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  • 1.
    Anghel, Clara
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Dong, Qian
    Rundgren, John
    Hultquist, Gunnar
    Saeki, Isao
    Limbäck, Magnus
    Gas-tight oxides – Reality or just a Hope2006Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 522-523, s. 93-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A better understanding of the transport properties of gases in oxides is certainly very important in many applications. In the case of metals, a general protection measure against corrosion implies formation of a dense metal oxide scale. The scale should act as a barrier against gas transport and consequently it needs to be gas-tight. This is often assumed but rarely, if ever, confirmed. Hence there is a need for characterization of micro- and/or meso- pores formed especially during the early oxidation stage of metallic materials. This paper presents a novel and relatively straightforward method for characterization of gas release from an oxide previously equilibrated in a controlled atmosphere. The geometry of the sample is approximated to be a plate. The plate can be self-supporting or constitute a scale on a substrate. A mathematical model for calculation of diffusivity and gas content is given for this geometry. A desorption experiment, involving a mass spectrometer placed in ultra high vacuum, can be used to determine diffusivity and amount of gas released with aid of the mathematical model. The method is validated in measurements of diffusivity and solubility of He in quartz and applied in characterization of two Zr-oxides and one Fe oxide. From the outgassed amounts of water and nitrogen the H2O/N-2 molar ratio can be used to estimate an effective pore size in oxides.

  • 2.
    Anghel, Clara
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Limbäck, M.
    Szakalos, P.
    Effects of Pt surface coverage on oxidation of Zr and other materials2008Inngår i: Journal of ASTM International, ISSN 1546-962X, Vol. 5, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Certain elements, including noble metals, are identified to influence corrosion behavior of many metals in high-temperature water/steam and O 2. We have previously reported effects of porous Pt coatings on the thermal oxidation of Zr, Fe, Ni, Cr and GaAs in O2. Effects of Pt on oxidation of Zircaloy-2 In H2O have also been observed at temperatures near 400°C. An enhanced oxidation rate Is observed in all of the studied systems upon a sufficiently high surface Pt-particle density. Even more interesting, low Pt-particle density in most cases leads to a decreased oxidation rate. In the case of Zr and Zircaloy-2 the beneficial effect of Pt is stronger when hydrogen is present In the metal substrate and in the oxide layer. From 18O/SIMS experiments it is concluded that, for a sufficiently high Pt-particle density on the surface, enhanced transport of dissociated oxygen, On- (n=0; 2), towards the oxide/metal interface occurs in all of the studied systems. An oxygen spillover from Pt particles to the adjacent surface is a known phenomenon in catalysis and partly explains the results observed also in the current study of oxidation of Zr-based materials. Such a spillover involves a high surface diffusivity of dissociated oxygen, O n-, which results In an increased gradient of On- across the oxide scale. In turn, the high oxygen gradient enhances the transport of oxygen towards the substrate/oxide-interface. This shows that not only diffusivlty but also an effective activity of dissociated oxygen at the external oxide surface influences the oxidation rate. Naturally, the effects of Pt are maximized when small (nm-sized) and evenly distributed Pt particles are present on the surface. In our presentation a summary of obtained results of Pt additions on different materials will be given with suggested interpretations. Especially, the observed beneficial combination of Pt and hydrogen in the oxidation of Zr-based materials Is discussed with a possible mechanistic explanation. Parallels are also drawn to the potential effect of Noble Metal Chemical Application (NMCA), used in a large fraction of the U.S. BWRs, on the corrosion resistance of Zr-based claddings.

  • 3.
    Anghel, Clara
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Limbäck, Magnus
    Influence of Pt, Fe/Ni/Cr–containing intermetallics and deuterium on the oxidation of Zr-based materials2005Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 340, nr 2-3, s. 271-283Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An in situ gas phase analysis technique and the 18O-SIMS technique are used to evaluate the transport of oxygen and hydrogen in oxidation of Zr-based materials. At 400 °C, it is found that oxygen dissociation efficiency decreases in the order: Pt > Zr2Fe > Zr2Ni > ZrCr2 Zircaloy-2. Two Zr-plates partly coated with 200 Å porous Pt, with and respectively without D in the substrate, were oxidized in two stages at 400 °C. SIMS depth profiles in the Pt area show that an enhanced oxidation takes place mainly by inward oxygen transport. A minimum in the oxide thickness was found near the Pt area on both Zr plates. Two Ar-filled Zircaloy-2 tubes with ZrSn liner were exposed at 370 °C to 22 mbar water, filled in from one side. Our experimental results suggest that a proper choice of the SPP composition and size distribution can lead to reduced hydrogen uptake during oxidation of Zr-based materials in water.

