Measuring the Surface Energy of Metals through Structure-Property Analysis of Electrodeposition Instabilities

表面能是金属表面最基本和最重要的热物理性质之一，因为它对固体的机械、电、催化和形态特征有很大的影响。这些性质对于理解腐蚀、催化行为、在固体基质上的吸附和晶体形成都很重要。表面能的测量被认为是一个重要的参数，几十年来一直困扰着研究人员。该项目旨在发展结构-性能关系，使固体金属在环境温度附近的表面能直接测量成为可能。该方法是基于在微流控通道中金属电沉积期间在阴极上形成的定义良好的模式。电沉积允许高度精确的电位梯度和间距，可以在室温下进行，以获得可靠的模式。这些定义明确的图案与作用在表面上的不同力之间的竞争有关，从而可以确定金属表面的表面能。该方法可以应用于任何已知热物理参数的金属表面，使其能够进行电沉积反应。该项目还包括与当地学校的K-12推广活动，包括课堂演示、夏季研究项目和工程博览会。技术概要金属表面能的实验估计很难获得，并且具有未知量级的不确定性。该项目的目的是直接测量固体金属的表面能，以铜表面为例进行研究。中心假设是，电沉积的不稳定性导致与铜表面的表面能相关的可预测波长的明确的不稳定性模式。该项目利用了测量电沉积过程中单波不稳定模式形成的能力，从而直接测量表面能。表面的不稳定图案是由电沉积过程中结构、电位或浓度的固有扰动引起的，是阴极激发图案的反馈机制的结果。智能选择电极尺寸可以在不稳定开始时形成并检测到单个波形。这些起始条件和伴随模式与固体金属的表面能直接相关，并由耦合输运和反应动力学方程预测。该项目的预期结果是一种直接测量固体金属表面接近环境温度的表面能的方法。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical SummarySurface energy is one of the most fundamental and important thermophysical properties of metal surfaces as it has a strong influence on the mechanical, electrical, catalytic, and morphological characteristics of the solid. These properties are important to understanding corrosion, catalytic behavior, adsorption on solid substrates, and crystal formation. Measurements of the surface energy have been recognized as an important parameter that has eluded researchers for several decades. This project seeks to develop the structure-property relationships that enable the direct measurement of the surface energy of solid metals near ambient temperature. The approach is based on well-defined patterns that form on the cathode during the electrodeposition of metals in microfluidic channels. Electrodeposition allows highly accurate potential gradients and spacings that can be conducted at room temperature to obtain reliable patterns. These well-defined patterns are associated with the competition between different forces acting on the surface, allowing determination of the surface energy of the metal surface. The method can be translated to any metal surface that is capable of electrodeposition reactions in which the thermophysical parameters are known. The program also includes K-12 outreach with local schools, which include in-class demonstrations, summer research programs, and engineering fairs.Technical SummaryExperimental estimates of the surface energy of metals are very difficult to obtain and have uncertainties of unknown magnitude. The objective of this project is to measure directly the surface energy of solid metals using copper surfaces as a case study. The central hypothesis is that electrodeposition instabilities result in well-defined instability patterns of predictable wavelengths that correlate with the surface energy of the copper surface. The project capitalizes on the ability to measure the formation of a single wave instability pattern during electrodeposition thereby leading to the direct measurement of surface energy. Instability patterns at the surface arise from inherent perturbations of structure, potential or concentration during electrodeposition and are a result of a feedback mechanism that encourages patterns at the cathode. An intelligent choice of electrode dimensions enables a single wave pattern to be formed and detected at the onset of the instability. These onset conditions and the companion patterns are directly related to the surface energy of the solid metal and predicted by the coupled transport and reaction kinetic equations. The expected outcome of this project is a direct method to measure the surface energy of a solid metal surface near ambient temperatures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.