Influence of whisker reinforcement on the abrasive wear behavior of silicon nitride- and alumina-based composites

The abrasive wear of brittle materials, while not a true property of materials, is generally modeled as an inverse function of both the bulk hardness and fracture toughness. According to these models, an increase in the hardness and/or fracture toughness of a material will therefore enhance its wear resistance. In ceramic materials, the addition of whisker reinforcement is a proven method of enhancing long-crack fracture toughness via such mechanisms as crack bridging and whisker debonding. However, less is known about how whisker reinforcement influences the properties that are dependent upon the short-crack toughness, such as abrasive wear. The results of this study indicate that while the addition of randomly oriented SiC whiskers can dramatically improve the abrasive wear resistance of an alumina-based ceramic, the addition of SiC reinforcement to silicon nitride ceramics does not always result in improved wear resistance. This variation in the influence of whisker reinforcement on wear behavior is attributed to the residual stress state created in the composites as a result of the addition of the second phase whiskers.