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潮湿对SiO2的强度有重要影响.采用反应场分子动力学模拟方法,研究液态水对无定形SiO2(a-SiO2)准静态拉伸特性的影响.准静态拉伸模拟的结果表明,在干燥条件下,a-SiO2的拉伸强度为9.4 GPa,而在含液态水时则下降为4.7 GPa,表明液态水使得a-SiO2拉伸强度发生显著下降.根据应力-应变曲线分析可知,干燥条件下a-SiO2结构的刚度随着拉伸应变的增加保持稳定,而含液态水的a-SiO2刚度随着拉伸应变的增加而逐步降低,并且应变为16%—20%时的应力-应变曲线类似于金属的屈服现象.通过对拉伸过程的原子图像分析可知,含液态水a-SiO2的拉伸过程并没有发生塑性变形,而是因为应力增大加速了水解反应,使得应力-应变曲线表现出上述塑性现象.
Moisture has an important influence on the strength of SiO2. The effect of liquid water on the quasi-static tensile properties of amorphous SiO2 (a-SiO2) was investigated by the molecular dynamics simulation of reaction field. The results of quasi-static tensile simulation showed that under the dry conditions , The tensile strength of a-SiO2 is 9.4 GPa, but drops to 4.7 GPa when containing liquid water, which indicates that the liquid water makes the tensile strength of a-SiO2 decrease significantly.According to the stress-strain curve analysis, The stiffness of a-SiO2 structure remains stable with increasing tensile strain, while the stiffness of a-SiO2 with liquid water gradually decreases with increasing tensile strain, and the stress-strain curve at strain of 16% -20% Similar to the yield phenomenon of metal, the atomic image analysis of the stretching process shows that the plastic deformation of a-SiO2 containing liquid water does not occur during the stretching process, but the stress is accelerated to accelerate the hydrolysis reaction so that the stress-strain curve Show the above plastic phenomenon.