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  • 1.
    Alipour, Yousef
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Furnace Wall Corrosion in a Wood-fired Boiler2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of renewable wood-based fuel has been increasing in the last few decades because it is said to be carbon neutral. However, wood-based fuel, and especially used wood (also known as recycled wood or waste wood), is more corrosive than virgin wood (forest fuel), because of higher amounts of chlorine and heavy metals. These elements increase the corrosion problems at the furnace walls where the oxygen level is low.

    Corrosion mechanisms are usually investigated at the superheaters where the temperature of the material and the oxygen level is higher than at the furnace walls.  Much less work has been performed on furnace wall corrosion in wood or used wood fired boilers, which is the reason for this project.    Tests are also mostly performed under simplified conditions in laboratories, making the results easier to interpret.  In power plants the interpretation is more complicated. Difficulties in the study of corrosion processes are caused by several factors such as deposit composition, flue gas composition, boiler design, and combustion characteristics and so on. Therefore, the laboratory tests should be a complement to the field test ones. This doctoral project involved in-situ testing at the furnace wall of power boilers and may thus contribute to fill the gap.

    The base material for furnace walls is a low alloy steel, usually 16Mo3, and the tubes may be coated or uncoated. Therefore tests were performed both on 16Mo3 and more highly alloyed materials suitable for protective coatings.

    Different types of samples exposed in used-wood fired boilers were analysed by different techniques such as LOM (light optical microscopy), XRD (X-ray diffraction), SEM (scanning electron microscopy), EDS (energy dispersive spectroscopy), WDS (wavelength dispersive spectroscopy), FIB (focused ion beam) and GD-OES (glow discharge optical emission spectroscopy). The corrosion rate was measured. The environment was also thermodynamically modelled by TC (Thermo-Calc ®).

    The results showed that 16Mo3 in the furnace wall region is attacked by HCl, leading to the formation of iron chloride and a simultaneous oxidation of the iron chloride. The iron chloride layer appeared to reach a steady state thickness.  

    Long term exposures showed that A 625 (nickel chromium alloy) and Kanthal APMT (iron-chromium-aluminium alloy) had the lowest corrosion rate (about 25-30% of the rate for 16Mo3), closely followed by 310S (stainless steel), making these alloys suitable for coating materials. It was found that the different alloys were attacked by different species, although they were exposed in the boiler at the same time in the same place. The dominant corrosion process in the A 625 samples seemed to be by a potassium-lead combination, while lead did not attack the APMT samples. Potassium attacked the alumina layer in the APMT samples, leading to the formation of a low-protective aluminate and chlorine was found to attack the base material.  The results showed that stainless steels are attacked by both mechanisms (Cl- induced attack and K-Pb combination).

    Decreasing the temperature of the furnace walls of a waste wood fired boiler could decrease the corrosion rate of 16Mo3. However, this low corrosion rate corresponds to a low final steam pressure of the power plant, which in not beneficial for the electrical efficiency.

    The short term testing results showed that co-firing of sewage sludge with used wood can lead to a reduction in the deposition of K and Cl on the furnace wall during short term testing. This led to corrosion reduction of furnace wall materials and coatings. The alkali chlorides could react with the aluminosilicates in the sludge and be converted to alkali silicates. The chromia layer in A 625 and alumina in APMT were maintained with the addition of sludge. 

  • 2.
    Alipour, Yousef
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    High temperature corrosion in a biomass-fired power boiler: Reducing furnace wall corrosion in a waste wood-fired power plant with advanced steam data2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The use of waste (or recycled) wood as a fuel in heat and power stations is becoming more widespread in Sweden (and Europe), because it is CO2 neutral with a lower cost than forest fuel. However, it is a heterogeneous fuel with a high amount of chlorine, alkali and heavy metals which causes more corrosion than fossil fuels or forest fuel.

    A part of the boiler which is subjected to a high corrosion risk is the furnace wall (or waterwall) which is formed of tubes welded together. Waterwalls are made of ferritic low-alloyed steels, due to their low price, low stress corrosion cracking risk, high heat transfer properties and low thermal expansion. However, ferritic low alloy steels corrode quickly when burning waste wood in a low NOx environment (i.e. an environment with low oxygen levels to limit the formation of NOx). Apart from pure oxidation two important forms of corrosion mechanisms are thought to occur in waste environments: chlorine corrosion and alkali corrosion.

    Although there is a great interest from plant owners to reduce the costs associated with furnace wall corrosion very little has been reported on wall corrosion in biomass boilers. Also corrosion mechanisms on furnace walls are usually investigated in laboratories, where interpretation of the results is easier. In power plants the interpretation is more complicated. Difficulties in the study of corrosion mechanisms are caused by several factors such as deposit composition, flue gas flow, boiler design, combustion characteristics and flue gas composition. Therefore, the corrosion varies from plant to plant and the laboratory experiments should be complemented with field tests. The present project may thus contribute to fill the power plant corrosion research gap.

    In this work, different kinds of samples (wall deposits, test panel tubes and corrosion probes) from Vattenfall’s Heat and Power plant in Nyköping were analysed. Coated and uncoated samples with different alloys and different times of exposure were studied by scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), X-ray diffraction (XRD) and light optical microscopy (LOM). The corrosive environment was also simulated by Thermo-Calc software.

    The results showed that a nickel alloy coating can dramatically reduce the corrosion rate. The corrosion rate of the low alloy steel tubes, steel 16Mo3, was linear and the oxide scale non-protective, but the corrosion rate of the nickel-based alloy was probably parabolic and the oxide much more protective. The nickel alloy and stainless steels showed good corrosion protection behavior in the boiler. This indicates that stainless steels could be a good (and less expensive) alternative to nickel-based alloys for protecting furnace walls.

    The nickel alloy coated tubes (and probe samples) were attacked by a potassium-lead combination leading to the formation of non-protective potassium lead chromate. The low alloy steel tubes corroded by chloride attack. Stainless steels were attacked by a combination of chlorides and potassium-lead.

    The Thermo-Calc modelling showed chlorine gas exists at extremely low levels (less than 0.1 ppm) at the tube surface; instead the hydrated form is thermodynamically favoured, i.e. gaseous hydrogen chloride. Consequently chlorine can attack low alloy steels by gaseous hydrogen chloride rather than chlorine gas as previously proposed. This is a smaller molecule than chlorine which could easily diffuse through a defect oxide of the type formed on the steel.

  • 3.
    Alipour, Yousef
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Reducing furnace wall corrosion by coating the furnace tubes in a waste wood fired boiler plant2012Conference paper (Refereed)
  • 4.
    Alipour, Yousef
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Henderson, Pamela
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Initial Corrosion of Waterwalls Materials in a Waste Wood Fired Power PlantManuscript (preprint) (Other academic)
  • 5.
    Alipour, Yousef
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Henderson, Pamela
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    The effect of co-firing of sewage sludge with waste wood on furnace wall corrosion2014In: International Symposium On High-Temperature Oxidation And Corrosion Hakodate, Hokkaido Japan, 2014, 23-27 June, 2014Conference paper (Refereed)
  • 6.
    Alipour, Yousef
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Henderson, Pamela
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Szakalos, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    The effect of a nickel alloy coating on the corrosion of furnace wall tubes in a waste wood fired power plant2014In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 65, no 2, 217-225 p.Article in journal (Refereed)
    Abstract [en]

    The use of waste wood as a fuel in power plants is becoming more widespread in Europe, because it is a renewable energy source with a lower cost than forest fuel. However it is more corrosive than coal and corrosion problems have arisen in the furnace wall area of a low NOx heat and power boiler. The furnace walls are made of a low alloy steel which has been coated in some parts with a nickel alloy to reduce corrosion. In this work, furnace tubes coated with a nickel alloy were compared to the uncoated tubes of the low alloy steel 16Mo3 after 3 years of exposure in the boiler. The nickel alloy coating and uncoated material were also compared with more controlled testing on a corrosion probe lasting for about 6 weeks. The corrosion rates were measured and the samples were chemically analysed by SEM/EDS/WDS and XRD methods. The corrosive environment was also modelled with Thermo-Calc software. The corrosion rates measured from the probe and tube samples of 16Mo3 agreed well with each other, implying linear corrosion rates. The results also showed that the use of nickel alloy coatings changes the corrosion mechanism, which leads to a dramatic reduction in the corrosion rate. The results are discussed in terms of the corrosion mechanisms and thermodynamic stability of the corrosion products.

