Modeling the Formation of Self-Ordered Nanoporous Anodic Oxides

该奖项的研究目标是开发合理设计高度有序多孔阳极氧化膜（PAO）的新方法。 这些膜通过在电化学电池中向金属如铝和钛施加电压而电化学地形成。 该膜包含自有序的纳米级孔的六边形阵列，覆盖宏观区域。 虽然很多注意力都集中在使用PAO作为功能器件的模板，这些结构已经开发经验，在控制膜生长的过程中没有强大的理解。 本研究的目标是开发一个完全预测模型的孔隙形成和自排序。这项工作将指导的概念，即氧化物材料的电场和机械应力的综合影响进行运输。实验应力测量将确定粘性，静电和氧化引起的应力控制界面运动PAO膜的操作平衡。 利用这些知识，运输过程和驱动力的描述将制定为一个预测模拟PAO的增长，揭示电化学极化，浴化学，和动力学的自ordered.If成功的，PAO形成的化学-力学模型之间的关系将提供一个基本的基础，基于模型的设计自组织多孔阳极膜。 因此，该模型可以允许合理操纵的工艺条件，高速率制造无缺陷的薄膜，从而提高太阳能转换，催化和生物医学应用的PAO为基础的功能器件的商业潜力。 学生培训将受益于该项目的独特方面：化学和力学的紧密结合;各种实验和建模方法的严格结合;以及与英格兰材料表征小组的现场合作。 在爱荷华州的学生培训将利用研究生和本科生课程的强大存在，促进代表性不足的群体，无论是在部门和大学的水平。

The research objective of this award is to develop new methods for the rational design of highly ordered porous anodic oxide (PAO) films. These films are formed electrochemically by applying voltages to metals such as aluminum and titanium, in electrochemical cells. The films contain self-ordered hexagonal arrays of nanoscale pores, covering macroscopic areas. While much attention has focused on the use of PAO as templates for functional devices, these structures have been developed empirically, in the absence of robust understanding of processes controlling film growth. The goal of this research is to develop a fully predictive model of pore formation and self-ordering. The work will be guided by the concept that oxide material is transported by the combined influence of the electric field and mechanical stress. Experimental stress measurements will determine the operative balances of viscous, electrostatic and oxidation-induced stress governing interface motion in PAO films. Using this knowledge, descriptions of transport processes and driving forces will be formulated as a predictive simulation PAO growth, revealing the relations between electrochemical polarization, bath chemistry, and the dynamics of the self-ordering.If successful, the chemical-mechanical model of PAO formation will provide a fundamental basis for model-based design of self-organized porous anodic films. Thus, the model may permit rational manipulation of process conditions for high-rate fabrication of defect-free films, thus enhancing the commercial potential of PAO-based functional devices for solar energy conversion, catalysis, and biomedical applications. Student training will benefit from the unique aspects of this project: close integration of chemistry and mechanics; rigorous combination of a variety of experimental and modeling approaches; and on-site collaboration with a materials characterization group in England. Student training at Iowa State will take advantage of the strong presence of graduate and undergraduate programs promoting underrepresented groups, both at the Department and University levels.