Na_(2)WO_(4)含量对镁合金微弧氧化膜层颜色和耐蚀性的影响  

Effect of Na_(2)WO_(4) Content on Color and Corrosion Resistance of Micro-arc Oxidation Coating on Magnesium Alloy

作　　者：祝海涛 孙金峰 孟永强[1,3] 王立伟 彭珍珍 汪殿龙 ZHU Hai-tao;SUN Jin-feng;MENG Yong-qiang;WANG Li-wei;PENG Zhen-zhen;WANG Dian-long(School of Materials Science and Engineering,Hebei University of Science and Technology,Shijiazhuang 050018,China;Key Laboratory of Material Near-net Forming Technology in Hebei Province,Shijiazhuang 050018,China;Hebei Key Laboratory of Flexible Functional Materials,Shijiazhuang 050000,China)

机构地区：[1]河北科技大学材料科学与工程学院,石家庄050018 [2]河北省材料近净成形技术重点实验室,石家庄050018 [3]河北省柔性功能材料重点实验室,石家庄050000

出　　处：《表面技术》2023年第10期241-249,共9页Surface Technology

基　　金：国家自然科学基金(52101015);河北省高等学校科学技术研究项目(BJK2022020);河北省自然科学基金(E2022208070/E2021208005)。

摘　　要：目的 研究电解液中的Na_(2)WO_(4)含量对AZ31B镁合金微弧氧化膜层的形成过程、颜色、微观结构、耐蚀性能的影响。方法 通过添加不同含量的NH_(4)VO_(3)和Na_(2)WO_(4)的碱性铝酸盐电解液体系,在AZ31B镁合金表面制备黑色的微弧氧化膜层。采用SEM、EDS分析加入不同含量的Na_(2)WO_(4)后膜层表面的微观形貌及元素组成,采用XRD分析物相组成,通过电化学实验表征膜层的耐腐蚀性能。结果 随着Na_(2)WO_(4)含量的增加,微弧氧化过程中的起弧电压下降,膜层的致密性提高,厚度呈先增加后减小的趋势。当Na_(2)WO_(4)的质量浓度为0.5 g/L时,膜层的厚度最大,且此时膜层表面微孔分布均匀,色度最低,耐蚀性最好,自腐蚀电位为-0.138 V,自腐蚀电流密度为2.36×10^(-7)A/cm^(2),相较于基体降低了3个数量级。结论 增加Na_(2)WO_(4)含量会使微弧氧化成膜过程中的电弧发生变化,适当增加Na_(2)WO_(4)会提高膜层的厚度,降低膜层的CIE色度,使陶瓷膜层表面的微孔分布得更加均匀致密,从而提高膜层的耐蚀性能。当Na_(2)WO_(4)含量过高时,会使膜层的离子浓度升高,电阻增大,介电击穿电压上升,导致膜层表面被烧蚀,耐腐蚀性能降低。In this work,the method preparing micro-arc oxide coating on AZ31B magnesium alloy surface was studied,the formation process of AZ31B magnesium alloy micro-arc oxide ceramic layer was explored by the content of Na_(2)WO_(4) in electrolyte,and the microstructure and corrosion resistance of AZ31B magnesium alloy were characterized.By using NaAlO_(2) as the basic electrolyte and adding a small amount of NH_4VO_(3) and Na_(2)WO_(4) on the surface of AZ31B magnesium alloy,a black micro-arc oxidation ceramic layer was prepared.Scanning electron microscope(SEM) and EDS were adopted to analyze the surface morphology and composition of the coatings with different contents of Na_(2)WO_(4) and XRD was applied to analyze the phase structure.Electrochemical workstation was used to test the self-corrosion potential and self-corrosion current density of the micro-arc oxidation ceramic layer,and the CIE chromaticity of the coating layer was measured by 3nh chromaticity meter.After experimental verification,NH_4VO_(3) with interaction to Na_(2)WO_(4) contributed to the successful preparation of the black micro-arc oxidation ceramic layer.Through observation,it was found that with the increase of Na_(2)WO_(4) content,the arc started to drop.The arc starting voltage was reduced from 320 V to 210 V.In the process of preparation,the micro-arc oxidation coating density was significantly increased and coating thickness increased firstly and then decreased.With the increase of Na_(2)WO_(4) content,CIE chromaticity decreased firstly and then increased,and the corrosion resistance of the sample increased.When the content of Na_(2)WO_(4) was 0.5 g/L,the micropores on the surface of the coating were evenly distributed,uniform in size and low in porosity,and the thickness of the coating was the largest at this time.The thickness was 23.8 μm.The CIE chromatic value was the smallest,which was 27.99,and the corrosion resistance was the best.The electrochemical test in 3.5% NaCl solution showed that the self-corrosion potential was-0.138 V and

关 键 词：镁合金 黑色膜层 微弧氧化 Na_(2)WO_(4) 耐腐蚀性 微观结构 

分 类 号：TG174.4[金属学及工艺—金属表面处理]