(Cu-15Ti)+SiC反应−复合扩散钎焊Cf/SiC复合材料与不锈钢

Reaction-composite diffusion brazing of Cf/SiC composites and stainless steel with (Cu-15Ti)+SiC filler metal

  • 摘要:
    目的 旨在获得低应力耐高温的Cf/SiC与不锈钢接头。
    方法 采用Cu-15Ti和SiC的混合粉末在960 ℃×30 min工艺下连接Cf/SiC复合材料和镀镍不锈钢。焊后利用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、综合热分析仪(TG-DSC)和万能试验机等设备,研究了接头微观组织,测试了接头耐热性能和力学性能,分析了接头形成演变机制。
    结果 结果表明,Cu-Ti合金中的活性元素Ti与Cf/SiC复合材料反应形成TiC和Ti5Si3组成的反应层。添加的SiC粉末快速消耗连接层基体中元素Ti并原位合成有利于缓解热应力的TiC,Ti5Si3和Ti3SiC2增强相;同时,Ti元素的消耗也提高了接头的耐热性能。镀镍层不仅可以完全阻碍TiFe化合物的生成,还向连接层基体中扩散少量Ni元素,利于连接层耐热性能进一步提高。
    结论 (Cu-15Ti)+SiC钎料钎焊Cf/SiC复合材料与不锈钢接头的室温抗剪强度达到193.7 MPa±20.8 MPa,焊后连接层的起始熔化温度约为1 020 ℃,接头在短时间内实现了“低温连接/高温服役”。

     

    Abstract: Objective The aim is to obtain a Cf/SiC and stainless steel joint with low stress and high temperature resistance. Methods Cf/SiC composites and nickel plating stainless steel were brazed at 960 ℃ for 30 min with mixed powders of Cu-15Ti and SiC. After brazing, microstructure of the joints was studied and heat resistance and mechanical properties of the joints were tested by means of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), comprehensive thermal analyzer (TG-DSC), and universal testing machine. The mechanism of joint formation and evolution was also analyzed. Results The results showed that active element Ti in the Cu-Ti alloy reacted with Cf/SiC composites to form a reaction layer composed of TiC and Ti5Si3. The added SiC powders rapidly consumed the element Ti in the matrix of joining layer and in-situ synthesized reinforcements of TiC, Ti5Si3 and Ti3SiC2, which are beneficial for relieving thermal stress. At the same time, consumption of Ti element also improved heat resistance of the joints. The nickel plating layer can not only completely prevent the generation of TiFe compounds, but also diffuse a small amount of Ni elements into the matrix of the joining layer, which is beneficial to further improve heat resistance of the connection layer. Conclusion The room-temperature shear strength of Cf/SiC composites and stainless steel joint brazed with (Cu-15Ti)+SiC filler metal reached 193.7 MPa ± 20.8 MPa. The initial melting temperature of the joints after brazing was approximately 1 020 ℃, achieving the “low temperature bonding/high temperature servicing” within a short brazing period.

     

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