不同电源模式下的镁合金微弧氧化工艺研究
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摘要
微弧氧化是利用微小区域电弧放电产生局部高温使金属氧化，在其表面原位生成陶瓷膜层的一种表面处理技术。目前广泛采用的微弧氧化电源模式为双极性脉冲电源模式，但是对于什么样的电源模式最适合微弧氧化工艺，至今尚未得出一个确切的回答。为了确定微弧氧化的最优电源模式及电源加载参数。本课题以AZ91D镁合金为基体材料，采用自行研制的具有多种输出方式和特性的大功率微弧氧化脉冲电源，分别在直流及单极性脉冲、双极性脉冲和带放电回路的脉冲形式下进行大量实验。基于实验现象、结果、微区放电理论及微弧氧化负载特性，研究了电源模式对镁合金微弧氧化的影响并对电源加载参数进行了优化。
为评价成膜效率和能量利用率，计算了不同工艺条件下，单位膜厚对应的电源输出电能，称之为平均能耗。双极性脉冲电源中负电压作用仅是抑制了微弧氧化的大弧倾向，理论分析和实验结果均未找出负电压存在的充分理由。在带放电回路模式下，当预设脉冲参数相同时，随放电电阻阻值的增大，微弧氧化过程电流减小，能耗降低，但得到的膜层性能相差无几。比较研究结果表明，带放电回路的脉冲电源与目前大量采用的双极性脉冲电源相比，更适合镁合金微弧氧化工艺。主要表现在：过程一致性及稳定性好，参数可控性优，放电弧斑均匀；膜层表面质量明显好于双极性电源；同等条件下得到的膜层其耐蚀性略好。
基于对电源加载方式的研究，确定了最优的电源加载参数。微弧氧化的不同阶段采用不同的电压增量，开始阶段通常将其恒定为10V/min，当电压达到350V后，改增量为5V/min直到终止电压或恒定电流为5A/dm~2～15A/dm~2时，微弧氧化过程的综合性能最好；取值过大会使膜层质量变差，过小则使成膜效率变低。
The micro-arc oxidation is one surface treatment technology which can make themetal be oxidized in the local high temperature which was produced by micro-arcdischarge, and generate ceramic membrane in situ surface of the metal. It was thedouble-polarity pulse power supply mode that has been widely used, however therehas not yet been a exact answer what power supply mode is most suitable formagnesium alloy MAO process. In order to determine the optical power supply modeand loading parameters of power supply of the micro-arc oxidation, with AZ91Dmagnesium alloy as the substrate material, using the experimental platform withmultiple output power pulse modes, a large number of experiments were carried outwith the different power supply modes of direct current, single-polarity pulse,double-polarity pulse and the pulse power supply with a discharge loop. Based on thephenomenon and the results of the experiments, micro-arc discharge mechanism andthe load characteristics of MAO, the impacts of different power supply modes onmicro-arc oxidation were studied, and it was determined that what loading parameterof power supply is most optimal.
For evaluating the film-forming efficiency and energy utilization rate, the outputelectric energy that correspond to unit membrane thickness of different conditionswas calculated, which was called the average energy consumption. The only effect ofnegative voltage in double-polarity pulse power supply is to inhibit the tendency oflarge-arc discharge, both theoretical analysis and experimental results show nosufficient sign for the existence of negative voltage. Under the power supply modewith a discharge loop，with the same preinstalled pulse parameters，the current and theenergy consumption of the process of MAO are all reduced when the value of thedischarge resistor increases, but the performance of the film of MAO are all most thesame. Comparative study shows that the pulse power supply with discharge loop ismore suitable for magnesium alloy MAO process than the double-polarity one. Mainlybecause of good consistency and stability in the process, excellent controllabilityparameters, uniform arc spots; the quality of coating surface is obviously better thanthe double-polarity one; the corrosion resistance that was obtained under the samecondition is little better than the latter.
Based on the study of loading modes of the power supply, the optimal loading parameters of power supply are determined. When the loading mode is that differentvoltage increment is adopted in different stage of the micro-arc oxidation experiment.10V/min is usually set in the beginning stage, when the voltage reaches350V, changethe increment to5V/min until the terminal voltage, or constant current in5A/dm~2~15A/dm~2, the process is the best overall performance. The film quality will bedeteriorated when the value is too large; the efficiency will be low when the value istoo small.