  • 7.
    Alipour, Yousef
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Talus, A.
    Henderson, Pamela
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Vattenfall AB, Stockholm 169 92, Sweden.
    Norling, R.
    The effect of co-firing sewage sludge with used wood on the corrosion of an FeCrAl alloy and a nickel-based alloy in the furnace region2015In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 138, 805-813 p.Article in journal (Refereed)
    Abstract [en]

    The effect of digested sewage sludge as a fuel additive to reduce corrosion of furnace walls has been studied. The nickel base alloy Alloy 625 and the iron-chromium-aluminium alloy Kanthal APMT™ were exposed for 14.25. h at the furnace wall in a power boiler burning 100% used (also known as waste or recycled) wood. The test was then repeated with the addition of sewage sludge to the waste wood. The samples were chemically analysed and thermodynamically modelled and the corrosion mechanisms were investigated. The results showed that the co-firing of sewage sludge with recycled wood leads to a reduction in the corrosion. Attack by a potassium-lead combination appeared to be the main corrosion mechanism in Alloy 625 during waste wood combustion, while attack by alkali chloride was found to be dominant in APMT alloy.

  • 8.
    Alipour, Yousef
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Viklund, Peter
    Henderson, Pamela
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    The analysis of furnace wall deposits in a low-NOx waste wood-fired bubbling fluidised bed boiler2012In: VGB PowerTech Journal, ISSN 1435-3199, Vol. 92, no 12, 96-100 p.Article in journal (Other academic)
    Abstract [en]

    Increasing use is being made of biomass as fuel for electricity production as the price of natural wood continues to rise. Therefore, more use is being made of waste wood (recycled wood). However, waste wood contains more chlorine, zinc and lead, which are believed to increase corrosion rates. Corrosion problems have occurred on the furnace walls of a fluidised bed boiler firing 100 % waste wood under low-NOx conditions. The deposits have been collected and analysed in order to understand the impact of the fuel.

  • 9. Antikhovich, I. V.
    et al.
    Kharitonov, Dima S.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Belarusian State Technological University, Belarus.
    Chernik, A. A.
    Dobryden, Illia B.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Corrosion Resistance of Nickel Coatings Deposited from Low-Temperature Nickel-Plating Electrolytes2017In: Russian journal of applied chemistry, ISSN 1070-4272, E-ISSN 1608-3296, Vol. 90, no 4, 566-573 p.Article in journal (Refereed)
    Abstract [en]

    The corrosion resistance of nickel coatings on a copper substrate, plated from low-temperature electrolytes based on acetates, tartrates, and isobutyrates, was studied by the methods of electrochemical impedance spectroscopy (EIS) and polarization curves. The tests were performed in a 0.3% NaCl solution. The nickel coatings exhibit high chemical activity, dissolving in the NaCl solution. The electrochemical step is the limiting step of the corrosion process.

  • 10.
    Belonoshko, Anatoly B.
    et al.
    KTH, Superseded Departments, Physics.
    Rosengren, Anders
    KTH, Superseded Departments, Physics.
    Dong, Qian
    KTH, Superseded Departments, Materials Science and Engineering.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    First-principles study of hydrogen diffusion in α-Al 2O3 and liquid alumina2004In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 69, no 2, 243021-243026 p.Article in journal (Refereed)
    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.

  • 11.
    Bengtsson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Investigation of Galvanic Corrosion between Graphite Gaskets and Stainless Steel Flanges2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    At Forsmark, several cases of suspected galvanic corrosion have been detected and

    believed to be caused by an inappropriate use of graphite gaskets in brackish water.

    This report studies the likelihood of galvanic corrosion between the graphite gasket

    and stainless steels and aims to be a reference when investigating galvanic corrosion in

    the future. To evaluate galvanic corrosion, several electrochemical experiments were

    studied, such as galvanic series, polarization curves, and galvanic current

    measurements with a ZRA.

    The electrochemical results showed that when immersing the stainless steel (254

    SMO) and the graphite gasket (Novatec) into brackish water, there was a current

    flowing between the electrodes. However, the current was very small, which could be

    explained by the protection from a passive film on the stainless steel. The difference

    in corrosion potential between the two materials was measured and compared to

    results from polarization curves. It appeared that 254 SMO would be protected by a

    passive film at the measured potential. Galvanic current measurements also indicated

    the presence of a passive film under the investigated conditions.

    The results indicate that galvanic corrosion itself should not have caused the

    corrosion attacks at Forsmark. The found corrosion is more likely due to crevice

    corrosion that was accelerated by the combination of a crevice, a welded flange

    surface, chlorides in water and possibly a graphite gasket.

  • 12.
    Berendson, Jaak
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Electrochemical methods2007In: Surface Characterization: A User's Sourcebook, Wiley-Blackwell, 2007, 590-606 p.Chapter in book (Other academic)
  • 13.
    Bettini, Eleonora
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Influence of carbides and nitrides on corrosion initiation of advanced alloys: A local probing study2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Advanced alloys often present precipitated carbides and nitrides in their microstructure following exposure to elevated temperatures. These secondary phases are usually undesirable, because potentially deleterious for the corrosion and mechanical performances of the material. Carbides and nitrides are enriched in key alloying elements that are subtracted from their surrounding matrix areas, creating alloying element depleted zones, which might become initial sites for corrosion initiation. In this study, the influence of micro- and nano-sized precipitated carbides and nitrides on the corrosion initiation of biomedical CoCrMo alloys and duplex stainless steels has been investigated at microscopic scale, by using a combination of local probing techniques. The microstructures of the alloys were first characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and magnetic force microscopy (MFM). The Volta potential mapping of carbides and nitrides revealed their higher nobility compared to the matrix, and particularly compared to their surrounding areas, suggesting the occurrence of some alloying element depletion in the latter locations, which may lead to a higher susceptibility for corrosion initiation. In-situ electrochemical AFM studies performed at room temperature showed passive behavior for large potential ranges for both alloy families, despite the presence of the precipitated carbides or nitrides. At high anodic applied potential, at which transpassive dissolution occurs, preferential dissolution started from the areas adjacent to the precipitated carbides and nitrides, in accordance with the Volta potential results. Thus, the presence of carbides and nitrides doesn’t largely affect the corrosion resistance of the tested advanced alloys, which maintain passive behavior when exposed to highly concentrated chloride solutions at room temperature with no applied potential. The effect of nitrides on the corrosion initiation of duplex stainless steels was investigated also at temperatures above the critical pitting temperature (CPT). Depending on the type, distribution and size range of the precipitated nitrides different corrosion behaviors were observed. Intragranular (quenched-in) nano-sized nitrides (ca. 50-100 nm) finely dispersed in the ferrite grains have a minor influence on the corrosion resistance of the material at temperatures above the CPT, while larger intergranular (isothermal) nitrides (ca. 80-250 nm) precipitated along the phase boundaries cause a detrimental reduction of the corrosion resistance of the material, in particular of the austenite phase

  • 14.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kivisäkk, Ulf
    Sandvik Materials Technology.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Study of corrosion behavior of a 22% Cr duplex stainless steel: influence of nano-sized chromium nitrides and exposure temperature2013In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 0019-4686, Vol. 113, 280-289 p.Article in journal (Refereed)
    Abstract [en]

    Chromium nitrides may precipitate in duplex stainless steels during processing and their influence on the corrosion behavior is of great importance for the steel performance. In this study, the influence of nano-sized quenched-in chromium nitrides on the corrosion behavior of a heat treated 2205 duplex stainless steel was investigated at room temperature and 50 °C (just above critical pitting temperature). The microstructure was characterized by SEM/EDS and AFM analyses, and quenched-in nitrides precipitated in the ferrite phase were identified by TEM analysis. Volta potential mapping at room temperature suggests lower relative nobility of the ferrite matrix. Electrochemical polarization and in-situ AFM measurements in 1 M NaCl solution at room temperature show a passive behavior of the steel despite the presence of the quenched-in nitrides in the ferrite phase, and preferential dissolution of ferrite phase occurred only at transpassive conditions. At 50 °C, selective dissolution of the austenite phase was observed, while the ferrite phase with the quenched-in nitrides remained to be stable. It can be concluded that the finely dispersed quenched-in nitrides do not cause localized corrosion, whereas the exposure temperature has a strong influence on the corrosion behavior of the duplex stainless steel.

