Wear Particles of Single-Crystal Silicon Carbide in Vacuum
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
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An investigation was conducted to examine the nature of fracture of silicon carbide and particle formation in wear. Sliding friction experiments were conducted with the single-crystal silicon carbide 0001 surface sliding in the 1010 direction in contact with various iron-based binary alloys. Experiments were conducted with a load of 0.2 N, at a sliding velocity of 3x10exp-3 meter per minute in a vacuum of 10exp-8 pascal at room temperature. The results of the investigation indicate that multi-angular and spherical wear particles of silicon carbide are observed as a result of multipass sliding. The multiangular wear particles are produced by primary and secondary cracking of cleavage planes 0001, 1010, or 1120 under the Hertzian stress field or local inelastic deformation zone at the interface. The spherical wear particles of silicon carbide may be produced by two mechanisms 1 a penny-shaped fracture along the circular stress trajectories under the local inelastic deformation zone, and 2 attrition of wear particles.