SiC/BN层状陶瓷的阻力曲线行为

R-curve behavior of SiC/BN laminated ceramic

利用压痕强度法测定了SiC/BN层状陶瓷的阻力曲线行为,并与SiC单相陶瓷做对比。结果表明:2种材料均呈现出上升阻力曲线行为,其中,SiC/BN层状陶瓷显示出更为优越的抗裂纹扩展能力,其阻力曲线上升较陡,上升幅度较大;SiC单相陶瓷的阻力曲线上升较缓且上升幅度较小。分析认为,这与其不同的增韧机制有关。原位增韧是SiC单相材料韧性提高的主要原因,而裂纹遇到弱界面时发生偏转、分叉、脱层等是层状陶瓷材料抗裂纹扩展能力提高的主要原因。

The Rcurve of SiC/BN laminated ceramic was evaluated by the indentationstrength method and compared with that of monolithic SiC. The results show that the two materials possess up Rcurve behaviors: a steep Rcurve behavior for SiC/BN laminated ceramic, showing higher crack propagation resistance; a plateau Rcurve behavior for monolithic SiC, which is closely related to their different toughening mechanisms. Insitu toughening accounts for the fracture toughness increase of monolithic SiC, while, crack deflection, crack branching and crack delamination contribute to the higher fracture resistance of SiC/BN laminated ceramic.