摘要
镁合金具有密度低、比强度大、能量衰减系数大、优良的电磁屏蔽特性以及辅助散热功能等性能,已成为有色金属材料中最具有开发和应用前景的金属结构材料之一,但是镁合金耐腐蚀性差的弱点严重影响着镁合金的广泛应用,因此对镁合金进行表面改性具有明确的应用背景和实际意义。本论文提出的微弧氧化着色技术,意图在制取镁合金表面防护膜的同时,也能获得良好的装饰性,实现镁合金微弧着色膜颜色的多样化。
本文首先研究了,在以硅酸盐体系为基础溶液添加KMnO_4和络合剂的溶液中,在镁合金表面制备微弧氧化着色膜的工艺条件,包括电流密度、反应时间、溶液浓度、着色盐和络合剂配比对微弧氧化着色膜的影响。通过实验找出了能制得性能优异膜层的条件。并借助SEM,XRD等方法,观察了陶瓷层的形貌、结构,并测定了陶瓷层的相组成。对不同实验条件下制备的陶瓷膜的厚度、耐腐蚀性等性能进行了测试分析。结果表明,经电子探针检测后发现显色的元素主要是Mn元素,而经过XRD检测可以进一步确认显色的物相主要是Mn_2O_3;考察溶液浓度、反应时间、电流密度三个参数对颜色的影响,发现溶液浓度对颜色的改变影响最大。着色盐浓度过高或过低对膜层颜色和表面质量都不好,因此选用中等浓度组溶液为宜。保持相同电流密度和溶液浓度,随处理时间的延长,试样的厚度在增大;而在相同着色盐浓度、相同处理时间条件下,电流密度大的试样膜层厚度的增长趋势要大于电流密度小的试样。
其次,在电解着色的过程中,将在添加KMnO_4的电解液中进行微弧氧化着色过的试样,放置在硫酸镍溶液中,通过改变反应时间和改变电解液浓度,观察膜层相组成、形貌、厚度等的变化。试样在处理的过程中由于放置于阴极,对于膜层起到了加载负脉冲的作用,因此会使膜层有消融的现象;在电解液中也不宜处理时间过长,否则容易导致表面部分氧化膜脱落;在电解着色的过程中,延长电解时间或者提高硫酸镍含量,都会使膜层里镍的含量提高。经过电解着色的试样耐蚀性有所提高。
最后,将在硅酸盐基础电解液进行微弧氧化的试样放置在硫酸镍溶液中,通过改变反应时间和改变电解液浓度,观察膜层相组成、形貌、厚度等的变化。在电解液中处理时间过长也会引起表面膜层的部分氧化膜的剥落。通过在硫酸镍溶液中电解着色试样的耐蚀性有所提高,但总的来说先进行微弧氧化着色再进行电解着色的试样耐蚀性好。
Magnesium alloys is low density, high strength/weight ratio, large coefficient of energy attenuation, excellent electromagnetic shield and capability of emitting heat and so on. Therefore it becomes one of the most important metal in the way of its development and application. However, corrosion resistance of magnesium alloys is very poor, which mainly effects its wide application in the field of automotive and electro-mmunication. This thesis is to use MAO coloring to obtain the good corrosive resistance and colouring ceramic coating on magnesium alloys.
Firstly, how the processing parameter including current density、treating time、colourant's concentration、thepropotion of potassium permanganate and complexing agent effect on magnesium alloy cecamic coating by the micro-arc oxidation colouring in sodium silicate solution which is added potassium permanganate and complexing agent has been investigated. The condition being able to make the outstanding colouring ceramic coatings by the experiment have been found out.Draw support from method such as SEM and XRD, morphology, microstructure and phase composition of colouring ceramic coatings were observed. Thickness and corrosion-resistance of colouring ceramic coatings in different experiment condition were tested and analysed. The results show that, The element discovering a coloration by TEM testing is Mn element mainly; but being able to affirm the coloration thing further by that XRD checks is Mn_2O_3; Colourant's concentration influence coating's colour most in sodium silicate solution. Both too high and too low colourant's concentration is disadvantageous for the quality of colouring ceramic coatings, so selecting and using the medium colourant's concentration solution will be suitable. Keep identical current density and colourant's concentration, the samples thickness is enhancing by prolonging treatment time; But under identical concentration of potassium permanganate and treatment time condition, the more current density of colouring ceramic coatings, the thickness increase trend is more quick.
Secondly, in the electrolytic colouring process, the coloring samples with micro-arc oxidation were placed in nickel sulfate solution. With changing reaction time and colourant's concentration, the changes of phase composition, morphology and thickness for colouring ceramic coatings were observed. Because the samples were assigned as cathode, the effect of loading undershoot has been on the colouring ceramic coatings, and the ablation phenomenon of the colouring ceramic coatings can be observed; the treated-time was not too long in electrolyte, otherwise, it can result in the colouring ceramic coatings of surface exfoliated, during the electrolytic colouring process, prolonging the electrolytic process or improving nickel sulfate content, that both can improve the content of nickel in the coating. In the electrolytic colouring process, prolonging the electrolytic process or improving nickel sulfate content, that both can improve the content of nickel in the coating. The coloring samples' corrosion-resistance have been improved with electrolytic colouring.
