The Solution Precursor Plasma Spray (SPPS) process involves the injection of atomized droplets of precursor into the plasma plume, instead of powder that is used in conventional plasma spray. The resultant thermal barrier coating (TBC) microstructure consists of (1) through-coating-thickness cracks, (2) ultra-fine splats, and (3) nanometer and micrometer-sized dispersed pores. These unique SPPS microstructural features provide highly durable TBCs. The SPPS TBCs in 1121°C /1 hour cyclic furnace tests exhibit a significantly improved spallation life compared to APS, DVC, and EB-PVD/Pt-Al TBCs. Extensive process diagnostic and modeling studies have been conducted to provide a foundation for understanding and control of the process. Process/microstructure/property relationships have been defined. Extension of the process for making thick coatings (> 3mm) and low thermal conductivity coatings are described.

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