High-temperature corrosion behavior of zirconia ceramic in molten Na2SO4+NaVO3 salt mixture

Cyclic Hot Corrosion Failure Behaviors of EB-PVD TBC Systems in the Presence of Sulfate and Vanadate Molten Salts

“…Due to the melting point of Na2SO4 + V2O5 salt mixture, about 900 °C, and that our test temperature is above this temperature, this salt mixture become molten during the test [18]. Hui et al stated in their research [7] that after SEM, XRD, and EDS analyses, YVO4 formations with rod-shaped crystal structure were observed as a result of isothermal hot corrosion tests with 6, 12, 24, 48, and 96 h time periods that were conducted at 1100 °C in a Na2SO4-30 mol % NaVO3 environment. YVO4 phases were only observed in 48 and 96 h periods, while monoclinic ZrO2 was observed in all hot corrosion test periods according to XRD analysis.…”

“…Moreover, the presence of NaVO 3 increases the mobility of Y 3+ . Thus, exhaustion of yttria and growth of YVO 4 crystal is enhanced [7]. It is accepted that YSZ usually stabilizes in tetragonal phase due to the presence of Y 2 O 3 .…”

“…This may be related to the presence of V2O5 in our hot corrosion salts. Liu et al [30] observed a volumetric increase in thermal barrier coating samples comprising of Sc2O3-Y2O3-ZrO2 (ScYSZ) subjected to hot corrosion test at 1000 °C in a Na2SO4 + V2O5 environment, which was attributed to the phase transformation of zirconium dioxide, from tetragonal to monoclinic phase [1,7,11,16,19,21]. This phase transformation caused crack formation in the coating.…”

“…The ceramic top coat has a substantially low thermal conductivity and partially low thermal expansion. The metallic bond coat is deposited between the metallic substrate and ceramic top coat for improving adherence of the ceramic top coating to the substrate alloy [7]. Sample surfaces were prepared by sandblasting for the coating process.…”

Degradation of Al2O3f/SiO2 composites exposed to Na2SO4 environment and MMH/N2O4 bipropellants test

“…The impurities sucked in from the environment or introduced by the fuel might react to form low‐melting point salts such as Na 2 SO 4 , NaCl, Na 2 CO 3 , NaVO 3 , KCl, and/or volcanic ash. The molten salts could accelerate the corrosion of CMCs composites 24‐30 . The corrosion behavior of Al 2 O 3f /SiO 2 composites in a molten salts environment has rarely been studied.…”