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Hydrogen and yttria...
Hydrogen and yttria in chromium : Influence on the high-temperature oxidation kinetics in O-2, oxide-growth mechanisms and scale adherence
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Tveten, B. (författare)
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- Hultquist, Gunnar (författare)
- KTH,Materialvetenskap
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Wallinder, D. (författare)
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(creator_code:org_t)
- 2001
- 2001
- Engelska.
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Ingår i: Oxidation of Metals. - 0030-770X .- 1573-4889. ; 55:04-mar, s. 279-289
- Relaterad länk:
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https://urn.kb.se/re...
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visa fler...
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https://doi.org/10.1...
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visa färre...
Abstract
Ämnesord
Stäng
- The effects of hydrogen and Y2O3 on high-temperature oxidation of Cr in 20 mbar O-2 have been studied at 900 degreesC. Oxidation- and O-2-dissociation rates were determined from gas-phase measurements. Hydrogen in Cr leads to breakdown of the oxide scale. The oxide scale on Cr-1%Y2O3 charged with hydrogen for 4 hr (resulting in Cr-1%Y2O3 with approximately 10 ppm hydrogen) is adherent to the metal substrate. The oxidation rate is similar for Cr with less than or equal to1 ppm hydrogen and Cr-1%Y2O3 with less than or equal to1 ppm hydrogen, but significantly lower for 4-hr H-charged Cr-1%Y2O3.. The oxidation rate of Cr-5%Fe-1%Y2O3-25 ppm H is also lower than the oxidation rate of Cr-5%Fe-1%Y2O3-less than or equal to1 ppm? H. This indicates that unless hydrogen is present, there are virtually no effects of the addition of 1% Y2O3 to Cr. Using labeled oxygen, O-16,16(2) and O-18,18(2), was found that at 900 degreesC the dissociation rate of O-2 is higher on Y2O3 than on Cr2O3 It is suggested that the well-known improvement of the oxidation resistance of Cr as an effect of additions of Y or Y2O3 is related to an increase in the dissociation rate of O-2 and that there is a synergetic effect in combining Y2O3 and hydrogen.
Nyckelord
- chromium
- oxidation
- hydrogen content
- yttria additions
- oxygen dissociation
- grain-boundary segregation
- o-2/h2o-gas mixtures
- protective scales
- oxygen-exchange
- cr metal
- alloys
- cr2o3
- platinum
- adhesion
- elements
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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