A study of the reliability of brazed Al/sub O3/ joint systems

Brazing experiments were performed at 830/spl deg/C for Al/sub 2/O/sub 3//Al/sub 2/O/sub 3/ and Al/sub 2/O/sub 3//Fe-Ni-Co alloy joints, which are used in electronic and structural applications. The brazing was done with Ag-Cu and Ag-Cu-Ti and changes in fracture mode and fracture strength of the Al/sub 2/O/sub 3/-Al/sub 2/O/sub 3/ joint were investigated after heat treatment at 400 and 600/spl deg/C for 100 h. For as-brazed samples, the fracture occurred within Al/sub 2/O/sub 3/, but a long heat exposure at a medium temperature caused the fracture path to move to the joint region. For the ceramic-metal joining, Al/sub 2/O/sub 3//Fe-Ni-Co alloy joints were prepared with a variety of interlayers. Among the interlayer materials, a Mo-Ni double-interlayer provided the highest fracture strength. The fracture strength of the joints was measured and interpreted in terms of microstructure changes.