  • 4.
    Anghel, Clara
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Limbäck, Magnus
    Szakalos, Peter
    Effects of Pt Surface Coverage on Oxidation of Zr and Other Materials2009Inngår i: ZIRCONIUM IN THE NUCLEAR INDUSTRY: 15TH INTERNATIONAL SYMPOSIUM, 2009, Vol. 1505, s. 285-302Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Certain elements, including noble metals, are identified to influence corrosion behavior of many metals in high-temperature water/steam and O-2. We have previously reported effects of porous Pt coatings on the thermal oxidation of Zr, Fe, Ni, Cr, and GaAs in O-2. Effects of Pt on oxidation of Zircaloy-2 in H2O have also been observed at temperatures near 400 degrees C. An enhanced oxidation rate is observed in all of the studied systems upon a sufficiently high surface Pt-particle density. Even more interesting, low Pt-particle density in most cases leads to a decreased oxidation rate. In the case of Zr and Zircaloy-2 the beneficial effect of Pt is stronger when hydrogen is present in the metal substrate and in the oxide layer. From O-18/SIMS experiments it is concluded that, for a sufficiently high Pt-particle density on the surface, enhanced transport of dissociated oxygen, On- (n=0; 2), towards the oxide/metal interface occurs in all of the studied systems. An oxygen spillover from Pt particles to the adjacent surface is a known phenomenon in catalysis and partly explains the results observed also in the current study of oxidation of Zr-based materials. Such a spillover involves a high surface diffusivity of dissociated oxygen, On-, which results in an increased gradient of On- across the oxide scale. In turn, the high oxygen gradient enhances the transport of oxygen towards the substrate/oxide-interface, This shows that not only diffusivity but also an effective activity of dissociated oxygen at the external oxide surface influences the oxidation rate. Naturally, the effects of Pt are maximized when small (nm-sized) and evenly distributed Pt particles are present on the surface. In our presentation a summary of obtained results of Pt additions on different materials will be given with suggested interpretations. Especially, the observed beneficial combination of Pt and hydrogen in the oxidation of Zr-based materials is discussed with a possible mechanistic explanation. Parallels are also drawn to the potential effect of Noble Metal Chemical Application (NMCA), used in a large traction of the U.S. BWRs, on the corrosion resistance of Zr-based claddings.

  • 5.
    Anghel, Clara
    et al.
    KTH, Tidigare Institutioner, Materialvetenskap.
    Hörnlund, Erik
    KTH, Tidigare Institutioner, Materialvetenskap.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner, Materialvetenskap.
    Limbäck, Magnus
    Gas phase analysis of CO interactions with solid surfaces at high temperatures2004Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 233, nr 1-4, s. 392-401Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An in situ method including mass spectrometry and labeled gases is presented and used to gain information on adsorption of molecules at high temperatures (>300 degreesC). Isotopic exchange rate in H-2 upon exposure to an oxidized zicaloy-2 sample and exchange rate in CO upon exposure to various materials have been measured. From these measurements, molecular dissociation rates in respective system have been calculated. The influence of CO and N-2 on the uptake rate of H-2 in zirconium and oxidized zicaloy-2 is discussed in terms of tendency for adsorption at high temperatures. In the case of oxidized Cr exposed to CO gas With C-12, C-13, O-16 and O-18, the influence of H2O is investigated with respect to dissociation of CO molecules. The presented data supports a view of different tendencies for molecular adsorption of H2O, CO, N-2, and H-2 molecules on surfaces at high temperatures.

