| Effects of ZrO₂ stabilizers such as 3㏖% Y₂O₃, 8㏖% Y₂O₃, and 9㏖% MgO on the joining phenomena of Ni-Cr steel/Al/ZrO₂ joints have been examined by the concept of solid state diffusion bonding. Irrespective of stahilizers used, the Al/ZrO₂ joint whose reaction layer could not be detected showed a good contact while the reaction layer of the Ni-Cr steel/Al was the diffusion layer of Al and Fe. The joint shear strength of this system did not show any distinct differences even though ZrO₂ stabilizers are varying. The maximun shear strength was 27 ㎫ under a pressure of 100 ㎫, temperature of 635℃, and the time of 120min. The residual stress resulting from the thermal expansion mismatch between ZrO₂ and A1 was different depending on the A1 layer depth sites. It was shown that compressive residual stress could be found at the Al/ZrO₂ interface while tensile residual stress at the NI-Cr steel/Al interface. |
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