DUCTILE BRITTLE TRANSITIONS AND WEAR MAPS FOR THE EROSION AND ABRASION OF BRITTLE MATERIALS

Transitions in wear rate and mechanism are a common feature of the erosive and abrasive wear of ceramics and other brittle materials. In such cases, a relatively small change in applied conditions, such as impact velocity or angle in the case of erosion, or of applied load in abrasion, results in a significant change in the mechanism of wear. Such a transition often represents a change in the extent or nature of fracture, leading to a concomitant change in the rate of material removal. Transitions in wear mechanism can also be associated with a change in the shape, hardness or size of the abrasive particles. In this paper, theoretical models for the onset of fracture and plastic flow in a material being eroded or abraded, and also in the abrasive or erosive particles, are used to define regimes over which a single wear mechanism will be dominant. A method is outlined by which these regimes can be illustrated graphically on plots of particle size against impact velocity or applied load, and it is suggested that in this way 'maps' showing wear rates and mechanisms might be developed for the abrasive and erosive wear of brittle materials.