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

Abstract

In this study, thermal barrier coatings (TBC) consisting of 3.5 mol% Yb2O3-stabilized ZrO2 co-doped with 1 mol% Gd2O3 and 1 mol% Yb2O3 (referred to as GdYb-YSZ) were fabricated by means of air plasma spraying. The as-fabricated coatings exhibited a metastable tetragonal (t′) structure. The hot-corrosion behavior of the GdYb–YSZ TBCs was investigated at 700, 800, 900, and 1000 °C for 10 h in the presence of V2O5 molten salt. During the corrosion tests, the t′ phase transformed into a monoclinic (m) phase; nevertheless, it was still detected on the corroded surfaces. The amount of t′ phase decreased with increasing corrosion temperature. The corrosion products formed on the GdYb-YSZ TBCs in V2O5 comprised Yb, Gd-doped YVO4, and m-ZrO2, irrespective of the temperature of corrosion. However, higher temperatures changed the morphologies of the Yb- and Gd-doped YVO4 corrosion products. The GdYb–YSZ TBCs exhibited improved corrosion resistance to V2O5 molten salt when compared to YSZ TBCs, and the related mechanism is discussed in detail in this paper.

Hot corrosion resistance of oxide‐doped yttria‐stabilized zirconia powder in V2O5 molten salt

“…[ 13–16 ] Doping with other metal oxides such as MgO, Sc 2 O 3 , TiO 2 , CeO 2 , Gd 2 O 3 , or La 2 O 3 have been widely reported in the literature. [ 17–20 ] To develop YSZ‐based materials with high hot corrosion resistance, Raghavan and Mayo [ 13 ] prepared 4.5 mol% YSZ powder co‐doped with 10 mol% Y 2 O 3 and 10 mol% Ta 2 O 5 to form (ZrO 2 −20YTaO 4 ) and 4.5 mol% YSZ powder doped with 14 mol% Ta 2 O 5 to YSZ (ZrO 2 −14Ta 2 O 5 ) using the co‐precipitation technique and examined their hot corrosion resistance in mixtures ranging from pure NaVO 3 to pure V 2 O 5 over a temperature range of 700–900°C. ZrO 2 ‐20YTaO 4 and ZrO 2 ‐14Ta 2 O 5 sintered pellets showed higher resistance to hot corrosion than 8 wt.% yttria‐stabilized zirconia (8YSZ) coatings when exposed to acidic molten salts with high concentrations of V 2 O 5 at 900°C.…”

CMAS Corrosion Behavior of Nanostructured YSZ and Gd-Yb-Y-Stabilized Zirconia Coatings

“…Bahamirian et al [37] found that APS 9.5Y 2 O 3 -5.6Yb 2 O 3 -5.2Gd 2 O 3stabilized ZrO 2 TBCs exhibited superior thermal shock resistance under CMAS exposure compared with YSZ coatings. Li et al [38] reported that Gd-Yb-YSZ coatings showed better V 2 O 5 corrosion resistance than YSZ coatings. On the contrary, Wang et al [39] reported that the CMAS penetration depth and phase transition were greater in Yb-Gd-YSZ coatings compared with YSZ coatings, indicating lower corrosion resistance.…”