AZ91D镁合金微弧氧化陶瓷膜制备及其电偶腐蚀性能
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摘要
本文采用微弧氧化单脉冲直流电源,在AZ91D镁合金上制备了含氧化锆相的陶瓷膜层,研究了电解液浓度和电参数对陶瓷膜及其耐蚀性的影响规律,分析了陶瓷膜的生长特点,测试了陶瓷膜与碳纤维等异种材料偶接的电偶腐蚀性能。
利用X射线衍射分析(XRD)、X射线散射能谱(EDS)分析及扫描电子显微镜(SEM)分析技术研究了陶瓷膜的组成及形貌;涡流测厚仪测定陶瓷膜的厚度,电化学分析技术研究了陶瓷膜的耐腐蚀性能。
XRD和EDS结果表明:通过微弧氧化技术在AZ91D镁合金表面制备的陶瓷膜层中引进了锆、镁元素,锆相对含量较高,且大多以晶相存在于陶瓷膜层中;而镁的含量相对较低。SEM研究表明:在单脉冲条件下,随着电解液浓度的提高,膜层变粗糙;电流密度越大,膜层越粗糙,表面裂纹越多;低电源频率下的膜层比较平整,裂纹少,较致密。陶瓷膜的结构是典型的双层结构,由内层致密阻挡层和外层多孔疏松层组成。膜层生长前期双层结构不明显,生长后期膜层向基体内部发展,以及电解液反应沉积的加快,使阻挡层和疏松层的厚度都增大,膜层的双层结构明显。
陶瓷膜的结构对膜层的耐蚀性有很大的影响。Na5P3O10浓度的增加,陶瓷膜厚度先减小后增加,膜层耐蚀性呈相反规律,当Na5P3O10浓度为3g·L-1时膜层的耐全面腐蚀性能最好;而随K2ZrF6浓度的提高,膜层厚度随之增加,膜层变致密,耐蚀性提高。电流密度增加使陶瓷膜厚度增加,但是膜层表面裂纹变大,耐蚀性下降;低电源频率下,膜层较薄,但表面裂纹少,有利于陶瓷膜耐蚀性的提高。电源频率为100Hz时的膜层耐蚀性最好。
经微弧氧化处理后,陶瓷膜的电偶腐蚀电流密度减小,电偶腐蚀性能比镁合金基体的提高。在两种偶接材料中,虽然与M40碳纤维偶接的热力学腐蚀倾向大,但电偶腐蚀电流密度较小,在13μA·cm-2左右。与LY12铝合金偶接的电偶腐蚀电流密度很大,达到80μA·cm-2,陶瓷膜破坏严重,LY12铝合金也有一定程度的腐蚀,陶瓷膜不能与LY12铝合金接触使用。
Ceramic coatings including ZrO2 were prepared on surface of AZ91D magnesium alloy by micro-arc oxidation (MAO) with single-polar anode pulse MPO power source. The thickness, composition, structure and galvanic corrosion property of the coatings were investigated.
The composition and microstructures of the ceramic coatings were characterized by X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM). The thickness and corrosion resistance of the coatings were evaluated by eddy current thickness meter, and electrochemical instrument respectively.
The results of EDS and XRD analyses revealed that the zirconium and magnesium were brought into the ceramic coatings prepared on the surface of AZ91D magnesium alloy by micro-arc oxidation (MAO) with different electric parameters and electrolyte. Zirconium is crystalline in the coating. The results of SEM showed that the coating became cruder as the concentration of electrolyte increasing. The coating prepared by low current density and low frequency is of flatness, crackles, and compactness. The ceramic coating was representatively double-layer structure. It included compact barrier layer and pores layer. The double-layer structure was unconspicuous in early period. In the later period of MAO, the growth of the coating developed towards to Mg substrate direction. The thickness of barrier layer and pores layer increased rapidly. The ceramic coating appeared double-layer structure obviously.
The corrosion resistance of ceramic coating was greatly affected by the structure of coating. The study showed that the thickness of the ceramic coatings first decreased and later increased with the Na5P3O10 concentration increasing, but the corrosion resistance of coatings changed contrary. As the K2ZrF6 concentration increasing, the coating was thicker and much more compact, the corrosion resistance of coating enhanced. With the current density increasing, the crackle of the coating was larger, and the corrosion resistance of coatings became worse. The low frequency could help enhancing the corrosion resistance of coatings.