  • 6.
    Belonoshko, Anatoly B.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Rosengren, Anders
    KTH, Tidigare Institutioner, Fysik.
    Dong, Qian
    KTH, Tidigare Institutioner, Materialvetenskap.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner, Materialvetenskap.
    Leygraf, Christofer
    KTH, Tidigare Institutioner, Materialvetenskap.
    First-principles study of hydrogen diffusion in alpha-Al2O3 and liquid alumina2004Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have studied the energetics and mobility of neutral hydrogen in alumina Al2O3 using ab initio density-functional calculations. The mobility of hydrogen was studied in corundum (alpha-Al2O3) as well as in liquid alumina. Using both static as well as molecular-dynamics calculations, and applying classical transition state theory, we derive the temperature-dependent diffusivity of hydrogen in alpha-Al2O3 as D(T)=(21.7x10(-8) m(2)/s)exp(-1.24 eV/kT). The corresponding diffusivity of hydrogen in liquid/amorphous alumina, derived directly from ab initio molecular dynamics calculations, is D(T)=(8.71x10(-7) m(2)/s)exp(-0.91 eV/kT). The computed diffusivity compares very well to experimental data. We conclude that diffusion of neutral hydrogen through the bulk of alumina is a good approximation of the mechanism for hydrogen mobility in corrosion scales. The representation of grain-boundary structures by amorphous alumina is, probably, realistic at higher temperatures.

  • 7.
    Belonoshko, Anatoly B.
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Rosengren, Anders
    KTH, Tidigare Institutioner, Fysik.
    Dong, Qian
    KTH, Tidigare Institutioner, Materialvetenskap.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner, Materialvetenskap.
    Leygraf, Christofer
    KTH, Tidigare Institutioner, Materialvetenskap.
    First-principles study of hydrogen diffusion in α-Al 2O3 and liquid alumina2004Inngår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 69, nr 2, s. 243021-243026Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have studied the energetics and mobility of neutral hydrogen in alumina Al2O3 using ab initio density-functional calculations. The mobility of hydrogen was studied in corundum (α-Al2O 3) as well as in liquid alumina. Using both static as well as molecular-dynamics calculations, and applying classical transition state theory, we derive the temperature-dependent diffusivity of hydrogen in α-Al 2O3 as D(T)=(21.7 × 10-8 m 2/s)exp(-1.24 eV/kT). The corresponding diffusivity of hydrogen in liquid/amorphous alumina, derived directly from ab initio molecular dynamics calculations, is D(T)=(8.71 × 10-7 m2/s)exp(-0.91 eV/kT). The computed diffusivity compares very well to experimental data. We conclude that diffusion of neutral hydrogen through the bulk of alumina is a good approximation of the mechanism for hydrogen mobility in corrosion scales. The representation of grain-boundary structures by amorphous alumina is, probably, realistic at higher temperatures.

  • 8.
    Belonoshko, Anatoly B.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Rosengren, Anders
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Thermal regimes of passivative oxide film formation on Al surface: Theoretical and experimental study2006Inngår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 600, nr 20, s. 4796-4800Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report results of ab initio molecular dynamics simulations of an Al surface exposed to an oxygen atmosphere. The results, supported by experiments performed in this study, demonstrate that the Al surface, by reacting with the oxygen molecules, can be heated above melting temperature and transformed into a liquid. This process is potentially capable of creating an amorphous corrosion scale which might possess an enhanced resistance to deterioration.

  • 9. Dong, Q.
    et al.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Sproule, G. I.
    Graham, M. J.
    Platinum-catalyzed high temperature oxidation of metals2007Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 49, nr 8, s. 3348-3360Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Samples of At, Cr, Ni, and Zr were sputter-coated with porous Pt-films with a particle size of 20-30 nm. Thermal oxidation of these samples was studied by gas phase analysis (GPA) and secondary ion mass spectrometry (SIMS). SIMS analysis on partly Pt-coated samples of At, Cr, Ni, and Zr at different oxide depths in areas with Pt and in areas away from Pt indicates an enhanced inward oxide growth in the Pt area and mm-ranged distance from Pt-area. Weight gain measurements on Pt-coated Ni samples show a reduced or increased oxidation rate depending on the amount of porous Pt-coating. Pt has two effects on the thermal oxidation of metals and the overall effect of Pt on the oxidation of metals depends on the mechanism of oxide growth in the absence of Pt.