  • 15.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kivisäkk, Ulf
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Study of Corrosion Behavior of a 2507 Super Duplex Stainless Steel: Influence of Quenched-in and Isothermal Nitrides2014In: International Journal of Electrochemical Science, ISSN 1452-3981, Vol. 9, no 1, 61-80 p.Article in journal (Refereed)
    Abstract [en]

    Precipitation of different types of chromium nitrides may occur during processing of super duplex stainless steels, affecting the properties of the material. In this study the influence of quenched-in (size range ca. 50-100 nm) and isothermal (size range ca. 80-250 nm) types of nitrides on the corrosion behavior of a 2507 super duplex stainless steel has been investigated at room temperature and at 90 degrees C (above the critical pitting temperature) in 1 M NaCl solution. The microstructure has been characterized by scanning electron microscopy and magnetic force microscopy. The isothermal nitrides exhibit a higher Volta potential compared to the matrix, but such difference could not be observed for the quenched-in nitrides. In-situ electrochemical AFM measurements at room temperature show stable surfaces for a wide range of applied potentials despite the presence of either type of nitrides. In the transpassive region isothermal nitrides appear to be slightly more deleterious than quenched-in nitrides. At 90 degrees C isothermal nitrides largely reduce the corrosion resistance of the austenite phase, while the quenched-in nitrides reduce the corrosion resistance of the material to a much lesser extent. The size difference between isothermal and quenched-in chromium nitrides may be crucial, in particular above the critical pitting temperature.

  • 16.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nature of current increase for a CoCrMo alloy: "transpassive" dissolution vs. water oxidation2013In: International Journal of Electrochemical Science, ISSN 1452-3981, Vol. 8, no 10, 11791-11804 p.Article in journal (Refereed)
    Abstract [en]

    The “transpassive” behavior of a CoCrMo alloy has been investigated to clarify the nature of the current increase at high anodic potential (0.5-0.7 VAg/AgCl). The total amount of released metal ions was determined after the potentiostatic measurements. According to the calculation through Faradays’ law, the metal dissolution only contributes to part of the total current recorded. Electrochemical AFM mapping did not show pronounced topography changes at 0.65 VAg/AgCl, while light optical microscopy observation revealed fast evolution of oxygen bubbles. Evidently water oxidation is another important process largely contributing to the current increase at the high potential.

  • 17.
    Bexell, Ulf
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Engkvist, Josefin
    Chalmers University of Technology, Göteborg, Sweden.
    Malmberg, Per
    Chalmers University of Technology, Göteborg, Sweden.
    Comparing 69Ga+ and C60+ for ToF-SIMS sputter depth profiling in a Cr2O3 formed during oxidation of a Ce coated FeCr steel substrate2012Conference paper (Other academic)
  • 18.
    Björlenstam, Philip
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Evaluation of corrosion in crevices in screw joints2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this Master of Science thesis screws with different coatings were exposed to an accelerated corrosion test in order to investigate the corrosion development. The test matrix constituted of hexagonal and flange screws (fastened on frames) coated with either zinc/iron (ZnFe) or a flake system of aluminum and zinc (GEOMET). The corrosion results were analyzed by means of X-ray diffraction (XRD). In this study the screws were also crosscut and analyzed by means of FEG-SEM in order to determine the thickness and the elemental content of the surface coating. The result of the corrosion test showed that the screws coated with GEOMET showed a very good corrosion resistance whilst the screws coated with ZnFe failed to fulfill the demands on corrosion resistance of Scania.

  • 19.
    Boubitsas, Dimitrios
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Betong & Berg. Lund University, Lund Institute of Technology, Division of Building Materials.
    Chloride transport and chloride threshold values: studies on concretes and mortars with Portland cement and limestone blended cement2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Reinforced concrete is one of the most widely used building materials and if it is properly designed and produced, it is an extremely durable material with a service life up to 100 years. However, under certain environmental conditions the service life of reinforced concrete structures is more limited. Deterioration ofconcrete structure is in most cases caused by the penetration of aggressive media from the surrounding environment. Chloride initiated reinforcement corrosion is one of the major causes of deterioration of Concrete structures. One conflicting issue is how replacing Portland cement with mineral additions influences chlorideinitiated reinforcement corrosion. This issue is of immediate interest, as there is a steady growth in the use of cement blended with mineral additions, such as blast-furnace slag, fly ash and limestone filler. This is done by the cement and concrete industry to reduce the CO2 emissions linked to Portland cement manufacturing, bylimiting the use of clinker in the cement.The main objective of this work has been to further clarify the role of limestone filler as partial substitute to Portland cement on the two main decisive parameters for chloride induced reinforcement corrosion: chloride ingress rate and chloride threshold values. In the first part of this work the chloride ingress was studied both with accelerated laboratory methods and also after field exposure. The initial focus for the second part of the study was to determine the chloride threshold values for the binders investigated in the first part, so a comprehensive view of the effect of limestone addition on chloride initiated corrosion could be presented.However, during the work the need for the development of a practice-related method for determining the chloride threshold values was identified and the focus of the research was redirected to meet that need.The efficiency of limestone filler concerning chloride ingress showed to be dependent on replacement ratio, time (age) and on the test method. It was not possible to draw any rigid conclusion of the limestone filler’s efficiency regarding chloride ingress. But part of the inconsistency in the results was identified to be that limestone filler has two opposite effects on chloride ingress, on one hand contribute to a refinement of microstructure and on the other hand diminishing the chloride binding.The steel surface condition was shown to have a strong effect on the corrosion initiation, and can likely be one of the most decisive parameters attributing to the variability in the reported chloride threshold values obtained in laboratory experiments. The chloride threshold value for the sulphate resistant Portland cement fromthe laboratory experiments was estimated to be about 1% by weight of binder. For the concrete with limestone blended cement (CEM II/A-LL 42.5R) tested in this work the chloride threshold value was at the same level as for the sulphate resistant Portland cement. From the field study but with a somewhat different definition ofchloride threshold value, a chloride threshold value of about 1% by weight of binder was also estimated for ordinary Portland cement and sulphate resistance Portland with 5% silica fume exposed to marine environment.

  • 20.
    Broström, Markus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Enestam, Sonja
    Backman, Rainer
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Mäkelä, Kari
    Condensation in the KCl-NaCl system2013In: Fuel processing technology, ISSN 0378-3820, Vol. 105, 142-148 p.Article in journal (Refereed)
    Abstract [en]

    Condensation of gaseous KCl and NaCl is known to participate in deposit formation and high temperature corrosion processes in heat and power plants. Little is known about interaction between the two salts, which is of interest for the overall understanding of deposit and corrosion problems. Within this study, condensation at different material surface temperatures and salt mixtures was investigated.

    Salt vapors were prepared by temperature controlled evaporation. A cooled condensation probe with a temperature gradient was inserted in the hot gas. After exposure, the probe surface was visually inspected and analyzed with SEM/EDS and XRD for elemental and phase composition. TGA/DTA was used to provide complementary information on vaporization and sintering.

    The results indicated that a mixture of KCl and NaCl probably condenses as separate phases at concentrations and temperatures below the melting points of the salts. Condensation was possibly followed by a secondary sintering process. It was verified by TGA/DTA that a mixture of solid KCl and NaCl particles sinters and melts rapidly at temperatures above the melting temperature of a corresponding solution. It was also seen that sintering took place at lower temperatures with slow solid-gas interactions, possibly with the formation of solid solutions.

  • 21.
    Chai, Guocai
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Sandvik Mat Technol, Sandviken, Sweden.
    Kangas, Pasi
    Sandvik Mat Technol, Sandviken, Sweden.
    Super and hyper duplex stainless steels: structures, properties and applications2016In: 21ST EUROPEAN CONFERENCE ON FRACTURE, (ECF21), ELSEVIER SCIENCE BV , 2016, Vol. 2, 1755-1762 p.Conference paper (Refereed)
    Abstract [en]

    In oil-gas industry, the exploration and development are now targeted to the deep reservoirs with high pressures, high temperatures and extreme corrosive environments. This requires that the materials used should have a good combination of extra high strength and excellent corrosion resistance. In order to meet these challenges, hyper duplex stainless steels have recently been developed. These materials have nitrogen contents up to about 0.5% and PRE-values close to 50, and show both highest corrosion pitting resistance and highest strength among the existing duplex stainless steels. The purpose of this paper is to provide an overview on hyper duplex stainless steels. It will mainly focus on the material development, microstructures, corrosion properties such as critical pitting corrosion temperature and crevice corrosion resistance, heterogeneous deformation behaviour of duplex stainless steel, and mechanical properties such as tensile properties and fatigue properties. These properties and the ratios of strength/weight will then be compared with those of other type of duplex stainless steels. The potential applications for hyper duplex stainless steels are also discussed. Copyright (C) 2016 The Authors. Published by Elsevier B.V.