为评价成膜效率和能量利用率，计算了不同工艺条件下，单位膜厚对应的电源输出电能，称之为平均能耗。双极性脉冲电源中负电压作用仅是抑制了微弧氧化的大弧倾向，理论分析和实验结果均未找出负电压存在的充分理由。在带放电回路模式下，当预设脉冲参数相同时，随放电电阻阻值的增大，微弧氧化过程电流减小，能耗降低，但得到的膜层性能相差无几。比较研究结果表明，带放电回路的脉冲电源与目前大量采用的双极性脉冲电源相比，更适合镁合金微弧氧化工艺。主要表现在：过程一致性及稳定性好，参数可控性优，放电弧斑均匀；膜层表面质量明显好于双极性电源；同等条件下得到的膜层其耐蚀性略好。
基于对电源加载方式的研究，确定了最优的电源加载参数。微弧氧化的不同阶段采用不同的电压增量，开始阶段通常将其恒定为10V/min，当电压达到350V后，改增量为5V/min直到终止电压或恒定电流为5A/dm~2～15A/dm~2时，微弧氧化过程的综合性能最好；取值过大会使膜层质量变差，过小则使成膜效率变低。
The micro-arc oxidation is one surface treatment technology which can make themetal be oxidized in the local high temperature which was produced by micro-arcdischarge, and generate ceramic membrane in situ surface of the metal. It was thedouble-polarity pulse power supply mode that has been widely used, however therehas not yet been a exact answer what power supply mode is most suitable formagnesium alloy MAO process. In order to determine the optical power supply modeand loading parameters of power supply of the micro-arc oxidation, with AZ91Dmagnesium alloy as the substrate material, using the experimental platform withmultiple output power pulse modes, a large number of experiments were carried outwith the different power supply modes of direct current, single-polarity pulse,double-polarity pulse and the pulse power supply with a discharge loop. Based on thephenomenon and the results of the experiments, micro-arc discharge mechanism andthe load characteristics of MAO, the impacts of different power supply modes onmicro-arc oxidation were studied, and it was determined that what loading parameterof power supply is most optimal.
For evaluating the film-forming efficiency and energy utilization rate, the outputelectric energy that correspond to unit membrane thickness of different conditionswas calculated, which was called the average energy consumption. The only effect ofnegative voltage in double-polarity pulse power supply is to inhibit the tendency oflarge-arc discharge, both theoretical analysis and experimental results show nosufficient sign for the existence of negative voltage. Under the power supply modewith a discharge loop，with the same preinstalled pulse parameters，the current and theenergy consumption of the process of MAO are all reduced when the value of thedischarge resistor increases, but the performance of the film of MAO are all most thesame. Comparative study shows that the pulse power supply with discharge loop ismore suitable for magnesium alloy MAO process than the double-polarity one. Mainlybecause of good consistency and stability in the process, excellent controllabilityparameters, uniform arc spots; the quality of coating surface is obviously better thanthe double-polarity one; the corrosion resistance that was obtained under the samecondition is little better than the latter.
Based on the study of loading modes of the power supply, the optimal loading parameters of power supply are determined. When the loading mode is that differentvoltage increment is adopted in different stage of the micro-arc oxidation experiment.10V/min is usually set in the beginning stage, when the voltage reaches350V, changethe increment to5V/min until the terminal voltage, or constant current in5A/dm~2~15A/dm~2, the process is the best overall performance. The film quality will bedeteriorated when the value is too large; the efficiency will be low when the value istoo small.
引文
[1]韩夏云,龙晋明,薛方勤等.镁及镁合金应用与表面处理现状及发展[J].轻金属,2003,(2):48.
[2]王祝堂.镁与汽车[J].轻合金加工技术,1994,22(6):2.
[3]王祝堂.镁在汽车中应用现状与前景[J].铝加工,1998,21(6):54-58.
[4]刘列安.镁合金加工技术发展趋势与开发应用前景[J].轻合金加工技术,2001,29(6):1-7.
[5]王辉.镁合金及其在工业中的应用[J].稀有金属,2004,28(1):229-232.
[6] Froes F H, Eliezer D. The Science, Technology and Application of Magnesium[J]. J MineMetals and Mater Soc,1998,5(9):30-34.
[7]卡恩R W,哈森P,克雷默E J,丁道云等译.材料科学与技术丛书,第8卷,非铁合金的结构与性能[M].北京:科学出版社,1999:101-182.
