| 1. |
- Eklund, Johan, 1991, et al.
(author)
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Field exposure of FeCrAl model alloys in a waste-fired boiler at 600°C: The influence of Cr and Si on the corrosion behaviour
- 2019
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In: Materials and Corrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 70:8, s. 1476-1485
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Journal article (peer-reviewed)abstract
- Materials and Corrosion WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The aim of this study was to examine the performance of FeCrAl model alloys in a waste-fired boiler and investigate the influence of chromium and silicon content on the corrosion behaviour. The investigation was executed by utilising an air-cooled probe, giving a material temperature of 600°C throughout a 672 hr exposure. The material loss measurements were performed by utilizing an ultrasonic thickness gauge in combination with scanning electron microscopy analysis. It was found that increasing the chromium content significantly reduced the overall material loss of the FeCrAl model alloys but further accelerated the corrosion attack on the windward side. Simultaneously, the increased chromium content caused embrittlement of the material. Minor additions of silicon drastically reduced the material loss of the FeCrAl model alloys, whereas the sample ring with no silicon present was completely deteriorated. The trends observed in this field study correlated well with what has been observed in previous laboratory studies. A state-of-the-art alloy in the present environment, Inconel 625, was simultaneously exposed and showed similar performance to the silicon-containing FeCrAl model alloys with ≥10 wt% Cr.
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| 2. |
- Eklund, Johan, 1991, et al.
(author)
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The influence of silicon on the corrosion properties of FeCrAl model alloys in oxidizing environments at 600 °C
- 2018
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In: Corrosion Science. - : Elsevier BV. - 0010-938X. ; 144, s. 266-276
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Journal article (peer-reviewed)abstract
- The present study investigates the influence of Si on the high temperature corrosion behaviour of FeCrAl model alloys in O2, O2+H2O and O2+H2O + KCl at 600 °C for up to 168 h. The investigation by SEM/EDX showed that all alloys displayed a protective behaviour in dry O2. In the more corrosive environments (O2+H2O and O2+H2O + KCl) the addition of Si affected the oxidation properties in two ways; Alloys containing Si resisted breakaway oxidation caused by Cr-evaporation (O2+H2O) and the thickness of the oxide formed after breakaway oxidation decreased with increasing amount of Si (O2+H2O + KCl).
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| 3. |
- Olivas Ogaz, Mercedes Andrea, 1985, et al.
(author)
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Microstructural Study of the Influence of KCl and HCl on Preformed Corrosion Product Layers on Stainless Steel
- 2017
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In: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 87:5-6, s. 801-811
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Journal article (peer-reviewed)abstract
- Metallic construction materials in biomass- and waste-fired boilers are exposed to corrosive environments due to the considerable amounts of alkali chlorides and HCl(g) released in renewable fuels combustion. Alkali chlorides corrosivity toward stainless steels exposed at high temperature has been extensively studied. Nevertheless, the corrosion attack propagation is still not fully understood and it is expected that chlorine diffusivity through oxide layers plays a major role in accelerating the corrosion. In order to investigate the role of chlorine on the propagation step of the corrosion attack, tailor-made oxides were produced. The samples were subsequently exposed to chlorine-containing environments for short period of time. The reaction atmospheres were O2 + H2O + KCl(s) and O2 + H2O + HCl(g) at 600 °C. Since in this study chlorine diffusivity through the corrosion product layer is of great interest, samples were analyzed with XRD and SEM/EDX. High-quality BIB cross sections were performed. Summarizing, for the preformed oxide layers on the stainless steel in the presence of HCl(g), chlorine seemed to penetrate to the oxide/metal interfaces in the material. However, in the presence of KCl(s) there seems to be no effect of the salt on the corrosion rate.
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| 4. |
- Olivas Ogaz, Mercedes Andrea, 1985, et al.
(author)
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The Influence of Oxide-Scale Microstructure on KCl(s)-Induced Corrosion of Low-Alloyed Steel at 400 °C
- 2019
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In: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 91:3-4, s. 291-310
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Journal article (peer-reviewed)abstract
- The high-temperature corrosion of low-alloyed steels and stainless steels in the presence of KCl(s) has been studied extensively in the last decades by several authors. The effect of KCl(s) on the initial corrosion attack has retained extra focus. However, the mechanisms behind the long-term behavior, e.g., when an oxide scale has already formed, in the presence of KCl(s) are still unclear. The aim of this study was to investigate the effect of the microstructure of a pre-formed oxide scale on low-alloyed steel (Fe–2.25Cr–1Mo) when exposed to small amounts of KCl(s). The pre-oxidation exposures were performed at different temperatures and durations in order to create oxide scales with different microstructures but with similar thicknesses. After detailed characterization, the pre-oxidized samples were exposed to 5%O2 + 20%H2O + 75%N2 (+KCl(s)) at 400 °C for 24, 48, and 168 h and analyzed with scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and focused ion beam. The microstructural investigation indicated that Cl-induced corrosion is a combination of oxide thickness and microstructure, and the breakaway mechanism in the presence of KCl(s) is diffusion-controlled as porosity changes prior to breakaway oxidation were observed.
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