NSF-EC Activity: Dynamics of Layered, Multifunctional Surfaces

摘要：0099695大学。圣巴巴拉大学的卡洛斯·G·莱维亚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。最主要的智力挑战是建立一个基于科学的协议，用于优化功能，同时集成经历极高温度的热机械和热化学不同的材料。这些系统本质上是亚稳定的，并通过形态变化、扩散相互作用和通常会降低性能和限制耐用性的热机械诱导应力而演变。该计划旨在发展对潜在机制的基本理解，为设计优质、耐用的表面提供基础。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、变形的基本机制以及氧化物生长的基本机制方面。具体目标力求阐明：(A)组成对萤石结构氧化物的表面扩散机制以及金属间化合物的边界扩散机制的作用；(B)各层的热机械行为，因为它们与化学和微观结构有关，以及与其相互作用有关的复杂性；(C)工艺参数和材料参数之间通过微结构修改的相互作用；(D)控制多孔多组分氧化物中热传输的机制。感兴趣的材料系统是以氧化锆和稀土氧化物为基础的陶瓷，以及由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，前驱体方法和熔融处理用于生成模型样品。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、科学和技术效益。技术动机来自于扩大结构材料的极限和耐用性的努力，其中耐用的多功能表面代表着最优先考虑的材料挑战。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、飞机和海运以及许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，但目前是有限的，因为科学认识不足，无法指导在材料设计、加工和性能方面所需的改进。与这些层面的动态相关的基本问题的复杂性和丰富性提供了科学动机以及跨学科研究方法的必要性。组建的团队拥有前所未有的专业知识和可用的设施来进行这项研究。他们都密切参与与学生的合作，并受到NSF-EC项目提供的独特教育机会的激励。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。将提供机制，让学生就特定主题共同工作，扩大互访，亲身体验合作机构是如何进行研究的。通过在一个宽阔的

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