[8] Raymond F, Decker. The Renaissance in magnesium[J]. Adv Mate Pro,9/1998,154(3):31-33.
[9] Alex J Z, Duane E B. Anodized Coatings for Magnesium Alloys[J]. Metal Finishing,1994,92(3):39-44.
[10] Makar GL, K ruger J. Corrosion of magnesium[J]. International Materials Reviews,1993,38(3):138-153.
[11] Rudd A L, Breslin C B, Mans feld F. The Corrosion Protection Afforded by Rare EarthConversion Coatings Applied to Magnesium[J]. Corr Sci,2000,42(2):275-288.
[12] Takaya M, Narashino. Anodizing of Magnesium Alloys in KOH-Al(OH)3Solution[J].Aluminium,1989,12:1244-1248.
[13] Pourbaix M. Atlas of Electrochemical Equilibria in Aqueous Solutions[M]. Houston,TX:Pergament Press Ltd,1974.
[14] Perrault G G. The Potential-pH Diagram of the Magnesium-Water System[J]. JElectroanalytical Chemistry and Interfacial Electrochemistry,1974,51:107-119.
[15] Allan F orats, Terje Kr.Aune, David Hawke etal. Metal Handbook9thEdition (Vo112)Corrosion[M]. U S A:ASM International,1987:740-754.
[16] Gray J E，Luan B. Protective coatings on magnesium and its alloys-a critical review. Journalof Alloys and Compounds,2002,336:88~113.
[17]蒋百灵,李均明.铝、镁合金微弧氧化技术的研究现状及应用前景.第八次全国热处理大会论文集,2003.
[18]张欣宇,石玉龙等.离子体微弧氧化技术及其应用[J].青岛化工学院学报,2002,23(1):72
[19]辛铁柱,袭建军,韩荣第等.铝.镁.钛合金微弧氧化表面处理技术[J].电加工与模具,2004增刊:36-37.
[20]潘明强,迟关心,韦东波等.我国铝/镁合金微弧氧化技术的研究及应用现状[J].材料保护,2010,43(4):10.
[21] Van T. B, Brow n S. D., and Wirt z G. P. Mechanism of Anodic Spark Deposition[J]. Am.Ceram.Soc.Bul l.,1977,56(6):563-566.
[22] Wirtz G. P., Brow n S. D., Kriven W. M.Ceramic Coatings by Anodic Spark Depostion[J].Mater. M anuf. Process.,1991,6(1):87-115.
[23] Krysmann W., Kurze P., Ditt rich K.H., Schneider H. G.. Process Characteristics andParamet ers of Anodic Oxidation by Spark Discharge (ANOF)[J]. Cryst.Res. Technol.,1984,19(7):973-979.
[24] Kurze P. Krysmann W., Schreckenbach J., S chw arz Th., Rabending K..Coloured ANOFLayers on Aluminium[J]. Cryst. Res.T echnol.,1987,22(1):53-58.
[25] KurzeP. Magnesium legierungen elektro chemisch beschichten[J]. Metalloberfche,1994,48(2):104-105.
[26]薛文斌,邓志威,来永春等.有色金属表面微弧氧化技术评述[J].金属热处理,2000,(1):1.
[27]杨眉,雷正,王平等.镁合金微弧氧化技术研究进展[J].热加工工艺,2011,40(20):111-115.
[28] WoodGC, PearsonC. The theory of avalanche break down in solid dielectrics [J]. Corros. Sci.1967,7(2):119-125.
[29] Robert S, Alivait C, Ortega. Ion transport through duplex amorphous/crystalline barrieraluminum oxidation [J]. Electrochem Soc.,1977,135(11):2686-2700.
[30] Kadary V, Klein N. Reverse avalanche break down in gated diodes [J]. Electrochem Soc.,1980,127(1):139-151.
[31] Montero I, Martinez-duart J M. Anodization and breakdown model of Ta2O5films [J].J.Eleltrochem. Soc.,1985,132(4):814-847.
[32]陈妍君,冯长杰,邵志松等.铝合金微弧氧化技术的研究进展[J].材料导报,2010,24(5):132-136.
[33] Mecuson F, Czerwiec T, Belmonte T, etal. Diagnostics of an elect rolytic microarc processfor aluminium alloy oxidation [J]. Surf. Coat. Techn.,2005,200:804-808.
[34]贺永胜,赵志龙,刘一洋.铝合金微弧氧化热力学机理及影响因素的分析[J].电镀与环保,2005,25(6):38-40.
