Fracture toughness of Si3N4 fibers: A combined methodology based on single-edge notch tension and micropillar splitting

Abstract

A novel methodology was proposed to quantify the effect of processing history of ceramic matrix composites on the fracture toughness (KIC) of the reinforced ceramic fibers. This was achieved by combining single edge notch tension (SENT) and micropillar splitting methods to measure independently KIC of the as-received Si3N4 fiber and that in a polycarbosilane derived SiC matrix composite. The SENT method gave a reference KIC ≈ 2.01 MPa m½ for the as-received fiber, which was also quite similar to that measured in the composite by the micropillar splitting method (KIC ≈ 2.08 MPa m½). This proves the robustness of both methods on the toughness measurement of Si3N4 fibers and gives strong evidence that the harsh processing history did not alter the microstructure, thus not degrade the fracture toughness of the novel Si3N4 fiber.