Influence of water on the tensile properties of amorphous silica: a reactive molecular dynamics simulation

YA Zhang and JY Tao and X Chen and B Liu, ACTA PHYSICA SINICA, 62, 246801 (2013).

DOI: 10.7498/aps.62.246801

Humidity has an important influence on the strength of the silica (SiO2). We examine the influence of liquid water on the tensile properties of amorphous silica (a-SiO2) using reactive molecular dynamics simulation. The results of the quasi-static tension show that liquid water reduces the tensile strength of a-SiO2 significantly. The tensile strength of dry a-SiO2 is 9.4 GPa while the tensile strength of a-SiO2 in the presence of liquid water is only 4.7 GPa. The strain- stress curve of dry a-SiO2 indicates that the stiffness of the a-SiO2 structure becomes stable with the increase of strain. On the other hand, the stiffness of the a-SiO2 with liquid water is gradually reduced with the increase of tensile strain. Moreover, the strain-stress curve of a-SiO2 in a strain range of 16% to 20% in the presence of liquid water is similar to the yielding phenomenon of plastic metal. The snapshots of the a-SiO2 in the presence of liquid water during the tension show that no plastic deformation is observed. We propose that the stress-enhanced hydrolysis releases part of the stress for the rupture of the Si-O bonds, so that the stiffness of the a-SiO2 in the presence of liquid water decreases with the increase of strain.

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