Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Hertzian Fracture in Ceramics and Ceramic Coatings" By Nesredin F. Kedir Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Weinong W. Chen ABSTRACT Advancement of gas turbine technology requires improvements in both cycle efficiency and overall performance. Much of the limitation, in this regard, emanates from the hot-section of the engine where a significant amount of thermal energy from combustion is wasted as exhaust. A promising approach to negate such loss considers substitution of standard Nickle-based superalloy components with advanced high-temperature ceramics. However, the inherent brittle nature of this material class has been shown to accentuate the effectiveness of impact damage by foreign debris. Hence, development of a robust semiempirical understanding of the process by which impact damage promotes failure becomes essential in accelerating ongoing technology transition efforts. A pervasive impact damage mechanism that is observed in both engine grade ceramics and coatings is Hertzian fracture. Subsequently, the underlying theory of Hertzian contact is presented with accompanying relations to observed quasi-static and dynamic fracture processes in glass, structural ceramics and ceramic coatings. Knowledge gaps in the dynamic loading regime are also discussed. Finally, progress on the development of an in-situ characterization method for observing impact induced fracture is offered. Date: Thursday, January 18, 2018 Time: 1:30 P.M. Place: ARMS 1028