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The bouncing threshold in silica nanograin collisions

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Abstract

Using molecular dynamics simulations, we study collisions between amorphous silica nanoparticles. Our silica model contains uncontaminated surfaces, that is, the effect of surface hydroxylation or of adsorbed water layers is excluded. For central collisions, we characterize the boundary between sticking and bouncing collisions as a function of impact velocity and particle size and quantify the coefficient of restitution. We show that the traditional Johnson–Kendall–Roberts (JKR) model provides a valid description of the ingoing trajectory of two grains up to the moment of maximum compression. The distance of closest approach is slightly underestimated by the JKR model, due to the appearance of plasticity in the grains, which shows up in the form of localized shear transformation zones. The JKR model strongly underestimates the contact radius and the collision duration during the outgoing trajectory, evidencing that the breaking of covalent bonds during grain separation is not well described by this model. The adhesive neck formed between the two grains finally collapses while creating narrow filaments joining the grains, which eventually tear.

Graphical abstract: The bouncing threshold in silica nanograin collisions

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Publication details

The article was received on 01 Apr 2017, accepted on 30 May 2017 and first published on 30 May 2017


Article type: Paper
DOI: 10.1039/C7CP02106B
Citation: Phys. Chem. Chem. Phys., 2017, Advance Article
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    The bouncing threshold in silica nanograin collisions

    M. L. Nietiadi, P. Umstätter, T. Tjong, Y. Rosandi, E. N. Millán, E. M. Bringa and H. M. Urbassek, Phys. Chem. Chem. Phys., 2017, Advance Article , DOI: 10.1039/C7CP02106B

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