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MSE Seminar: Dr. David Clarke, Harvard University Title: Materials Challenges for the Next Generation Power and Aerospace Gas Turbines ABSTRACT: One of the major materials successes of the last few decades has been the development of the thermal protection system for high-temperature gas turbines, enabling ever higher efficiencies and performance. For the last thirty years, the material of choice as a thermal barrier coating has been yttria-stabilized zirconia containing 8 weight percent yttria (8YSZ). In its meta-stable phase, it exhibits ferroelastic toughening at high temperatures, a requirement for withstanding long-term cyclic thermal mismatch stresses during service. As the development of even more efficient gas turbines proceeds there is a need for an oxide coating that can sustain higher operating temperatures than 8YSZ. However, no existing oxide has the required combination of low thermal conductivity, exceptional fracture toughness, low optical absorption in the infra red and high temperature stability as well as compatibility with the alumina protective oxide that forms on superalloys at high temperatures. In this presentation, I will discuss the design requirements for the next generation gas turbines as well as the new challenges that coatings must meet to operate at the significantly higher temperatures than today’s engines. This Event is For: Graduate • Faculty
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