【作者】 郑宏晔；

【导师】 韩高荣；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2004， 硕士

【摘要】 本论文系统的介绍了铝合金微弧氧化技术的机理、影响因素、制备方法等研究进展。微弧氧化陶瓷层与基体结合牢固、结构致密，具有良好的耐磨性、耐腐蚀性、耐高温冲击和电绝缘性能，其工艺对环境无污染，具有广阔的应用前景。 采用正交实验的方法研究了铝合金微弧氧化的电解液配方、处理工艺及影响微弧氧化陶瓷层生长的因素，评估了电解液的稳定性，利用XRD、SEM、硬度、厚度等数据，分析了添加剂Na₂WO₄、电源波形、电流密度等参数对该电解液体系微弧氧化工艺和陶瓷层的影响，并与其他电解液体系制备的样品及硬质氧化样品进行了比较。 实验优化的电解液配方为：硼酸含量为10 g／L，氢氧化钾含量为2 g／L，钨酸钠含量为2 g／L；在微弧氧化过程中该配方比硅酸钠体系的电解液稳定；在铝合金表面形成陶瓷层的主要成分为α-Al₂O₃和γ—Al₂O₃两相和少量的W。 适量的Na₂WO₄添加剂的加入，有利于微弧氧化反应的进行。Na₂WO₄浓度影响陶瓷层的沉积速度和陶瓷层的成分，随着Na₂WO₄质量体积浓度的降低，表面放电中心减少，使电压上升，陶瓷层的厚度和陶瓷层中硬质相α-Al₂O₃的含量均增加，陶瓷层的硬度和耐磨性略有提高。 电参数的控制和选择对陶瓷层的生长速度和成分均有影响。正半波和大电流作用在陶瓷层上的能量密度大，陶瓷层生长速度快，α-Al₂O₃的含量较高，硬度较大。 溶液体系不仅影响陶瓷膜的沉积速度，还影响其表面形貌和组分含量，但对孔隙率和耐腐蚀性影响不是很大。在微弧氧化工艺高电压下制备的陶瓷层含有硬质相α-Al₂O₃，硬质氧化工艺制备的陶瓷层是非晶相，微弧氧化工艺在耐磨、耐腐蚀等方面均优于硬质氧化工艺。更多还原

【Abstract】 In this paper, a comprehensive introduction of micro-arc oxidation, including its mechanism, influence factors and preparation methods was described. By means of the micro-arc oxidation (MAO) technique, ceramic coatings with high micro-hardness, strong adhesion, high strength and high wear resistance can be fabricated.The water solution composed of H3BO3, KOH and Na2WO4 was used as the electrolyte for MAO derived coatings on aluminum alloy substrates. The electrolyte composition was optimized by means of orthogonal design from both technical and economic points of view, and the stability was evaluated. The MAO process was studied by measuring the voltage as a function to time. The coatings fabricated in different technical parameters were characterized by XRD and SEM with respect to the phases and microstructures, and by testing micro-hardness and the wear resistance with respect to mechanical properties. Final, the samples were compared with hard anodic oxidation and others fabricated in other solutions.The results showed that electrolyte containing H3BO3 10 g/1, KOH 2 g/1 and Na2WO4 2 g/1 was the most optimal in terms of the hardness and thickness measurements. This solution was more stable than Na2SiO3 solution. The ceramic coating in this electrolyte mainly consisted of -Al2O3 phase, -A12O3 phase and a small amount of W. The concentration of Na2WO4 had direct effects on the behavior of MAO process and the quality of the MAO coatings as well. With decreasing Na2WO4 concentration in the electrolyte, the number of the discharge centers on the aluminum alloys surface decreased, the working voltage at the micro-arc discharge stage increased, the thickness and the content of -Al2O3 phase in the coating both increased. The micro-hardness and the wear resistance were both enhanced as the content of -Al2O3 phase increased.The control of electrical parameters in MAO plays an important role in the coating growth rate and phase composition. The more energy density acts on theceramic coatings using positive half wave and stronger currents, faster the coatings grow and harder the coatings are.The different solutions influence the growth rate, surface morphology and phase composition of the coatings. But the porosity and corrosion-resistance are not influenced. The micro-arc oxidation is super to hard anodic oxidation in anti-wear and corrosion-resistance.更多还原