6061铝合金钛锆铈化学转化成膜过程及膜层的耐蚀性能
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摘要
为进一步改善6061铝合金表面无铬化学转化膜的综合性能,以H_2TiF_6和H_2ZrF_6为主成膜剂,铈盐、偏磷酸盐等辅助成膜剂,制备了具有较高耐蚀性能的Ti-Zr-Ce化学转化膜。通过扫描电镜及能谱仪分析转化膜表面形貌及元素构成,并采用电子探针显微分析仪观察不同成膜阶段的铝合金微区结构的变化规律,研究了6061铝合金表面Ti-Zr-Ce化学转化成膜过程及膜层耐蚀性能。结果表明:膜层主要含有Al、O、Ti、P元素,还含有少量F、Zr元素,推测主要成分为TiO_2、ZrO_2、Al_2O_3及少量磷化物;极化曲线和交流阻抗测试表明Ti-Zr-Ce化学转化膜具有较好的耐蚀性能,反应时间为150 s时制备的Ti-Zr-Ce转化膜试样的腐蚀电位为-0.577 V,腐蚀电流密度较低,为0.115μA/cm~2。
In order to further improve the comprehensive performance of the chromium-free chemical conversion coating of 6061 aluminum alloy,a chemical conversion coating with high corrosion resistance was obtained on the surface of the aluminum alloy with H_2TiF_6 and H_2ZrF_6 as the main coating formers and cerium salt and metaphosphate as auxiliaries. The surface morphology and elemental composition of the conversion coating were observed by SEM and EDS. The variation of micro-area structure of aluminum alloy at different coating formation stages was studied by EPMA. Results showed that the coating was mainly composed of Al,O,Ti,and P elements,and also contained a small amount of F and Zr. It was presumed that the main components were TiO_2,Zr O_2,Al_2O_3 and a small amount of phosphate. The Tafel curves and AC impedance tests showed that the chemical conversion coating had the better corrosion resistance. When the reaction time was 150 s,the corrosion potential of the chemical conversion coating was-0.577 V,and the corrosion current significantly decreased to 0.115 μA/cm~2.
In order to further improve the comprehensive performance of the chromium-free chemical conversion coating of 6061 aluminum alloy,a chemical conversion coating with high corrosion resistance was obtained on the surface of the aluminum alloy with H_2TiF_6 and H_2ZrF_6 as the main coating formers and cerium salt and metaphosphate as auxiliaries. The surface morphology and elemental composition of the conversion coating were observed by SEM and EDS. The variation of micro-area structure of aluminum alloy at different coating formation stages was studied by EPMA. Results showed that the coating was mainly composed of Al,O,Ti,and P elements,and also contained a small amount of F and Zr. It was presumed that the main components were TiO_2,Zr O_2,Al_2O_3 and a small amount of phosphate. The Tafel curves and AC impedance tests showed that the chemical conversion coating had the better corrosion resistance. When the reaction time was 150 s,the corrosion potential of the chemical conversion coating was-0.577 V,and the corrosion current significantly decreased to 0.115 μA/cm~2.
引文
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[2]KULINICH S A,AKHTAR A S.On conversion coating treatments to replace chromating for Al alloys:Recent developments and possible future directions[J].Russian Journal of Non-Ferrous Metals,2012,53(2):176-203.
[3]DARDONA S,CHEN L,KRYZMAN M,et al.Polarization controlled kinetics and composition of trivalent chromium coatings on aluminum.[J].Analytical Chemistry,2011,83(16):6 127-6 131.
[4]刘晓辉,占稳,欧阳贵.铝合金Ti/Zr/Mo复合盐化学转化成膜机理[J].材料保护,2016,49(11):32-35.
[5]陈泽民,宋勇朝,程志民.铝材表面制备钼锰钛系化学转化膜的研究[J].电镀与涂饰,2015,34(8):454-457.
[6]LEE D J,KANG T,SOHN H J,et al.Structural and Electrochemical Properties of Al-Added Molybdate Conversion Coatings on Zinc[J].Materials Transactions,2005,43(1):49-54.
[7]刘淑红,兰喜杰.铝合金表面镍钼二元化学转化膜的制备及其耐腐蚀性[J].大连交通大学学报,2014,35(6):85-88.
[8]姚泽江,武卫社,杜军,等.6063铝合金表面Ce-Mn/Mo复合转化膜的组织及性能[J].材料保护,2014,47(10):23-26.
[9]KOROLEVA E V,THOMPSON G E,HOLLRIGL G,et al.Surface morphological changes of aluminium alloys in alkaline solution:effect of second phase material[J].Corrosion Science,1999,41(8):1 475-1 495.
[10]HINTON B R W,ARNOTT D R,RYAN N E.Cerium Conversion Coatings for the Corrosion Protection of Aluminum[J].Materials Forum,1986,9(3):162-173.
[11]ANDREATTA F,TURCO A,GRAEVE I D,et al.SKPFMand SEM study of the deposition mechanism of Zr/Ti based pre-treatment on AA6016 aluminum alloy[J].Surface and Coatings Technology,2007,201(18):7 668-7 685.
[12]SOLMAZ R,Karda爧G,ulha M,et al.Investigation of adsorption and inhibitive effect of 2-mercaptothiazoline on corrosion of mild steel in hydrochloric acid media[J].Electrochimica Acta,2008,53(20):5 941-5 952.
[13]STEFANOV P,ATANASOVA G,STOYCHEV D,et al.Electrochemical deposition of Ce O2on Zr O2and Al2O3thin films formed on stainless steel[J].Surface and Coatings Technology,2004,180(3):446-449.