Strength of Silicon Nitride-Silicon Nitride Joints Bonded with Oxynitride Glass

The use of oxynitride glasses in the Y-Si-Al-O-N system to join sintered silicon nitride was investigated. Flexural strength of joined silicon nitride was dependent upon joining temperature, joint morphology, and joining glass composition. Non- brittle behavior was observed at test temperatures of 1100°C or higher with joint morphologies characterized by thick glass layers (40–50 μm). In contrast, brittle behavior was observed to test temperatures of 1300°C with joint morphologies characterized by thin glass layers (<5 μm). Joint strengths comparable to the strength of as-received silicon nitride were observed to test temperatures as high as 1100°C. Oxidation of the fracture surfaces was observed at lest temperatures of 1300°C and higher.