  • 22.
    Chang, Tingru
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    de la Fuente, D.
    Chico, B.
    Morcillo, M.
    Welter, J. -M
    Leygraf, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Analysis of historic copper patinas. Influence of inclusions on patina uniformity2017In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, no 3, 298Article in journal (Refereed)
    Abstract [en]

    The morphology and elemental composition of cross sections of eight historic copper materials have been explored. The materials were taken from copper roofs installed in different middle and northern European environments from the 16th to the 19th century. All copper substrates contain inclusions of varying size, number and composition, reflecting different copper ores and production methods. The largest inclusions have a size of up to 40 μm, with most inclusions in the size ranging between 2 and 10 μm. The most common element in the inclusions is O, followed by Pb, Sb and As. Minor elements include Ni, Sn and Fe. All historic patinas exhibit quite fragmentized bilayer structures, with a thin inner layer of cuprite (Cu2O) and a thicker outer one consisting mainly of brochantite (Cu4SO4(OH)6). The extent of patina fragmentation seems to depend on the size of the inclusions, rather than on their number and elemental composition. The larger inclusions are electrochemically nobler than the surrounding copper matrix. This creates micro-galvanic effects resulting both in a profound influence on the homogeneity and morphology of historic copper patinas and in a significantly increased ratio of the thicknesses of the brochantite and cuprite layers. The results suggest that copper patinas formed during different centuries exhibit variations in uniformity and corrosion protection ability.

  • 23. Chen, Jiaxin
    et al.
    Obitz, C
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Forssgren, B
    CORROSION KINETICS OF NICKEL-BASE ALLOYS WITH HIGH CHROMIUM CONTENTS UNDER SIMULATED BWR NORMAL WATER CHEMISTRY CONDITIONS AND HIGH FLOW VELOCITY2015Conference paper (Refereed)
    Abstract [en]

    In light water reactors corrosion-induced material degradation is a critical issue not only for material integrity but also for plant radiation field build-up. In BWRs nickel-base alloys, such as Alloy 600, Alloy 82 and Alloy 182, are applied in various parts of reactor components including welds. However, their corrosion mechanisms are not very well understood. Although the complex compositions of different nickel-base alloys generally prohibit us to single out some specific alloy constituent having a major impact on alloy corrosion rate, a higher chromium content is often thought to be beneficial to forming a more protective oxide film against corrosion attack. In this paper we report a corrosion kinetics study on high chromium nickel-base alloy welding consumables, Alloy 52M and Alloy 152, under simulated BWR normal water chemistry conditions and high flow velocity for up to nine weeks exposure. The corrosion rates are derived from measurements of weight losses of test coupons, oxide thicknesses with infrared ellipsometry, and microstructures of oxide films with electron microscopy. The obtained corrosion rates are then compared to that for Alloy 182, Alloy 82 and Alloy 600. The results show that the corrosion rate for Alloy 52M is similar to those for Alloy 182, whereas the rate for Alloy 152 is reduced to less than half. These observations indicate that the corrosion kinetics for nickel-base alloys is complex and alloy chromium content alone is not a dominant factor in influencing alloy corrosion rate.

  • 24.
    Danielsson, Olivia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Sonja
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Mildenberger, Ida
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Corrosion in the coolant circuit of Pansarterrängbil 2032016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The military vehicle, Pansarterrängbil 203 (PATGB 203) demonstrates a fault. There are some components in a coolant circuit that fail due to corrosion while others are unaffected. One of the affected components that will be investigated in this report is the water heater. The subject of this technical investigation has been an issue for FMV, Swedish Defence Materiel Administration since a decade. While seeking out the cause of the coolant circuit failing, this investigation aim to analyzing the underlying problems considering material, factors of corrosion and organization.

    In order to establish the origin of material and appearance of corrosion, experiments were performed. The experiments showed that the original material is an Al-Si alloy. The micrographs indicated varying stratification of the corrosion throughout the unit. The corrosive deposits consisted mainly of oxygen, silicon, aluminum and sodium.

    Consequently, the protecting passive oxide layer is compromised, which results in a direct connection between the coolant and the underlying material. This direct connection gives rise to the development of corrosion in the material. Clear underlying causes of the corrosion were not found but the most probable suggest on galvanic corrosion accelerated by a stray current. Properly grounding the components decreases the stray current in the system and is essential to avoid corrosion. If grounding the components is not sufficient, additional checks of the coolant with attention to the pH-value and the function of corrosion inhibitors may indicate corrosion at an earlier stage.

  • 25.
    Ejenstam, Jesper
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Corrosion resistant alumina-forming alloys for lead-cooled reactors2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Generation IV nuclear power technologies provide attractive solutions to the common issues related to conventional nuclear power plants currently in operation worldwide. Through a significant reduction of the long-term radiotoxicity of nuclear waste, a more efficient use of nuclear fuel resources, and implementation of inherent safety features, Generation IV will make nuclear power sustainable and thus increase the public acceptance of nuclear power. Due to its attractive safety features, the lead-cooled fast reactor (LFR) is one of the most studied Generation IV reactor concepts currently. It is well known that liquid lead is corrosive to steels at elevated temperatures, thus limiting the operation temperature of the LFR. The use of alumina-forming FeCrAl alloys has been proposed to mitigate oxidation and corrosion issues. Commercial FeCrAl alloys have Cr-concentrations typically about 20 wt. % and are thus prone to α-α’ phase separation and embrittlement at temperatures up to about 500 °C. Reducing the Cr-concentration to levels around 10 wt. % would theoretically resolve the said issue. However, the oxidation and corrosion resistance may be impaired. In the scientific literature, compositional limits indicating the formation of protective alumina layers at various temperatures have been presented. Long-term corrosion studies are however scarce. Moreover, in-depth studies on the compositional limits regarding α-α’ phase separation are lacking. In this thesis, the long-term (up to 10,000 h) corrosion resistance and phase stability of alumina-forming alloys are studied at temperatures up to 550 °C. In addition, the influence of reactive elements (RE), e.g. Ti, Zr, and Y, on the liquid lead corrosion resistance of Fe10CrAl alloys is evaluated. By balancing the reactive element and the carbon content, with respect to carbide formation, it is demonstrated in this thesis that it is possible to form protective alumina layers on Fe10Cr4Al alloys from 450 °C, despite the low Al and Cr concentrations. It was found that the RE/carbon ratio needed to form protective alumina layers on Fe10Cr4Al alloys must be larger than unity to mitigate the detrimental effect of Cr-carbide formation.  The underlying phenomena are discussed, and a mechanism is suggested based on the outcome of the long-term oxidation studies. The phase stability of Fe10CrAl alloys was studied through thermal aging experiments in the temperature interval of 450 to 550 °C. In addition, the results were well reproducible using a developed Kinetic Monte Carlo (KMC) model of the FeCrAl system. Furthermore, the model indicated that the Cr-concentration should be limited to about 11 wt. % in a FeCr4Al alloy to mitigate α-α’ phase separation at all temperatures of interest for an LFR. The liquid lead corrosion resistance of alumina-forming austenitic stainless steels was shown to be superior compared to regular stainless steels, albeit the effect of ferrite stabilizing elements needs to be further addressed. The results included in this thesis provide a valuable input on the key issues related to the development of corrosion resistant alumina-forming alloys of interest for liquid lead applications. Moreover, the superior oxidation properties of the studied alumina-forming alloys make them of interest for use in other energy applications, where corrosion issues limits the operation temperature and thus the efficiency.

