GOALI: Adhesion, Lubrication, and Wear of Aluminum

0101840 adams该奖项是GOALI（与行业学术联络的资助机会）资助，支持铝表面粘附，润滑和磨损领域的研究和教育。该GOALI奖涉及与美国铝业公司（ALCOA）和通用汽车公司（GM）的合作研究，并解决影响铝加工和铝零件长期耐用性的基本摩擦学问题。粘附和磨损过程是复杂的，可能涉及许多机制。该项目侧重于三个重要的机制，即金属粘附（当润滑剂和大块氧化物渗透时），润滑剂粘附（如何在高应力和高温下保持表面上的润滑剂）和磨损过程（如何去除材料，以及控制去除的因素）。这项工作有三个主要目标。了解控制金属-陶瓷粘附的因素：在之前的工作中，研究了铝与模型氧化物和模型碳化物之间的界面。密度泛函计算探索了许多可能的界面结构，以确定最有利的一种。PI研究了这些界面的电子结构，使用了态密度、电荷密度、键序、Mulliken居群分析和电子定位函数，当这些结合起来时，对界面上的键合类型有了丰富的理解。PI将把这项工作从模型系统扩展到新的碳化物和氮化物界面，因为这些材料是最有希望成为耐磨涂层的候选者。常见的合金元素（Cu, Mg, Mn， Zn和Si）对附着力的影响将被研究，因为已知它们对附着力和磨损有主要影响。为了支持这项工作，GM将进行实验研究来测量界面粘附能，以便与这些计算结果进行直接比较。研究润滑油边界添加剂是如何与铝表面发生反应并结合的：将这些分子添加到润滑剂中，使其一端与表面结合，而另一端与润滑剂兼容，从而使润滑剂在高应力下保持在表面。以前的工作涉及典型的边界添加剂（醇、羧酸和酯）如何与表面反应和结合的电子结构研究。结合ab-initio分子动力学和几何优化，确定了几种边界添加剂的最佳反应路径和典型产物。该奖项将把先前的研究重点从金属加工添加剂扩展到汽车发动机润滑油添加剂的研究。一套类似的互补模拟和计算将执行，以确定最佳的反应途径和最终结构的典型结合物种。PI还将探索高压缩和剪切载荷如何导致一些界面润滑剂与表面发生反应并软化表面。研究控制纳米压痕和磨损的因素：在之前的工作中，经验MD模拟被用来研究影响纳米压痕的许多因素，包括温度、表面取向、压痕载荷/速度、尖端几何形状和尖端与基底的相互作用。原子尺度的变形机制，包括局部非晶化/熔化和位错成核和运动。对粗糙-粗糙剪切也进行了类似的研究。这些计算得到了通用汽车公司纳米压痕实验研究、美国铝业公司AFM尖端拖曳研究以及通用汽车公司纳米压痕/磨损的连续力学/有限元模型的补充。在这个奖项中，PI计划扩展这些纳米压痕和粗糙-粗糙模拟，包括合金元素（Cu和Mg）的影响，无论是低浓度（固溶体）还是高浓度（沉淀形成），看看它们是如何影响变形机制的。对AFM尖端的拖拽进行了仿真，并与实验结果进行了比较。薄的天然氧化物对表面和边界润滑剂的影响也将被探讨。该奖项是GOALI（与工业界学术联络的资助机会）资助，支持铝表面粘附，润滑和磨损领域的研究和教育。这项研究是亚利桑那大学、美国铝业公司（ALCOA）和通用汽车公司（GM）共同努力的成果，旨在解决影响铝加工和铝部件长期耐用性的基本摩擦学问题。大块铝成形过程中的粘合剂和磨料磨损会限制可施加的应力，损坏加工设备，并影响表面性能，如图像清晰度，点焊性和润滑剂保留性。同样，铝在磨损和润滑方面的改进将使铝在汽车发动机应用中得到更多的应用，从而减轻重量，提高燃油效率、耐久性和性能。该奖项支持使用分子动力学模拟和电子结构工具与工业界就基础和工业利益问题进行互动。结果将在ALOCA和GM实验室进行测试。该奖项为使用材料模拟方法和电子结构理论的研究生提供了一个机会，以解决现实世界的问题，并培养对工业界和学术界有用的技能

0101840AdamsThis award is a GOALI (Grant Opportunities for Academic Liaison with Industry) grant supporting research and education in the area of adhesion, lubrication, and wear of aluminum surfaces. This GOALI award involves collaborative research with the Aluminum Company of America (ALCOA) and General Motors (GM) and addresses fundamental tribological issues that impact aluminum processing and long-term durability of aluminum parts. Adhesion and wear processes are complex, and can involve many mechanisms. This project focuses on three important mechanisms, namely metal adhesion (when the lubricant and bulk oxide are penetrated), lubricant adhesion (how to maintain the lubricant on the surfaces during high stresses and temperatures), and wear processes (how material is removed, and the factors that control that removal). There are three major goals of the work.1. Understand the factors that control metal-ceramic adhesion: In previous work, interfaces between aluminum and a model oxide and a model carbide were investigated. Density functional calculations explored many possible interface structures to determine the most favorable one. The PI investigated the electronic structure of these interfaces, using density of states, charge density, bond-order, Mulliken population analysis, and the Electron Localization Function, which, when combined, give a rich understanding of the type of bonding across the interface. The PI will extend this work from model systems to new carbide and nitride interfaces, as those materials are the most promising candidates for wear-resistant coatings. The effect of common alloying elements (Cu, Mg, Mn, Zn, and Si) on adhesion will be investigated because it is known that they have a major effect on adhesion and wear. In support of this work, GM will carry out experimental studies to measure interfacial adhesion energies for direct comparison with these calculations.2. Investigate how lubricant boundary additives react with and