Fractographic study of crack growth near ceramic/metal interface
Arai Yoshio; Tsuchida Eiichiro; Miyagaki Junji; Yoshino Motoki; Meisner Mark J
Abstract:Four point bending tests on Si3N 4/SUS304 joints after thermal cycling were conducted and their fracture surfaces were examined by a fractographic method. Based on these results, the fracture path and the criterion for unstable fracture are discussed by a interface fracture mechanics approach. A crack initiates in the ceramic side very close to the ceramic/brazing filler interface; the unstable fracture occurs when K1 of the subinterface crack reaches KIC for the ceramic material. Consequently, strength degradation during thermal cycling is caused by micro cracking. Key Words:fractography, ceramics/metal joint, interface mechanics, residual stress, deflection angle