Abstract
Factors affecting the bonding strength of Si3N4-metals joints were discussed through examining the causes for improvement in tensile strength of Si3N4-molybdenum joints by controlling the reaction layer thickness using Cu-5%Cr, Cu-1%Nb and Cu-3%V insert metals. Microstructures of reaction layers being thinner than the optimum thickness were almost homogeneous and the interfaces between Si3N, and the reaction layers were still smooth. Defects such as porous zone and crack occurred in the reaction layers thickening than the optimum thickness, while the asperity of the interface became larger.
The insufficient reactivity of insert metals against Si3N4 substrate provided the planar fracture at the interface between Si3N4 and the reaction layer and followed to diminish the bonding strength. The fracture in the reaction layer was due to the defects in the reaction layer and as a result, the bonding strength was deteriorated again.
