SGER: Surface Reactivity of Nanostructured Light Weight Metals

技术：本SGER项目将研究衬底微结构对在常温条件下形成的自然氧化膜的结构和电学特性的影响。这一检验旨在检验这样一种假设，即观察到的纳米结构、超细颗粒和正常粗晶金属之间的表面反应性差异是电化学差异的结果，局部表面电荷的变化证明了这一点，这些差异被认为是由于在紧接在高角度晶界上方形成的自然氧化膜区域与在远离这些边界的基材上方形成的非晶膜区域之间的非晶氧化膜厚度和结构的差异所引起的。此外，随着单位体积的晶界表面积随着纳米结构的增加而增加，与表面氧化物表面和电荷相关的基质和晶界之间的差异将变得越来越重要。这些研究的主要智力价值在于注意了解自然氧化膜和衬底之间的直接区域和界面，其长度范围在0.5到2 nm之间，以及这种纳米级结构如何受到衬底微结构的影响，特别是与金属衬底相交的晶界的存在。将使用EFM和HRSEM，前者的长度范围低于以前获得的长度范围。最后，将在该纳米尺度范围内获得的结果与在远离衬底缺陷处获得的结果进行比较。高风险/高回报：风险存在于用于考试的技术的长度范围能力内。所需的EFM和HRTEM程序将在先前获得的边际或更远的范围内运行-EFM在衬底晶界附近应用0.5-2 nm，而HRTEM将检查位于金属衬底上的约0.5-1 nm厚的非晶膜的界面和原子结构。虽然预计可以获得这些限制，但包括场离子显微镜和扫描探针AFM在内的其他方法也在考虑之中。非技术性：这一高风险努力的成功将提供一种途径，以定制衬底结构和化学，以确定表面电荷分布。可以预见，这种知识将导致增强骨整合，利用纳米结构金属作为细胞生长支架，减轻细胞附着的自我修复，改善耐腐蚀性和催化响应，所有这些都不需要依靠表面处理或涂层。

TECHNICAL: This SGER project will examine the role of substrate microstructure on the structure and electrical characteristics of native oxide films formed under ambient temperature conditions. This examination is intended to examine the hypothesis that observed differences in surface reactivity between the nanostructured, ultra-fine grained and normal coarse grained metals arise as a result of electrochemical differences, as evidenced by variations in local surface charge, these believed to arise from differences in amorphous oxide film thickness and structure between regions of native oxide films formed immediate above high angle grain boundaries and amorphous films which are formed above the substrate at distances removed from these boundaries. Furthermore as the grain boundary surface area per unit volume increases with nanostructuring, the differences between matrix and boundaries associated surface oxide surface and charge will become of increasing importance. The primary intellectual merit of these studies resides in the attention given to understanding the immediate region and interface lying between the native oxide film and the substrate, this being at length scales between 0.5 and 2 nm, and how this nanoscale structure is affected by the substrate microstructure, in particular by the presence of grain boundaries intersecting the metal substrate. EFM and HRSEM will be used, the former within a length scale below that previously attained. Finally the results obtained within this nanoscale region will be compared with those obtained at distances far removed from substrate defect. High Risk/High Payoff: The risk resides within the length scale capabilities of the techniques used for the examination. The EFM and HRTEM procedures required will be operating at and beyond the margin previously obtained - EFM being applied at 0.5-2 nm in the vicinity of the substrate grain boundary, while HRTEM will be examining the interface and atomic structure of amorphous films approximately 0.5-1 nm thick lying on a metallic substrate. While it is expected that these limits can be obtained, other approaches including field ion microscopy and scanning probe AFM are also under consideration. NON-TECHNICAL: Success of this high risk endeavor will provide a gateway to tailoring substrate structure and chemistry to define surface charge distribution. It can be envisioned that this knowledge will lead to enhanced osteointegration, utilization of nanostructured metals for cell growth scaffolds, self-healing mitigation of cell attachment, improved corrosion resistance, and catalytic response, all without recourse to surface treatment or coatings.