  • 10.
    Dong, Qian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Does nitrogen transport in vitreous silica only take place in molecular form?2006Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, nr 10, s. 104904-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is generally believed that nitrogen transport in vitreous silica exclusively takes place in molecular form, although no evidence for this is found in the literature. Actually, an analysis of literature data of transport of nitrogen and noble gases in vitreous silica at 900 °C suggests it may not be the case. In order to clarify the operative species of nitrogen transport in this material, experiments of permeation and uptake/release have been performed with the use of gas phase analysis and isotopic labeling of nitrogen. By comparing the relative distributions of N2 14,14, N2 14,15, and N2 15,15 in exposure gas, permeated gas and released gas with distribution of equilibrated nitrogen molecules, the percentage of dissociated nitrogen in the transport has been evaluated at different temperatures. It has then been found that nitrogen undergoes dissociation not only on the surface of vitreous silica but also in its bulk and that the overall dissociation of nitrogen increases with temperature. It is concluded that nitrogen diffuses both in molecular and atomic forms with approximately 15% atomic nitrogen transport at 900 °C. The observed transport rates are explained by diffusion of molecular nitrogen combined with a retardation of dissociated nitrogen in reversible traps.

  • 11. Hornlund, E.
    et al.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Experimental findings in support of atomic transport of hydrogen in silica2003Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 94, nr 8, s. 4819-4823Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Data supporting a view of both molecular and atomic transport of hydrogen in quartz is presented. By studying isotopic equilibration, it is shown that virtually all of the molecules diffusing through a 1.5 mm thick quartz membrane at 900 degreesC have undergone dissociation. The catalytic properties of platinum for the dissociation of H-2 are used to increase the surface concentration of atomic hydrogen on a quartz membrane. It is found that the high surface concentration increases the total flux of hydrogen through the membrane. It is also found by comparison with literature data that diatomic molecules probably diffuse in two modes in quartz. We suggest that these two modes are one atomic and one molecular.

  • 12.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Why copper may be able to corrode in pure water2015Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 93, s. 327-329Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In exposure of copper to water molecules there will be relatively strong bonds (reversible traps) between copper and hydrogen. One copper-hydrogen bond corresponds to the thermal energy of a temperature of approximately 250 degrees C and this explains an unusual temperature influence on hydrogen uptake in the metal and in corrosion of copper in pure water-vapour without O-2. This unusual temperature influence is exemplified in exposure of copper at 180 degrees C and 500 degrees C where Cu corrodes more at 180 degrees C than at 500 degrees C.

  • 13.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Anghel, Clara
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Szakalos, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Effects of hydrogen on the corrosion resistance of metallic materials and semiconductors2006Inngår i: High-Temperature Oxidation And Corrosion 2005 / [ed] Taniguchi, S; Maruyama, T; Yoshiba, M; Otsuka, N; Kawahara, Y, 2006, Vol. 522-523, s. 139-146Konferansepaper (Fagfellevurdert)
    Abstract [en]

    For long time it is known that protons in aqueous solutions have a detrimental effect on metallic materials. Relatively recently, it has also been observed in aqueous solution that the pitting corrosion resistance of Cr, stainless steel 304 and 310 decreases and the anodic dissolution rate increases due to the presence of hydrogen in the metal. In gas phase a high oxidation rate has been observed for hydrogen containing Cr and Fe. Hydrogen in the substrate can also enhance the oxidation of Fe in SS 316 and As in GaAs. All these results suggest enhanced dissolution in aqueous solution and enhanced oxide growth at the oxide/gas interface in gas phase oxidation due to hydrogen promoted outward-transport of substrate components. A possible mechanism for such out-transport is an increased metal ion diffusivity in the metal-oxide due to a high abundance of metal ion vacancies generated by hydrogen. In contrast to all the above examples, also positive effects of hydrogen have been identified under certain conditions. In an attempt to understand both the negative and the positive effects the concept of a beneficial, balanced oxide growth is used. In this concept a certain amount of hydrogen can be beneficial in the oxidation by improving the balance between oxygen-ion and metalion transport, leading to more dense and protective oxides. Depending on the temperature, H(2) in air is considered as either a sink or a source for hydrogen in materials.

