微弧氧化小阴极放电及膜层均匀性
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摘要
针对微弧氧化工艺中小功率电源大面积处理或局部腔体处理问题,研究小阴极微弧氧化工艺方法。采用550V恒压模式,阳极为Φ70mm×0.5mm的纯铝样件,阴极为Φ15mm不锈钢棒,浸没到硅酸钠基的电解液内的长度可变,探讨放电伏安特性和膜层厚度、表面形貌以及电化学行为的均匀性。结果表明:小阴极可以实现微弧氧化,但小阴极增加了阴极-阳极间放电的等效阻抗,会造成微弧放电较弱、成膜速率较低,微弧氧化样品的径向膜层厚度和耐蚀性呈现不均匀性,靠近样品边缘膜层较厚,中心区域膜层较薄;增加阴极尺寸,膜厚均匀性从74%(阴极深入20mm)提高到78%(阴极深入40mm),同时膜层的耐腐蚀区域加大。结果对于小功率电源大面积微弧氧化和腔体内部微弧氧化具有重要的指导意义。
Micro-arc oxidation(MAO)with a small-size cathode was investigated for surface treatment of large area workpiece using electrical unit with lower rating power or local treatment of cavity-shaped objects.The MAO processes were performed in a constant-voltage mode with a voltage of 550 V.The aluminum samples with size ofΦ70 mm×0.5mm act as anode and a stainless steel rod with a diameter ofΦ15mm works as cathode with variable length immersed in the electrolyte.The arcing behavior and uniformity of coating thickness,surface morphology and electro-chemical behavior were investigated.The results show that MAO processes may be conducted using small-size cathodes.However,the small-size cathode may lead to a weak arcing behavior and lower formation rate of MAO coatings,and it may contribute to larger equivalent resistance between electrodes.The thickness and corrosion-resistance along the radical direction on the samples are not uniform.The coatings are thick near the sample edge while they are thin at the central zone.With the increase of the cathode size,the uniformity of coating thickness increases from 74% for 20 mm cathode to 78% for40 mm cathode,and the corrosion-resistance area grows larger.The results are significant for surface treatment of large area parts using lower electrical power,as well as local treatment of cavity-shaped objects.
Micro-arc oxidation(MAO)with a small-size cathode was investigated for surface treatment of large area workpiece using electrical unit with lower rating power or local treatment of cavity-shaped objects.The MAO processes were performed in a constant-voltage mode with a voltage of 550 V.The aluminum samples with size ofΦ70 mm×0.5mm act as anode and a stainless steel rod with a diameter ofΦ15mm works as cathode with variable length immersed in the electrolyte.The arcing behavior and uniformity of coating thickness,surface morphology and electro-chemical behavior were investigated.The results show that MAO processes may be conducted using small-size cathodes.However,the small-size cathode may lead to a weak arcing behavior and lower formation rate of MAO coatings,and it may contribute to larger equivalent resistance between electrodes.The thickness and corrosion-resistance along the radical direction on the samples are not uniform.The coatings are thick near the sample edge while they are thin at the central zone.With the increase of the cathode size,the uniformity of coating thickness increases from 74% for 20 mm cathode to 78% for40 mm cathode,and the corrosion-resistance area grows larger.The results are significant for surface treatment of large area parts using lower electrical power,as well as local treatment of cavity-shaped objects.
引文
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[2]杜楠,王帅星,赵晴,等.TC4钛合金微弧氧化Cr2O3复合膜的结构及摩擦磨损性能[J].稀有金属材料与工程,2013,42(3):621-624.Du N,Wang S X,Zhao Q,et al.Microstructure and tribological properties of microarc oxidation composite coating containing Cr2O3particles on TC4titanium alloy[J].Rare Metal Materials and Engineering,2013,42(3):621-624(in Chinese).
[3]Yoichi Mori,Akihiko KOshi,Jinsun Liao,et al.Characteristics and corrosion resistance of plasma electrolytic oxidation coatings on AZ31B Mg alloy formed in phosphateSilicate mixture electrolytes[J].Corrosion Science,2014,88:254-262.
