Interfacial characteristics of high frequency induction brazed Cu and pre-metalized graphite joints

摘要

Oxygen-free copper and pre-metalized graphite were brazed using CuNiSnP braze alloy by high frequency induction heating method. Interfacial microstructures and reaction phases were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The strength and resistance of the joints were tested. It is found that when the brazing parameters are optimized,the structures of the joints are graphite/(Cu,Ni)/Ni(s.s)+NixPy/Cu3P+Cu(s.s) (including Sn)+eutectic structures (Cu3P+Ni3P+Cu(s.s)/Cu (s.s)/Cu). When the temperature increases to 750 ℃ or the holding time prolongs to 300 s,the eutectic structures disappear and the amount of Cu3P increases. The maximum shear strength of the joints is 5.2 MPa,which fracture at the interface of graphite and metallization. The resistance of the joints is no more than 5 m-.