Non-Brittle Behavior of Inorganic Glasses

无机玻璃非脆性行为的存在还没有得到广泛的研究，但从压痕-断裂分析以及断裂能与静态表面能的比较来看，无机玻璃的非脆性行为是常见的。因此，作为公认的评价非脆性程度的方法，本研究对多种方法进行了考察。结果表明：在水分子存在下，硼玻璃的慢裂纹扩展行为与硅酸盐玻璃不同，它在断裂时表现出较大的非弹性变形，即在应力强度因子很低的区域观察到与应力无关的裂纹扩展。用新发展的应力波断口DCDC慢裂纹扩展测量方法测量了二硅酸锂和钠钙硅酸盐玻璃在不同温度下的惰性条件下的慢裂纹扩展行为，即固有的慢裂纹扩展行为。在相同的裂纹扩展速率下，二硅酸锂玻璃的应力强度因子大于钠钙硅酸盐玻璃的应力强度因子。前者的慢裂纹扩展激活能远小于后者。在前一种玻璃中，在150℃以上观察到非阿累尼乌斯温度依赖关系。在稀土掺杂的六角晶中观察到可见光区的断裂诱导发光。这一现象的根源应该是激发稀土离子的六角线在紫外区的断裂发光。

Existence of the non-brittle behavior of inorganic glass has not been studied widely though it will be common from the analysis of indentation-fracture and the comparison between fracture and static surface energies. So, as the commonly accepted method to evaluate the order of non-brittleness, many approaches are examined in this study. Results are as follows :In the existence of water molecules, slow crack growth behavior of borate glasses which shows large inelastic deformation at fracture is found to be different from that of silicate glasses, I.e., stress-independent crack propagation is observed in borate glasses at a region with very low stress intensity factor.Slow crack growth behavior at inert condition, I.e., intrinsic slow crack growth, with various temperatures is measured for lithium disilicate and soda lime silicate glasses using a newly developed DCDC measurement of slow crack growth with stress-wave fractography. The stress intensity factor with the same crack growth rate of the lithium disilicate glass is found to be larger than that of soda lime silicate. The activation energy of slow crack growth for the former glass is much smaller than that of latter one. In the former glass, non-Arrhenius temperature dependence is observer above 150℃.Fracture-induced luminescence in the visible region is observed in rare-earth doped hexacelsian crystals. The origin of this phenomenon should be fractoluminescence of hexacelsian in the UV region that would excite the rare-earth ions.