Influence of the component of weaklayer in the SiC/BN multilayered ceramics on its resistance behavior

The R-curve behavior of SiC/BN multilayered ceramics with different components in the weak layer was(evaluated) using the indentation-strength-in-bending technique.The influence of the components of the weak layer on the R-curve of the SiC/BN multilayered ceramics was studied.The results show that a rising R-curve behavior is demonstrated for the laminated SiC/BN ceramics,and varies with the components of the weak layer.The SiC/BN multilayered ceramic with 30% Al_(2)O_(3) addition in the weak layer has a steepest rising R-curve.The above results are attributed to their different toughening mechanisms and interfacial coherent states.In-situ toughening is the main toughening mechanism for the monolithic SiC ceramics,while crack deflection,crack branching and crack delami-(nating) at the SiC/BN weak interfaces for SiC/BN multilayered ceramics.The components in the weak layer have an important effect on the crack deflection.The interface with a right coherent stress contributes to the crack def-(lection),and the interface with too weak or very strong coherent stress does harm to the crack deflection.