Brazing Si₃N₄ ceramic with Ag-Cu-Ti+Mo composite filler

A commercial Ag-Cu-Ti alloy with Mo particles reinforcement was introduced for joining Si₃N₄ ceramic.The effect of Mo content on the microstructure and flexural strength of the resultant joints was investigated by SEM,TEM and nanoindentation. The results indicate that a compact reaction layer consisting of TiN and Ti₅Si₃ formed at the Si₃N₄/filler interface.The central part of the joint was composed of Ag-based solid solution, Cu-based solid solution and Mo particles together with Ti-Cu intermetallics. The modulus and hardness of Ti-Cu intermetallics and the brazing alloy in the joint were measured by nanoindentation. With increasing the Mo particles content in the joint,the thickness of reaction layer decreased while the amount of Ti-Cu intermetallics in the brazed layer increased.In addition,Ag-and Cu-based solid solutions in the brazed layer became finer.The maximal bending strength reached 429.4 MPa while incorporating 15vol.% Mo particles,and the joint strength was 114.7% higher than that without adding Mo particles.