FATIGUE-STRENGTH AND FRACTURE MECHANISM OF CERAMIC-METAL JOINTS UNDER CYCLIC BENDING

Abstract

The cyclic fatigue strength and fracture mechanism of the ceramic-metal joint Si3N4-SS304 were investigated under cyclic bending loading. The results show that the fatigue strength at 10(7) cycles was about half the static bending strength. Different types of failure were observed for the low-cycle fatigue and high-cycle fatigue regions. Fracture surfaces were examined with SEM and EPMA. Three distinctive failure zones, including a fatigue striation zone, were clearly identified. The fatigue crack initiates and grows at the copper interlayer and finally kinks to the ceramic side. It is concluded that the copper interlayer dominates the fatigue strength of the joint.