ABSTRACT
Recent results on the wear behavior of aluminum oxide are reviewed, and the effects of contact load and temperature on the wear mechanisms are described. It is shown that the results of wear tests can be consolidated into a single diagram, which can be used to delineate the effects of load and temperature, and to identify the boundaries between the regions dominated by different mechanisms. The tribological characteristics of alumina can be divided into four distinct regions, based on the fundamental mechanisms involved in the wear process. These regions are tribochemical reaction, plastic flow and plowing, microfracture, and formation of a glassy surface film. The transition from mild to severe wear observed at the intermediate temperature range is analyzed using a fracture mechanics model. The model indicates that this transition is controlled by propagation of microcracks from preexisting near-surface flaws in the material. The utility of the "wear transition diagram" is discussed, and it is shown that this type of diagram is useful for design and material selection for tribological applications.
