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石墨与铜真空钎焊接头的组织与强度

Microstructure and strength of graphite and copper brazed joints in vacuum

  • 摘要: 采用Ag-Cu-Ti钎料对石墨与铜进行了真空钎焊连接,利用扫描电镜、X射线衍射和室温压剪试验等分析手段对接头的微观组织和室温抗剪强度进行了研究.结果表明,利用Ag-Cu-Ti钎料可以实现石墨与铜的连接;接头的界面结构为石墨/TiC/Ag-Cu共晶组织+铜基固溶体/铜基固溶体/铜;随着钎焊温度的提高或保温时间的延长,TiC层的厚度逐渐增大,但并不是随着保温时间延长和钎焊温度的升高无限制增厚;在钎焊温度为870℃,保温时间为15 min的真空钎焊条件下,接头的抗剪强度达到17 MPa的最大值.剪切性能试验时断裂均发生在石墨母材的近界面处.

     

    Abstract: The vacuum brazing of graphite to copper was carried out by Ag-Cu-Ti brazing filler metal,and the microstructures and strength of the joints were also investigated by means of SEM,XRD and shearing test.The experimental results show that the bonding of graphite to copper can be performed by Ag-Cu-Ti filler metal in vacuum.The interfacial microstructure of the joint is graphite/TiC/Ag-Cu eutectic+Cu solid solution/Cu solid solution/copper.With increasing of the brazing temperature and holding time,TiC layer became thicker,but thickness of layer could not continuously increase.The maximum shear strength of the joint,which was brazed at 870℃ for 15 min in vacuum,was up to 17 MPa.The brazed specimens fractures occurred at the graphite near the interface between graphite and filler metal.

     

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