  • 14.
    Hultquist, Gunnar B.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära (stängd 20081231).
    Szakálos, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära (stängd 20081231).
    Graham, M. J.
    Sproule, G. I.
    Wikmark, G.
    Detection of hydrogen in corrosion of copper in pure water2008Inngår i: Int. Corros. Congr.: Corros. Control Serv. Soc., 2008, s. 2378-2386Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Copper is generally assumed to be immune to corrosion by water itself. However, this is not supported by any scientific experimental evidence. Corrosion results from 15 years of exposure are presented here. A transition from O 2-consuming to H 2-evolving copper corrosion is concluded, which implies that copper can corrode by water itself. The complex corrosion product contains hydrogen. We have also measured a hydrogen uptake in the copper metal as a result of metallic copper corrosion by water which implies a sample thickness dependence on hydrogen uptake. The results are described in terms of autoionisation of water which offers an explanation why copper corrosion can take place in pure O 2-free water.

  • 15.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Graham, M. J.
    Kodra, O.
    Moisa, S.
    Liu, R.
    Bexell, U.
    Smialek, J. L.
    Corrosion of copper in distilled water without O2 and the detection of produced hydrogen2015Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 95, s. 162-167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports on hydrogen pressures measured during ~19,000. h immersion of copper in oxygen-free liquid distilled water. Copper corrosion products have been examined ex-situ by SEM and characterized by XPS and SIMS. XPS strongly indicates a corrosion product containing both oxygen and hydrogen. SIMS shows that oxygen is mainly present in the outer 0.3. μm surface region and that hydrogen penetrates to depths well below the corrosion product. Thermal desorption spectroscopy shows that the reaction product formed near room-temperature is less stable than that formed in air at 350. °C.

  • 16.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Graham, M. J.
    Smialek, J. L.
    Jonsson, B.
    Hydrogen in metals studied by Thermal Desorption Spectroscopy (TDS)2015Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 93, s. 324-326Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This short communication presents Thermal Desorption Spectroscopy (TDS) of hydrogen desorption from various metals and alloys [Au, Pd, Cu, Ni, Zr, Y, stainless steel and ODS (oxide dispersion strengthened) alloy] after long-term exposure (up to 20 years) to ambient humid air at room-temperature. Of the metals studied only gold does not contain a measurable level of hydrogen. For polycrystalline metals there is a strong correlation between the amount of hydrogen in the metal and the tendency for oxidation of the metal.

  • 17.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Graham, M. J.
    Smialek, J. L.
    Kodra, O.
    Response to comment by A. Hedin et al. on "Corrosion of copper in distilled water without oxygen and the detection of produced hydrogen"2016Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 106, s. 306-307Artikkel i tidsskrift (Annet vitenskapelig)
  • 18.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Graham, M. J.
    Szakalos, P.
    Sproule, G. I.
    Rosengren, Anders
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Gråsjö, L..
    Hydrogen gas production during corrosion of copper by water2011Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 53, nr 1, s. 310-319Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the corrosion of copper in water by (1) short term open system weight measurements and (2) long term closed system immersion in distilled water (13 800 h) without O-2 at 21-55 degrees C In the latter experiments the hydrogen gas pressure is measured above the immersed copper and approaches similar to 10(-3) bar at equilibrium This pressure is mostly due to copper corrosion and greatly exceeds that in ambient air Accordingly this measured hydrogen pressure from copper corrosion increases with temperature and has the same dependency as the concentration of OH- in the ion product [OH-] [H+].

