Mascaraque Nerea, Bauchy Mathieu, Fierro José Luis G, Rzoska Sylwester J, Bockowski Michal, Smedskjaer Morten M
Department of Chemistry and Bioscience, Aalborg University , 9220 Aalborg, Denmark.
Department of Civil and Environmental Engineering, University of California , Los Angeles, California 90095, United States.
J Phys Chem B. 2017 Sep 28;121(38):9063-9072. doi: 10.1021/acs.jpcb.7b04535. Epub 2017 Sep 14.
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). 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) acting within the molecular network.
氧化物玻璃的化学耐久性是广泛应用中的一项重要性能，在某些情况下可通过成分优化进行调整。然而，这些可能性相对有限，因为大多数氧化物玻璃中约五分之三的原子是氧原子。另一种方法是对玻璃进行后处理。在这项工作中，我们关注热压缩对溶解动力学的影响，因为已知热压缩能提高例如弹性模量和硬度，而其对化学耐久性的影响却知之甚少。具体而言，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转变温度（T）下于0.5、1.0和2.0吉帕压力下压缩后的块状玻璃溶解速率。我们对浸泡在酸性（pH 2）和中性（pH 7）溶液中的块状样品进行了失重和补充改性剂浸出测量。从失重测量结果来看，压缩通常会提高化学耐久性，但这种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由永久致密化引起的拓扑变化，而这又反过来取决于非桥氧数量的变化和网络交联情况。我们还证明了化学耐久性与分子网络中每个原子的化学拓扑约束数量（n）之间存在直接关系。
