A FRACTURE-MECHANICS APPROACH TO CERAMIC WEAR

Wear of ceramics occurs in two major modes, i.e., tribochemical wear and microscopic fracture wear. The present paper discusses the possibility of a fracture-mechanics approach to the latter, which is responsible for detrimental surface damage. A longitudinal contact-point model is employed, and stress intensity at wear cracks is evaluated by three-dimensional finite element analysis. It is revealed that, when a contact point passes over an L-shaped crack which is composed of a vertical and an interconnected horizontal rectangular component or a horizontal rectangular subsurface crack, amplitudes of the Mode II stress-intensity factor having a considerable magnitude are predicted. A brief review of literature on fatigue of ceramics suggests that wear cracks could grow under reasonable loading conditions, and that growth should occur more readily when the absence of the toughening mechanisms with small cracks is taken into account.