[35]陈宏,郝建民,冯忠旭.微弧氧化机理及电击穿模型[J].长安大学学报,2008,28(5):116-119.
[36]杨威,赵玉峰,杨世彦.微弧氧化电源特性和参数对膜层性能及电能消耗的影响[J].材料工程,2010,(2):86-88.
[37]刘君,强颖怀,熊党生.3种溶液体系中镁合金微弧氧化研究第一部分.电镀与涂饰.2006,10—0038—05.
[38]姜兆华,李爽,姚忠平等.电解液对微弧氧化陶瓷膜结构与耐蚀性的影响.材料科学与工艺.2006,1005－0299．
[39]梁军,郭宝刚,田军等.工艺参数对AZ91C镁合金生成微弧氧化膜层的影响[J].材料科学与工程学报,2005,23(2):263-265.
[40]马跃洲,马凤杰,陈明等.电解液温度对镁合金微弧氧化成膜过程的影响[J].兰州理工大学学报.2008,34(3):25-28.
[41] CH EN X, CH EN G, YUE P L. Investigation on the electrolysis voltage of electrocoagulation[J]. Chemical Engineering Science,2002,57(13):2449-2455.
[42]赵玉峰,杨威,杨世彦.微弧氧化脉冲电源的负载模型及其定量表征[J].材料工程,2011,(6):72-76.
[43]张英,孟保平,杨国英.镁合金表面微弧氧化法[J].轻合金加工技术,2004,32(10):23-25.
[44]徐晋勇,王斌,高原.铝及铝合金等离子体微弧氧化技术的研究[J].机械,2006,33(9):1-4.
[45]陈小红,曾敏,曹彪.微弧氧化电源研究现状[J].新技术新工艺,2008,(3):87-89.
[2]王祝堂.镁与汽车[J].轻合金加工技术,1994,22(6):2.
[3]王祝堂.镁在汽车中应用现状与前景[J].铝加工,1998,21(6):54-58.
[4]刘列安.镁合金加工技术发展趋势与开发应用前景[J].轻合金加工技术,2001,29(6):1-7.
[5]王辉.镁合金及其在工业中的应用[J].稀有金属,2004,28(1):229-232.
[6] Froes F H, Eliezer D. The Science, Technology and Application of Magnesium[J]. J MineMetals and Mater Soc,1998,5(9):30-34.
[7]卡恩R W,哈森P,克雷默E J,丁道云等译.材料科学与技术丛书,第8卷,非铁合金的结构与性能[M].北京:科学出版社,1999:101-182.
[8] Raymond F, Decker. The Renaissance in magnesium[J]. Adv Mate Pro,9/1998,154(3):31-33.
[9] Alex J Z, Duane E B. Anodized Coatings for Magnesium Alloys[J]. Metal Finishing,1994,92(3):39-44.
[10] Makar GL, K ruger J. Corrosion of magnesium[J]. International Materials Reviews,1993,38(3):138-153.
[11] Rudd A L, Breslin C B, Mans feld F. The Corrosion Protection Afforded by Rare EarthConversion Coatings Applied to Magnesium[J]. Corr Sci,2000,42(2):275-288.
[12] Takaya M, Narashino. Anodizing of Magnesium Alloys in KOH-Al(OH)3Solution[J].Aluminium,1989,12:1244-1248.
[13] Pourbaix M. Atlas of Electrochemical Equilibria in Aqueous Solutions[M]. Houston,TX:Pergament Press Ltd,1974.
[14] Perrault G G. The Potential-pH Diagram of the Magnesium-Water System[J]. JElectroanalytical Chemistry and Interfacial Electrochemistry,1974,51:107-119.
[15] Allan F orats, Terje Kr.Aune, David Hawke etal. Metal Handbook9thEdition (Vo112)Corrosion[M]. U S A:ASM International,1987:740-754.
[16] Gray J E，Luan B. Protective coatings on magnesium and its alloys-a critical review. Journalof Alloys and Compounds,2002,336:88~113.
[17]蒋百灵,李均明.铝、镁合金微弧氧化技术的研究现状及应用前景.第八次全国热处理大会论文集,2003.
[18]张欣宇,石玉龙等.离子体微弧氧化技术及其应用[J].青岛化工学院学报,2002,23(1):72
[19]辛铁柱,袭建军,韩荣第等.铝.镁.钛合金微弧氧化表面处理技术[J].电加工与模具,2004增刊:36-37.
