NH4F浓度对镁合金表面微弧氧化制备氟化物膜层结构和性能的影响  

Effect of NH4F Concentration on Microstructure and Properties of Fluoride Coatings on Magnesium Alloy by Plasma Electrolytic Oxidation

作　　者：罗兰 彭振军[3] 周健松[1,2] 梁军 LUO Lan;PENG Zhen-jun;ZHOU Jian-song;LIANG Jun(Key Laboratory of Science and Technology on Wear and Protection of Materials,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Lanzhou 730000,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Lanzhou 730000,China;School of Materials Science and Engineering,Dongguan University of Technology,Guangdong Dongguan 523808,China)

机构地区：[1]中国科学院兰州化学物理研究所,中国科学院材料磨损与防护重点实验室,兰州730000 [2]中国科学院大学材料与光电研究中心,北京100049 [3]中国科学院兰州化学物理研究所,固体润滑国家重点实验室,兰州730000 [4]东莞理工学院材料科学与工程学院,广东东莞523808

出　　处：《表面技术》2023年第6期70-79,共10页Surface Technology

基　　金：国家自然科学基金(52071325)。

摘　　要：目的考察乙二醇-氟化铵电解液中氟化铵浓度对镁合金表面微弧氧化制备氟化物膜层结构和性能的影响,提高镁合金氟化物膜层的耐腐蚀性能。方法在含不同浓度NH_(4)F的EG-NH_(4)F电解液中,采用微弧氧化的方法制备氟化物膜层,NH_(4)F质量浓度分别为40、60、80、100、120 g/L。通过扫描电子显微镜(SEM)、X射线能量色散谱仪(EDS)和X射线衍射仪(XRD),对膜层表面微观形貌和成分组成进行分析,并通过电化学测试表征了膜层的腐蚀防护性能,通过盐雾试验评估了膜层长效防腐蚀行为,通过SEM和EDS表征了腐蚀形貌和腐蚀产物。结果在EG-NH_(4)F中制备膜层的物相组成主要是MgF_(2)。随着NH_(4)F浓度的提高,微弧氧化的起弧电压与工作电压均逐渐减小,膜层中氟含量逐渐增加,膜层的孔径减小,孔数量分布更加均匀,膜层表面粗糙度降低。质量浓度为100 g/L NH_(4)F的膜层自腐蚀电流密度(J_(corr))为2.226×10^(-7)A/cm^(2),较镁合金基材降低了1个数量级,极化电阻Rp增大到90.156kΩ·cm^(2),其阻抗模量|Z|_(f=0.01 Hz)=8.55×10^(5)Ω·cm^(2),与镁合金基材的阻抗模量|Z|_(f=0.01 Hz)=8.86×10^(2)Ω·cm^(2)相比,提高了3个数量级。结论微弧氧化处理能够显著改善AZ31镁合金的腐蚀防护性能。NH_(4)F浓度的增加有利于提高膜层的耐腐蚀性能,质量浓度为100 g/L NH_(4)F的膜层耐腐蚀性能最优。This work aims to study the effect of NH_(4)F concentration on phase composition,microstructure and corrosion resistance of fluoride coatings on AZ31 magnesium alloy in EG-NH_(4)F electrolytic solution by plasma electrolytic oxidation(PEO).The EG-NH_(4)F electrolytic solutions with NH_(4)F concentration of 40 g/L,60 g/L,80 g/L,100 g/L and 120 g/L were used to prepare PEO coatings on AZ31 magnesium alloy.A scanning electron microscope(SEM),an X-ray energy dispersion spectrometer(EDS)and an X-ray diffractometer(XRD)were used to analyze the surface morphology and composition of the coatings.The electrochemical corrosion behavior was evaluated by potentiodynamic polarization tests in neutral corrosive media,while the long-term corrosion behavior by salt spray tests.The corrosion morphologies and corrosion products after salt spray tests were characterized by the SEM and the EDS.The coating was mainly composed of MgF_(2).The working voltage and breakdown voltage of PEO process decreased gradually with the increase of the NH_(4)F concentration.The pore size and surface roughness of the coating decreased.The MgF_(2) coating can significantly improve the corrosion resistance of AZ31 magnesium alloy,and the coating prepared at 100 g/L NH_(4)F has optimal corrosion protection performance.

关 键 词：镁合金 非水电解液 腐蚀防护 

分 类 号：TG172[金属学及工艺—金属表面处理]