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).
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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