セラミックス/金属接合体の破面解析と強度評価

概要

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In order to evaluate the strength of Si_3N_4/SUS304 joints with Cu interlayers, bending tests were carried out from room temperature to high temperature in air, vacuum, or argon gas. Fractography and fracture mechanics studies were also carried out. The results obtained are as follows, The typical crack initiation site is the interface between Si_3N_4 and a brazing filler. The crack propagates along the interface, and kinks into Si_3N_4. The bending strength is not influenced by the testing atmosphere (air, vacuum, argon). When testing temperature is under 300℃, bending strength is constant, and when testing temperature over is 300℃, bending strength decreases because of the softening of the brazing filler. When α_<min> is over 30μm, the stress intensity factor considering residual stress, Κ_<pr>, at which the crack kinks into Si_3N_4 is constant and almost agree with the fracture toughness, Κ_<ic>, of monolithic Si_3N_4. On the other hand, when α_<min> is under 30μm, Κ_<pr> is lower than the fracture toughness of monolithic Si_3N_4.
1996-06-25