不锈钢激光熔敷Ni-Cr-B-Si合金涂层的组织及腐蚀行为
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摘要
采用激光熔敷技术在316L不锈钢表面制备成形良好、无宏观裂纹、组织致密的Ni-Cr-B-Si合金涂层。利用扫描电子显微镜、X射线衍射仪分析涂层的显微组织和物相组成,通过动电位极化曲线和电化学阻抗谱测试研究涂层和基材在3.5%Na Cl溶液中的腐蚀行为。结果表明:涂层从底部到顶部,组织形态变化依次为平面晶、胞状晶、柱状树枝晶和等轴树枝晶,涂层主要由γ-(Ni,Fe)固溶体、Fe Ni3、M23C6(M=Fe,Ni,Cr)以及Cr0.19Fe0.7Ni0.11相组成;在3.5%Na Cl溶液环境中,涂层的自腐蚀电位比基材正移了0.14 V,腐蚀电流密度较基材减小71.84%,腐蚀阻抗值也显著高于基材,耐腐蚀性能优于基材,这是由于涂层表面形成钝化膜的致密度和稳定性更高。
The Ni-Cr-B-Si alloy coating with good formation,no macro-cracks and dense microstructure was prepared on 316 L stainless steel surface by laser cladding technology. The microstructure and phase composition of the coating were analyzed by scanning electron microscopy and X-ray diffractometer. The corrosion behavior of the coating and substrate in 3.5% Na Cl solution was investigated by means of potentiodynamic polarization curve and electrochemical impedance spectroscopy.The results show that the microstructure changes are planar crystal,cellular crystal,columnar dendrites and equiaxed dendrites from the bottom to the top of the coating. The coatings are mainly composed of γ-(Ni,Fe)solid solution,Fe Ni3,M23 C6(M=Fe,Ni,Cr)and Cr0.19 Fe0.7 Ni0.11 phases. In the 3.5% Na Cl solution environment,the corrosion potential of the coating moves positively 0.14 V and the corrosion current density reduces by 71.84% compared to the substrate. The corrosion impedance modulus of the coating is also significantly higher than that of the substrate,the corrosion resistance of the coating is better than that of the substrate,which is due to the higher density and stability of the passivation film formed on the surface of the coating.
The Ni-Cr-B-Si alloy coating with good formation,no macro-cracks and dense microstructure was prepared on 316 L stainless steel surface by laser cladding technology. The microstructure and phase composition of the coating were analyzed by scanning electron microscopy and X-ray diffractometer. The corrosion behavior of the coating and substrate in 3.5% Na Cl solution was investigated by means of potentiodynamic polarization curve and electrochemical impedance spectroscopy.The results show that the microstructure changes are planar crystal,cellular crystal,columnar dendrites and equiaxed dendrites from the bottom to the top of the coating. The coatings are mainly composed of γ-(Ni,Fe)solid solution,Fe Ni3,M23 C6(M=Fe,Ni,Cr)and Cr0.19 Fe0.7 Ni0.11 phases. In the 3.5% Na Cl solution environment,the corrosion potential of the coating moves positively 0.14 V and the corrosion current density reduces by 71.84% compared to the substrate. The corrosion impedance modulus of the coating is also significantly higher than that of the substrate,the corrosion resistance of the coating is better than that of the substrate,which is due to the higher density and stability of the passivation film formed on the surface of the coating.
引文
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[3]PARDO A,MERINO M C,COY A E,et al.Pitting corrosion behaviour of austenitic stainless steels-combining effects of Mn and Mo additions[J].Corrosion Science,2008,50(6):1796-1806.
[4]PAN C,LIU L,LI Y,et al.Pitting corrosion of 304ss nanocrystalline thin film[J].Corrosion Science,2013,73:32-43.
[5]石林,郑志军,高岩.不锈钢的点蚀机理及研究方法[J].材料导报:综述篇,2015,29(12):79.
[6]白子恒,黄运华,李晓刚,等.硫硼酸阳极氧化处理的7050铝合金在工业海洋大气中的腐蚀行为[J].中国腐蚀与防护学报,2016,36(6):580-586.
[7]CONRAD J R,RADTKE J L,DODD R A,et al.Plasma source ion-implantation technique for surface modification of materials[J].Journal of Applied Physics,1987,62(11):4591-4596.
[8]LIU H X,WANG C Q,ZHANG X W,et al.Improving the corrosion resistance and mechanical property of 45 steel surface by laser cladding with Ni60Cu Mo W alloy powder[J].Surface&Coatings Technology,2013,228(S8):296-300.
[9]RIVEIRO A,MEJíAS A,LUSQUI?OS F,et al.Laser cladding of aluminium on AISI 304 stainless steel with high-power diode lasers[J].Surface&Coatings Technology,2014,253(9):214-220.
[10]MA C L,GU D D,HONG C,et al.Formation mechanism and microstructural and mechanical properties of in-situ Ti-Nibased composite coatings by laser metal deposition[J].Surface&Coatings Technology,2016,291:43-53.
[11]赵兵,路远航,李章,等.低碳钢表面激光熔覆Ni60合金的工艺及性能[J].金属热处理,2014,39(7):124-129.
[12]LEI J B,SHI C,ZHOU S F,et al.Enhanced corrosion and wear resistance properties of carbon fiber reinforced Ni-based composite coating by laser cladding[J].Surface&Coatings Technology,2018,334:274-285.
[13]FARAHMAND P,KOVACEVIC R.Corrosion and wear behavior of laser cladded Ni-WC coatings[J].Surface&Coatings Technology,2015,276:121-135.