| 1. |
- Aastrup, T., et al.
(författare)
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Experimental in situ studies of copper exposed to humidified air
- 2000
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 42:6, s. 957-967
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Tidskriftsartikel (refereegranskat)abstract
- Three complementary experimental techniques for in situ surface analysis have been combined for the first time in order to explore the chemistry and physics of a copper surface exposed to humidified air. Infrared reflection absorption spectroscopy, quartz crystal microbalance and atomic force microscopy provide a congruent picture of the processes occurring at the surface. At a given relative humidity, cuprous oxide forms according to an approximately logarithmic rate law. In addition, an aqueous adlayer of constant mass physisorbs on the surface. Increased relative humidity stimulates the physisorption of water and enhances the nucleation rate of oxide grains, thereby increasing the formation rate of cuprous oxide.
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| 2. |
- Femenia, M., et al.
(författare)
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In situ study of selective dissolution of duplex stainless steel 2205 by electrochemical scanning tunnelling microscopy
- 2001
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 43:10, s. 1939-1951
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Tidskriftsartikel (refereegranskat)abstract
- Selective dissolution of duplex stainless steel 2205 in acidic chloride solutions was studied in situ by electrochemical scanning tunnelling microscopy (STM). In 0.05 M H2SO4 + 1 M NaCl, no appreciable active dissolution was observed by in situ STM imaging at the corrosion potential (E-corr), but at potentials higher than E-corr + 1000 mV some selective dissolution at the austenite-ferrite boundary region occurred. In 4 M H2SO4 + 1 M HCl, STM images revealed active dissolution of ferrite grains at around E-corr + 50 mV. Dissolution of austenite grains started to occur at around E-corr + 150 mV, exhibiting steps of submicron scale on the edges.
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| 3. |
- He, W., et al.
(författare)
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A laboratory study of copper and zinc runoff during first flush and steady-state conditions
- 2001
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 43:1, s. 127-146
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Tidskriftsartikel (refereegranskat)abstract
- The influence of environmental conditions and corrosion layer characteristics have been investigated on the runoff rate of copper and zinc, used as roofing material. For this purpose, a rain device has been constructed, capable of simulating rain episodes of varying intensity and pH, and used on new and aged copper and zinc panels of varying origin and corrosion product composition. The setup, using artificial rain with a composition resembling the southern and central part of Sweden, has proven to result in realistic runoff rates for all materials investigated. During a rain event, easily soluble corrosion products will be removed in the first rain volume, commonly referred to as the first flush, followed by a more or less constant runoff rate during subsequent rain. The magnitude of the first flush depends on environmental conditions prior Co a rain episode, e.g., length of dry periods and extent of dry deposition, as well as on rain volume and rain intensity. A defect-rich and porous corrosion layer increases the magnitude of the first flush. The total metal runoff quantity increases with decreasing pH for both copper and zinc. In agreement with previous findings outdoors, an effect of patina age can be seen on copper. The laboratory data can be used to explain variations in runoff rate between different sampling periods observed in field data.
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| 4. |
- Hultquist, Gunnar, et al.
(författare)
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Platinum-induced oxidation of chromium in O-2 at 800 °C
- 2003
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 45:12, s. 2697-2703
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Tidskriftsartikel (refereegranskat)abstract
- The effects of porous Pt on the oxidation of Cr at 800degreesC have been studied with the (OSIMS)-O-18 technique, gas phase analysis and XPS. In oxide areas with Pt a pronounced inward oxygen transport takes place and a substantial oxide growth near the Cr substrate is observed. In oxide grown on areas without Pt the counts of CrO ions in SIMS and the binding energy of O (1s) in XPS depend on the distance from the area with Pt. The experimental observations are believed to be a consequence of a high dissociation efficiency of O-2 on areas with Pt in combination with a high diffusivity of O in external and internal oxide surfaces on areas both with and without Pt.
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| 5. |
- Kivisäkk, Ulf
(författare)
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A test method for dewpoint corrosion of stainless steels in dilute hydrochloric acid
- 2003
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 45:3, s. 485-495
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Tidskriftsartikel (refereegranskat)abstract
- When acid-containing gases condense on a steel surface a phenomenon called dewpoint corrosion can occur. In this case severe attack can appear and the attack cannot be predicted from traditional immersion test data. Dewpoint corrosion can for instance be found in refinery overhead condensers and in waste incineration plants. An experimental set-up consisting of a closed glass loop has been constructed in which stainless steel samples are exposed to condensing conditions simulating a formed condensate of about 1% HCl. In the loop three stainless steels have been tested. For all three materials higher corrosion rates were found in the loop than obtained in immersion tests but in the same range as can be predicted from service experience.
