Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 9 No. 4 December 1999|
（Department of Welding and Materials Engineering; East China Shipbuilding Institute; Zhenjiang 212003; P. R. China；
Department of Mechanical Engineering; South China University of Scien）
Abstract:The interfacial reactions in partial transient liquid-phase bonding of Si_3N_4 ceramics with Ti/Ni/Ti interlayers were studied by means of scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffractometry (XRD). It was shown that the interfacial structure of Si_3N_4/TiN/Ti_5Si_3+Ti_5Si_4 + Ni_3Si/ (NiTi ) /Ni_3Ti/ Ni was formed after bonding. The activation energies for TiN layer and the mixed reaction layer of Ti_5Si_3 + Ti_5Si_4 + Ni_3Si are 546. 8 kJ/mol and 543. 9 kJ/mol, respectively. The formation and transition processes of interface layer sequence in the joint were clarified by diffusion path. An important characteristic, which is different from the conventional brazing and soid-state diffusion bonding, has been found, i. e., during the partial transient liquid-phase bonding, not only the reaction layers which have formed grow, but also the diffusion path in the subsequent reaction changes because of the remarkable variation of the concentration on the metal side.
Key words: ceramic joining; transient liquid-phase bonding; interfacial reactions; diffusion