Hot corrosion behavior of ZrO2–MgO coatings in LiCl–Li2O molten salt

In this study, a magnesia-stabilized zirconia (MgO–ZrO2) top coat was applied to the surface of Inconel 713LC with an aluminized NiCoCrAlY bond coat by an optimized plasma spray process. The resulting materials were tested for corrosion behavior at 948 K for 216 h in a LiCl–Li2O molten salt under an oxidizing atmosphere. The as-coated and tested specimens were analyzed by scanning electron microscopy (SEM)/X-ray energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The bare superalloy reveals an obvious weight loss due to spalling after scale growth and thermal stress. The top coatings exhibited a superior resistance to hot corrosion in the presence of LiCl–Li2O molten salt when compared to the bare Inconel 713LC and the aluminized bond coatings. These coatings have been found to be beneficial for improving the hot corrosion resistance of the structural materials for high-temperature lithium molten salts.

► Inconel 713LC with MgO–ZrO2 top coat and aluminized NiCoCrAlY bond coat.
► Corrosion resistance test in LiCl–Li2O molten salt at 923 K.
► Experimental and theoretical analysis of phase composition of corrosion layers.
► The crucial role of Al for superior corrosion resistance is discussed.