Interfacial microstructure of Si_3N_4/Si_3N_4 brazing joint with Cu-Zn-Ti filler alloy

摘要

In this study, Si_3N_4 ceramic was jointed by a brazing technique with a Cu-Zn-Ti filler alloy. The interfacial microstructure between Si_3N_4 ceramic and filler alloy in the Si_3N_4/Si_3N_4 joint was observed and analyzed by using electron-probe microanalysis, X-ray diffraction and transmission electron microscopy. The results indicate that there are two reaction layers at the ceramic/filler interface in the joint, which was obtained by brazing at a temperature and holding time of 1223 K and 15 min, respectively. The layer nearby the Si_3N_4 ceramic is a TiN layer with an average grain size of 100 nm, and the layer nearby the filler alloy is a Ti_5Si_3N_x layer with an average grain size of 1-2 μm. Thickness of the TiN and Ti_5Si_3N_x layers is about 1 |xm and 10 u-m, respectively. The formation mechanism of the reaction layers was discussed. A model showing the microstructure from Si_3N_4 ceramic to filler alloy in the Si_3N_4/Si_3N_4 joint was provided as: Si_3N_4 ceramic/TiN reaction layer/Ti_5Si_3N_x reaction layer/Cu-Zn solution.