实验采用β-SiC为起始原料，Y2O3、A12O3为烧结助剂，通过适当的烧结控制，获得了具有长柱状晶粒结构的α－SiC陶瓷，材料以液相烧结机制密化，在烧结过程中发生了与柱状晶形成有关的SiC晶粒3C→4H相变．材料的力学性能与晶粒的形态即长径比存在一定的依从关系，并显示出原位增强的特性．在较佳工艺条件下，材料的强度和韧性最大值分别达到620MPa、6．1MPa.m1/2．压痕裂纹扩展的途径表明，裂纹偏转和晶粒桥联是主要的增韧机理，这得益于其弱的界面结合．
SiC ceramics with rod-like grains were obtained by pressureless sintering of β-SiC powders with Y2O3 and Al2O3 as additives. The materials were densified based on liquid phase sintering mechanism. Thephase transformation of 3C→4H in SiC occurred during sintering, which was associated with the formationof rod-like grains. The mechanical properties of the materials depended on the aspect ratio of SiC grains,on the optimum, the maximum values of the flexural strength and fracture toughness reached 620MPa and 6.1MPa.m1/2 respectively. The trajectory of indentation crack revealed that the crack deflection and grain-bridging sere the main toughening mechanisms due to the weak grain-boundary.
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