Comparing with the mg alloy substrate, the galvanic corrosion current of ceramic coating was lower, the property of galvanic corrosion enhanced. Between two coupled materials, the corrosion tendency of coating coupled with M40 carbon fiber was larger, but the corrosion current was lower, so the ceramic coating could couple with M40 carbon fiber in practical application. Coupling with LY12Al alloy, the galvanic corrosion current was greatly high, and the destruction of coating was serious. Ceramic coating was impossible to couple with LY12Al alloy in practical application.
利用X射线衍射分析(XRD)、X射线散射能谱(EDS)分析及扫描电子显微镜(SEM)分析技术研究了陶瓷膜的组成及形貌;涡流测厚仪测定陶瓷膜的厚度,电化学分析技术研究了陶瓷膜的耐腐蚀性能。
XRD和EDS结果表明:通过微弧氧化技术在AZ91D镁合金表面制备的陶瓷膜层中引进了锆、镁元素,锆相对含量较高,且大多以晶相存在于陶瓷膜层中;而镁的含量相对较低。SEM研究表明:在单脉冲条件下,随着电解液浓度的提高,膜层变粗糙;电流密度越大,膜层越粗糙,表面裂纹越多;低电源频率下的膜层比较平整,裂纹少,较致密。陶瓷膜的结构是典型的双层结构,由内层致密阻挡层和外层多孔疏松层组成。膜层生长前期双层结构不明显,生长后期膜层向基体内部发展,以及电解液反应沉积的加快,使阻挡层和疏松层的厚度都增大,膜层的双层结构明显。
陶瓷膜的结构对膜层的耐蚀性有很大的影响。Na5P3O10浓度的增加,陶瓷膜厚度先减小后增加,膜层耐蚀性呈相反规律,当Na5P3O10浓度为3g·L-1时膜层的耐全面腐蚀性能最好;而随K2ZrF6浓度的提高,膜层厚度随之增加,膜层变致密,耐蚀性提高。电流密度增加使陶瓷膜厚度增加,但是膜层表面裂纹变大,耐蚀性下降;低电源频率下,膜层较薄,但表面裂纹少,有利于陶瓷膜耐蚀性的提高。电源频率为100Hz时的膜层耐蚀性最好。
经微弧氧化处理后,陶瓷膜的电偶腐蚀电流密度减小,电偶腐蚀性能比镁合金基体的提高。在两种偶接材料中,虽然与M40碳纤维偶接的热力学腐蚀倾向大,但电偶腐蚀电流密度较小,在13μA·cm-2左右。与LY12铝合金偶接的电偶腐蚀电流密度很大,达到80μA·cm-2,陶瓷膜破坏严重,LY12铝合金也有一定程度的腐蚀,陶瓷膜不能与LY12铝合金接触使用。
Ceramic coatings including ZrO2 were prepared on surface of AZ91D magnesium alloy by micro-arc oxidation (MAO) with single-polar anode pulse MPO power source. The thickness, composition, structure and galvanic corrosion property of the coatings were investigated.
The composition and microstructures of the ceramic coatings were characterized by X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM). The thickness and corrosion resistance of the coatings were evaluated by eddy current thickness meter, and electrochemical instrument respectively.
The results of EDS and XRD analyses revealed that the zirconium and magnesium were brought into the ceramic coatings prepared on the surface of AZ91D magnesium alloy by micro-arc oxidation (MAO) with different electric parameters and electrolyte. Zirconium is crystalline in the coating. The results of SEM showed that the coating became cruder as the concentration of electrolyte increasing. The coating prepared by low current density and low frequency is of flatness, crackles, and compactness. The ceramic coating was representatively double-layer structure. It included compact barrier layer and pores layer. The double-layer structure was unconspicuous in early period. In the later period of MAO, the growth of the coating developed towards to Mg substrate direction. The thickness of barrier layer and pores layer increased rapidly. The ceramic coating appeared double-layer structure obviously.