[20]潘明强,迟关心,韦东波等.我国铝/镁合金微弧氧化技术的研究及应用现状[J].材料保护,2010,43(4):10.
[21] Van T. B, Brow n S. D., and Wirt z G. P. Mechanism of Anodic Spark Deposition[J]. Am.Ceram.Soc.Bul l.,1977,56(6):563-566.
[22] Wirtz G. P., Brow n S. D., Kriven W. M.Ceramic Coatings by Anodic Spark Depostion[J].Mater. M anuf. Process.,1991,6(1):87-115.
[23] Krysmann W., Kurze P., Ditt rich K.H., Schneider H. G.. Process Characteristics andParamet ers of Anodic Oxidation by Spark Discharge (ANOF)[J]. Cryst.Res. Technol.,1984,19(7):973-979.
[24] Kurze P. Krysmann W., Schreckenbach J., S chw arz Th., Rabending K..Coloured ANOFLayers on Aluminium[J]. Cryst. Res.T echnol.,1987,22(1):53-58.
[25] KurzeP. Magnesium legierungen elektro chemisch beschichten[J]. Metalloberfche,1994,48(2):104-105.
[26]薛文斌,邓志威,来永春等.有色金属表面微弧氧化技术评述[J].金属热处理,2000,(1):1.
[27]杨眉,雷正,王平等.镁合金微弧氧化技术研究进展[J].热加工工艺,2011,40(20):111-115.
[28] WoodGC, PearsonC. The theory of avalanche break down in solid dielectrics [J]. Corros. Sci.1967,7(2):119-125.
[29] Robert S, Alivait C, Ortega. Ion transport through duplex amorphous/crystalline barrieraluminum oxidation [J]. Electrochem Soc.,1977,135(11):2686-2700.
[30] Kadary V, Klein N. Reverse avalanche break down in gated diodes [J]. Electrochem Soc.,1980,127(1):139-151.
[31] Montero I, Martinez-duart J M. Anodization and breakdown model of Ta2O5films [J].J.Eleltrochem. Soc.,1985,132(4):814-847.
[32]陈妍君,冯长杰,邵志松等.铝合金微弧氧化技术的研究进展[J].材料导报,2010,24(5):132-136.
[33] Mecuson F, Czerwiec T, Belmonte T, etal. Diagnostics of an elect rolytic microarc processfor aluminium alloy oxidation [J]. Surf. Coat. Techn.,2005,200:804-808.
[34]贺永胜,赵志龙,刘一洋.铝合金微弧氧化热力学机理及影响因素的分析[J].电镀与环保,2005,25(6):38-40.
[35]陈宏,郝建民,冯忠旭.微弧氧化机理及电击穿模型[J].长安大学学报,2008,28(5):116-119.
[36]杨威,赵玉峰,杨世彦.微弧氧化电源特性和参数对膜层性能及电能消耗的影响[J].材料工程,2010,(2):86-88.
[37]刘君,强颖怀,熊党生.3种溶液体系中镁合金微弧氧化研究第一部分.电镀与涂饰.2006,10—0038—05.
[38]姜兆华,李爽,姚忠平等.电解液对微弧氧化陶瓷膜结构与耐蚀性的影响.材料科学与工艺.2006,1005－0299．
[39]梁军,郭宝刚,田军等.工艺参数对AZ91C镁合金生成微弧氧化膜层的影响[J].材料科学与工程学报,2005,23(2):263-265.
[40]马跃洲,马凤杰,陈明等.电解液温度对镁合金微弧氧化成膜过程的影响[J].兰州理工大学学报.2008,34(3):25-28.
[41] CH EN X, CH EN G, YUE P L. Investigation on the electrolysis voltage of electrocoagulation[J]. Chemical Engineering Science,2002,57(13):2449-2455.
[42]赵玉峰,杨威,杨世彦.微弧氧化脉冲电源的负载模型及其定量表征[J].材料工程,2011,(6):72-76.
[43]张英,孟保平,杨国英.镁合金表面微弧氧化法[J].轻合金加工技术,2004,32(10):23-25.
[44]徐晋勇,王斌,高原.铝及铝合金等离子体微弧氧化技术的研究[J].机械,2006,33(9):1-4.
[45]陈小红,曾敏,曹彪.微弧氧化电源研究现状[J].新技术新工艺,2008,(3):87-89.