     

  • 26.
    Ejenstam, Jesper
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Thuvander, Mattias
    Olsson, Pär
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Rave, Fernando
    Szakalos, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Microstructural stability of Fe–Cr–Al alloys at 450–550 °C2015In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 457, 291-297 p.Article in journal (Refereed)
    Abstract [en]

    Iron–Chromium–Aluminium (Fe–Cr–Al) alloys have been widely investigated as candidate materials for various nuclear applications. Albeit the excellent corrosion resistance, conventional Fe–Cr–Al alloys suffer from α–α′ phase separation and embrittlement when subjected to temperatures up to 500 °C, due to their high Cr-content. Low-Cr Fe–Cr–Al alloys are anticipated to be embrittlement resistant and provide adequate oxidation properties, yet long-term aging experiments and simulations are lacking in literature. In this study, Fe–10Cr–(4–8)Al alloys and a Fe–21Cr–5Al were thermally aged in the temperature interval of 450–550 °C for times up to 10,000 h, and the microstructures were evaluated mainly using atom probe tomography. In addition, a Kinetic Monte Carlo (KMC) model of the Fe–Cr–Al system was developed. No phase separation was observed in the Fe–10Cr–(4–8)Al alloys, and the developed KMC model yielded results in good agreement with the experimental data.

  • 27.
    Ejenstam, Lina
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science.
    Swerin, Agne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science.
    Pan, J.
    Claesson, Per M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. Department of Chemistry Surface and Corrosion Science, KTH Royal Institute of Technology.
    Corrosion protection by hydrophobic silica particle-polydimethylsiloxane composite coatings2015In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 99, 89-97 p.Article in journal (Refereed)
    Abstract [en]

    In this study, the time-dependent corrosion protection ability of 10-15. μm thin polydimethylsiloxane-nanoparticle composite coatings was evaluated using mainly open circuit potential and electrochemical impedance spectroscopy measurements. The best result was obtained for the coating containing 20. wt% hydrophobic silica nanoparticles, where it was possible to achieve protection for almost 80 days in 3. wt% NaCl solution. The protective properties offered by this coating are suggested to be due to a synergistic effect of the hydrophobicity of the polydimethylsiloxane matrix and the prolonged diffusion path caused by addition of hydrophobic silica particles.

  • 28.
    Ejenstam, Lina
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Chemistry, Division of Surface and Corrosion Science.
    Tuominen, Mikko
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik.
    Haapanen, J.
    Mäkelä, J. M.
    Pan, J.
    Swerin, Agne
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. KTH Royal Institute of Technology, Division of Surface and Corrosion Science.
    Claesson, Per M.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Material och ytteknik. Department of Chemistry Surface and Corrosion Science, KTH Royal Institute of Technology.
    Long-term corrosion protection by a thin nano-composite coating2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 357, no Part B, 2333-2342 p.Article in journal (Refereed)
    Abstract [en]

    We report and discuss the corrosion protective properties of a thin nano-composite coating system consisting of an 11μm thick polyester acrylate (PEA) basecoat, covered by an approximately 1-2μm thick layer of TiO2 nanoparticles carrying a 0.05μm thick hexamethyl disiloxane (HMDSO) top coat. The corrosion protective properties were evaluated on carbon steel substrates immersed in 3wt% NaCl solution by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements. The protective properties of each layer, and of each pair of layers, were also evaluated to gain further understanding of the long-term protective properties offered by the nano-composite coating. The full coating system showed excellent corrosion protective properties in the corrosive environment of 3wt% NaCl-solution for an extended period of 100 days, during which the coating impedance, at the lower frequency limit (0.01Hz), remained above 108 Ωcm2. We suggest that the excellent corrosion protective properties of the complete coating system is due to a combination of (i) good adhesion and stability of the PEA basecoat, (ii) the surface roughness and the elongated diffusion path provided by the addition of TiO2 nanoparticles, and (iii) the low surface energy provided by the HMDSO top coat.

  • 29.
    Ekström, Madeleine
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Development of a ferritic ductile cast iron for improved life in exhaust applications2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to coming emission legislations, the temperature is expected to increase in heavy-duty diesel engines, specifically in the hot-end of the exhaust system affecting components, such as exhaust- and turbo manifolds. Since the current material in the turbo manifold, a ductile cast iron named SiMo51, is operating close to its limits there is a need for material development in order to maintain a high durability of these components. When designing for increased life, many material properties need to be considered, for example, creep-, corrosion- and fatigue resistance. Among these, the present work focuses on the latter two up to 800°C improving the current material by additions of Cr, for corrosion resistance, and Ni, for mechanical properties. The results show improved high-temperature corrosion resistance in air from 0.5 and 1wt% Cr additions resulting in improved barrier layer at the oxide/metal interface. However, during oxidation in exhaust-gases, which is a much more demanding environment compared to air, such improvement could not be observed. Addition of 1wt% Ni was found to increase the fatigue life up to 250°C, resulting from solution strengthening of the ferritic matrix. However, Ni was also found to increase the oxidation rates, as no continuous SiO2-barrier layers were formed in the presence of Ni. Since none of the tested alloys showed improved material properties in exhaust gases at high temperature, it is suggested that the way of improving performance of exhaust manifolds is to move towards austenitic ductile cast irons or cast stainless steels. One alloy showing good high-temperature oxidation properties in exhaust atmospheres is an austenitic cast stainless steel named HK30. This alloy formed adherent oxide scales during oxidation at 900°C in gas mixtures of 5%O2-10%H2O-85%N2 and 5%CO2-10%H2O-85%N2 and in air. In the two latter atmospheres, compact scales of (Cr, Mn)-spinel and Cr2O3 were formed whereas in the atmosphere containing 5%O2 and 10%H2O, the scales were more porous due to increased Fe-oxide formation. Despite the formation of a protective, i.e. compact and adherent, oxide scale on HK30, exposure to exhaust-gas condensate showed a detrimental effect in form of oxide spallation and metal release. Thus, proving the importance of taking exhaust-gas condensation, which may occur during cold-start or upon cooling of the engine, into account when selecting a new material for exhaust manifolds. 

  • 30.
    Emtlind, Johannes
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Galvaniska strömmar mellan olika material i mark2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Strömmar ut från metall till elektrolyt orsakar korrosion vilket försvagar metallen och kan leda till sönderfall.

    Det finns sätt att skydda mot korrosion. Ett isolerande skikt kan läggas mellan metall och elektrolyt för att dämpa strömmen ut i elektrolyt. För att hindra att ström alls går ut i elektrolyt kan anod och katod sammankopplas metalliskt. Vissa ämnen som kallas inhibitorer kan hämma korrosionshastigheten när tillagda i rätt mängd. Kan också mota elektroner som vill ut med elektroner in.

    I uppsatsen undersöks läckströmmars beteende för olika marktyper, metaller och spänningar. 

  • 31.
    Engkvist, Josefin
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science. Chalmers University of Technology, Göteborg, Sweden.
    Israelsson, Niklas
    Chalmers University of Technology, Göteborg, Sweden.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    The initial effect of KCl deposit on alumina scales characterized by ToF-SIMS and AES2013In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 45, no 1, 445-448 p.Article in journal (Refereed)
    Abstract [en]

    A FeCrAl alloy was preoxidized to form a protective alumina scale, and the effect of KCl deposits on the alumina scale was investigated while exposed during 1 and 24 h at 600 °C. However, impurity concentrations in the alumina scale change the ion conductivity and hence affect its protective properties. Therefore, Auger electron spectroscopy and time-of-flight secondary ion mass spectrometry were used to characterize the alumina scales and detect traces of K and Cl. The results showed that K and Cl existed as large sharp-edged crystals surrounded by a dendritic network after 1 h. However, after 24 h, those were dissolved, and K together with Cl was detected only in the outer layer of the duplex alumina scale, which was formed during preoxidation.

  • 32.
    Eriksson, Robert
    et al.
    Siemens AG, Energy Sector, Berlin, Germany.
    Yuan, Kang
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Science & Engineering.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Corrosion of NiCoCrAIY Coatings and TBC Systems Subjected to Water Vapor and Sodium Sulfate2015In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 24, no 6, 953-964 p.Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coating (TBC) systems are commonly used in gas turbines for protection against high-temperature degradation. Penetration of the ceramic top coat by corrosive species may cause corrosion damage on the underlying NiCoCrAlY bond coat and cause failure of the TBC system. In the current study, four oxidation/corrosion conditions were tried: (i) lab air, (ii) water vapor, (iii) sodium sulfate deposited on the specimens, and (iv) water vapor + sodium sulfate. The test was done at 750 °C in a cyclic test rig with 48 h cycles. The corrosion damage was studied on NiCoCrAlY-coated specimens, thin APS TBC specimens, and thick APS TBC specimens. Water vapor was found to have very minor influence on the oxidation, while sodium sulfate increased the TGO thickness both for NiCoCrAlY specimens and TBC-coated specimens; the influence of the TBC thickness was found to be very small. Sodium sulfate promoted thicker TGO; more Cr-rich TGO; the formation of Y oxides, and internally, Y sulfides; pore formation in the coating as well as in the substrate; and the formation of a Cr-depleted zone in the substrate.