bond to aluminum surfaces: These molecules are added to lubricants so that one end can bind to the surface while the other end is compatible with the lubricant, so that the lubricant is kept on the surface during high stresses. Previous work involved electronic structure investigations of how typical boundary additives (alcohols, carboxylic acids, and esters) react and bond to the surface. A combination of ab-initio molecular dynamics and geometry optimization enabled the determination of optimal reaction paths and typical products for several boundary additive species. This award will extend previous work that focused on additives used for metals processing to investigate additives used for automotive engine lubricants. A similar set of complementary simulations and calculations will be performed to determine optimal reaction pathways and final structures of typical bound species. The PI will also explore how high compressive and shear loads can cause some interfacial lubricants to react with and soften the surface.3. Investigate the factors that control nanoindentation and wear: In previous work, empirical MD simulations were used to investigate many factors that affect nanoindentation, including temperature, surface orientation, indent load/speed, tip geometry, and tip-substrate interactions. Atomic scale deformation mechanisms, including local amorphization/melting and dislocation nucleation and motion, were visualized. Similar studies for asperity-asperity shear were also carried out. These calculations were complemented by experimental nanoindentation studies at GM, AFM tip dragging studies at ALCOA, and GM's continuum mechanics/finite element modeling of nanoindentation/wear. In this award, the PI plans to extend these nanoindentation and asperity-asperity simulations to include the effect of alloying elements (Cu and Mg), for both low concentrations (solid solutions) and high concentrations (precipitate formation), to see how those affect deformation mechanisms. Simulations of AFM tip dragging will be performed and compared with experimental results. The effect of thin native oxides on the surface, and boundary lubricants will also be explored.%%%This award is a GOALI (Grant Opportunities for Academic Liaison with Industry) grant supporting research and education in the area of adhesion, lubrication, and wear of aluminum surfaces. The research is a collaborative effort involving the University of Arizona, the Aluminum Company of America (ALCOA), and General Motors (GM) and addresses fundamental tribological issues that impact aluminum processing and long-term durability of aluminum parts. Adhesive and abrasive wear during bulk aluminum forming limits the stresses that can be applied, damages processing equipment, and impacts surface properties such as image clarity, spot weldability, and lubricant retention. Similarly, improvements in wear and lubrication of aluminum will enable greater use of aluminum in automobile engine applications, allowing weight reduction and increases in fuel efficiency, durability, and performance. The award supports interaction with industry on problems of fundamental and industrial interest using the tools of molecular dynamics simulation and electronic structure tools. The results will be tested at ALOCA and GM laboratories. The award provides an opportunity for graduate students trained in the use of materials simulation methods and electronic structure theory to tackle real-world problems and develop skills useful for industry and academe alike.***