Lastly, in the electrolytic colouring process, the coloring samples with micro-arc oxidation were placed in nickel sulfate solution. With changing reaction time and colourant's concentration, the changes of phase composition, morphology and thickness for film layer were observed. The treated-time was too long in electrolyte can result in the oxide film of surface exfoliated. The coloring samples' corrosion-resistance have been improved with electrolytic colouring. On the whole, The coloring samples' corrosion-resistance is great by the micro-arc oxidation colouring first and then electrolytic colouring treated.
引文
[1]崔晓鹏,刘勇兵,刘喜明.半固态触变注射成型镁合金的组织与性能分析.汽车工艺与材料,2004,(2):22-25
[2]Mordike B L,Ebert T.Mganesium properties applications potential.Materials Science and Engineering A,2001,(302):37-45
[3]Martin R Elgar.The surface treatment of magnesium alloys for aerospace applications.Finishing Foundry Trade Journal,1998,(7):554-556
[4]Avid Hawkeq,Albright D L A.Phosphate Permanganate Conversion Coating for Magnesium.Metal Finishing,1995,(10):34-38.
[5]Hiroyuki Umehara.An Investigation of the Structure and Corrosion Resistance of a Permanganate Conversion Coating on AZ91D Magnesium Alloys.Journal of Japan Institute of Light Metals.2000,50(3):109-115
[6]张勇,许越,周德瑞等.稀土铈对AZ91镁合金表面腐蚀性能的影响.哈尔滨工业大学学报,2002,34(3):376-378
[7]许越,陈湘,吕祖瞬等.金属表面稀土转化膜的研究进展.稀土,2002,23(3):58-62
[8]Krymann W,Kurze P,Dittrich K H.Process Characteristics and Parameters of Andoic Oxidation by Spray Deposition(ANOF).Crystsl Research and Technology,1984,19:975-979
[9]Kurze P,Krymann W.Coloured ANOF Layers on Aluminum.Crystal Research and Technology,1987,22:35-38
[10]张永君,严川伟.压铸镁合金AZ91D环保型阳极氧化电解液配方研究.腐蚀与防护.2002,23(4):148-151
[11]冯忠信,何家文,张建中等.ZM1镁合金的滚扎形变强化及机理.机械工程学报,1996,32(1):103-108
[12]冯忠信,张建中,陈新增.ZM1镁合金的表面滚压强化.金属学报,1994,30(9):422-426
[13]Altenberger I,Scholters B.mprovement of Fatigue Behaviour of Machanically Surface Treatmented Materials by Annealing.Scripta Materilalia,1999,41(8):873-881
[14]高波,郝胜智,董闯等,镁合金表面处理研究的进展.材料保护,2003,36(10):1-3
[15]Dube E M,Couture A.Characterization and performance of laser melted AZ91D and AM60B.Materials Science and Engineering A,2001,299:38-45
[16]Bruckner J,Gunzel R,Moller W.Metal plasma immersion ion implantation and deposition(MPIIID):Chromium on magnesium.Surface and Coatings Technology,1998,103-104:227-230
[17]高引慧.镁合金微弧氧化黄色陶瓷膜的制备和结构研究:[华南理工大学硕士学位论文].广州:华南理工大学图书馆,2005,6:3-4
[18]朱祖芳.铝合金阳极氧化与表面处理技术.北京:化学工业出版社2004:266-268
[19]蔡积庆.Mg合金化学镀Ni/电镀Au工艺.新工艺新技术新设备,1994(6):22-23
[20]张津,孙智富.AZ91D镁合金表面热喷铝涂层研究.中国机械工程,2002,13(23):2057-2058
[21]高引慧.镁合金微弧氧化黄色陶瓷膜的制备和结构研究:[华南理工大学硕士学位论文].广州:华南理工大学图书馆,2005,6:5-6
[22]郭红霞.铝及铝合金着色技术.表面处理.2004,30(1):59-60
[23]刘登良.表面工程.北京:机械工业出版社,2002:173-179
