Al₂O₃ composites reinforced with (0-40)mass% SiC whisker were prepared at a temperature range 1673 K-2123 K for 3.6 ks under 40 MPa by hot-pressing and the effects of pretreatment process of SiC whisker and SiC whisker content on the mechanical properties of the composites were mainly investigated. The toughening mechanism of Al₂O₃ by addition of SiC whisker was also discussed.
The results obtained were summarized as follows: The bending strength of the Al₂O₃-30 mass% SiC whisker composites with SiC whisker pretreated by ultrasonic disperser and filtration was remarkably improved comparing with that of the composites with untreated SiC whisker, then it showing about 1 GPa. The desification temperature to get full density of each composite increased with SiC whisker content. The SiC whisker in the composites was preferentially aligned in normal direction to the hot-pressing axis and the directional dependence of the mechanical properties was observed. The mechanical properties at room temperature and the failure resistance of the composites with pretreated SiC whisker increased with SiC whisker content. The toughening mechanism of Al₂O₃ by the addition of SiC whisker was considered to be due to the increase of fracture energy generating suppression against crack growth and crack deflection.