Study On The Microstructure And Property Of High Temperature Brazing Joint Of Si₃N₄Ceramic Using Cu-Ti System Active Filler Metal

In this paper,, two Ti-activated brazes had been investigated for joining of silicon nitride ceramic to itself. The properties of the joints brzaed by different filler metal was investigated using EDS and ESEM.Self-joining of Si3N4using Cu80Ti20active filler metal was demonstrated.under different process parameters. Joints without open defect and crack were obtained after5-15min joining at1413K-1493K. Through the joint organization and composition analysis,the microstructure of the joint can be described as:Si3N4ceramic/interface reaction layer/Cu[Ti] solid solution+Ti5Si3/interface reaction layer/Si3N4ceramic.And the interface reaction layer was manly consist of TiN.The effects of brazing temperature and holding time on the width of the brazing seam and interface layer were investigated separately.The joining of silicon nitride ceramic to40Cr was carried out using Cu80Ti20active filler metal by holding10min at1453K.There were interface layer in the joint. The microstructure of the joint can be described as:Si3N4ceramic/interface reaction layer/Cu [Ti] solid solution+Ti5Si3/interface reaction layer/Si3N4ceramic And the interface reaction layer next to ceramic was manly consist of TiN, while the one next to the metal was mainly consist of TiFe.A composition design of CuCoTi active filler metal was carried out in this paper. Self-joining of Si3N4using the designed active filler metal was demonstrated.under the same process parameter. Through the analysis of the interface reaction layer in the joint and tissue interface reaction layer and the test of mechanical properties, the joint brazed by Cu50(Co26Ti74)50active filler metal was superior to the Cu40(Co26Ti7460active filler metal. By employing the EDS, the microstructure of the joint can be described as:S13N4ceramic/interface reaction layer/brazing seam/interface reaction layer/Si3N4ceramic. And the interface reaction layer was manly consist of TiN, while there were Co-Si compound, Cu-Si compound and Ti5Si3next to the interface. The components in the brazing seam were Cu[Ti] solid solution, Co[Ti] solid solution and Ti5Si3. The effects of brazing temperature and holding time on the width of the brazing seam and interface layer were investigated separately by changing process parameter.