Improvement in Bonding Strength of Si_3N_4-Mo Joint by Controlling Reaction Layer Thickness

概要

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Effect of the reaction layer on bonding strength of Si_3N_4-Mo joints bonded using Cu-base active insert metals was investigated in order to improve the bonding strength by controlling the reaction layer thickness. Bondings of Si_3N_4-Mo joints were conducted in vacuum at 1573K for 0-4.8ks to alter the reaction layer thickness. Bonding strength was evaluated by tensile tests. Bonding strength of joints could be improved up to about 100MPa, 90MPa and 120MPa by controlling the reaction layer thickness to about 40μm, 2μm and 4μm for Cu-5%Cr, Cu-1%Nb and Cu-3%V insert metals, respectively. In the joints with optimum thickness of reaction layer, the fractured surfaces were composed of the surfaces fractured in the reaction layer and at the interface between Si_3N_4 and reaction layer. Microstructures in reaction layers with less than optimum thickness were almost homogeneous, and the shape of interface between Si_3N_4 and reaction layer was almost flat. Defects such as porous zone and crack occurred in reaction layers with more than optimum thickness, and unevenness of the interface became larger. The insufficient reactivity of insert metals against Si_3N_4 resulted in the inferior bonding strength, and it was due to fracture near the interface between Si_3N_4 and the reaction layer. The defects in the reaction layer also caused the bonding strength to decrease.
1990-10-01