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  • 1.
    Dömstedt, Peter
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Lundberg, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Szakalos, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Corrosion Studies of Low-Alloyed FeCrAl Steels in Liquid Lead at 750 degrees C2019In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 91, no 3-4, p. 511-524Article in journal (Refereed)
    Abstract [en]

    New ductile experimental FeCrAl alloys, based on the composition of Fe-10Cr-4Al, were exposed to stagnant liquid lead at 750 degrees C for up to 1970h. Two exposures with different test conditions were performed: one with addition of oxygen (as H2O) to the liquid lead and one without. The experimental alloys showed generally good oxidation and self-healing properties. The exposures showed that this specific category of steels has the potential to operate in liquid lead at very high temperatures with only minor oxidation. With this new material development, new energy technologies such as the CSP plants may be able to utilize liquid lead at very high temperatures as heat transfer fluid, thus achieving increased thermal efficiency.

  • 2.
    Ejenstam, Jesper
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Sandvik Heating Technology AB.
    Jonsson, Bo
    Szakalos, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Optimizing the Oxidation Properties of FeCrAl Alloys at Low Temperatures2017In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 88, no 3-4, p. 361-370Article in journal (Refereed)
    Abstract [en]

    FeCrAl alloys are proposed candidate materials for liquid lead applications. Chromium is needed to assist the formation of a protective alumina layer, albeit has to be limited to avoid alpha' precipitation. Reactive elements (RE) improve oxidation properties, but little is known about the RE effects at lower temperatures. An alloy matrix based on Fe-10Cr-4Al (wt%), with varying Zr, Y and Ti contents, was exposed to liquid lead up to 1 year in the temperature interval of 450-550 A degrees C. It was found that the formation of protective alumina was dependent on the RE/carbon ratio. All alloys with ratios lower than unity showed poor oxidation properties due to the formation of Cr-carbides in the metal-oxide interface. A sufficiently high amount of Zr and Ti was shown to significantly improve the oxidation properties at both temperatures. The positive effect is related to the suppression of Cr-carbides by addition of stronger carbide formers.

  • 3.
    Ekström, Madeleine
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Szakalos, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Influence of Cr and Ni on High-Temperature Corrosion Behavior of Ferritic Ductile Cast Iron in Air and Exhaust Gases2013In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 80, no 5-6, p. 455-466Article in journal (Refereed)
    Abstract [en]

    Due to an expected temperature increase of the exhaust gases in heavy-duty engines in order to meet future emission regulations, there is a need to develop materials that can operate at higher temperatures. The exhaust manifold in the hot end of the exhaust system is specifically affected since the most common material today, SiMo51, is already operating close to its limits. Accordingly, the effects of Cr and Ni-additions on the high-temperature corrosion resistance of this material in air and exhaust gases were examined. It was found that the addition of 0.5 and 1 wt% Cr improved the oxidation resistance in air at 700 and 800 A degrees C by the formation of an SiO2 barrier layer as well as a Cr-oxide at the oxide/metal interface. However, no Cr-oxide was detected after exposure to exhaust gases, probably due to a water vapor-assisted evaporation of Cr from the oxide. The addition of 1 wt% Ni resulted in a deteriorated SiO2 barrier layer and reduced oxidation resistance.

  • 4.
    Elger, Ragna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Swerea KIMAB.
    Pettersson, Rachel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Jernkontoret.
    Effect of Addition of 4% Al on the High Temperature Oxidation and Nitridation of a 20Cr-25Ni Austenitic Stainless Steel2014In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 82, p. 469-490Article in journal (Refereed)
  • 5.
    Gheno, Thomas
    et al.
    Univ Paris Saclay, ONERA, DMAS, F-92322 Chatillon, France..
    Lindwall, Greta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    On the Simulation of Composition Profiles in NiCoCrAl Alloys During Al2O3 Scale Growth in Oxidation and Oxidation-Dissolution Regimes2019In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 91, no 3-4, p. 243-257Article in journal (Refereed)
    Abstract [en]

