This Broadening Participation Research Initiation Grants in Engineering (BRIGE) award provides support to meet goals to control and enhance the durability of high temperature ceramic coating systems or thermal barrier coatings for advanced turbine technology. Advances in high efficiency power generation systems that produce lower emissions must be accompanied by enhanced durability of these coatings to higher turbine temperatures and fuel impurities. This will be achieved through in-depth studies on degradation mechanisms from thermo-mechanical and contaminant environments, leading to the development of mitigation solutions. Recent advances integrating high-resolution synchrotron X-ray diffraction and piezospectroscopic techniques in situ with operational environments will be utilized to study the evolution of strain within the multilayered high temperature ceramic coatings. Selected mitigation solutions, with a focus on overlay coatings to prevent contaminant infiltration, will be explored to assess effects on the strain compliance of the multi-layer coating system. The outcome of the novel studies will unravel the immediate and long-term effects of thermo-mechanical environment and contaminants on the coating compliance and life. Results will enable mitigation through material and process modifications, to achieve durability and reliability of these coatings for energy applications.
The significance of the proposed work is in the potential for enabling a new class of ceramic coatings applicable to the clean and efficient operation of turbines with alternative fuels. Through the advancement of high temperature coatings to meet these operating environments, the research has far reaching societal benefits in achieving reliability and energy efficiency goals for the next generation turbine technology. Research goals will be integrated with efforts aimed at broadening participation and encouraging early interest in engineering research through unique research experiences at a synchrotron facility as well as mentoring.
Researchers from the University of Central Florida investigated the mechanisms controlling durability of ceramic coatings that protect aircraft engines from the extreme environments they encounter with every flight. Successful efforts in the replication of the complex operating conditions of turbine coatings under extreme temperatures of 1,000°C, while simultaneously capturing the in-cycle mechanics of material response using synchrotron x-rays, have validated current views of high-temperature relaxation. The real-time measurements also captured the strain variations at the interface between the superalloy blade and the coating showing their individual dependencies on thermal gradients and mechanical loads. Studies on ingression of impurities such as sand and its effect on the coating strains have revealed that these thermomechanical effects are less critical than published outcomes on thermochemical effects for the coatings tested. These results will be used to develop more accurate models and close the design loop in creating more durable coatings by adjusting the processing parameters and optimizing material choices. The pioneering efforts present a game-changing approach to the study of materials under extreme environments in general - it takes high temperature materials testing to the next level. Broader societal benefits lie in the future creation of a new class of high temperature ceramic coatings for next generation energy and propulsion needs. The research success was achieved while providing opportunities for graduate students and undergraduate students to experience advanced research opportunities and facilities through collaboration with scientists at the Argonne National Laboratory and at the German Aerospace Center. The experiences opened new doors for student success and the extensive outreach through experimental visits at the synchrotron, presentations at undergraduate and graduate forums and formal mentoring efforts had a broader impact on a diverse student population including women and minorities.