セラミックス/金属接合材のフラクトグラフィと破壊強度の評価

抄録

Four point bending tests for Si₃N₄/steel joints were conducted and their fracture surfaces were examined by advanced fractographic method. Based on these results, the fracture mechanism was discussed by the fracture mechanics approach.
The crack initiates at the ceramics/adhesive interface. A part of crack front is arrested at the microcrack in the ceramics side of the interface. Another part of the crack front grows along the interface. Then, the stress intensity factor, K, at the arrested crack front increases as the profile of the whole crack front becomes like a Chevron notch. The unstable fracture occurs when K at the arrested crack front reaches K_IC for ceramics.