Transient thermo-mechanical interactions during slip at dissimilar material interfaces under extreme conditions.

摘要对具有耐磨滑动界面的先进摩擦系统的需求遍及当前技术、新兴技术以及可预见的未来的许多技术。无论是在前台，如高温燃气涡轮发动机的设计，高可靠的导航和跟踪系统的开发，以及磁存储设备的性能，还是在后台，如在聚变反应堆中使用，滑动界面摩擦学对技术的成功起着至关重要的作用。更好地理解这些恶劣条件下物质相互作用的物理学，有望导致更有效的摩擦系统的发展，这将在许多方面使我们的社会受益。在拟议的调查中，我们寻求利用我们在板冲击压力-剪切摩擦实验和扭转科尔斯基杆摩擦实验的发展过程中获得的经验，以更好地理解技术上重要的材料界面在极端条件下的行为。将对这些结构进行关键修改，以便更直接地访问摩擦界面，以便使用高速数字摄影和热成像系统直接测量局部关键界面量。通过这种方式，这些实验不仅可以提供界面牵引力和滑移历史等量的信息，还可以提供摩擦学界面附近关键的局部热-力学相互作用的信息。感兴趣的界面量包括但不限于局部塑性应变、塑性应变率、温度分布、第三体形成和生长的细节、熔融界面层形成和生长的动力学，以及摩擦对界面上强烈的局部热-力学相互作用期间产生的滑移波的细节。详细的光学和扫描电子显微镜以及原子力显微镜将被用来检查在滑移过程中摩擦对表面拓扑结构的微观和/或纳米变化。此外，x射线衍射和荧光（EDS）将有助于我们理解在滑动界面及其附近发生的复杂化学/机械相互作用过程中微观结构和材料转移的变化。在进行实验研究的同时，还将对实验进行有限元模拟，以便将实验观测结果与我们目前对高速滑移现象的理解联系起来。所提出的方法是创新和新颖的，需要相当大的实验和计算挑战。它代表了与过去研究动态摩擦的实验程序的显著背离。该建议预计将通过以下方式对加强我们的国家能力做出重大贡献：(a)促进发展极端条件下高速滑动行为表征的实验方法，(b)扩展我们目前对技术上重要的材料界面高速滑动过程中关键机制的理解。(c)在重要的技术领域培养固体力学和材料科学相结合的研究生。

ABSTRACTThe need for advanced tribo-systems with wear resistant sliding interfaces pervades current technology, emerging technology, and much of the technology of the foreseeable future. Whether in the foreground, as in the design of high-temperature gas turbine engines, the development of highly reliable navigational and tracking systems, and the performance of magnetic storage devices, or in the background, as used in fusion reactors, tribology of sliding interfaces play a critical role in the success of the technology. Better understanding of the physics of material interaction under these harsh conditions is expected to lead to the development of more efficient tribo-systems would benefit our society in many ways.In the proposed investigation we seek to capitalize on our experience gained during the development of the plate-impact pressure-shear friction experiments and the torsional Kolsky bar friction experiments, to better understand the behavior of technologically important material interfaces under extreme conditions. Key modifications will be made to these configurations in order to provide a more direct access to the frictional interface such that local critical interfacial quantities can be directly measured by using high-speed digital photography and thermal imaging systems. In this way, these experiments will not only provide information on quantities such as interfacial tractions and slip history, but also on key local thermo-mechanical interactions in the vicinity of the tribological interface. Interfacial quantities of interest include but are not limited to local plastic strains, plastic strain rates, temperature profiles, details of formation and growth of third body, kinetics of formation and growth of molten interfacial layers, and the details of slip-waves generated during the intense local thermo-mechanical interactions at the tribo-pair interface. Detailed optical and scanning electron microscopy along with the atomic force microscope will be used to examine the micro- and/or nano- changes in the topology of the tribo-pair surfaces during the slip process. In addition, X-ray diffraction and flourescence (EDS) will be employed to contribute to our understanding of the changes in the microstructure and transfer of material during the complex chemical/mechanical interactions that occur at and near the sliding interfaces. Along with the experimental study finite element simulations of the experiments will be conducted to correlate the experimental observations with our present state of understanding of the high-speed slip phenomena.The proposed approach is innovative and novel and entails considerable experimental and computational challenges. It represents a marked departure from experimental procedures to investigate dynamic friction in the past. The proposed is expected to contribute significantly towards strengthening our national capability by (a) contributing to the development of an experimental methodology for characterization of high speed sliding behavior under extreme conditions, (b) extending our present state of understanding of critical mechanisms operative during high-speed slip at technologically important material interfaces, and (c) by training graduate students at the interface of solid mechanics and materials science in technologically important areas.