An interdisciplinary academic/industry team has been convened to perform research on fundamental aspects of layered multifunctional systems used for the thermal and environmental protection of gas turbine components. These material systems offer quantum-leap improvements in engine efficiency with attendant benefits to the economics and environmental impact of the national energy and transportation sectors, as well as to the global competitiveness of the US industry. Fulfillment of this promise is currently hindered by inadequate understanding of how these multi-material non-equilibrium systems evolve over time upon exposure to one of the harshest environments encountered in modern technology. The research team aims to advance this understanding by focusing on the fundamental connections between the chemistry, internal structure and morphology of the layers and interfaces, their evolution over time, the impact on properties and the relevance to mechanisms that eventually compromise the integrity of the system and lead to failure. The program provides unique educational opportunities by (i) motivating students to learn the scientific foundation of their discipline within the context of a technologically important problem, (ii) working as members of an interdisciplinary team that includes scientists from a world leading company in this area (General Electric) collaborating with academics with diverse background and expertise, and (iii) having access to internships at a premier corporate research center (GE-Global Research). As research becomes increasingly global, it is deemed invaluable for students to have experiences in doing research abroad. This program offers such opportunities at collaborating institutions in Europe, Latin America and Pacific Rim countries, including GE-GRC in Bangalore. The program will benefit from the excellent outreach infrastructure of the participating universities, and the proven record of the investigators involving undergraduates and members of underrepresented groups in their research. The fundamental nature of the program, its prospective impact on a technology of critical importance to the US economy, and the educational enrichment experiences available to students are fully consistent with the goals of NSF and its sponsoring programs. TECHNICAL DETAILS: The overarching objective of this program is to develop a fundamental understanding of the dynamics of structure evolution in layered systems subject to the extreme environments typical of gas turbine engines, and how these influence system performance. Establishing the fundamentals governing the physico-chemical phenomena within and between layers will enable the design of improved protection concepts for next generation turbine systems that operate at higher temperature. The information generated will also facilitate validation and refinement of system-level models used for design and durability assessments. The research aims to distil phenomena having crucial impact on a technologically important system by integrating component/layer functionalities with the evolutionary processes that lead to their degradation. Because of the complexity of the system and the scale of the layers, new high-resolution probes occupy a central role. Scientific advances are envisaged within the following five themes. (a) Phase evolution in refractory oxides caused by the decomposition of metastable phases and of clustering in multi-doped systems. (b) Surface diffusion in oxides, including its dependence on dopants, and its effects on the sintering of textured columnar structures. (c) The evolution of stresses and deformations induced by the thermal growth of alumina. (d) The effects of inter-diffusion between layers on phase evolution, on volumetric strains and on stress-inducing transformations; including the behavior of structurally compatible diffusion barriers. (e) The effects of structural evolution on the critical properties, especially the toughness of the various layers and interfaces, the constitutive behavior at high temperature, and the optical and thermal properties of the oxides. Projects are designed to foster collaboration, especially among students and post-docs, and to promote co-advising. Extramural experiences, especially at GE-GRC, allow students to have access to unique facilities and the interaction with industrial scientists contributes to developing an appreciation of how their dissertation research contributes to the overall effort and the progress of the field. FUNDING: This project is co-funded by the Office of International Science and Engineering, the Engineering directorate, and the Ceramics Program within the Mathematical and Physical Sciences directorate.
