【作者】 刘哲；

【导师】 唐子龙；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 本文采用一种新型的铝合金“绿色”着色工艺,即室温条件下,用电化学方法,在对环境无污染的介质中对铝合金进行着色处理。在0.2mol/L NaOH溶液中应用直流电解着色法制备了黄绿色、橙色、黄褐色、灰色和深绿色膜。研究了在0.2mol/L NaOH溶液中直流电解着色工艺,电压低、着色时间短不能得到着色膜,电压高、着色时间长又会造成着色膜厚度不均。通过对比着色电压、着色时间对着色膜耐蚀性能的影响,初步确定了最佳工艺参数:电压幅值为5.0V、着色时间为4min。此工艺下得到的着色膜表面均匀,耐磨性、结合力及耐热性都很好。采用多种电化学测试技术包括动电位扫描法、恒电位阶跃法、和电化学阻抗谱(EIS)等方法研究了着色膜的耐蚀性能。并结合表面分析技术研究了制备工艺对膜层结构的影响,进而探讨膜层成分、结构对着色膜耐蚀性能的影响。铝合金着色膜在强酸性介质中的阳阴极Rp分别为12kΩ·cm2和5 kΩ·cm2,在碱性介质中阳阴极Rp大约都是70kΩ·cm2,比未着色的铝合金在相应介质的耐蚀性有较大提高。在弱碱性介质中能承受长时间浸泡达1000h;在中性介质中承受浸泡达1000h以上。着色膜在含有Cl-的中性介质和酸性介质中耐点蚀性能都较好,而且比着色前的铝合金耐点蚀性能明显提高。采用环境扫描电子显微镜、X射线衍射仪等设备研究了着色膜的表面形貌、成分和结构。着色膜层中富含氧,主要成分为铝的氧化物或水合物,还有少量的铜、镁、铁、锰等元素。着色膜厚度大致在5μm左右,比天然氧化膜厚很多。在碱性溶液中使用时,合金元素的氧化物不易溶解,所以此着色膜在碱性介质中的耐蚀性极好。合金氧化物颗粒的弥散分布在一定程度上也提高了着色膜的结合力和硬度。更多还原

【Abstract】 A new technology, environmentally friendly process, was developed for aluminum alloy coloring. A serial of colored films were prepared by applying constant-current electrolytic coloring in 0.2mol/L NaOH solution. The color serial contained yellow-green, orange, tan, gray and bottle green.During the coloring, the coloring voltage and time dependence of corrosion resistance for colored films were analyzed to confirm optimum parameters with potential amplitude of 5V and 4 min. The colored film obtained was uniform, good wear-resistant, binding force and heat resistance.Corrosion resistances of colored films were evaluated by multi-electrochemical techniques including potentialdynamic, and electrochemical impendance spectroscopy. And microstructure and composition was investigated by surface analysis technology and correlation of film structure and corrosion resistance of films is studied. Rp of anodic and cathodic colored film were 12 kΩ·cm2 and 5 kΩ·cm2respectively in strong acidic media, and both about 70 kΩ·cm2 in strong alkaline media. Colored films can hold good corrosion resistance for 1000h in weak alkaline media and more than 1000h in neutral media. Colored films show good pitting corrosion resistance in both neutral and acidic Cl- contained media. Corrosion resistance of Al alloy had improved after being colored in corresponding media. Surface morphology, elements, microstructure and properties were studied by means of met allograph, Scanning electron microscopy and X-ray Diffraction. The chemical composition of colored film was mainly Al, O, and essential component was oxide and hydrate of aluminum, plus some alloy elements, like Cu, Mg, Fe and Mn. The thickness of colored film was about 5μm, which was thicker than that formed in natural oxidation film.Oxide of alloy elements had a low dissolvability in alkaline solution, so corrosion resistance of colored films was excellent in it. Dispersion distribution of alloy oxide enhanced binding force and hardness in a certain extent.更多还原