Present day thermal barrier coating (TBC) systems predominantly involve yttria-stabilized-zirconia (YSZ) coatings deposited through either atmospheric plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD). However, TBCs developed employing the solution precursor plasma spray (SPSS) technique have gained considerable research interest in recent times due to the inherent advantages that it offers by virtue of its ability to yield interesting features like vertical cracks, nano-sized pore structure, fine splats etc. while enabling elimination of expensive powder-feedstock and flexibility over coating chemistry. Studies have also demonstrated that SPPS coatings can potentially offer extended durability under thermal cycling conditions. A novel approach of hybridizing the conventional APS technique with the SPPS route to achieve TBCs with tailored configurations is presented. Such a hybrid process can be conveniently adopted for forming composite, multi-layered and graded coatings employing simultaneous and/or sequential feeding of solution precursor as well as powder feedstock, yielding distinct TBC microstructures that bear promise to further extend coating durability. TBC specimens generated using conventional APS technique, the SPPS method and through APS-SPPS hybrid processing have been comprehensively characterized for microstructure, hardness, thermal cycling life etc. and the results compared.
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