Development of Electrically Mediated Electrophoretic Deposition for Thermal Barrier Coating Systems

The gas turbine engine manufacturing industry is an important aspect of the U.S. commercial economy and critical to both the Departments of Energy and Defense. This project will develop an improved manufacturing process to deposit thermal barrier coating materials to enable operation at higher temperatures in natural gas and synthesis gas environments, while maintaining the necessary durability and reliability required to sustain the engine life expectancy. Specifically, an electrically-mediated electrophoretic process for the deposition of thermal barrier systems will be developed. The process will be easier to control and more cost efficient compared to the more conventional techniques of plasma spray and electron beam physical vapor deposition. In Phase I, an electrically mediated electrophoretic deposition (EPD) process was used to apply thermal barrier coating materials to Inconel 718 substrates. It was demonstrated that electrically mediated EPD could uniformly deposit thermal barrier material sets, including yttria stabilized zirconia and rare-earth-doped yttria stabilized zirconia, and could increase deposition rates compared to conventional industrial processes. Phase II will: (1) optimize and validate the process to permit the introduction of appropriate microstructures, in order to prevent coating failure during standard and accelerated turbine engine operation; (2) develop and validate a post-deposition thermal treatment for the EPD coatings, in order to preserve the microstructure needed to maintain coating durability and reliability during operation; and (3) conduct tests (thermal stability, thermal cycling, thermal conductivity) to determine coating durability and reliability. Commercial Applications and other Benefits as described by the awardee: With the application of thermal barrier coatings composed of new materials, higher operating temperatures should be achieved, which would increase fuel efficiency and reduce waste energy and energy costs.