Controllable fracture in shocked ceramics: Shielding one region from severely fractured state with the sacrifice of another region

Abstract

Pre-existing defects in ceramics induce shock-wave compression fractures and may lead to the failure of designed functions. Instead of sintering fully dense ceramics, which is difficult to implement and ineffective under shock, we propose a novel strategy for fracture modulation by deliberately adding more pores into the ceramics. This approach may seem counterintuitive, but it has been shown numerically and experimentally that a “shielded region”, which is free of severe shock fracture, can be formed with the sacrifice of a “damaged region” in the porous ceramics. The damage evolution and the shock response of porous ceramics were simulated with a lattice–spring model. The mechanism is interpreted from the relationship between the collapse of mesoscopic voids and the evolution of the macroscopic shock wave. Shock and soft-recovery experiments were conducted and the results confirmed the existence of the shielded region. It was found that, under shock conditions, where a dense sample was damaged, all the voids in a porous sample close to the impact surface had collapsed; however, in the other half of the sample, numerous intact voids still remained. This new concept provides guidance for the avoidance or delay of shock failure in functional ceramics.