  • 19.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Graham, M. J.
    Wee, A. T. S.
    Liu, R.
    Sproule, G. I.
    Dong, Q.
    Anghel, C.
    Effects of O-2 dissociation on a porous platinum coating in the thermal oxidation of GaAs2006Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, nr 2, s. G182-G186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 20-30-nm-thick porous Pt layer has been sputter-coated on a portion of a GaAs sample and subsequently the sample was oxidized at 500 degrees C in O-16(2) followed by O-18-enriched O-2. The oxide formed was characterized by Auger electron spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy, all with a lateral resolution of about 100 mu m. Away from the Pt area, a mm-ranged gradually decreasing degree of As oxidation was observed in the outermost oxide layer. In the Pt area, Ga was preferentially oxidized at the oxide/substrate interface producing a five to seven times thicker oxide than in an area without the influence of Pt. A strongly enhanced dissociation rate of O-2 on Pt particles and a subsequent O spillover to adjacent oxide explain the experimental observations. The mm-ranged spillover is believed to take place via fast lateral surface diffusion and results in the observed variation of oxidized As at the gas/oxide interface. In the Pt area, a high concentration gradient of dissociated oxygen across the oxide layer supplies a high flux of dissociated oxygen to the GaAs substrate where Ga is preferentially oxidized. The results clearly demonstrate that both a surface reaction and solid-state diffusion influence the oxidation rate. A localized high effective oxygen (O) activity that spills over to a nearby oxide area is believed to be a general phenomenon that is operating in oxides where a dissociating element such as Pt is present at O-2/oxide interfaces.

  • 20.
    Hultquist, Gunnar
    et al.
    KTH, Tidigare Institutioner                               , Kemi.
    Hörnlund, Erik
    KTH, Tidigare Institutioner                               , Kemi.
    Dong, Qian
    KTH, Tidigare Institutioner                               , Kemi.
    Platinum-induced oxidation of chromium in O-2 at 800 °C2003Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 45, nr 12, s. 2697-2703Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of porous Pt on the oxidation of Cr at 800degreesC have been studied with the (OSIMS)-O-18 technique, gas phase analysis and XPS. In oxide areas with Pt a pronounced inward oxygen transport takes place and a substantial oxide growth near the Cr substrate is observed. In oxide grown on areas without Pt the counts of CrO ions in SIMS and the binding energy of O (1s) in XPS depend on the distance from the area with Pt. The experimental observations are believed to be a consequence of a high dissociation efficiency of O-2 on areas with Pt in combination with a high diffusivity of O in external and internal oxide surfaces on areas both with and without Pt.

  • 21.
    Hultquist, Gunnar
    et al.
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Sproule, G. I.
    Moisa, S.
    Graham, M. J.
    Sodervall, U.
    Influence of deuterium and platinum on the thermal oxidation of GaAs2003Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, nr 10, s. G617-G623Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The thermal oxidation of GaAs at 500 degreesC in O-18 labeled O-2 has been studied with gas phase analysis, Auger electron spectroscopy, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy. The influence of a few hundred atomic parts per million of deuterium in the GaAs substrate and of surface platinum have been evaluated with respect to oxide growth mechanisms and the degree of As buildup. Deuterium increased the transport from the substrate interface of both Ga and As toward the gas interface thereby lowering the degree of preferential Ga oxidation and As buildup at the substrate interface. Platinum, on the other hand, catalyzed the dissociation of the oxygen molecule at the gas interface and thereby facilitated an increased transport of oxygen toward the substrate interface. That results in an increased overall oxidation rate with a high degree of preferential Ga oxidation and concomitant As buildup. When the oxygen pressure was increased from 20 to 720 mbar, a lowered degree of As buildup was observed due to the lower degree of preferential Ga oxidation.

