Assessment in Si3N4 of a new method for determining the fracture toughness from a surface notch micro-machined by ultra-short pulsed laser ablation

The determination of the fracture toughness in a well characterized gas pressure sintered silicon nitride by the single edge V-notch beam method is analyzed in specimens with a surface shallow sharp notch produced by ultra-short pulsed laser ablation. The fracture surfaces and the damage in front of the notch tip are analyzed in detail by using focus ion beam/scanning electron microscopy and micro-Raman spectroscopy. It is concluded that the fracture toughness can be successfully determined by this technique and its importance for nano-grain size ceramics is outlined.