【作者】 范松岩；

【导师】 阎峰云；

【作者基本信息】 兰州理工大学 ， 材料学， 2008， 硕士

【摘要】 微弧氧化技术是一种在金属表面原位生长陶瓷膜的先进成型技术，是镁合金表面处理技术的重点发展方向。本文通过试验，对AZ91D镁合金微弧氧化电解液配方及其工艺参数进行了优化，并对微弧氧化着色技术进行了研究和探讨。在电解液配方优化部分，借鉴微弧氧化目前已有和正在研究的电解液配方，参考前期尝试性试验结果，通过正交试验，综合直观分析和方差分析结果，对微弧氧化电解液配方及工艺参数进行了优化，确定电解液最佳配方为铝酸钠5g／L、氢氧化钠4g／L、30％过氧化氢3ml/L；最佳工艺参数为电流密度1．0A/am²、频率600Hz、占空比20％、微弧氧化时间20分钟。在最佳电解液配方和工艺参数条件下制备的微弧氧化膜层耐蚀性能良好、硬度适中、膜厚均匀、致密度高。对微弧氧化膜层微观表面形貌和截面形貌进行SEM观察分析发现：膜层表面是由许多微孔构成的网状结构；膜层截面由致密层和疏松层组成。对微弧氧化膜层进行XRD物相分析发现：氧化膜层主要是由MgO、Al₂O₃和MgAl₂O₄组成。在膜层着色研究部分，通过试验证明陶瓷膜颜色的深浅可以通过着色盐添加量和微弧氧化时间来控制。着色盐添加量越多，微弧氧化陶瓷膜颜色越深；微弧氧化时间越长，微弧氧化陶瓷膜颜色越深。研究着色盐重铬酸钾添加量和微弧氧化时间对着色膜层的影响规律，最终确定在电流密度1．0A／dm²、频率600Hz、占空比20％、微弧氧化时间20分钟的工艺参数条件下，AZ91D镁合金在5g／L铝酸钠、4g／L氢氧化钠、3ml／L30％过氧化氢和0．5g／L重铬酸钾组成的电解液中进行微弧氧化着色试验，可以制得表面光滑、颜色均匀的绿色陶瓷膜层。通过XRD物相分析发现：绿色陶瓷膜层的成分主要由MgO、Al₂O₃和MgCr₂O₄组成，其中MgCr₂O₄是使膜层产生颜色的物质。对微弧氧化绿色陶瓷膜层进行性能测试分析发现：陶瓷膜层与基体具有良好的结合力，膜层表面光滑致密、颜色均匀持久，硬度和耐蚀性能同镁合金基体相比有了很大的提高。更多还原

【Abstract】 Micro-arc oxidation （MAO） is an advanced surface protective treatment technology of forming ceramic coatings on the metals. It is a development direction of magnesium alloy surface treatment technology. In this paper through a lot of tests, a micro-oxidation electrolyte formula and some process parameters of AZ91D magnesium alloy are obtained, then the micro-oxidation and coloring technology are studied.On the parts of electrolyte optimization, according to contrast test and orthogonal test, adopting visual analysis and variance analysis, a good MAO composition of the electrolyte system for magnesium AZ91D alloy is found out: NaAoO₂5g/L, NaOH4g/L, H₂O₂3ml/L; and the best technical parameters is: current density 1.0A/dm², frequency 600Hz, duty cycle 20%, oxidation time 20min. Through the best electrolyte formula and process parameters, we make the film of MAO which has good corrosion resistance, thickness, density and hardness. By using SEM the surface and cross-section morphology of the ceramic coatings have been analyzed, the results show that coating main including many network structures, and the cross-section is composed of the compact layer and loose layer. The XRD observation analysis shows the film is mainly made up of the MgO, Al₂O₃ and MgAl₂O₄.On the parts of coloring study, tests show that the depth of ceramic coating color can be controlled by colored salt content and micro-oxidation time. The more coloring salt content, the more deeply film color, and the longer micro-oxidation time, the more deeply film color. At last by using the new best electrolyte and the best technical parameters: NaAlO₂5g/L, NaOH4g/L, H₂O₂3ml/L, K₂Cr₂O₇0.5g/L, current density 1.0A/dm², frequency 600Hz, duty cycle 20%, oxidation time 20min, we can get the green ceramic coating with smooth and evenly coloring surface. The XRD analysis shows: the main composition of the green ceramic coating is MgO, Al₂O₃ and MgCr₂O₄, and the MgCr₂O₄ colored the film. The performance testing shows: the ceramic coating has relatively good surface appearance, excellent corrosion resistance and color sustainability, better thickness, hardness than basal magnesium alloy and tight combine with basal magnesium alloy.更多还原