Tuesday, 12 October 2004 - 10:55 AM

This presentation is part of : Wear and Tribology

Simulations of atomic-scale sliding friction of a-SiC, nc-SiC, c-Si and c-C surfaces

Volodymyr I. Ivashchenko, Institute for problems of material science, NAS of Ukraine, Krzhyzhanovsky str. 3, Kyiv, 03680, Ukraine and Patrice E.A. Turchi, Lowrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94753.

Molecular dynamics simulations are employed to investigate a-SiC/c-C, a-SiC/a-SiC, nc-SiC/c-C, c-Si/c-C sliding systems interacting via the Tersoff empirical potential. An a-SiC sample was generated by means of cooling the melt equilibrated at 8000 K down to 300 K. Nanocrystalline SiC was generated by using the same approach provided that a part of atoms were fixed during simulation to embed a 3C-SiC islet into the amorphous matrix. The friction coefficient is obtained from the analysis of the sliding friction of two slabs that have one outside reservoir, where external normal and tangential forces are applied to each atom. The reservoirs are thermostated. The friction coefficient and the atomic structure of the sliding systems are studied as functions of sliding velocity, temperature and applied load. The friction coefficient is found to be a decreasing function of velocity, temperature and external normal force. No mixing was observed at the sliding interfaces. The friction has an initial transient before reaching an apparent steady state. In the case of the nc-SiC/c-C sliding, the crystallite transforms into an amorphous fragment during the transient period. The friction coefficient of the nc-SiC/c-C sliding pair at low sliding velocities is slightly lower then that of the a-SiC/c-C system. For the a-SiC/c-C and c-Si/c-C slidings pairs, the wear of the a-SiC block is suggested to be lower than the one of the silicon slab because of the high adhesion of the c-Si slab to the diamond surface.

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