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

The R-curve behavior of SiC/ BN multilayered ceramics with different component s in the weak layer wasevaluated using the indentation-st rength-in-bending technique. The influence of the component s of the weak layer onthe R-curve of the SiC/ BN multilayered ceramics was studied. The results show that a rising R-curve behavior isdemonst rated for the laminated SiC/ BN ceramics , and varies with the component s of the weak layer. The SiC/ BNmultilayered ceramic with 30 % Al₂O₃ addition in the weak layer has a steepest rising R-curve. The above result s areatt ributed to their different toughening mechanisms and interfacial coherent states. I n-si tu toughening is the maintoughening mechanism for the monolithic SiC ceramics , while crack deflection , crack branching and crack delaminating at the SiC/ BN weak interfaces for SiC/ BN multilayered ceramics. The component s in the weak layer have animportant effect on the crack deflection. The interface with a right coherent st ress cont ributes to the crack deflection , and the interface with too weak or very st rong coherent stress does harm to the crack deflection.