  • 33.
    Ferraris, Sara
    et al.
    Politecnico di Torino.
    Perero, S.
    Politecnico di Torino.
    Miola, M.
    Politecnico di Torino.
    Vernè, E.
    Politecnico di Torino.
    Rosiello, A.
    Aero Sekur S.p.A.
    Ferrazzo, V.
    Aero Sekur S.p.A.
    Valletta, G.
    Aero Sekur S.p.A.
    Sanchez, Javier
    Bactiguard AB.
    Ohrlander, Mattias
    Bactiguard AB.
    Tjörnhammar, Staffan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Fokine, Michael
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP Technical Research Institute of Sweden, Chemistry, Materials and Surfaces, Sweden.
    Skoglund, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ferraris, M.
    Politecnico di Torino.
    Chemical, mechanical and antibacterial properties of silver nanocluster/silica composite coated textiles for safety systems and aerospace applications2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 317, 131-139 p.Article in journal (Refereed)
    Abstract [en]

    This work describes the chemical, mechanical and antibacterial properties of a novel silver nanocluster/silica composite coating, obtained by sputtering, on textiles for use in nuclear bacteriological and chemical (NBC) protection suites and for aerospace applications.

    The properties of the coated textiles were analyzed in terms of surface morphology, silver concentration and silver release in artificial sweat and synthetic tap water, respectively. No release of silver nanoparticles was observed at given conditions.

    The water repellency, permeability, flammability and mechanical resistance of the textiles before and after sputtering demonstrated that the textile properties were not negatively affected by the coating.

    The antibacterial effect was evaluated at different experimental conditions using a standard bacterial strain of Staphylococcus aureus and compared with the behavior of uncoated textiles.

    The coating process conferred all textiles a good antibacterial activity. Optimal deposition conditions were elaborated to obtain sufficient antibacterial action without altering the aesthetical appearance of the textiles.

    The antibacterial coating retained its antibacterial activity after one cycle in a washing machine only for the Nylon based textile.

  • 34.
    Forsberg, Urban
    et al.
    Sandvik Mat Technology, Sweden.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Sandvik Mat Technology, Sweden.
    Hernblom, Johan
    Sandvik Mat Technology, Sweden.
    Peltola, Timo
    Sandvik Mat Technology, Sweden.
    Darley, Glenn
    Sandvik Mat Technology, Sweden.
    UNS S31035/1.4990-a newly developed high strength heat resistant austenitic stainless steel for advanced high efficient coal fired power plants2016In: ADVANCES IN MATERIALS TECHNOLOGY FOR FOSSIL POWER PLANTS: PROCEEDINGS FROM THE EIGHTH INTERNATIONAL CONFERENCE, 2016, ASM INTERNATIONAL , 2016, 310-317 p.Conference paper (Refereed)
    Abstract [en]

    Energy requirement and environmental concerns have promoted a development in higher efficiency coal fired power technologies. Advanced ultra-super critical power plant with an efficiency of higher than 50% is the target in the near future. The materials to be used due to the tougher environments become therefore critical issues. This paper provides a review on a newly developed advanced high strength heat resistant austenitic stainless steel, Sandvik Sanicro 25, for this purpose. The material shows good resistance to steam oxidation and flue gas corrosion, and has higher creep rupture strength than any other austenitic stainless steels available today, and has recently obtained two AMSE code cases. This makes it an interesting option in higher pressures/temperature applications. In this paper, the material development, structure stability, creep strength, steam oxidation and hot corrosion behaviors, fabricability and weldability of this alloy have been discussed. The conclusion is that the Sanicro 25 is a potential candidate for superheaters and reheaters in higher-efficiency coal fired boilers i.e. for applications seeing up to 700 degrees C material temperature.

  • 35.
    Forslund, Mattias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hosseinpour, Saman
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Corrosion Inhibition of Two Brass Alloys by Octadecanethiol in Humidified Air with Formic Acid2015In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 71, no 7, 908-917 p.Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayers of octadecanethiol (ODT) have previously shown to provide excellent corrosion inhibition on copper exposed to humidified air containing formic acid, mimicking indoor atmospheric corrosion. ODT layers are, however, much less efficient corrosion inhibitors for zinc. In this work, we elucidate the possibility of using ODT monolayers to inhibit corrosion of brass. Based on a quantitative analysis of corrosion products, we found that ODT provides equally good corrosion inhibition of single-phase Cu20Zn as of pure copper, retarding the transportation of corrosion stimulators to the brass surface. On double-phase Cu40Zn, however, local galvanic effects led to less efficient corrosion inhibition and more corrosion products than on Cu20Zn.

  • 36.
    Fuertes, Nuria
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Swerea KIMAB AB.
    Use of local electrochemical techniques for corrosion studies of stainless steels2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The excellent corrosion resistance of stainless steels arises from the presence of a passive film on its surface. Above 10.5wt% Cr a chromium oxide of 1-3 nm is formed on the surface of the metal that in case of damage will reform and hinder further dissolution of the metal. However, the passivity of the stainless steel can be altered by material factors and external factors; such as the composition of the underlying phases, external loads or thermal treatments.

    In this work the local electrochemical techniques Scanning Vibrating Electrode Technique (SVET) and Scanning Kelvin Probe Force Microscopy (SKPFM) and the local characterization techniques X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) have been used to investigate corrosion phenomena of stainless alloys based on measurements of corrosion current density, work function, thickness and composition of the oxide.

    The effect on work function of the thickness of the passive film and composition of the underlying phases was investigated for 301LN austenitic stainless steel (Paper I) and a heat treated superduplex 25Cr7Ni type stainless steel (Paper II). It was shown that the work function can be an indicator of corrosion resistance of the phases in the microstructure, and that the composition of the underlying phases had a greater effect on the work function than the thickness of the passive film.

    External factors such mechanical deformation (Paper I) and welding (Paper III) altered the passivity of the steel and work function. It was found that plastic deformation decreased irreversibly the work function, whereas elastic deformation did not have any permanent effect. Thermal oxides affected the passivity of stainless steels welded joints and were detrimental for its corrosion resistance. Anodic activity, observed with SVET, and pitting corrosion were detected at the heat tint and attributed to the interaction between the composition and the thickness of the oxide. Brushing combined with pickling was recommended for recovering the passivity of stainless steels.

  • 37.
    Fuertes, Nuria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Rachel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Review—Passive Film Properties and Electrochemical Response of Different Phases in a Cu-Alloyed Stainless Steel after Long Term Heat Treatment2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 7, C377-C385 p.Article in journal (Refereed)
    Abstract [en]

    In this work the influence of copper (0–4 wt%) on the microstructure, passive film properties and local electrochemical response of 25Cr7Ni-type duplex stainless steel is investigated after long term heat-treatment at 800◦C for 6 months. This heat-treatment was done to promote the formation of different phases which could be studied in terms of passive film properties and electrochemical response. The unique microstructures of the alloys comprise austenite, sigma phase, Cr2N nitrides and, for the 2 wt% and 4 wt% Cu alloys, epsilon-Cu phase. The results show that alloying with Cu increases slightly the amount of isothermal Cr2N nitrides and epsilon-Cu phase, but decreases the sigma phase fraction. The location of pitting corrosion as well as the Electrochemical Potential (EP), or electron work function, measured with Scanning Kelvin Probe Force Microscopy (SKPFM) show that the epsilon-Cu phase has the lowest corrosion resistance. The EP appears to depend more on the composition of the underlying phase than on the thickness of the passive film. Cr-nitrides have the highest EP followed by sigma phase, austenite and epsilon-Cu phase. There is a clear decrease of EP of the austenitic phase when 2 wt% Cu is added in the alloy.