The corrosion resistance of ceramic coating was greatly affected by the structure of coating. The study showed that the thickness of the ceramic coatings first decreased and later increased with the Na5P3O10 concentration increasing, but the corrosion resistance of coatings changed contrary. As the K2ZrF6 concentration increasing, the coating was thicker and much more compact, the corrosion resistance of coating enhanced. With the current density increasing, the crackle of the coating was larger, and the corrosion resistance of coatings became worse. The low frequency could help enhancing the corrosion resistance of coatings.
Comparing with the mg alloy substrate, the galvanic corrosion current of ceramic coating was lower, the property of galvanic corrosion enhanced. Between two coupled materials, the corrosion tendency of coating coupled with M40 carbon fiber was larger, but the corrosion current was lower, so the ceramic coating could couple with M40 carbon fiber in practical application. Coupling with LY12Al alloy, the galvanic corrosion current was greatly high, and the destruction of coating was serious. Ceramic coating was impossible to couple with LY12Al alloy in practical application.
引文
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9. Rong-chang ZENG, Jin ZHANG, W.DIETZEL et al. Transactions of Nonferrous Metals Society of China. 2006, 16(2): 763-771
10.宋雨来,刘耀辉,朱先勇等.压铸镁合金腐蚀行为研究进展.铸造. 2007, 56(1): 36-40
11. Makar G L, Kruger J. Corrosion of magnesium. International Materials Reviews. 1993, 38(3): 13-15
12.战广深. Mg-Al-Zn-Mn合金在NaCl溶液中的接触腐蚀行为.上海有色金属. 1996, (17): 8-11
13. Guang Ling Song, JOHANNESSON Birgir. Galvanic corrosion of magnesium alloy AZ91D in contact with an aluminium alloy, steel and zinc. Corrosion Science. 2004(46): 955-977
14.赵艳娜,朱元良,齐台公.稀土元素(La、Ce)对镁合金电偶腐蚀的影响.材料保护. 2005, 38(15): 14-16
15.王莹,张津,麻彦龙等.镁合金表面处理新进展.表面技术. 2006, 35(6): 61-66
16.杨晓飞,林文光,毛广雷.镁合金表面处理的现状及趋势.汽车工艺与材料. 2007(3): 10-16
17.曲明,刘忆. AZ91D镁合金表面电弧喷涂铝锌涂层组织的研究.表面技术. 2006, 35(6): 18-21
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19.罗小萍,夏兰廷,臧东勉.镁合金表面化学转化处理研究现状.铸造设备研究. 2007, 2: 44-47
20.刘元刚等.镁合金微弧氧化膜结构及耐蚀性的初步研究.材料保护. 2004, 37(1): 17-20
21. Günthers chulze A, Betz H. Neue Untersuchungenüber Die Eletroltische Ventilwirkung. Z Phys. 1932, 78: 196-210
22. Güntherschulze A, Betz H. Elektronenstromung in Isolatoren bei Extremen Feldstarken. Z Phys. 1934, 91: 70-96
23. H.F.Guo, M.Z.An, H.B.Huo et al. Microstructure characteristic of ceramic coatings fabricated on magnesium alloys by micro-arc oxidation in alkaline silicate solutions. Applied Surface Science. 2006, 252: 7911-7916
24.候亚丽,刘忠德.微弧氧化技术的研究现状.电镀与精饰. 2005, 5: 24-28
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33.吴振东,姜兆华,姚忠平等.纯铝及其合金的等离子体氧化成膜特征.中国有色金属学报. 2005, 15(6): 946-951
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2. Mehta D S, Masood S H, SongWQ. Investigation of wear properties of magnesium and aluminum alloys for automotive applications. Journ Mater Proc Technol. 2004, 155: 1526-1531
