NSF-EC Activity: Dynamics of Layered, Multifunctional Surfaces

摘要：0099695 Univ. Santa BarbaraCarlos G. LeviA多学科科学团队将开展一项合作计划，研究分层多功能表面的动力学。重点是为热结构部件提供隔热和氧化/腐蚀保护的涂层系统。首要的智力挑战是建立一个基于科学的协议，以优化功能，同时整合热机械和热化学不同的材料，经历大的温度极端。这些系统本质上是亚稳态的，并通过形态变化、扩散相互作用和热机械诱导应力而发展，这些通常会降低性能并限制耐久性。该计划的目的是发展的基本机制，可以为设计上级，耐用的表面提供基础的基本理解。科学主题涉及氧化物和金属间化合物之间的相平衡，氧化物中的扩散和热传输现象，变形的基本机制和氧化物生长的基本机械方面。具体目标是阐明（a）组成对萤石结构氧化物中表面扩散机制以及金属间化合物中边界扩散机制的作用;（B）与化学和微观结构有关的各个层的热机械行为，以及与它们相互作用有关的复杂性;（c）通过微观结构修改的工艺和材料参数之间的相互作用;和（d）多孔多组分氧化物中的热输运机制。感兴趣的材料系统是基于氧化锆和稀土氧化物的陶瓷，以及与铂族金属合金化的镍基金属间化合物。合成技术主要是基于蒸汽的，在生成模型样品中使用前体方法和熔融加工。热力学，动力学和力学建模活动将是实验活动的重要补充。该计划提供了一套平衡的教育，科学和技术利益。技术动机来自于扩展结构材料的极限和耐久性的驱动力，其中耐用的多功能表面代表了最高优先级的材料挑战。这些材料系统对于提高燃气轮机的效率和减少对环境的影响至关重要，燃气轮机是全球电气化、飞机和海上运输以及众多工业过程的主要动力来源。因此，社会和经济效益是不言而喻的，但目前由于科学认识不足，无法指导材料设计、加工和性能的必要改进，因此受到限制。与这些层的动态相关的基本问题的复杂性和丰富性提供了科学的动机，以及需要一个跨学科的研究方法。该团队集合了前所未有的专业知识和可用设施来进行这项研究。他们都密切参与与学生的工作，并由NSF-EC计划提供的独特的教育机会的动机。因此，这些项目将被定义为促进美国和欧洲学生之间的合作。将为共同研究某一专题的学生提供扩大互访的机制，以亲身体验伙伴机构是如何进行研究的。通过在一个广阔的

Abstract: 0099695Univ. of Santa BarbaraCarlos G. LeviA multidisciplinary scientific team will undertake a collaborative program to investigate the dynamics of layered, multifunctional surfaces. The focus is on coating systems that provide both thermal insulation and oxidation/corrosion protection for thermostructural components. The overarching intellectual challenge is establishing a science-based protocol for optimizing functionality while integrating thermomechanically and thermochemically disparate materials that experience large temperature extremes. These systems are inherently metastable and evolve via morphological changes, diffusional interactions and thermomechanically-induced stresses that generally degrade performance and limit durability. The program aims to develop a fundamental understanding of the underlying mechanisms that could provide a basis for designing superior, durable surfaces. The scientific themes involve phase equilibria between oxides and intermetallics, diffusive and thermal transport phenomena in oxides, fundamental mechanisms of deformation and basic mechanistic aspects of oxide growth. Specific objectives seek to elucidate (a) the role of composition on the mechanisms of surface diffusion in fluorite-structured oxides, as well as boundary diffusion in intermetallics; (b) the thermomechanical behavior of individual layers, as they relate to chemistry and microstructure, and complexities associated with their interaction; (c) the interplay between processing and material parameters via microstructural modifications; and (d) the mechanisms governing thermal transport in porous multicomponent oxides. The materials systems of interest are ceramics based on zirconia and rare earth oxides, as well as Ni-based intermetallics alloyed with platinum group metals. The synthesis technologies are predominantly vapor-based, with precursor methods and melt processing used in generating model specimens. Thermodynamic, kinetic and mechanics modeling activities will be an essential complement of the experimental activities.The program offers a balanced set of educational, scientific and technological benefits. The technological motivation derives from the drive to expand the limits and durability of structural materials, wherein durable multifunctional surfaces represent a materials challenge of highest priority. These material systems are essential to the pursuit of improved efficiency and reduced environmental impact for gas turbines, a predominant source of power for global electrification, aircraft and marine transportation, as well as numerous industrial processes. The societal and economic benefits are thus self-evident but are presently limited because of insufficient scientific understanding to guide needed improvements in materials design, processing and performance. The complexity and richness in fundamental issues associated with the dynamics of these layers provide the scientific motivation as well as the need for an interdisciplinary research approach. The team assembled has an unprecedented combination of expertise and available facilities to undertake this research. They are all closely involved in working with students and motivated by the unique educational opportunity afforded by the NSF-EC program. Accordingly, the projects will be defined to foster collaboration among American and European students. Mechanisms will be provided for extended reciprocal visits of students working together on a given topic, to experience first hand how research is done at the partner institution. By working on a broad