Materials Challenges for the Next Generation Thermal Protection Coatings

Speaker

David R. Clarke

School of Engineering and Applied Sciences, Harvard University

About This Talk

One of the major successes of materials has been the development of thermal protection systems for high-temperature gas turbines. These have enabled superalloy components to operate in the presence of combusted gases whose peak temperature can exceed the melting point of the alloys. For the last twenty-five years, the ceramic material of choice as a thermal barrier coating has, and continues to be, yttria-stabilized zirconia containing 8 weight percent yttria (8YSZ). In the pursuit of ever higher operating temperatures to enable higher efficiency there is a need for an oxide coating that can sustain higher operating temperatures than 8YSZ. With increasing gas temperatures, the thermal barrier coating must also block radiative heat transport from the combusted gas as well as minimize thermal conduction to the underlying metal alloy blades. Thermal protection against combined thermal conduction and thermal radiation is also a challenge in other areas of aerospace and hypersonic. Currently, no existing oxide has the combination of low thermal conductivity, adequate fracture toughness, high temperature stability, thermal radiation protection in the near and mid-wave infra-red required. In this Special Lecture, presented jointly by the Departments of Materials Science and Engineering and Aeronautics and Astronautics, Clarke will discuss how he and his team are making use of various materials design strategies to meet these challenges to enable even higher operating temperatures of the next generation engines and vehicles.
 

Biography

David Clarke is the inaugural holder of the Extended Tarr Family Professorship of Materials and Applied Physics at Harvard University and recently stepped down as Area Chair for Mechanical Engineering and Materials Science in the School of Engineering and Applied Sciences. He currently teaches the required undergraduate course on “Fundamentals of Heat Transfer” course (ES183) for students studying Mechanical Engineering at Harvard as well as the elective course on “Materials Selection” (ES 192). He has taught Freshman seminars on “Glass” and on “Materials, Energy and Society.” Before joining Harvard, he taught a variety of undergraduate and graduate level courses in materials, ranging from introductory classes to courses in phase equilibria, optical materials, phase transformations, thermodynamics and composites.

Clarke received his bachelor’s degree in applied science from the University of Sussex, England in 1968 and joined the National Physical Laboratory (NPL) in the UK as a scientific officer. He completed his doctoral degree in 1974, from the Cavendish Laboratory, University of Cambridge and rejoined NPL to work on fiber composites. In 2009, Clarke was appointed as Gordon McKay Professor of Materials and Applied Physics at Harvard University, and is now the Extended Tarr Family Professor of Materials and Applied Physics.