  • 38.
    Fuertes, Nuria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Rachel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Bengtsson, Viktor
    Swerea KIMAB.
    Rohwerder, Michael
    Max-Planck Institute .
    Use of SVET to evaluate corrosion resistance of heat tinted stainless steel welds and effect of post-weld cleaningManuscript (preprint) (Other academic)
    Abstract [en]

    The effect of heat tints on the corrosion resistance of a 2507 duplex stainless steel Tungsten Inert Gas (TIG) welded joint was assessed. The Scanning Vibrating Electrode Technique (SVET) was used to study oxide dissolution, initiation and propagation of corrosion on the weld at the open circuit potential (OCP) and at applied potentials. Small spot X-ray Photoelectron Spectroscopy (XPS) was used to investigate the composition and thickness of the heat tints. Both heat tinted and post-weld cleaned conditions were tested. Post-weld cleaning methods investigated were brushing, brushing plus polishing and brushing plus pickling paste. The results from the 2507 weld were also compared with results from a TIG 316L weld. SVET was shown to be an appropriate technique for characterising in-situ the activity of heat tints. It was seen that heat tints dissolve by electrochemical reactions that can be mapped with the SVET and correlated with the level of discoloration of the oxides, with the purple-brown oxide being the most active. The slow dissolution of the oxide gave a gradual decrease in current density over longer immersion times, leading to establishment of a passive state. The mechanical post-weld cleaning methods proved to be insufficient to remove the anodic activity in the heat tint. The most efficient process was brushing followed by pickling which resulted in a totally passive surface measured with SVET and a higher critical pitting temperature.

  • 39.
    Fuertes, Nuria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Rachel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nazarov, Andrej
    French Corrosion Institute.
    Thierry, Dominique
    French Corrosion Institute.
    Vucko, Fabien
    French Corrosion Institute.
    Influence of Mechanical Stress on the Potential Distribution on a 301 LN Stainless Steel Surface2015In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, C465-C472 p.Article in journal (Refereed)
    Abstract [en]

    The aim of the present work was to study the influence of the stress on the electrode potential of the austenitic stainless steel301LN using Scanning Kelvin Probe (SKP). It was found that elastic deformation reversibly ennobles the potential whereas plasticdeformation decreases the potential in both tensile and compressive deformation mode and this decrease is retained even 24 h afterremoval of the load. To interpret the stress effects, different surface preparations were used and the composition and thickness ofthe passive film were determined by GDOES. Slip steps formed due to plastic deformation were observed using AFM. The effect ofplastic strain on the potential is explained by the formation of dislocations, which creates more a defective passive film.

  • 40.
    Ghasemi, Rohollah
    KTH, School of Chemical Science and Engineering (CHE).
    Hydrogen-assisted stress corrosion cracking of high strength steel2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under free corrosion potential and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate(1×10-6s-1) in 1 wt% and 3.5 wt% NaCl solutions under free corrosion potential. It was con-firmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.

  • 41.
    Gil, Harveth
    et al.
    Department of Materials, University of Antioquia.
    Echavarria, Alejandro
    Department of Materials, University of Antioquia.
    Echeverria, Felix
    Department of Materials, University of Antioquia.
    Electrochemical reduction modeling of copper oxides obtained during in situ and ex situ conditions in the presence of acetic acid2009In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 0019-4686, Vol. 54, no 20, 4676-4681 p.Article in journal (Refereed)
    Abstract [en]

    We used the potentiodynamic reduction technique to study the mechanism of copper oxide formation inthe presence of acetic acid.We performed all reductions under neutral conditions (0.1MKCl) until hydrogenevolution. We produced the copper oxides in an environment containing 0, 500, and 800 ppb aceticacid at high relative humidity. We then compared experimental results between electrochemically producedoxide films obtained by imposing anodic potentials to copper specimens in several concentrationsof pure acetic acid (1, 0.1, 0.01 and 0.001 M). We found that, as the concentration of the acid decreases,the formation of the copper oxide (I) increases.We also found the same peaks in samples produced underthe synthetic environment.We modeled the curves, taking into account the electrochemical reduction ofcopper (II) oxide (CuO), amorphous cuprite (Cu2O)am, intermediate cuprite (Cu2O)in, crystalline cuprite(Cu2O)cr, and hydrogen. These oxides have been previously detected in similar conditions. We found noevidence of copper carboxylate founding samples produced by the electrochemical method.

  • 42.
    Gil, Harveth
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tidblad, Johan
    GILDES Model Simulations of the Atmospheric Corrosion of Copper Induced by Low Concentrations of Carboxylic Acids2011In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 158, no 12, C429-C438 p.Article in journal (Refereed)
    Abstract [en]

    A computer simulation with a GILDES-based model using the COMSOL multiphysics software was performed for copper exposedto low concentrations of carboxylic acids in humidified air at room temperature. GILDES is a six-regime computer model (Gas,the Interface between gas and liquid, the Liquid, the Deposition layer, the Electrodic region near the surface and the Solid). Thesimulations were compared to previously published in-situ results for copper at the same conditions analysed by a quartz crystalmicrobalance (QCM) and infrared reflection absorption spectroscopy (IRAS). Experimental and calculated results agree with eachother with respect to the effect of corrosion, showing formic acid as the most aggressive followed by acetic and propionic acid.This is supported by a higher ligand- and proton-promoted dissolution found in formic acid exposures, followed by acetic andpropionic exposures. The dominating precipitated phases were Cu2O, Cu(OH)2, Cu(CH3COO)2 · H2O, Cu(HCOO)2 · 4H2O andCu(CH3CH2COO)2 · H2O. Besides Cu2O, the simulations suggest that the hydrated form of the respective carboxylates is the mostlikely compound to be formed in this type of atmospheres.

  • 43.
    Gil, Harveth
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tidblad, Johan
    Swerea Kimab.
    GILDES model simulations of the atmospheric corrosion of zinc induced by low concentrations of carboxylic acids2012In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 159, no 3, C123-C128 p.Article in journal (Refereed)
    Abstract [en]

    The GILDES computer based model was successfully applied to the atmospheric corrosion of zinc exposed to low concentrations of carboxylic acids in humidified air at room temperature. Under these exposure conditions the expected precipitated phases are zinc oxide (ZnO), zinc hydroxide (Zn(OH)(2)) and several forms of hydrated zinc carboxylate, Zn(CH3CH2COO)(2) center dot 2H(2)O, Zn(CH3COO)(2) center dot 2H(2)O and Zn(HCOO)(2) center dot 2H(2)O. The results were compared to those from laboratory exposures obtained in the same conditions. The model correctly predicts the trend for ZnO and zinc carboxylate formation found in experimental exposures for the three acids tested. According to the simulations, surface protonation, surface acid base reactions, as well as ligand- and proton-induced dissolution reactions play a major role in the initial atmospheric corrosion of zinc. Henry's law constant (K-H) is found to be an important parameter but uncertain due to different reported literature values. When K-H is increased the formation rate of zinc carboxylate also increases. K-H increases in the sequence propionic acid < acetic acid < formic acid, the same order as found for the calculated dissolution rate.

  • 44. Goidanich, S.
    et al.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Arenas, M. A.
    De Damborenea, J.
    Ormellese, M.
    Sánchez Amaya, J. M.
    Botana, F. J.
    Le Bozec, N.
    Effect of the environment on the metal release and corrosion behaviour of different copper-based alloys: Field exposures at 5 different test sites in Europe2008Conference paper (Refereed)
    Abstract [en]

    Diffuse emissions and dispersion of metals from different sources in the society have lately received an increased concern from an environmental perspective. Large research efforts have been initiated and undertaken by the division of Corrosion Science at KTH to fill knowledge gaps on corrosion-induced metal release from external constructions and buildings. The generation of such data is of paramount importance for the on-going assessment of flows and potential adverse environmental effects caused by released metals. Generated information is also essential for an improved understanding of prevailing atmospheric corrosion processes of importance for the preservation of our cultural heritage, e.g. bronze statues exposed to the atmosphere. This paper summarizes and compares long-term metal release data from pure copper, bronze (6%wt Sn) and brass (20%wt Zn) exposed at unsheltered conditions in five European environments of significantly different climatic and pollutant conditions; three urban sites (Stockholm-Sweden, Milan-Italy and Madrid-Spain) and two marine sites (Brest-France, Cadiz-Spain). Generated data are interpreted with respect to parallel multi-analytical studies of changes in patina characteristics, corrosion rates and differences in prevailing environmental conditions.