    The ability to simulate the oxidation behavior of multicomponent alloys is a powerful tool for alloy development and oxidation research. The present work shows how the DICTRA module of Thermo-Calc can be applied to reproduce composition profiles in NiCoCrAl alloys during Al2O3 scale growth when used in conjunction with appropriate Calphad thermodynamic and diffusion mobility databases. Profiles were calculated in pure oxidation and oxidation-dissolution regimes to simulate reaction in air and in a molten silicate. For each regime, a simple analytical expression was used to set the outward Al flux at the alloy surface as a boundary condition. The simulations were performed using different combinations of thermodynamic and diffusion mobility databases, which demonstrated the relative importance of the thermodynamic and kinetic contributions to the interdiffusion coefficients, and in turn to the concentration profiles. The simulations done with the developmental NISTCoNi-mob mobility database were found to be in good agreement with experimental data, while those done with MOBNI4 significantly underestimated Al depletion (and Co, Cr and Ni enrichment), due in part to an incomplete description of diffusivity in the Co-Ni binary system. All the tested thermodynamic databases yielded similar results. This work provides a quantitative illustration of the importance of critically assessed diffusion mobility descriptions in designing oxidation-resistant materials.

  • 6. Heinonen, M. H.
    et al.
    Kokko, K.
    Punkkinen, Marko Patrick John
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nurmi, E.
    Kollar, J.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Initial Oxidation of Fe-Al and Fe-Cr-Al Alloys: Cr as an Alumina Booster2011In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 76, no 3-4, p. 331-346Article in journal (Refereed)
    Abstract [en]

    The boosting effect of Cr on the growth of the protective alumina scale on Fe-Al alloys is investigated by X-ray photoelectron spectroscopy. Using low oxygen pressure the surface chemistry of the alloys is monitored starting from the first moments of oxidation. Chromium affects the Fe/Al surface-bulk exchange which is clearly detected by analyzing the measured surface concentrations within the atomic concentration models. Experimental results presented are in good agreement with the previous ones obtained by experiments at ambient conditions and ab initio calculations.

  • 7.
    Hultquist, Gunnar
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Tveten, B.
    Hornlund, E.
    Hydrogen in chromium: Influence on the high-temperature oxidation kinetics in H2O, oxide-growth mechanisms, and scale adherence2000In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 54, no 02-jan, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Oxidation of 1-mm thick chromium samples with 7 to < I wt, ppm hydrogen has been studied at 900 degrees C in a closed reaction chamber. The gases used were O-2, H2O, and gas mixtures of Oz; H2O at a total pressure of about 20 mbar. By means of oxygen labeling in two-stage oxidations, H2O followed by (H2O)-O-18, the position of oxide growth within the oxide scale was determined with secondary-ion mass spectrometry (SIMS). The results are consistent with visual observations and scanning electron microscopy (SEM), which shows flat oxides with good adherence when formed in H2O. When replacing O-2 out H2O in the atmosphere, the oxidation rate increases by a factor of two with an increase of oxide growth at both the inner and outer part of the oxide. An increased metal (cation) transport is observed when 5 wt. ppm hydrogen is present in the chromium metal prior to oxidation in both Oz and H2O. This is detrimental for the adherence of the oxide scale. The uptake of hydrogen in H2O exposure for 1600 min was measured to 1.5 wt. ppm. In exposures to O-2 + H2O mixtures, no H-2 is formed and no net water is consumed as long as O-2 is present. A plausible reaction scheme based on an experiment with (H2O)-O-18 is presented to explain this observation.

  • 8.
    Hultquist, Gunnar
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Tveten, B.
    Hornlund, E.
    Limback, M.
    Haugsrud, R.
    Self-repairing metal oxides2001In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 56, no 04-mar, p. 313-346Article in journal (Refereed)
    Abstract [en]

    The oxidation of Cu, Zr, and alloys forming chromia, alumina, and zirconia was studied in a closed reaction chamber in O-2 gas near 20 mbar. Information on the position of oxide growth has been gained from the O-18/SIMS technique. Rates Of O-2 dissociation on metal oxides, Au, and Pt have been evaluated from measurements in labeled O-2. The experimental results indicate that hydrogen in the metal substrates induces increased metal-ion transport in internal oxide surfaces during oxidation, which leads to increased oxide growth at the oxide-gas interface. Experiments also show that oxides of rare-earth metals (REM) and Pt catalyze the dissociation Of O-2. An increased rate of O-2 dissociation can lead to increased transport of oxygen ions in the oxides and increased oxide growth at the substrate-oxide interface. A balanced transport of metal and oxygen ions in metal oxides that leads to oxide growth at both the metal-oxide and at the oxide-gas interface is found to be favorable for the formation of protective oxides with good adherence to the metal substrate. Depending on the original proporation of metal-to-oxygen ion transport in the oxide, an addition of hydrogen will increase or decrease the oxidation kinetics. In analogy, an addition of REM will increase or decrease the oxidation kinetics, depending on the original proportion of metal-to-oxygen ion transport.

