Molten sodium corrosion of laser surface remelted yttria-stabilized zirconia thermal barrier coatings

Liquid-metal corrosion in molten sodium is a significant issue to Thermal Barrier Coatings (TBCs) proposed for in-core fast breeder reactor applications. In this study, the viability of attenuating molten sodium corrosion of plasma-sprayed yttria-stabilized zirconia TBCs is investigated by microstructure re-engineering using Laser Surface Remelting (LSR). LSR produced a smooth and dense surface with columnar microstructure and segmented vertical cracks. At the onset of molten sodium corrosion, the remelted layer retained structural integrity but exhibited localized corrosive attack along the surface-network cracks. However, on further exposure, the vertical cracks lead to molten sodium infiltration down the non-remelted layers, causing corrosive damage and spallation of coating.