Thermal Barrier Coatings for High Temperature Turbine Systems

Featuring Matthew D. Weeks
Ph.D. candidate
Chemical Engineering and Materials Science
The Henry Samueli School of Engineering, UC Irvine

Location:  PCB 1200
Free and open to the public

Abstract:
Gas turbine engines are a staple of 21st century air and sea propulsion systems and are also a critical component in large-scale electricity generation. The hot-section components of these engines are protected by a complex ceramic and metal multi-layer coating called a thermal barrier coating (TBC) system. The failure of TBC systems occurs as a result of both thermo-chemical and thermo-mechanical degradation. This research involves exploring both of these mechanisms for two distinctly different issues. The United States Navy is currently making a push to implement the use of alternative fuels by 2012, but the use of these fuels (syngas, high hydrogen content, and alternatives to JP-8) presents significant materials durability challenges. Initial data suggests that high water vapor levels, high sulfur concentrations, and ash deposits from fuel impurities lead to unique, and severe, degradation modes. This talk will address the effects of differing combustion environment characteristics on TBC systems. On the industrial front, there is an constant driver to better understand and predict coating failure, particularly in air-plasma sprayed (APS) TBC systems. The morphology of the BC–TBC interface is known to play a key role in the generation of compressive and tensile stresses that eventually cause coating failure in typical engine environments. In direct contradiction to this understanding, experimental and field experience have shown that a tortous interface is generally beneficial to coating lifetime. Nevertheless, for the past 40 years engineers have struggled to find a functional correlation between BC topology and coating system lifetime. This talk will also address the progress being made toward the estabilishment of this functional correlation.

About the Speaker:
Matthew Weeks is a fourth-year chemical engineering and materials science Ph.D. student in The Henry Samueli School of Engineering at the University of California, Irvine. He received a B.S. degree in chemistry with minors in physics and mathematics at the University of Redlands in 2006, and an M.S. degree in materials science and engineering at UC Irvine in 2007. His research at the University of Redlands crossed boundaries between chemistry and physics, manipulating the properties of visible light to measure chemical phenomena. Weeks’ primary focus at UC Irvine is on using optical profilometry and scanning electron microscopy (SEM) to study the oxidation, thermal-stress, and microstructural evolution of thermal barrier coating systems in extremely aggressive environments.