3.左铁镛.中国镁及镁合金发展战略.科学中国人: 28-29
4.王智文,张治民,张星.镁合金的应用现状及其塑性成形技术.华北工学院学报. 2005, 26(1): 70-74
5.王文先,张金山,许并社.镁合金材料的应用及其加工成型技术.太原理工大学学报. 2001, 32(6): 600
6.唐全波,黄少东,伍太宾.镁合金在武器装备中的应用分析.兵器材料科学与工程. 2007, 32(2): 69-71
7.王虹.镁合金自行车车架应用进展.广西轻工业. 2007, (2): 39
8.楚雄.首钢远东镁合金制品有限公司强劲推出镁合金电动自行车.中国自行车. 2005 (7): 46-47
9. Rong-chang ZENG, Jin ZHANG, W.DIETZEL et al. Transactions of Nonferrous Metals Society of China. 2006, 16(2): 763-771
10.宋雨来,刘耀辉,朱先勇等.压铸镁合金腐蚀行为研究进展.铸造. 2007, 56(1): 36-40
11. Makar G L, Kruger J. Corrosion of magnesium. International Materials Reviews. 1993, 38(3): 13-15
12.战广深. Mg-Al-Zn-Mn合金在NaCl溶液中的接触腐蚀行为.上海有色金属. 1996, (17): 8-11
13. Guang Ling Song, JOHANNESSON Birgir. Galvanic corrosion of magnesium alloy AZ91D in contact with an aluminium alloy, steel and zinc. Corrosion Science. 2004(46): 955-977
14.赵艳娜,朱元良,齐台公.稀土元素(La、Ce)对镁合金电偶腐蚀的影响.材料保护. 2005, 38(15): 14-16
15.王莹,张津,麻彦龙等.镁合金表面处理新进展.表面技术. 2006, 35(6): 61-66
16.杨晓飞,林文光,毛广雷.镁合金表面处理的现状及趋势.汽车工艺与材料. 2007(3): 10-16
17.曲明,刘忆. AZ91D镁合金表面电弧喷涂铝锌涂层组织的研究.表面技术. 2006, 35(6): 18-21
18. Hikmet Altun, Sadri Sen. The effect of DC magnetron sputtering AN coatings on the corrosion behavior of magnesium alloys. Surface and Coatings Technology. 2005, 197: 193-200
19.罗小萍,夏兰廷,臧东勉.镁合金表面化学转化处理研究现状.铸造设备研究. 2007, 2: 44-47
20.刘元刚等.镁合金微弧氧化膜结构及耐蚀性的初步研究.材料保护. 2004, 37(1): 17-20
21. Günthers chulze A, Betz H. Neue Untersuchungenüber Die Eletroltische Ventilwirkung. Z Phys. 1932, 78: 196-210
22. Güntherschulze A, Betz H. Elektronenstromung in Isolatoren bei Extremen Feldstarken. Z Phys. 1934, 91: 70-96
23. H.F.Guo, M.Z.An, H.B.Huo et al. Microstructure characteristic of ceramic coatings fabricated on magnesium alloys by micro-arc oxidation in alkaline silicate solutions. Applied Surface Science. 2006, 252: 7911-7916
24.候亚丽,刘忠德.微弧氧化技术的研究现状.电镀与精饰. 2005, 5: 24-28
25. JIANG Bailing, WU Guojian, ZHANG Shufen. The growth process and microstructure study of microarc oxdation ceramic coating on magnesium alloy. Transaction of Material and Heat Treatment. 2002, 23(1): 5-7
26.王卫锋,蒋百灵,时惠英.镁合金微弧氧化深色陶瓷膜制备及耐蚀性研究.腐蚀科学与防护技术. 2007, 21(1): 51-56
27. Hongping Duan, Keqin Du, Chuanwei Yan, et al. Electrochemical corrosion behavior of composite coatings of sealed MAO film on magnesium alloy AZ91D. ELECTROCHIMICA ACTA. 2006, 51(14): 2898-2908
28. X. P. ZHANG, G. CHEN. Corrosion protection of AZ91D Mg alloy coating with micro-arc oxidation film evaluated by immersion and electrochemical tests. Surface Review and Letters. 2005, 12(2): 279-287
29. H.F. Guo, M.Z. An. Growth of ceramic coatings on AZ91D magnesium alloys by micro-arc oxidation in aluminate–fluoride solutions and evaluation of corrosion resistance. Applied Surface Science. 2005, 246: 229-238
30.蒋百灵,袁芳,袁森等.镁、铝合金间的连接腐蚀行为及不同表面处理的保护效果研究.中国表面工程. 2005, 18(5): 39-42
31.王玲,张巍,李久青.镁合金微弧氧化及涂装耐电偶腐蚀的研究.材料保护. 2005, 38(4): 12-14
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33.吴振东,姜兆华,姚忠平等.纯铝及其合金的等离子体氧化成膜特征.中国有色金属学报. 2005, 15(6): 946-951
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