CAJ | 학술논문

在硅酸钠电解液中添加不同浓度的钨酸钠，对6061铝合金进行微弧氧化处理，采用 SEM、EDX、XRD 分析了膜层的组成和结构，利用电化学工作站和全浸泡试验测试了膜层的耐蚀性。结果表明，在硅酸钠电解液中添加适量的钨酸钠，可减少膜层的微孔和裂纹的形成，提高膜层的致密性。钨酸钠促进了膜层中α-Al2 O 3相的形成、抑制莫来石的形成，并以 W 单质的形式留在了膜层中，当钨酸钠的浓度为2．0 g/L 时膜层中α-Al2 O 3相的含量达66％。电化学试验结果表明，钨酸钠能提高膜层的耐蚀性，当钨酸钠浓度4．0 g/L时，交流阻抗相对未添加 Na2 WO 4的硅酸盐电解液中形成膜层的阻抗提高了1个数量级，在浓缩的80℃流动海水中浸泡20 h 后，该膜层表面较完整，没有出现大面积脱落和基体腐蚀现象，表现出良好的耐蚀性能；但浓度过高对膜层耐蚀性能的提高并无益处。
재규산납전해액중첨가불동농도적오산납，대6061려합금진행미호양화처리，채용 SEM、EDX、XRD 분석료막층적조성화결구，이용전화학공작참화전침포시험측시료막층적내식성。결과표명，재규산납전해액중첨가괄량적오산납，가감소막층적미공화렬문적형성，제고막층적치밀성。오산납촉진료막층중α-Al2 O 3상적형성、억제막래석적형성，병이 W 단질적형식류재료막층중，당오산납적농도위2．0 g/L 시막층중α-Al2 O 3상적함량체66％。전화학시험결과표명，오산납능제고막층적내식성，당오산납농도4．0 g/L시，교류조항상대미첨가 Na2 WO 4적규산염전해액중형성막층적조항제고료1개수량급，재농축적80℃류동해수중침포20 h 후，해막층표면교완정，몰유출현대면적탈락화기체부식현상，표현출량호적내식성능；단농도과고대막층내식성능적제고병무익처。
This research concerns ceramic coatings on 6061 aluminum alloy formed by micro-arc oxidization (MAO)using sodium silicate electrolyte and varying amounts of added Na2 WO 4 .The composition and structure of coatings are analyzed using scanning electron microscopy (SEM),energy-dispersive X-ray spectroscopy (EDX),and X-ray diffraction (XRD).Corrosion resistance of coatings is tested using electrochemical worksta-tion and high temperature seawater immersion experiments.The results show that adding the appropriate amount of Na2 WO 4 to the sodium silicate electrolyte can reduce the formation of tiny holes and cracks on the coatings and improve the coatings’compactness because the right amount of sodium tungstate in the electrolyte can inhibit the deposition of mullite on the surface of the coating and contribute to the formation of theα-Al2 O 3 phase during the plasma discharge process and in the form of W in the coating.When the concentration of the sodium tungstate is 2.0 g/L,theα-Al2 O 3 phase accounts for 66% of the coating.The results of the electrochem-ical tests verify that the sodium tungstate improves the corrosion resistance of the coatings.When the concen-tration of the sodium tungstate is 4.0 g/L,the impedance of the coating decreases by nearly one order of magni-tude compared with that of the coating without Na2 WO 4 .Moreover,after being immersed in concentrated sea-water at 80 ℃ for 20 h,the coating shows an unbroken surface and favorable corrosion resistance without large areas of exfoliation and corrosion of the substrate.However,too high a concentration of Na2 WO 4 is unfavorable as far as improvement in corrosion resistance is concerned.