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MAE GRADUATE SEMINAR Self-Health Monitored Thermal Barrier Coating (TBC) Designs with Increased Reflectivity and Lower Thermal Conductivity for High Temperature Turbine Applications December 13, 2006, 1:00 PM, Room 355 ESB Jogender Singh** Applied Research Laboratory, The Pennsylvania State University, University Park, PA 16802 ABSTRACT Future thrust in turbine industry is designing and developing next generation thermal barrier coating (TBC) with lower thermal conductivity, increased reflectivity, and increased performance through nano-layered structures, microstructural modifications and rare-earth dopants for health monitoring and life prediction. A novel approach was investigated to introduce periodic strains in the form of microporosity within the columnar microstructure of ZrO2-8wt.%Y2O3 (YSZ) by periodically interrupting the condensing vapor reducing its thermal conductivity and increasing hemispherical reflectivity. The microstructural modification resulted in improved oxidation cyclic life (over 100%), 20-30% reduction in the thermal conductivity, 28-56% increase in hemispherical reflectance, and better strain tolerance as compared to standard YSZ. In addition, coatings consisting of multiply alternating nano-layers of Al2O3 and YSZ were applied in a one-step evaporation process that showed significant improvement in hemispherical reflectivity at 1 m. Changing the individual thickness of the Al2O3 / YSZ multi-nanolayered structure showed an increase in thermal reflectance over the range of wavelengths (i.e., temperature ranges) that will allow higher combustion temperatures, and thus increased efficiency. Lastly, TBC with luminescent properties offers non- intrusive evaluation techniques in monitoring and predicting TBC life. Incorporating rare-earth doped luminescent sublayers within the YSZ allows early detection of erosion and spallation which can lead to premature thermal barrier coating failure. All coating development effort was performed as one step process in industrial scale EB-PVD facility at Penn State University. ** Dr. Jogender Singh, Chief Scientist, Materials and Manufacturing Division, Applied Research Laboratory, Professor of Materials Science and Engineering and Engineering Science and Mechanic Departments, The Pennsylvania State University with over 170 publications, 7 patents and numerous awards. Dr. Singh is one of the top 214 highly cited researchers in the field of materials science in the world as published by the Institute for Scientific Information (ISI). Dr. Singh is a Fellow of three professional societies including American Society for Metals (ASM) International, American Association Advancement of Science (AAAS) and Institute of Materials (FIM), London. He is recipient of 1997R&D100 award.
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