  • 9. Sun, Yufu
    et al.
    Lv, Yezhe
    Zhengzhou University, China.
    Wang, Liuli
    Shen, Jingjie
    Jia, Xiangcai
    Zhao, Jingyu
    Effect of Aluminum on Microstructure and Properties of Martensitic Wear-Resistant and Heat-Resistant Steel2013In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 80, no 1-2, p. 113-124Article in journal (Refereed)
    Abstract [en]

    The effect of aluminum on microstructure and properties of martensitic wear-resistant and heat-resistant steels was investigated. The results indicate that as-cast microstructure of the specimens is composed of ferrite, pearlite and carbides. After quenching at 1,000 A degrees C and tempering at 600 A degrees C, the microstructure of the specimens consists of tempered sorbite and Fe-Cr-Al intermetallic compounds which distribute directionally in the matrix and increase with increase in Al content. The additions of Al enhance the ambient tensile strength which reaches the peak at 1,230 MPa when the specimens contain 1.97 % Al. Oxidation notably decreases with the increase of Al and the average oxidation rates reduce to 0.0095 g m(-2) h(-1) at 650 A degrees C and 0.0285 g m(-2) h(-1) at 800 A degrees C, respectively. Wear resistance of the specimens containing Al obviously increased when compared to the Al-free specimens.

  • 10. Tveten, B.
    et al.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Wallinder, D.
    Hydrogen and yttria in chromium: Influence on the high-temperature oxidation kinetics in O-2, oxide-growth mechanisms and scale adherence2001In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 55, no 04-mar, p. 279-289Article in journal (Refereed)
    Abstract [en]

    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.

  • 11.
    Viklund, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Rachel
    Outokumpu Stainless.
    HCl-induced high temperature corrosion of austenitic stainless steels under thermal cycling conditions and the effect of preoxidation2011In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 76, no 1/2, p. 111-126Article in journal (Refereed)
    Abstract [en]

    Gaseous HCl released during combustion is one reason for the severe materials degradation often encountered in power generation from waste and biomass. In this study, three stainless steels (the low alloyed EN 1.4982, the standard EN 1.4301 and the higher alloyed EN 1.4845) were tested by repeated thermal cycling in an environment comprising N2–10%O2–5%H2O–0.05%HCl at both 400 and 700 °C. The materials were exposed with ground surfaces and preoxidised at 400 or 700 °C. A positive effect of preoxidation is evident when alloys are exposed at 400 °C. Oxide layers formed during preoxidation effectively suppress chlorine ingress for all three materials, while chlorine accumulation at the metal/oxide interface is detected for surface ground specimens. The positive effect of preoxidation is lost at 700 °C and corrosion resistance is dependent on alloying level. At 700 °C metal chloride evaporation contributes significantly to the material degradation. Based on the results, high temperature corrosion in chlorinating environments is discussed in general terms.

  • 12.
    Öijerholm, Johan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Lu, Q.
    Kanthal AB, Hallstahammar.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    In-situ impedence spectroscopy study of electrical conductivity and ionic transport in thermally grown oxide scales on a commercial FeCrA1 alloy2007In: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 68, no 5-6, p. 253-269Article in journal (Refereed)
    Abstract [en]

    In-situ impedance-spectroscopy measurements were performed at temperatures between 600 and 1,000 degrees C to investigate ionic transport in oxide scales formed on Kanthal AF alloy. The samples were pre-oxidized at 800, 900 and 1,000 degrees C in air. The impedance spectra of the oxide formed at 1,000 degrees C exhibited essentially one semicircle, whereas samples oxidized at lower temperatures showed an additional semicircle at high frequencies suggesting a more heterogeneous oxide. The ionic-transference number, derived by measuring the voltage across the oxide scale, indicates that the oxide is a predominant electronic conductor. Ionic diffusivity in the oxide scales formed at different pre-oxidizing temperatures was calculated, using the ionic-transference number. The ionic diffusivities obtained in this way are in reasonable agreement with literature data acquired by other methods. The oxide-formation temperature has a significant influence on the conductivity and ionic-transport properties of the oxide scale.

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