层状ZrB_2基陶瓷的增韧机制分析

Toughness Mechanism of Layered ZrB_2 Based Composite Ceramic

将传统陶瓷中的轧膜工艺应用到超高温陶瓷的制备上,制备ZrB2基层状复合陶瓷。根据层间应力需求设计材料组分。基体层组分为ZrB2+10vol%SiCp+10volSiCw;中间层组分为ZrB2+44.1vol%SiCp+37vol%MoSi2。复合陶瓷在1950℃,25MPa条件下热压烧结制成并进行机械性能测试及微结构观察。结果显示,复合陶瓷有较高的致密度,力学性能较纯ZrB2陶瓷有较大的提升。微观结构观察表明,由于层状结构的存在,裂纹在扩展过程中反复偏转,吸收了大部分能量,有效的提高了复合陶瓷的韧性。复合陶瓷的增韧机制为弱界面层对裂纹的偏折、裂纹分支、基体片层的破坏以及基体片层内部增韧的协同增韧。

Layered ZrB2 based composite ceramic was prepared by traditional technology of rolling and hot pressing sintering. Materials were designed by the equation of interlayered residual stress. Materials content of the based layer were ZrB2+10vol%SiCp+10volSiCw and the interlayer were ZrB2+44.1vol%SiCp+37vol%MoSi2. The composite ceramic was sintered at 1950 oC, 25 MPa by hot pressing with argon atmosphere. The mechanical properties were tested and the microstructure was observed. The results show that the prepared composite ceramic has high density. The toughness is (7.03±0.49) MPa.m1/2, much higher than that of pure ZrB2 ceramic. The observation of microstructure shows that the crack’s deflection and splition occur resulted from the layered structure and the toughness is improved effectively. The toughness mechanism of the composite ceramic is crack deflection, splition, base layer damage and the toughness in the single layer.