[24]董伟虎.金属材料氧化和着色工艺设计.冶金矿山设计与建设.1995,27(2):34-38
[25]吴永,刘鸣江等.铝交流电整体氧化着色.电镀与表面处理1996,15(1):8-11
[26]白力静,蒋百灵,李均明等.微弧氧化技术在镁合金防护处理中的应用.汽车工艺和材料,2003,(5):24-27
[27]暨调和,曾凌三,张国芝等.建筑铝型材的阳极氧化和电解着色.湖南:湖南科学技术出版社,1994:132-133
[28]梁军,郭宝刚,田军等.氢氧化钠对镁合金微弧氧化的影响.材料保护,2005,38(4):6-8
[29]D.Laser,M-Ariel.Electro-optical study of the oxidative adsorption of naphthol on platinum and gold film electrodes.Electroanalytical Chemistry.1972,35(1):405-414
[30]M.Sandera.Dielectric film thickess measurement from the reflection relations.Solid-State Electronics.1975,18(1):110-112
[31]V.sautter,O.Jaoul,F.Abel.Aluminum diffusion in diopside using the 27Al(p,γ)28Si nuclear reaction:Preliminary results.Earth and Planetary Scence Aetter.1988,89(1):109-144
[32]Sheasy P G,Cooke W E.The effect of solute atoms on the energy and structure of grain boundaries.Acta Metallurgica.1977,25(4):467-473
[33]李宜,朱祖芳.铝阳极氧化膜锡盐电解着色沉积产物和分布.腐蚀与防护.1991,12(5):219
[34]朱祖芳,铝合金阳极氧化与表面处理技术.北京:化学工业出版社,2004:289-311
[35]GB8013-87,铝及铝合金阳极氧化膜的总规范[S]
[36]高引慧.镁合金微弧氧化黄色陶瓷膜的制备和结构研究:[华南理工大学硕士学位论文].广州:华南理工大学图书馆,2005,6:29
[37]焦树强,旷亚非,陈金华等.镁及其合金的腐蚀与阳极氧化处理.电镀与环保,2002,22(3):1-3
[38]J.E Gray,B.Luan.Protective coatings on magnesium and its alloys.Journal of Alloys and Compounds,2002,336(1):88-90
[39]王渠东,吕宜振,曾小勤.镁合金在电子壳体器材中的应用.材料导报,2000,14(6):22-24
[40]朱祖芳.镁合金部件(制品)的表面保护和装饰工艺.材料保护,2002,35(6):4-5
[41]高引慧,李文芳,杜军等.镁合金微弧氧化黄色陶瓷膜的制备和结构研究.材料科学与工程学报,2005,23(4):542-543
[42]张淑芬,张先锋,蒋百灵.溶液电导率对微弧氧化的影响.材料保护,2004,37(4):7-9
[43]高引慧.镁合金微弧氧化黄色陶瓷膜的制备和结构研究:[华南理工大学硕士学位论文].广州:华南理工大学图书馆,2005,6:16-17
[44]李炳.AZ91D镁合金耐磨性及其表面微弧氧化膜的制备与性能研究:[兰州理工大学硕士学位论文].兰州:兰州理工大学,2007,6:47-48
[45]朱祖芳.铝合金阳极氧化与表面处理技术.化学工业出版社,2004:163-166
[46]刘文亮,朱祖芳.铝及铝合金电解着色机理.电镀与环保,1995,15(6):17-19
[47]GB14952.3-94,铝及铝合金着色阳极氧化膜色差和外观质量检验方法[S]
[48]查康,魏晓伟.添加剂对镁合金微弧氧化的影响.表面技术.2006,35(4):56-58
[49]吴振东,姜兆华,姚忠平等.反应时间对LYl2铝合金微弧氧化膜层组织及性能的影响.无机材料学报.2007,22(3):555-559
[50]郭洪飞,安茂忠,徐莘等.电流密度对镁合金微弧氧化过程及氧化陶瓷膜性能的影响.稀有金属材料与工程,2005,34(10):1554-1557
[51]宋世漠,王正烈,李文斌.物理化学.北京:高等教育出版社,第三版,下册,273-288
[52]高引慧.镁合金微弧氧化黄色陶瓷膜的制备和结构研究:[华南理工大学硕士学位论文].广州:华南理工大学图书馆,2005,5:25
[53]VERDIER S,BOINETM,MAXIMOVITCH S,et al.Formation,structure and composition of anodic films on AM60 magnesium alloy obtained by DC plasma anodising.Corrosion Science,2005,47:1429-1434.
[54]周谟银.铝阳极氧化膜电解着色.电镀与环保.2004,24(2):21-24
[55]朱祖芳.铝合金阳极氧化与表面处理技术.北京:化学工业出版社,2004:181-183
[56]陈宏,冯忠绪,郝建民等.负脉冲对铝合金微弧氧化的影响.长安大学学报,2007,27(1):96-98
[57]吴永炘,刘鸣江.铝交流电整体氧化着色.电镀与涂饰.1996,15(1):8-12
[58]朱祖芳.铝合金阳极氧化与表面处理技术.化学工业出版社,2004:160-161
[59]李新,刘卫,余先涛.ZL108的激光表面合金化,武汉理工大学学报.2006,28(4):38-40
[60]刘文亮,朱祖芳.铝及铝合金电解着色机理.电镀与防护.1994,15(6):17-19
[61]GB/T14952.2-94,铝及铝合金阳极氧化膜的封孔质量评定(乙酸-乙酸钠腐蚀试验)
[62]朱祖芳.铝合金阳极氧化与表面处理技术.化学工业出版社,2004:178-179
[63]刘文亮,朱祖芳.电解着色工艺条件着色膜颜色的影响.电镀与环保.1995,15(1):14-16