Wear Behaviour of Ceramic Materials: A General Approach

In a previous study, the wear resistance of a large range of ceramic materials has been assessed on the basis of friction, abrasion, erosion (20 and 90 deg ) as well as scratch tests. Except for the last damaging mode, the wear behaviour has been compared with that of non-ceramic materials (metal, polymer, rubber, etc.) in order to determine the wear modes following which ceramic materials give rise to some improvement. This comparative study initially performed by dry testing has been extended to aqueous media (neutral and acid). In presence of such media, it has been shown that most of the previously established wear-mechanical properties relationships can no longer be used to predict the wear behaviour. Indeed, whereas some wear modes, such as abrasion, are only slightly affected by the medium, other, like erosion, are strongly dependent on the nature of the liquid. In presence of acid solutions, a synergetic effect between corrosive and mechanical processes, undoubtedly takes place, so that the wear level does not only depend on conventional mechanical parameters (K sub IC , E, H sub v ) but rather involves damaging phenomena strongly dependent on the amount and composition of the intergranular glassy phase. Therefore, when the matter removal increases, this effect must presumably be related to preferential crack growth along the grain boundaries whose strength is lowered as a consequence of the chemical etching. (Example materials: alumina, silicon nitride, zirconia.)