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| 6. |
- Kratschmer, A., et al.
(författare)
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The evolution of outdoor copper patina
- 2002
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 44:3, s. 425-450
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Tidskriftsartikel (refereegranskat)abstract
- A general reaction scheme has been deduced which describes the evolution of the copper patina, including altogether eight compounds, formed upon exposure to outdoor atmospheric environments. The scheme is based on data obtained from altogether 39 exposure sites, using a recently developed method for quantitative X-ray powder diffraction analysis of up to 8 year old patina still adhering to the copper substrate. In all cases, cuprite forms initially and continuously throughout the atmospheric exposure. Three main sequences have been identified on sheltered copper, representing different reaction routes in sulfur- or chlorine-dominated environments. In less sulfur-polluted environments, posnjakite forms on the cuprite as a precursor to brochantite. In more sulfur-polluted environments, strandbergite is a precursor to antlerite. Both reaction routes may operate simultaneously and the main route may change from the more sulfur-polluted to the less polluted route, as a result of decreased pollutant levels. In chlorine-dominated environments the initial cuprite formation is followed by nantokite and atacamite. By far the most dominating sequence on unsheltered copper includes cuprite, followed by posnjakite and brochantite formation.
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| 7. |
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| 8. |
- Odnevall Wallinder, Inger, et al.
(författare)
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Effects of exposure direction and inclination on the runoff rates of zinc and copper roofs
- 2000
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 42:8, s. 1471-1487
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Tidskriftsartikel (refereegranskat)abstract
- The effect of exposure direction and inclination on the runoff rates of both zinc and copper has been studied by field exposures on model roofs. Runoff rates decrease with higher inclinations from horizon and are higher for exposures directed towards the prevailing wind direction. At a given pollution concentration, the metal runoff is largely governed by the precipitation volume impinging on the surface. In this study the field exposure results were compared to laboratory tests on zinc and copper panels with different inclinations. Current literature mainly describes runoff rates for zinc and copper panels inclined 45 degrees facing south. Calculations of the average runoff rate using the runoff rates obtained on the model roofs as well as market information show that the effect of inclination, orientation and degree of sheltering are important parameters to consider while estimating runoff rates from existing buildings.
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| 9. |
- Odnevall Wallinder, Inger, et al.
(författare)
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Release rates of chromium and nickel from 304 and 316 stainless steel during urban atmospheric exposure : a combined field and laboratory study
- 2002
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 44:10, s. 2303-2319
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Tidskriftsartikel (refereegranskat)abstract
- Release rates of chromium and nickel from pickled and skin passed 304 and 316 stainless steel have been determined during a one-year field exposure in an urban environment (Stockholm, Sweden) and through complementary exposures in artificial rain. Measured annual release rates from 304 stainless steel are 0.25-0.3 mg Cr/m(2) and 0.3-0.4 mgNi/m(2), and slightly higher from 316 stainless steel, 0.35-0.4 mgCr/m(2) and 0.7-0.8 mgNi/m(2). The release rates decrease as the rain pH increases and exhibit no direct influence by rain intensity. Variations in release rates are thought to be a result of a non-uniformly attack.
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| 10. |
- Szakalos, Peter, et al.
(författare)
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An active corrosion mechanism for metal dusting on 304L stainless steel
- 2002
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Ingår i: Corrosion Science. - 0010-938X .- 1879-0496. ; 44:10, s. 2253-2270
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Tidskriftsartikel (refereegranskat)abstract
- A mechanism for metal dusting of chromia-forming stainless steels is proposed, based on results from laboratory exposures of 304L stainless steel at 650 degreesC for 1000 h in a synthesis gas low in water vapour, 25%CO + 3%H2O + H. The work focuses on the role of carbides and oxygen to explain the different corrosion mechanisms and give a description of the metal dusting phenomenon as it appears in engineering alloys. Metallographical examinations, FEG-SEM, SEM-EDX analysis and X-ray diffraction, as well as thermodynamic calculations were made in order to identify the proposed metal dusting mechanism.
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