Reliable evaluation of fracture toughness in ceramics via nanosecond laser notching method

As a new type of notching approach, laser notching method always neglecting the significant impact of equivalent notch angle (θ) on fracture toughness results, although it has successfully solved the problem of introducing sharp enough V-notches in ceramics. Here, porous ZrB₂ and dense ZrB₂-SiC ceramics are taken as the experimental targets, and the effect of θ on the fracture toughness values of these typical ceramics is investigated. To measure the fracture toughness accurately, the θ should be less than 60° namely, the laser notch depth should be larger than the traditional U-groove root radius. Nanosecond laser notching method shows great advantages in high notch depth (easy to reach 300 μm) and sufficient accuracy (tip radius less than 1 μm), and is deemed to have a good prospect of standardization.