Effect of doping on the microstructure and properties of zirconate-based emerging thermal barrier coating materials

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Modern gas turbines employ thermal barrier coatings (TBCs) to protect the hot section components from reaching excessive temperature. The use of TBCs can reduce the temperature on the metal surface by as much as 300°C, thereby allowing for higher gas turbine operating temperatures and achieving increased engine fuel-efficiency and thrust-to-weight ratio while reducing emissions and extending component life. The demand for ever increasing operating temperature dictates the need for continuous research into new and improved TBCs. Since TBCs are an integral part of a multiple layered system, they must satisfy many stringent thermal, physical, and mechanical property requirements in order ensure designed component life. The current and several emerging ceramic materials are not able to satisfy all the requirements. One of the solutions being proposed to mitigate many of these deficiencies is the modification of the TBC materials through doping (similar to alloying in superalloys). As such, the objective of the proposed research program is to advance our basic understanding of the relationship between dopant addition and the resulting microstructure and thermal, physical, and mechanical properties of current and emerging thermal barrier coating materials. The knowledge obtained from this research will provide the foundation on which to engineer the microstructure and optimize the properties through composition selection. Making use of a systematic approach to evaluate the doping effect, this research will provide a scientific basis on which a much wider variety of dopants may be selected for performance improvement, and expand our material choices beyond the limits of existing material types.