The chemical durability of oxide glasses is an important property for a wide range of applications and can in some cases be tuned through composition optimization. However, these possibilities are relatively limited because around 3/5 of the atoms in most oxide glasses are oxygens. An alternative approach involves post-treatment of the glass. In this work, we focus on the effect of hot compression on dissolution kinetics because it is known to improve, for example, elastic moduli and hardness, whereas its effect on chemical durability is poorly understood. Specifically, we study the bulk glass dissolution rate of phosphate, silicophosphate, borophosphate, borosilicate, and aluminoborosilicate glasses, which have been compressed at 0.5, 1.0, and 2.0 GPa at the glass transition temperature (T_g). We perform weight loss and supplementary modifier leaching measurements of bulk samples immersed in acid (pH 2) and neutral (pH 7) solutions. Compression generally improves the chemical durability as measured from weight loss, but the effect is highly composition- and pressure-dependent. As such, we show that the dissolution mechanisms depend on the topological changes induced by permanent densification, which in turn are a function of the changes in the number of nonbridging oxygens and the network cross-linking. We also demonstrate a direct relationship between the chemical durability and the number of chemical topological constraints per atom (n_c) acting within the molecular network.

中文翻译：

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热压氧化物玻璃的溶解动力学

氧化物玻璃的化学耐久性是广泛应用的重要属性，在某些情况下可以通过成分优化来调整。但是，这些可能性相对有限，因为大多数氧化物玻璃中约3/5的原子是氧。另一种方法是对玻璃进行后处理。在这项工作中，我们专注于热压缩对溶解动力学的影响，因为已知它可以改善（例如）弹性模量和硬度，而对化学耐久性的影响知之甚少。具体来说，我们研究了磷酸盐，硅磷酸盐，硼磷酸盐，硼硅酸盐和铝硼硅酸盐玻璃在玻璃化转变温度（T _g）。我们对浸入酸（pH 2）和中性（pH 7）溶液中的大块样品进行重量减轻和补充改性剂浸出测量。从重量减少的角度来看，压缩通常可提高化学耐久性，但其效果高度依赖于成分和压力。因此，我们表明溶解机制取决于永久致密化引起的拓扑变化，而拓扑变化又是非桥连氧原子数量变化和网络交联的函数。我们还证明了化学耐久性与分子网络内作用的每个原子（n _c）的化学拓扑约束数之间存在直接关系。