  • 22.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Szakalos, P.
    Graham, M. J.
    Belonoshko, A. B.
    Rosengren, Anders
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Reply to Lars O. Werme et al.: "Comments on 'Water Corrodes Copper'"2010Inngår i: Catalysis Letters, ISSN 1011-372X, E-ISSN 1572-879X, Vol. 135, nr 3-4, s. 167-168Artikkel i tidsskrift (Fagfellevurdert)
  • 23.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Szakalos, Peter
    Catalysed self-cleaning of air on the earth's surface2006Inngår i: Journal of Atmospheric Chemistry, ISSN 0167-7764, E-ISSN 1573-0662, Vol. 55, nr 2, s. 131-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Generally, it is assumed that UV-light, high temperature or reactive molecules like O-3 and OH are needed to activate gas reactions in air. In consequence, the catalytic activity on natural materials such as sand and soil on the earth's surface is assumed to be insignificant. We have measured O-2-dissociation rates on natural quartz sand at 40 degrees C and compared these with O-2-dissociation rates near 500 degrees C on materials with well-known catalytic activity. In terms of probabilities for dissociation of impinging O-2-molecules the measured rates are in the 10(-12)-10(-4) range. We have also measured dissociation rates of H-2 and N-2, water-formation from H-2 and O-2 mixtures, exchange of N between N-2, NO (x) and a breakdown of HNO3, NO2 and CH4 on natural quartz sand at 40 degrees C. The measured rates together with an effective global land area have been used to estimate the impact of thermodynamically driven reactions on the earth's surface on the global atmospheric budgets of H-2, NO2 and CH4. The experimental data on natural quartz sand together with data from equilibrium calculations of air suggest that an expected increase in anthropogenic supply of air pollutants, such as NO (x) or other reactive nitrogen compounds, hydrogen and methane, will be counter-acted by catalysis on the earth's surface. On the other hand, at Polar Regions and boreal forests where the reactive nitrogen concentration is below equilibrium, the same catalytic effect activates formation of bio-available nitrogen compounds from N-2, O-2 and H2O.

  • 24.
    Hultquist, Gunnar
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Szakalos, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Graham, M. J.
    Belonoshko, Antoly B.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Sproule, G. I.
    Grasjo, L.
    Dorogokupets, P.
    Danilov, B.
    Aastrup, T.
    Wikmark, G.
    Chuah, G. K.
    Eriksson, Jan Christer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Rosengren, Anders
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Water Corrodes Copper2009Inngår i: Catalysis Letters, ISSN 1011-372X, E-ISSN 1572-879X, Vol. 132, nr 3-4, s. 311-316Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    According to a current concept, copper canisters of thickness 0.05 m will be safe for nuclear waste containment for 100,000 years. We show that more than 1 m copper thickness might be required for 100,000 years durability based on water exposures of copper for 20 h, 7 weeks, 15 years, and 333 years. An observed evolution of hydrogen which involves heterogeneous catalysis of molecular hydrogen, first principles simulations, thermodynamic considerations and corrosion product characterization provide further evidence that water corrodes copper resulting in the formation of a copper hydroxide. These findings cast additional doubt on copper for nuclear waste containment and other important applications.

  • 25.
    Hultquist, Gunnar
    et al.
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Tveten, B.
    Hornlund, E.
    Hydrogen in chromium: Influence on the high-temperature oxidation kinetics in H2O, oxide-growth mechanisms, and scale adherence2000Inngår i: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 54, nr 02-jan, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 26.
    Hultquist, Gunnar
    et al.
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Tveten, B.
    Hornlund, E.
    Limback, M.
    Haugsrud, R.
    Self-repairing metal oxides2001Inngår i: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 56, nr 04-mar, s. 313-346Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 27.
    Rundgren, John
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Dong, Qian
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Concentration-dependent diffusion of hydrogen in vitreous silica2006Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, nr 10, s. 104902-1-104902-5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report diffusion experiments where hydrogen permeates through a 1 mm wall of vitreous silica at 550 °C with applied gas pressures of 70, 460, 840, and 1200 mbars. For each pressure, and at steady state, the flux and the amount of hydrogen in the material are measured. Within the experimental accuracy we find that the flux is proportional to the pressure and that the hydrogen amount increases with a falling gradient with respect to pressure. The result is a relationship between flux and mean concentration. A careful evaluation of the flux versus concentration relationship by means of the steady-state diffusion equation shows that the hydrogen diffusivity in the silica wall is concentration dependent and increases linearly with local concentration.

