Vanadium-induced hot corrosion behavior of 8YSZ and MgO-modified 8YSZ composite powders at 1100°C

Isothermal hot corrosion behavior of 8 yttria-stabilized zirconia (8YSZ) and a newly developed MgO/8YSZ composite powders was investigated in the presence of 5 wt.% V 2 O 5 . Hot corrosion tests were performed at 1100°C in a high-temperature furnace for a total duration of 10hrs. The samples were removed, and air-cooled after every 2hrs for a total duration of 10 hrs. The microstructure, elemental composition and phase evolution of the resulting specimens were characterized by field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD), respectively. Results showed that the dominant hot corrosion mechanism of 8YSZ in V 2 O 5 at 1100 o C was the destabilization of 8YSZ, owing to the reaction between Y 2 O 3 and V 2 O 5 resulting in the formation of YVO 4 . The predominant tetragonal structure of 8YSZ was thus, transformed to monoclinic phase. However, the addition of MgO to 8YSZ in various ratios (5, 10, and 15 wt.%) showed significant improvement in the hot corrosion performance by impeding the reaction between V 2 O 5 and Y 2 O 3 through the formation of magnesium orthovanadate. It was, however, observed that the effectiveness of the composite is dependent on the thermal stability of the vanadate formed. Magnesium orthovanadate traps free vanadium thereby preventing it from interacting with the yttria stabilizer in 8YSZ. The degradation mechanism were found to follow Lewis acid base theory. • Hot corrosion mitigation by the addition of MgO • Temperature-dependent trapping efficiency associated with MgO, vanadate and monoclinic phase transformation • The Lewis acid-base interaction drives the hot corrosion mechanisms • Sustainable and lowcost alternative to rare-earth stabilizers