铝阳极氧化膜介孔内超声电沉积与孔结构调控及其光谱干涉彩色着色机制研究

This research is aimed to develop a new “two-step” ultrasonic electrolytic coloring process for the anodized aluminum alloy，avoiding the performance deterioration caused by the pore enlargement of the conventionally three-step method. Through the Alternating Current and the Direct Current changes of the power supply, these two steps, the pore structure modification and the electro-deposition of the Sn-Ni metal particles in the mesopores of the oxide film, could be finished in the same electrolyte solution without using the phosphoric acid solution for the pore enlargement of the anodic oxide film. A broad range of colors within the visible spectrum can be obtained by the light interference between this two cleverly designed interfaces of the aluminum substrate/the barrier layer of aluminum oxide and electrolytically deposited metal layer/porous layer of aluminum oxide, according to the Bragg Law. An ultrasonic device will be designed to improve the electrolyte diffusion and the heat diffusion in the mesopore with high ratio of depth to width for easing the local thermal effect and the oxide film chalking problem of the oxide pores while improving the electro-deposition layer uniformity and the color reproducibility. This research will analyze the deposited metal particles morphology, structure and distribution in the pores, and learn the discharge and deposition behaviors of Ni2+/Sn2+ in the mesopores as well as the pore enlargement effect under the assistant of ultrasonic vibration. It will understand the light interference mechanism and the electrolytic coloring law in a broad range colors within the visible spectrum. Finally the established electrolytic coloring modulation will be verified with the multi-physical field simulation software. This new surface treatment technology, which will improve the coloring range, the weather ability and corrosion resistance of the colored anodized aluminum alloy used in the products of electronics, transit equipment, instrument and others, can also be applied to fabricate the metal / alumina composite film for iridescent material, solar thin film, optical devices , etc.

项目提出发展铝阳极氧化膜的“两步法”超声彩色电解着色新方法，避免传统“三步法”电解着色磷酸扩孔带来的性能劣化问题，在同一电解质溶液通过电源输出变换实现对氧化膜微纳结构的精细调控，构建满足布拉格定律的基材/阻挡层与沉积金属层/多孔氧化膜两个反射界面，实现可见光全光谱范围内彩色氧化膜的可控制备；还提出采用超声波辅助外场方法，强化高深宽比介孔内的溶液传质与散热过程，旨在解决孔内局部热效应与氧化膜粉化问题，提高电沉积层均匀性与颜色重现性。项目将揭示低频超声波作用下Ni2+/Sn2+在介孔内的传质、共沉积与结晶以及孔结构调控规律，发现介孔内多层精细结构与特征颜色的物理学定量关系；并对呈色模型进行仿真分析验证，提出可见光谱范围内的光谱干涉作用机理，为铝氧化膜的多色化可控着色提供理论支撑。该方法可用于制备电子电器、交通装备、仪器仪表的高耐候铝氧化膜，还可制备基于铝氧化膜的发光材料、太阳能薄膜、光学器件。

项目针对铝表面处理有机染料着色耐候性差、传统电解着色颜色单一等问题，研究在单一电解质溶液中制备彩色氧化膜的方法，避免磷酸扩孔带来的孔内污染问题，开展了复合有机酸与超声外场对铝阳极氧化膜成膜影响规律、电解着色溶液体系设计、Ni-Sn络合离子在氧化膜孔内的共沉积行为、孔内成分与微观结构、氧化膜光谱特性与光学干涉效应、孔内结构与颜色的物理学关系及着色机理、阳极氧化膜的环保型无镍封孔机理与耐蚀性能、阳极氧化铝光子晶体基结构色涂层的颜色调控规律等研究。.研究发现添加复合有机酸可将铝阳极氧化温度窗口扩展到20-30℃，超声外场能够减少氧化膜热敏感性并提高成膜质量。Ni-Sn金属离子在氧化膜高深宽比介孔的沉积反应由扩散速度所控制，超声辅助能够加快离子扩散，增大稳态电流密度，Ni2+不参与金属离子的析出反应，孔内沉积物由SnOx/Sn和SnO2组成。通过输出电源变化可以在单一电解质溶液中制备出具有三层微结构的彩色阳极氧化膜。氧化膜内形成了两个反射面，一为硫酸氧化层/中间反射层界面，第二为底部颜色调整层/铝合金基底，入射光分别在该两个反射界面形成反射光。测量出了用于理论计算和模拟的彩色氧化膜基本物理参数，通过布拉格干涉公式计算出的干涉增强波长和氧化膜反射峰波长具有一致的变化规律，氧化膜通过布拉格光学干涉增强而着色。使用COMSOL软件模拟出氧化膜的光学干涉着色过程，特征反射峰的模拟结果与实际测量相符。项目还研究了阳极氧化铝光子晶体基结构色涂层的纳米结构调控与光谱特性，伪正弦脉冲阳极氧化可制备出具有周期性微结构特征的AAO光子晶体材料，孔内进一步交流电沉积Sn金属粒子可以得到颜色可调控的氧化铝光子晶体基结构色涂层。还发现碱土金属盐封孔与镍盐封孔阳极氧化膜均具有较好的耐腐蚀性能。. 本项目研究的铝阳极氧化膜彩色着色方法可赋予铝氧化膜表面良好的装饰性与耐候性，在建筑型材、交通工具、电子产品、产品包装等表面处理以及光学薄膜、光学材料或元件具有重要应用前景。