  • 28. Siddle, A.
    et al.
    Castle, J. E.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Tan, K. L.
    Investigation of the initial reaction of the alloy Co86Cr14 and its constituent metals with oxygen using secondary ion mass spectrometry2002Inngår i: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 33, nr 11-okt, s. 807-814Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The initial oxidation of Co86Cr14 and its constituent metals is investigated using an in situ dynamic secondary ion mass spectrometry (SIMS) technique. Simultaneous analysis and controlled formation of oxidation products, rather than just analysis, allows the oxidation to be studied at the very early stages of the process, i.e. when the oxidation product is of submonolayer extent. The technique, initiated by Hultquist(5-7) for the study of pure metals in various in situ environments, involves exposing a sputter-cleaned sample to various partial pressures of oxygen in the SIMS chamber and achieving an equilibrium between the formation and removal of the reaction products under the normal dynamic SIMS conditions. Here, the study is extended to give some insight into the interpretation of the SIMS data obtained by this method, and to determine a model for the oxidation of materials. An empirical model is derived for the oxidation of cobalt. A theoretical model is also derived based on the Langmuir model, but allowing for the more energetic nature of ion bombardment and oxide removal. The theoretical and empirical models are indistinguishable at low oxygen pressures. The cobalt component in the alloy Co86Cr14 behaves in a similar way to that of the pure metal, which suggests that the cobalt oxidizes independently of the chromium in the alloy.

  • 29. Szakalos, P.
    et al.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Wikmark, G.
    Response to the comment on "Corrosion of copper by water" Electrochem. Solid-State Lett., 10, C63, (2007)2008Inngår i: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 11, nr 4, s. S2-S2Artikkel i tidsskrift (Fagfellevurdert)
  • 30. Szakalos, Peter
    et al.
    Hultquist, Gunnar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Wikmark, G.
    Corrosion of copper by water2007Inngår i: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 10, nr 11, s. C63-C67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have studied copper corrosion in a system comprised of deionized water, absolute pressure gauges, and a palladium membrane. A transition from O-2-consuming to H-2-evolving copper corrosion is observed, which indicates that copper can corrode by water itself. The equilibrium hydrogen pressure in corrosion of copper by water at 73 degrees C exceeds the steady-state atmospheric hydrogen pressure (5 x 10(-7) bar) by a factor of about 2000. The growth of a hydrogen-containing corrosion product in O-2-free water is controlled by the hydrogen removal from the corroding surface. The results are discussed in the perspective of conventional potential-pH diagram for copper.

  • 31. Tveten, B.
    et al.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Wallinder, D.
    Hydrogen and yttria in chromium: Influence on the high-temperature oxidation kinetics in O-2, oxide-growth mechanisms and scale adherence2001Inngår i: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 55, nr 04-mar, s. 279-289Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 32. Wallinder, D.
    et al.
    Hornlund, E.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Influence of hydrogen in iron and in two stainless steels on aqueous and gaseous corrosion2002Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, nr 9, s. B393-B397Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of hydrogen in Fe, 301 stainless steel (SS 301), and Avesta 353MA on corrosion resistance in aqueous solutions was studied. The oxidation kinetics of uncoated and Pt-coated Fe was also investigated in O-2 at 500 and 700degreesC. Electrochemical and weight loss measurements were used to evaluate the corrosion resistance in aqueous solutions, and the high-temperature oxidation rate was determined by measuring the pressure decrease in a closed volume. Observations of a high dissolution rate of Fe and SS 301 in deionized water, as well as a high oxidation rate in O-2, can be explained by an increased metal cation transport in the oxide film induced by hydrogen in the metal. However, hydrogen up to a certain concentration in Avesta 353MA was found to increase the resistance to localized corrosion in chloride solution. Pt coating on Fe was found to decrease the oxidation rate and improve scale adherence. The presented results are discussed in view of recent findings of balanced metal cation and oxygen anion transport in protective metal oxides.

  • 33. Wallinder, D.
    et al.
    Hultquist, Gunnar
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Tveten, B.
    Hornlund, E.
    Hydrogen in chromium: influence on corrosion potential and anodic dissolution in neutral NaCl solution2001Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 43, nr 7, s. 1267-1281Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of hydrogen charging, outgassing, pickling and passivation of mechanically polished chromium was investigated with respect to corrosion potential and anodic dissolution in 0.3 M NaCl solution. Secondary ion mass spectroscopy measurements were used to detect hydrogen after hydrogen charging by means of cathodic polarization. The results show that hydrogen in chromium decreases the corrosion potential and increases the anodic dissolution rate. Passivation in HNO3 and pickling in HNO3 + HF increases the corrosion potential, whereas no significant effect on the anodic dissolution could be observed, probably due to a hydrogen uptake in these surface treatments.

1 - 33 of 33
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