316L不锈钢等离子熔覆Ni基合金涂层的组织与性能
Microstructure and corrosion resistance of Ni-based alloy coating by plasma cladding on 316L stainless steel
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摘要: 利用等离子熔覆工艺在316L不锈钢基体上熔覆Ni基合金粉末制备耐磨耐蚀涂层,借助于金相显微镜、扫描电镜、X射线衍射仪分析了涂层的组织,利用显微硬度计测试了涂层的显微硬度,采用线性极化法研究了涂层在3.5%NaCl溶液中的耐蚀性能.结果表明,Ni基合金涂层组织主要为固溶大量Cr和Si元素的枝晶γ-(Ni,Fe)及Cr23C6相.涂层的显微硬度可达400~440 HV0.2,明显高于基体硬度(170~200 HV0.2),起到了显著的硬化效果。在3.5%NaCl溶液介质中,涂层的腐蚀电位负移约178 mV,基体的击破电位0.1 V高于熔覆层的击破电位-0.1V,说明该腐蚀体系下镍基合金涂层的耐腐蚀性能低于316L不锈钢基体.Abstract: A wear-resistant and corrosion-resistant coating was prepared by plasma cladding on 316L stainless steel with Ni-based alloy powder.The microstructure of the coating was investigated by optical microscope(OM),scanning electron microscopy(SEM) with energy dispersive spectroscopy(EDS),X-Ray diffractometer(XRD).The microhardness of the coating was tested by microhardness tester.The corrosion resistance of the coating in 3.5% NaCl solution was evaluated by linear polarization.The results showed that the microstructure of the coating consisted of dendritic γ-(Ni,Fe) solid solution and Cr23C6.The microhardness of the coating varied from 400 HV0.2 to 440 HV0.2,greater than that of the substrate(170~200 HV0.2).The corrosion potential of the coating in 3.5% NaCl solution moved reversely 178 mV,the breakdown potential(0.1 V) of the substrate was higher than that of coating(-0.1 V),which demonstrated the corrosion resistance of the substrate was better than coating.
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