稀土镁合金表面激光熔覆AlSi12/TiN复合涂层的组织及性能研究

    Study on Microstructure and Properties of Laser Cladding AlSi12/TiN Composite Coating on Rare Earth Magnesium Alloy

    • 摘要: 采用高速激光熔覆技术在Mg-Gd-Y-Zr镁合金表面制备了AlSi12/TiN复合涂层。通过光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、摩擦磨损实验以及电化学分析测试等方法,研究不同含量陶瓷强化相TiN涂层的显微结构、熔覆层结合强度、摩擦磨损性能以及耐腐蚀能力。结果表明,复合涂层主要由α-Mg、Mg2Si枝晶、Al12Mg17、Al3Mg2金属间化合物以及TiN强化相组成。由于存在强化的第二相和细化的晶粒,AlSi12/TiN复合涂层的摩擦系数、维氏硬度及结合强度分别达到0.45、210 HV0.1和40 MPa。此外,与镁合金基体相比,腐蚀电位提高683 mV,自腐蚀电流密度降低了2个数量级。利用激光熔覆技术可在Mg-Gd-Y-Zr镁合金表面制备结合强度高的AlSi12/TiN复合涂层,有合适含量强化相存在的涂层显著提高了基体表面的耐磨损与耐腐蚀性能。

       

      Abstract: AlSi12/TiN composite coating on the surface of Mg-Gd-Y-Zr magnesium alloy was prepared by high-speed laser cladding technology, and the effects of different contents of ceramic strengthening on the microstructure and properties of the composite coating were studied. The microstructure and cladding layer of TiN coatings with different contents of ceramic strengthening phase were studied by optical microscope (OM), X-ray diffractometer (XRD), scanning electron microscope(SEM), friction and wear experiment and electrochemical analysis and testing.The results show that, the composite coating is mainly composed of α-Mg, Mg2Si dendrites, Al12Mg17, Al3Mg2 intermetallic compounds and TiN strengthening phase. Due to the presence of the reinforced second phase and the refined grains, the friction coefficient, Vickers hardness and bonding strength of the AlSi12/TiN composite coating reach 0.45, 210 HV0.1 and 40 MPa respectively.In addition, compared with the magnesium alloysubstrate, thecorrosionpotentialisincreasedby 683 mV, and the self-corrosion current density is reduced by 2 orders. The AlSi12/TiN composite coating with high bond ing strength can be prepared on the surface of Mg-Gd-Y-Zr magnesium alloy by laser cladding technology. The coating with a suitable content of strengthening phase can significantly improve the wear resistance and corrosion resistance of the substrate surface.

       

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