Crystallization and Chemical Strengthening of Stuffed β‐Quartz Glass‐Ceramics

Metastable solid solutions with the β-quartz structure can be crystallized from most glasses in the system SiO2-Mg(AlO2)2-LiAlO2 as well as from many containing the additional components Zn(AlO2)2 Al(AlO2)3, Li2ZnO2, and Li2BeO2. Internal nucleation is afforded by additions of ZrO2 or TiO2. Either transparent or opaque crystalline materials can be formed from glasses containing about 70% SiO2. The transparency is due to a combination of low birefringence in the major stuffed β-quartz phase and minute crystal size. Thermal expansions vary from -20 to +50 × 10−7/°C. Thermal stability is highly variable. Breakdown products include spinel, cordierite, β-spodumene, willemite, mullite, and cristobalite. Magnesian compositions can be strengthened by a 2Li+⇌ Mg2+ ionexchange reaction. Abraded flexural strengths range from 30,000 to 160,000 psi.

具有β - 石英结构的亚稳固溶体可以从SiO₂ - Mg(AlO₂)₂ - LiAlO₂体系中的大多数玻璃中结晶出来，也可以从许多含有额外成分Zn(AlO₂)₂、Al(AlO₂)₃、Li₂ZnO₂和Li₂BeO₂的玻璃中结晶出来。通过添加ZrO₂或TiO₂可实现内部成核。从含有约70% SiO₂的玻璃中可以形成透明或不透明的晶体材料。透明度是由于主要的填隙β - 石英相的低双折射和微小的晶体尺寸共同作用的结果。热膨胀系数在 - 20到 + 50×10⁻⁷/°C之间变化。热稳定性差异很大。分解产物包括尖晶石、堇青石、β - 锂辉石、硅锌矿、莫来石和方石英。镁质成分可通过2Li⁺⇌Mg²⁺离子交换反应得到强化。磨损后的抗弯强度在30000到160000磅/平方英寸之间。