Hot Corrosion of Stabilized Zirconia Thermal Barrier Coatings and the Role of Mg Inhibitor

Abstract

The 3-4 mol% yttria-stabilized zirconia (YSZ) is widely used as a material for thermal barrier coating; however, the corrosive constituents present in fuel typically result in mechanical disintegration of YSZ coatings. The 3-4 mol% YSZ coatings with respective porosity of~3% and~22% have been undertaken with the objective to compare the hot corrosion behavior in air and sulfur-rich atmospheres. The coatings are kept in contact with V 2 O 5 + MgO powder mixture at 750°C for different dwell times of 24 and 76 h. The samples kept in air have shown intact YSZ layer for both the coatings, whereas a delamination of YSZ layer is observed for high porosity sample kept in sulfur-rich atmosphere. XRD patterns of all the samples treated in sulfur-rich atmosphere have indicated a phase transformation in YSZ from tetragonal to monoclinic. However, no such phase transformation has been found for samples treated in air. The V 2 O 5 -induced hot corrosion attack on YSZ coating in air has been successfully inhibited by MgO, which forms a thermally stable Mg 3 V 2 O 8 compound. However, in sulfur-rich atmosphere, MgO is partially consumed to form sulfates, which allows certain fraction of V 2 O 5 to react with Y 2 O 3 causing the degradation of top coat.

The Use of APS Thermal Barrier Coatings in Corrosive Environments

“…Another mechanism referred to in the literature relates to destabilization of the YSZ leading to the formation of the monoclinic YSZ phase, which undergoes a phase change during thermal cycling [3,8]. However, the literature suggests that an active phase such as V is required for this to occur and that in the presence of Na 2 SO 4 alone destabilization does not occur.…”

Hot-Corrosion Behavior of Gd2O3–Yb2O3 Co-Doped YSZ Thermal Barrier Coatings in the Presence of V2O5 Molten Salt

“…Researchers have made significant efforts to improve the corrosion resistance of YSZ coatings against vanadium. Studies have shown that doping YSZ with MgO and Sc 2 O 3 can enhance hot-corrosion resistance [29][30][31][32]. Furthermore, it has been reported that titania-or ceriastabilized ZrO 2 exhibits better resistance to hot corrosion compared to YSZ [33,34].…”

Integrated Regeneration Method for Used Mineral Motor Oils

“…Lithium aluminosilicates have a low value of TCLE (0.5-2.0)•10 -6 K -1 , but the most acceptable crystalline phase in the composition of such coatings is magnesium aluminosilicate -cordierite. From the practice and theoretical studies of coatings for high-temperature protection it is known [7][8][9][10][11][12][13][14][15] that the maximum protective effect and minimum energy consumption can be achieved by forming the required phase component in the coating 1 Lviv Polytechnic National University, 12, Bandera St., 79013 Lviv, Ukraine * orest.m.vakhula@lpnu.ua ã Vakhula O., Pona M., Solokha I., Koziy O., Petruk M., 2021 layer during coatings pre-burning or operation. Therefore, the main attention in the studies was paid to the synthesis of cordierite α-phase directly in the coating.…”