Toughening mechanisms of Al2O3-matrix composites with SiC whiskers

Abstract

Whisker reinforced ceramic tool is currently used in the field of high-speed machining of difficult-to-machine materials due to its excellent high temperature mechanical properties. However, the toughening contribution values of crack deflection, whisker bridging and whisker pull-out effect in the whisker toughening model still depend on experimental measurement, which are time-consuming and laborious. In this paper, the scanning electron microscope (SEM) and energy dispersive X-ray spectrometry (EDS) are used to observe the number of main toughening models on the whole crack under different loads (98 N, 196 N and 294 N). The weights of crack deflection, whisker bridging and whisker pull-out effect toughening mechanisms are calculated by analytic hierarchy process (AHP), entropy method and synthetic method. The model parameters are optimized. According to the relation between the areas of whisker cross section and crack cross section, the spacing size between the nearest neighbor whisker centers of crack deflection model is calculated. The variation law of the toughening contribution value of whisker bridging and whisker pull-out effect with the change of angles between crack propagation path and whisker axis (ACW) is calculated by simulation. The ACWs with the highest contribution of whisker toughening mechanism to fracture toughness are obtained. Finally, the toughening contribution values of the three toughening models are determined. It provides a reference for the prediction of fracture toughness of whisker toughened ceramic tools.