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| 2. |
- Jonsson, Torbjörn, 1970, et al.
(författare)
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Oxidation of Fe-10Cr in O-2 and in O-2+H2O environment at 600 degrees C: A microstructural investigation
- 2013
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 75, s. 326-336
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of Fe-10Cr in dry and wet O-2 was studied at 600 degrees C for up to 168 h. Oxide microstructure was investigated by STEM/EDX, FIB/SEM and TEM. Oxidation in dry O-2 gives a Cr-rich protective (Fe1-xCrx)(2)O-3 scale. The same protective oxide initially forms in O-2 + H2O environment, but after an incubation period scale breakdown is triggered by CrO2(OH)(2) evaporation that depletes the substrate in Cr and converts (Fe1-xCrx)(2)O-3 to FeCr spinel oxide. Internal oxidation occurs after breakaway. Alternating external and internal oxidation result in the inward-growing scale showing a characteristic banded morphology.
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| 3. |
- Jonsson, Torbjörn, 1970, et al.
(författare)
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The influence of H2O on iron oxidation at 600?C: a microstructural study.
- 2008
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Ingår i: Materials Science Forum. - 1662-9752 .- 0255-5476. ; 595-598:Pt. 2, High Temperature Corrosion and Protection o, s. 1005-1012
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of iron in dry O2 and in wet O2 (40% H2O) has been studied at 600°C. The oxide microstructure was investigated by SEM/EDX, FIB and XRD. Iron forms a layered scale in dry and wet oxygen at 600°C. The scale consists of a top hematite layer, a middle magnetite layer and a wüstite layer close to the scale metal interface. All three layers grow with time, but with different growth rates, the overall growth being approximately parabolic. The presence of water vapour increases the rate of oxidation and affects the evolution of the oxide microstructure. The higher rate of oxidation in the presence of water vapour is due to an increased growth rate of the magnetite layer and, especially, of the hematite layer, while the growth of the wüstite layer is not affected. It is suggested that water vapour influences grain boundary transport in the hematite layer.
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| 4. |
- Pujilaksono, Bagas, 1965, et al.
(författare)
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Oxidation of Binary FeCr Alloys (Fe–2.25Cr, Fe–10Cr, Fe–18Cr and Fe–25Cr) in O2 and in O2 + H2O Environment at 600 °C
- 2011
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Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 75:3, s. 183-207
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation behaviour of the binary alloys Fe-2.25Cr, Fe-10Cr, Fe-18Cr and Fe-25Cr (wt%) in dry and wet O 2 at 600 °C is investigated by isothermal exposures of carefully polished samples for up to 168 h. The oxidized samples are investigated gravimetrically and the oxides formed are studied by X-ray diffraction. X-ray photoelectron spectroscopy is used for depth profiling of the thin oxides. The scale surface is imaged by SEM. Cross-sections through the scale are analyzed by SEM/EDX for imaging and for measuring the chemical composition. The oxidation behavior of the four FeCr alloys is intermediate between those of iron and chromium. Fe-2.25Cr oxidizes in a way similar to iron in both environments, forming a poorly protective scale consisting of FeCr spinel at the bottom, magnetite in the middle and a hematite cap layer. In dry O 2, Fe-10Cr, Fe-18Cr and Fe-25Cr form a thin and protective (Fe,Cr) 2O 3 oxide similar to the chromia film formed on pure chromium. In wet O 2, Fe-10Cr, Fe-18Cr and Fe-25Cr initially form the same kind of protective oxide film as in dry conditions. After an incubation time that depends on alloy chromium content, all three alloys go into breakaway oxidation and form thick, poorly protective scales similar to those formed on Fe-2.25Cr. Breakaway oxidation in wet O 2 is triggered by the evaporation of CrO 2(OH) 2 from the protective (Fe,Cr) 2O 3 oxide.
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| 5. |
- Pujilaksono, Bagas, 1965, et al.
(författare)
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Oxidation of iron at 400-600 °C in dry and wet O2
- 2010
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 52:5, s. 1560-1569
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of iron in dry and wet O-2 at 400-600 degrees C has been re-investigated using gravimetry, SEM/EDX, XRD and FIB. In the presence of O-2, water vapour accelerates iron oxidation at 500 and 600 degrees C. At 400 and 500 degrees C the magnetite layer is duplex and exposure to water vapour results in the formation of blades on top of a fine-grained hematite layer. At 600 degrees C it results in a surface without needles and blades. The increased oxidation rate at 500 and 600 degrees C is attributed to a smaller grain size in the hematite layer resulting in faster ion transport.
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| 6. |
- Pujilaksono, Bagas, 1965, et al.
(författare)
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Paralinear Oxidation of Chromium in O2 + H2O Environment at 600–700 °C
- 2008
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Ingår i: Oxidation of Metals. - 1573-4889 .- 0030-770X. ; 70:3-4, s. 163-188
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of chromium in dry O2 and in O2 + 10%H2O at 600 and 700 °C is studied. Scale morphology is investigated by several methods, including scanning electron microscopy (SEM) of cross sections prepared by focussed ion beam milling (FIB). In O2 + H2O at 600 and 700 °C, chromium forms a duplex scale consisting of an inner barrier oxide and a discontinuous outer oxide made up of blade-shaped crystals. Thermogravimetric (TG) measurements show that water vapour influences chromium oxidation by causing vaporization of the protective oxide, resulting in paralinear oxidation kinetics. An extension of the original treatment by Tedmon is deduced, which allows for the determination of the evaporation rate constant k s and the parabolic oxidation rate constant k d from TG data acquired during short exposures. The results show that k d is the same in dry O2 and in O2 + 10%H2O. Equivalently, the transport properties of chromia are the same in the two environments. The equilibrium constant of CrO2(OH)2 formation from chromia is reported. The activation enthalpy of the vaporization reaction is determined.
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| 7. |
- Andersson, Thorvald, 1946, et al.
(författare)
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Preparation and characterization of the ITO surface and the Al/Alq3/ITO heterostructure for OLEDs
- 2007
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Ingår i: Materials Science and Engineering B. ; 145, s. 48-56
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Tidskriftsartikel (refereegranskat)abstract
- We have made a detailed investigation of structure and chemical composition in thermally grown Al/Alq3/ITO layer structures intended for light emission. The different parts of the structure were studied by X-ray photoelectron spectroscopy and microscopical techniques. The indium tinoxide substrate surface consisted of grains 20–50 nm in diameter and about 5 nm in height, which also showed molecular sized sub-grain features. Due to the ambient the ITO surface was covered by a 1 nm thick hydrocarbon layer which serves as the actual surface on which an organic layer is deposited for device fabrication. A structural model for the indium tin oxide surface, on which the small molecules were deposited, was suggested. The substrate surface was treated to study the relation between the surface manipulation and the hole injection barrier. Such surface modification significantly improved the performance of a single layer Alq3 organic light emitting diode. Depth profiling of the complete structure, revealed that the aluminium contact mostly consisted of aluminium oxide with some intermixing of carbon. Further, variations of the atomic concentration of the elements In, Sn, C and O and a minor shift in their binding energies were measured. Both, position and shape of the oxygen and indium peaks were changed during argon ion sputtering. At the Alq3/ITO interface an indium–oxygen compound, different from that on the original surface, hadformed. Various effects of the compositional findings on the light emission are discussed.
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