  • 45.
    Hagman, Henrik
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Perstorp Specialty Chemicals AB.
    Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler: ash transformation, availability and process improvements2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The direct variable costs for heat and electricity production based on solid biomass fuel combustion is approximately 3-5 times lower than the costs in a fossil fuel-oil based boiler in Sweden. In addition waste derived biomass fuels are typically much cheaper than biomass not classified as waste. The introduction of the waste derived fuels; wastewater treatment sludge, demolition wood, and animal waste in a 50MWth circulating fluidized bed (CFB) biomass boiler located in Perstorp, Sweden, led to rapid deposit buildup in superheaters, heavy ash accumulation in economizers and failing boiler tubes and vortex finders that forced frequent boiler shutdowns. This in turn increased the use of expensive oil (fossil fuel) in backup boilers and the CO2 footprint of the on-site energy conversion system. This work aims to increase the general mechanistic understanding of combustion systems using complex fuels, and includes: A mapping of the boiler failure and preventive maintenance statistics; elemental composition analysis of ash, deposits and fuel fractions; flue-gas composition measurements; chemical speciation analysis; an attempt to describe the overall ash transformation reactions and mass balance throughout the combustion process. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) was used to analyze the elemental composition of ash and deposits. The SEM-EDS results were used together with data from X-ray powder diffraction (XRD) analysis, thermodynamic phase data, and equilibrium calculations in an attempt to quantify the crystalline phases and the overall ash transformation of the process. Based on the findings concerning ash transformation and the failure statistics, it has been possible to identify generic key parameters regarding boiler design and process parameters, enabling major improvements of the CFB boiler availability, a lower overall energy conversion cost and a reduced CO2 footprint.

  • 46.
    Hedberg, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. IVL Swedish Environmental Research Institute, Sweden .
    Baresel, Christian
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Transport and fate of silver as polymer-stabilised nanoparticles and ions in a pilot wastewater treatment plant, followed by sludge digestion and disposal of sludge/soil mixtures: A case study2014In: Journal of Environmental Science and Health. Part A: Toxic/Hazardous Substances and Environmental Engineering, ISSN 1093-4529, E-ISSN 1532-4117, Vol. 49, no 12, 1416-1424 p.Article in journal (Refereed)
    Abstract [en]

    A case study of transport and changes in properties of polymer-stabilised Ag NPs is presented in this paper investigating their interaction in different treatment steps within a fully realistic pilot wastewater treatment plant (WWTP), in anaerobic digested sludge, and in soil/sludge mixtures. The fate of the same Ag NPs was tracked in these environments, hence taking the history of the Ag NPs into account. The results show that most of the Ag NPs end up in the sludge (80-100%), also after anaerobically digestion. Furthermore, the fraction of silver in the supernatant was very low after 48h incubation with silver-containing digested sludge mixed with different soil types. However, when Ag NPs were added directly to the sludge/soil mixture, soluble silver was present in the supernatant with sandy soil, but not with clayey soil. In all, generated findings show that risk assessments and toxicological studies of Ag NPs suspensions must take into account possible chemical and particle transformations upon environmental entry, as silver in general become less soluble when transported to WWTPs and interacting with sludge, and soil.

  • 47. Hedberg, Y. S.
    et al.
    Pradhan, S.
    Cappellini, F.
    Karlsson, M. -E
    Blomberg, Eva
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. Department of Chemistry, Surface and Corrosion Science, KTH Royal Institute of Technology.
    Karlsson, H. L.
    Odnevall Wallinder, I.
    Hedberg, J. F.
    Electrochemical surface oxide characteristics of metal nanoparticles (Mn, Cu and Al) and the relation to toxicity2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 212, 360-371 p.Article in journal (Refereed)
    Abstract [en]

    Most metal nanoparticles (NPs), except noble metal NPs, rapidly form a thin surface oxide in ambient conditions. The protective properties of these oxides improve or worsen depending on the environment, e.g., the human lung. Several properties, including the chemical/electrochemical stability and defect density, determine the capacity of these surface oxides to hinder the bulk metal from further oxidation (corrosion). The aim of this study was to investigate whether electrochemical surface oxide characterization of non-functionalized base metal NPs of different characteristics (Al, Mn and Cu) can assist in understanding their bioaccessibility (metal release) in cell media (DMEM+) and their cytotoxic properties following exposure in lung epithelial (A549) cells. The composition and valence states of surface oxides of metal NPs and their electrochemical activity were investigated using an electrochemical technique based on a graphite paste electrode to perform cyclic voltammetry in buffer solutions and open circuit potential measurements in DMEM+. The electrochemical surface oxide characterization was complemented and verified by Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The open circuit potential trends in DMEM+ correlated well with metal release results in the same solution, and provided information on the kinetics of oxide dissolution in the case of Cu NPs. Extensive particle agglomeration in cell medium (DMEM+) was observed by means of photon-cross correlation spectroscopy for all metal NPs, with sedimentation taking place very quickly. As a consequence, measurements of the real dose of added non-functionalized metal NPs to cell cultures for cytotoxicity testing from a sonicated stock solution were shown necessary. The cytotoxic response was found to be strongly correlated to changes in physico-chemical and electrochemical properties of the surface oxides of the metal NPs, the most potent being Cu NPs, followed by Mn NPs. No cytotoxicity was observed for Al NPs. The electrochemical surface oxide characterization corresponded well with other tools commonly used for nanotoxicological characterization and provided additional information.

  • 48.
    Hedberg, Yolanda S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Goidanich, Sara
    Herting, Gunilla
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Surface rain interactions: Differences in copper runoff for copper sheet of different inclination, orientation, and atmospheric exposure conditions2015In: Environmental Pollution, ISSN 0269-7491, E-ISSN 1873-6424, Vol. 196, 363-370 p.Article in journal (Refereed)
    Abstract [en]

    Predictions of the diffuse dispersion of metals from outdoor constructions such as roofs and facades are necessary for environmental risk assessment and management. An existing predictive model has been compared with measured data of copper runoff from copper sheets exposed at four different inclinations facing four orientations at two different urban sites (Stockholm, Sweden, and Milan, Italy) during a 4-year period. Its applicability has also been investigated for copper sheet exposed at two marine sites (Cadiz, Spain, for 5 years, and Brest, France, for 9 years). Generally the model can be used for all given conditions. However, vertical surfaces should be considered as surfaces inclined 60-80 degrees due to wind-driven effects. The most important parameters that influence copper runoff, and not already included in the model, are the wind and rain characteristics that influence the actual rainfall volume impinging the surface of interest. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  • 49.
    Hedberg, Yolanda S.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Metal release from stainless steel in biological environments: A review2016In: Biointerphases, ISSN 1934-8630, E-ISSN 1559-4106, Vol. 11, no 1, 018901Article, review/survey (Refereed)
    Abstract [en]

    Due to its beneficial corrosion resistance, stainless steel is widely used in, e.g., biomedical applications, as surfaces in food contact, and for products intended to come into skin contact. Low levels of metals can be released from the stainless steel surface into solution, even for these highly corrosion resistant alloys. This needs to be considered in risk assessment and management. This review aims to compile the different metal release mechanisms that are relevant for stainless steel when used in different biological settings. These mechanisms include corrosion-induced metal release, dissolution of the surface oxide, friction-induced metal release, and their combinations. The influence of important physicochemical surface properties, different organic species and proteins in solution, and of biofilm formation on corrosion-induced metal release is discussed. Chemical and electrochemical dissolution mechanisms of the surface oxides of stainless steel are presented with a focus on protonation, complexation/ligand-induced dissolution, and reductive dissolution by applying a perspective on surface adsorption of complexing or reducing ligands and proteins. The influence of alloy composition, microstructure, route of manufacture, and surface finish on the metal release process is furthermore discussed as well as the chemical speciation of released metals. Typical metal release patterns are summarized.

  • 50.
    Henderson, Pamela
    Vattenfall research and Development.
    Högtemperaturkorrosion i barkpannor: Del 12007In: Nordisk Papper & Massa, ISSN 1652-9995, no 2, 58-59 p.Article, review/survey (Other (popular science, discussion, etc.))
    Abstract [sv]

    Ökad eldning av retur- och avfallsbränslen i barkpannor har medfört att alltfler har fått problem med avlagringar och korrosion. Det finns ett stort intresse att minska kostnader för högtemperaturkorrosion genom att förlänga livslängden och att minska risken för oplanerade stopp. Samtidigt finns det starka drivkrafter att förbättra anläggningarnas elverkningsgrad genom högre ångdata.

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