Joining of alumina by vacuum brazing

The joinability of alumina to titanium and Ni-superalloys has been studied by wetting expts., nondestructive testing (NDT), and shear strength measurements. The spreading of the braze is affected not only by the surface conditions of mating materials but also by the type of brazing alloy. The Ag-Cu-base alloys give better wetting, strength and leak-tightness properties than the Ag-base alloys. A shear test method has been developed for the mech. testing of metal-ceramic joints. However, the sample geometry affects the measured values, namely a smaller specimen size provides better results. The correlation between the C-SAM results, which describe the ratio between the true bonded area and unbonded area, and measured shear strength values is presented. [on SciFinder (R)