【作者】 万小芳；

【导师】 张果戈； 单巍巍；

【作者基本信息】 华南理工大学 ， 材料工程， 2012， 硕士

【摘要】 镁及其镁合金由于具有优良的物理性能和力学性能而广泛应用于烟花、照明、冶金、化工、交通运输、航天航空、3C电子等领域。但是镁合金耐蚀性、耐磨性差和表面硬度低等特点限制了它的进一步使用。微弧氧化技术作为一种改性技术，通过等离子体化学、热化学和电化学的共同作用，在合金表面原位形成类陶瓷膜层，极大地提高了合金的耐蚀、耐磨性和绝缘性能，具有广泛的应用前景。同时微弧氧化黑色陶瓷膜因其具有独特的陶瓷性能和光学性能，在材料的防护和装饰方面有广泛的应用前景，受到不少研究者的关注。但是微弧氧化高能耗导致的高成本严重地限制了微弧氧化着色技术在工业生产上的广泛应用，所以微弧氧化低能耗着色工艺技术的研究是十分有意义的。本文研究开发了一种在AZ91D镁合金表面制备黑色陶瓷膜的低能耗的微弧氧化工艺。本研究采用硅酸钠、六偏柠酸钠、氟化钾、偏钒酸铵、EDTA为主溶液体系，通过单因素实验确定柠檬酸钠为添加剂，最后通过正交实验优化电解液和电参数，确定了制备性能优异且能耗相对较低的黑色陶瓷膜的最佳工艺。在该工艺下制备的微弧氧化陶瓷膜层颜色均匀、黑亮，与基体结合能力好，单位能耗为0.602kw·h/(m2.μm)，是一般的微弧氧化着色工艺的30%左右。利用SEM、EDS、XPS、XRD等表征手段对微弧氧化低能耗黑色膜的表面形貌、物质组成、结构和相组成进行了分析，利用电化学测量体系测量了微弧氧化黑色膜层的耐腐蚀性能。在最佳工艺水平下得到微弧氧化低能耗黑色陶瓷膜层微观表面有大小不一的放电孔洞存在；膜层结构致密，没有明显的分层现象；膜层主要由MgO和V2O5以及部分无定形态和微晶形态的氧化物组成，其中膜层的颜色是由V2O5和钒的其他氧化物共同作用的结果。微弧氧化低能耗黑色膜层硬度高达316HV左右，有良好的耐腐蚀性能，在3.5%NaCl中性介质中的腐蚀电流密度为0.00023μA/cm2，与镁合金基体相比降低了4个数量级。更多还原

【Abstract】 Magnesium and its alloy have many excellent physical and mechanical properties，whichmake them are widely applied to the field of fireworks, lighting, metallurgy, chemicalindustry, transportation, aerospace, and3C electronics. However，its lower surface hardnessand poor corrosion resistance limits its further application. The micro-arc oxidationtechnology is a kind of surface treatment technology and has broad application prospects, itcan convert to the ceramic-type coating in situ under the conditions of Plasma chemical，electrochemical and thermal-chemical effects and improved their anti-corrosion,wear-resisting and electrical-insulating. Micro-arc oxidation black ceramic coating have awide range of application prospect in protection of material，decoration and optical propertiesdue to ceramic properties and special optical properties. But the high energy consumption ofthe micro-arc oxidation coloring technique is expensive. This reason limits the micro-arcoxidation coloring technique widely used in industrial production. Therefore, the study ofmicro-arc oxidation of low-power coloring technology is very meaningful.Low energy black ceramic coating process has been developed by micro-arc oxidationon AZ91D magnesium alloy in an electrolyte system containing Na2SiO3,（Na2PO3）6,KF,NH4VO3,EDTA and additives. Through the single factor experiment and orthogonaltests optimization electrolyte and electric parameters, finally obtained optimal technologyparameters of Low energy black ceramic coating.The influences of technology parameters onmicro-arc oxidation process and performance of Low energy black ceramic coatings wereinvestigated, such as consumption of energy, color value and chromatic aberration. By thisMAO technique, the MAO black coating is color uniformity and shiny, have good bindingcapacity. At the same time the consumption of energy of the low energy coloring technologyis0.602kw h/(m2.μm), is30%of the general micro-arc oxidation coloring technology. BySEM, EDS, XPS, and XRD analysis the surface morphology, material composition, structureand phase composition of the low energy black ceramic coating. Using Electrochemicalmeasurement system measure the corrosion resistance of MAO coating. The results shownthat the low energy black ceramic coating have a few discharge pores，is dense,and noobvious hierarchical structure, the coating main mainly composed of MgO,VO2and amorphous or microcrystal oxides. The V2O5and another Vanadium oxide result in the blackcolor of ceramic layer. The hardness of Low energy black micro-arc oxidation film is up toabout316HV. The polarization curve shown that corrosion current density of black ceramiccoating was0.00023μA/cm2, four orders of magnitude lower than that of the bared alloy(3.664μA/cm2), which reveal that corrosion resistance of low energy black ceramic coatingformed on AZ91D magnesium alloys by MAO is significantly improved.更多还原