硅酸盐玻璃玻璃转变和晶化行为影响的物理机理尚不明晰。本研究以x ZnO·(11-x)MgO·22Al_(2)O_(3)·67SiO_(2)(x%=0%,2.2%,5.5%,8.8%,11.0%,摩尔分数)玻璃为研究对象,探究锌镁替换对铝硅酸盐玻璃的玻璃转变和晶化行为的调控规律。结果表明:随着锌逐步替换镁,玻璃转变温度慢慢下降,这是由于Zn^(2+)较弱的场强和多一个电子层的屏蔽作用,玻璃网络骨架整体键合强度降低;析出晶相从单一的莫来石相转变为莫来石与锌铝尖晶石的混合相,这是由于Zn^(2+)具有促进铝硅酸玻璃分相的作用;析晶温度降低,这主要是由于析晶温度附近黏温曲线变得更陡峭和析晶活化能降低。

As an important transparent glass ceramic system,ZnO-MgO-Al_(2)O_(3)-SiO_(2) glass exhibits excellent mechanical and optical properties.Numerous studies have focused on the mechanism of controllable nucleation and crystal growth,but the physical mechanism of the substitution of MgO by ZnO on glass transition and crystallization behavior of aluminosilicate glass is not clear.In this work,the effect of the substitution of MgO by ZnO on the glass transition and crystallization behaviors of x ZnO·(11-x)MgO·22Al_(2)O_(3)·67SiO_(2)(x%=0%,2.2%,5.5%,8.8%,11.0%,mole fraction)glasses was studied.The results show that the glass transition temperature of studied glasses decreases with the substitution of MgO by ZnO,and it can be ascribed to the decrease of the average bonding strength of the glass network,which is induced by the weaker field strength and shielding effect of an extra electron layer in Zn^(2+) compared to Mg^(2+).The crystallization phases transfer from singe mullite to the mixture of mullite and zinc aluminate gahnite due to the addition of ZnO causing the phase separation of aluminosilicate glass.The substitution of MgO by ZnO causes a steeper viscosity curve around crystallization temperature and decreases the crystallization activation energy of the glasses,resulting in the shift of crystallization peaks to lower temperature.