Technical Study On Brazing Of Graphite To Copper

In order to meet the requirement of joining graphite to copper, the interfacial microstructure and the mechanical properties of the graphite brazed to copper were investigated. By SEM, EDS, EPMA, XRD and shearing test, the interfacial microstructure and the mechanical properties of the graphite/Ag-Cu-Ti/Cu joints were studied at room temperature, and the effects of the different processing parameters on the microstructure and the growing process of brazing joint were also discussed. At the same time, by high frequency induction heating, the impact of processing parameters on the microstructure and the properties of the brazed graphite to copper with Sn-Ag-Cu filler metal were also investigated.The results showed that when using Ag-Cu-Ti filler metal to brazing graphite to copper, the join effect of the sample brazed at 870℃for 15 min was good. The interfacial microstructure of the sample brazed at 870℃for 15 min was graphite/TiC/Ag-Cu entectic+Cu solid solution/Cu solid solution/copper. However, shearing strength of this joint was not good, The brazed specimens fractures occurred at the graphite near the interface between graphite and filler metal. Choose the graphite with higher strength was helpful for improving the strength of joint the brazed joint.When joining the graphite to copper using induction brazing with the Sn-Ag-Cu filler metal, plating the metal to graphite was obligatory. Ni was chosen for plating material for its good properities The microstructure of the sample brazed at 275℃for 1 min was graphite/Ni/(Cu1-yNiy)6Sn5/βSn+(βSn+Ag3Sn) entectic/Cu6Sn5/Cu3Sn/copper。The strength of the joint would be slightly change as the brazing parameter changing. The brazed specimens fractures occurred at the graphite near interface between the graphite and Ni.