Solubility of Yttrium Oxide in Na2 SO 4 and NaCl Melts

Deanhardt, M. L.; Stern, Kurt H.

doi:10.1149/1.2123480

Cited by 26 publications

(7 citation statements)

References 5 publications

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“…If the activity coefficient of the dissolved nickel species is presumed to be constant, then a plot of the log of NiO solubility as a function of -log a(MsO) should show two distinct regimes of dissolution. [7] and [8]. This type of plot has been the primary interest of this work.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Solubility of NiO in Molten Li2 CO 3, Na2 CO 3, K 2 CO 3, and Rb2 CO 3 at 910°C

Orfield

Shores

1988

J. Electrochem. Soc.

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The solubility of NiO in molten Li2CO3, Na2CO3, K2COa, and Rb2CO3 was measured at 910~ as a function of the basicity or -log a(O 2-) of the salt. The basicity was controlled by varying the pCO2 in the gas phase above the melt. Acidic and basic dissolution were observed in all salts except Li2CO3, which underwent only basic dissolution. The slopes of the solubility lines in both acid and basic regime were related to the dissolution products where possible. The dependence of NiO solubility on the activity of 02 in the system was determined for both regimes of all the melts. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.254.159 Downloaded on 2015-05-27 to IP Vol. 135,No. 7

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Section: Theoretical Backgroundmentioning

confidence: 99%

Solubility of NiO in Molten Li2 CO 3, Na2 CO 3, K 2 CO 3, and Rb2 CO 3 at 910°C

Orfield

Shores

1988

J. Electrochem. Soc.

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“…For the crystals shown in Figure 6(b), the EDS analysis indicates that these crystals are composed of yttrium, vanadium, sodium and oxygen elements. In our experience, there is not great research done on the corrosion behaviour of silicates in molten salts containing both vanadium and sulfur compounds Jacobson, 1986;Jacobson and Fox, 1988;Deanhardt and Stern, 1982;Shi and Rapp, 1986;Rapp, 2002). However, the main mechanism present is the dissolution of 7YSZ (yttria stabilized zirconia) in the melt followed by the re-precipitation of both YVO 4 and Y-depleted (Jones, 1997;Hertl, 1988;Afrasiabi et al, 2008;Habibi et al, 2012).…”

Section: Resultsmentioning

confidence: 99%

“…At the substrate-salt interface, there is a higher PSO 3 partial pressure because of the release of acidic gases, whereas the PSO 3 partial pressure is lower at the salt-gas interface due to salt evaporation and flowing air. In acidic molten salts, it has been reported that the solubility of Y 2 O 3 increases with the acidity in a slope of 3/2 (Deanhardt and Stern, 1982;Shi and Rapp, 1986). From this, in our experiment, the Y 31 ions formed at the more acidic oxide-salt interface would transfer to the salt-gas interface due to the acidity negative solubility gradient, and re-precipitate as a Y-rich compound (4): On the other hand, it has been reported that silica has a very small solubility in acidic molten salts and the solubility is independent of the acidity (Siemers and McKee, 1982;Rapp, 2002).…”

Section: Resultsmentioning

confidence: 99%

Sintering and hot corrosion of yttria silicate tablets in molten salts prepared by spark plasma sintering

Villanueva

Hernández

Mendoza

et al. 2019

ACMM

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Purpose This paper aims to study the microstructural hot corrosion behaviour of the sintered Y2SiO5 ceramic silicate under a Na2SO4 + V2O5 mixture at an engine representative temperature of 1150°C. Y2SiO5 is a promising candidate for thermal barrier coatings (TBC) due to its excellent chemical stability at high temperatures. As a continuous source of Y3+, it is expected that Y2SiO5 environmental barrier coating may prolong the lifetime of TBC systems by stopping the degradation caused by the loss of the Y2O3 stabilizer. Design/methodology/approach Two routes were chosen for the yttria silicate powder synthesis by sol-gel from TEOS and APTES precursors as the difference in Si source changed the ratio of Y2SiO5/Y2Si2O7 phases. Hot corrosion studies using Na2SO4 and V2O5 mixtures were conducted on both surfaces of APTES and TEOS tablets at 1150°C for 8 h in atmospheric air. The morphology and microstructure analyses of the silicate samples after hot corrosion tests were carried out using a SEM and X-ray diffraction analyse techniques. Findings Based on the degradation, the general status of the APTES tablet after hot corrosion presents a better hot corrosion resistance at a temperature of 1150°C than does that of the TEOS tablet. In the TEOS tablet, the crystal morphology of NaY9Si60O26 woodchip shapes with a size of 60 µm is developed on the surface for finally initiating some cracks. In the APTES case, the crystal morphology of rod-like shapes with a size of 100 µm is developed; hence, a dense thick layer predominately postpones the reaction of V2O5 and Na2SO4 with yttria silicate, and consequently, less damage is observed. Originality/value Coating yttria silicate preparation is very complicated; the problems of a high synthesis temperature, long production period and low yield still need to be solved. Under these perspectives, ceramics prepared via spark plasma sintering (SPS) can reach theoretical high densities and a fine grain size can be retained after the SPS process; hence, well resistance to the corrosion in molten salts is expected to obtain for the sintered yttria silicate tablets.

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“…Deanhardt and Stern measured the solubility of Y 2 O 3 in sodium molten salt. 27 YO 2 − formed at the substrate/salt interface, which had a high Na 2 O activity and high YO 2 − solubility, would diffuse to the salt/gas interface and reprecipitate as yttria.…”

Section: Discussionmentioning

confidence: 99%