[4]Feng C J,Hu S L,Jiang Y F,et al.Effects of micro-arc oxidation of Ti6A14Valloy on adhesion property to electroless Ni-P-ZrO2composite platings and their wear resistance[J].Rare Metal Materials and Engineering,2013,42(12):2427-32.
[5]薛文斌,陈廷芳,李永良,等.AZ31镁合金搅拌摩擦焊接头微弧氧化表面防护研究[J].材料工程,2012,12:1-6.Xue W B,Chen T F,Li Y L,et al.Surface protection of friction stir welding joint for AZ31magneaium alloy coated by microaro oxidation[J].Journal Materials and Engineering,2012,12:1-6(in Chinese).
[6]张欣盟,田修波,巩春志,等.约束阴极微弧氧化放电特性研究[J].物理学报,2010,59(8):5613-8.Zhang X M,Tian X B,Kun C Z,et al.Discharge characteristics of confined cathode micro-arc oxidation[J].Acta Physica Sinica,2010,59(8):5613-8(in Chinese).
[7]吕鹏翔,狄士春.扫描式微弧氧化技术的研究[J].电加工与模具,2012(S1):45-48.Lv P X,Di S C.Research on film formation efficiency of aluminium alloy by scanning micro-arc oxidation[J].Electromachining&Mould,Supplement,2012(S1):45-48(in Chinese).
[8]李尚义,赵克定,常同立,等.铝合金微弧氧化技术在仿真转台用连续回转电液伺服马达中的应用研究[J].液压与气动,2004(12):43-45.Li S Y,Zhao K D,Chang T L,et al.Research on applying ceramic coating formed by microarc oxidation on aluminum alloy to the production of continuous rotary electro-hydraulic servo motor for three axis turntable[J].Chinese Hydraulics&Pneumatics,2004(12):43-45(in Chinese).
[9]Gu W C,Lv G H,Chen H,et al.PEO protective coatings on inner surface of tubes[J].Surface&Coatings Technology,2007,201(15):6619-22.
[10]但敏,高翚,金凡亚,等.阴阳极放置模式对圆筒工件微弧氧化膜厚的影响[J].材料保护,2011,44(4):67-69.Dan M,Gao C,Jin F,Y,et al.Effect of place mode of cathode and anode on thickness of inner-wall micro-arc oxidation coating of cylinder[J].Materials Protection,2011,44(4):67-69(in Chinese).
[11]吴汉华,汪剑波,龙北玉,等.电流密度对铝合金微弧氧化膜物理化学特性的影响[J].物理学报,2005,54(12):5743-8.Wu H H,Wang J B,Long B Y,et al.Effect of current density on physical and chemical properties of microarc oxidation coatings of aluminium alloy[J].Acta Physica Sinica,2005,54(12):5743-8(in Chinese).
[12]董海青,牛宗伟,赵东山,等.电流密度对6061铝合金微弧氧化陶瓷层的影响[J].腐蚀科学与防护技术,2014,26(2):137-142.Dong H Q,Niu Z W,Zhao D S,et al.Effect of current density on ceramic coating prepared by micro-arc oxidation on 6061aluminum alloy[J].Corrosion Science and Protection Technology,2014,26(2):137-142(in Chinese).
[13]李慕勤,刘江,蔡丁森,等.纯镁超声微弧氧化-HFNa2SiO3复合处理对生物涂层的影响[J].中国表面工程,2014,27(3):50-56.Li M Q,Liu J,Cai D S,et al.Effecion of pure magesium ultrasonic micro-arc oxidaton-HF-Na2SiO3compounded treatment on the bio-coating[J].China Surface Engineering,2014,27(3):50-56(in Chinese).
[14]Yusuke Tsutsumi,Mitsuo Niinomi,Masaaki Nakai,et al.Micro-arc oxidation treatment to improve the hard-tissue compatibility of Ti-29Nb-13Ta-4.6Zr alloy[J].Applied Surface Science,2012(262):34-38.
[15]Xia Y H,Zhang B P,Lu C X,et al.Improving the corrosion resistance of Mg-4.0Zn-0.2Ca alloy by micro arc oxidation[J].Materials Science&Engineering C-Materials for Biological Applications,2013,33(8):5044-50.