Effect of adhesive composition on bonding of silicon nitride ceramic

Si3N4–Si3N4 ceramics were bonded by using Y2O3–Al2O3–SiO2, Y2O3–La2O3–Al2O3–SiO2, Y2O3–CeO2–Al2O3–SiO2 solders. Joining was carried out at 1823 K for 15 min at atmospheric pressure. The effects of adhesive composition on interfacial wetting and joint strength were investigated. The microstructure and chemistry of joints were characterized by scanning electron microscopy, electron probe microanalyses and X-ray diffraction. The results show that some elements of the solder diffuse into silicon nitride to form a diffusion layer. As compared with the joint strength of silicon nitride bonded with Y2O3–Al2O3–SiO2 solder, the joint strength with Y2O3–La2O3–Al2O3–SiO2 solder increased, while the one with Y2O3–CeO2–Al2O3–SiO2 solder decreased. The results indicate that the effect of adhesive composition on joint strength is related to interfacial wetting and joint thickness.