Effect of collinear flaws on flexural strength and fracture behavior of ZrB₂-SiC ceramic

As a typical kind of multiple flaws, collinear flaws are particularly detrimental to the mechanical properties of ceramics. Here, two identical collinear micron-sized flaws with controllable length and spacing were successfully fabricated in ZrB₂-20 vol% SiC (ZS) ceramic using femtosecond laser, and the effect of flaw length and spacing on flexural strength as well as fracture behavior (i.e., load-displacement curve and fractography) of ZS ceramic were investigated. The flexural strength almost remained constant when the flaw spacing was less than the critical value, which strongly depended on the flaw length, then increased gradually with increasing flaw spacing and reached a plateau. If the ratio between flaw spacing and flaw length was small enough, flaws would tend to coalescence first before fracture, owing to the strong interaction between flaws. If the ratio was too large, the center of the mirror area in fracture surface would be offset.