Diffusion bonding of ceramics

Diffusion bonding of ceramics to ceramics (SiC, Si sub 3 N sub 4 , and Al sub 2 O sub 3 ) and to metals (Nb, Al, Fe, Pt, and steel) is reviewed, with primary emphasis on the effects of operational variables on joint strength. These include principal bonding parameters such as temperature, time, and pressure. In addition, the influence of atmosphere, mismatch in coefficient of thermal expansion between the joint members, interlayers, and surface structure are discussed. The mechanisms involved, i.e. plastic deformation, various forms of diffusion, and power law creep, imply that temperature is the most important process parameter. Finally, a survey of variables employed in bonding of different ceramic--metal and ceramic--ceramic joints is included as a guideline for selection of materials and parameters.