| 1. |
- Boman, Mats, et al.
(författare)
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Corrosion of copper in water free from molecular oxygen
- 2014
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Ingår i: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 49:6, s. 431-434
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of copper reacting with O-2-free water has been investigated by analysis of primary corrosion products, as well as by monitoring gas pressure change by time, in long term experiments for up to 6 months in a glove box environment. We establish hydrogen production, but being of the same magnitude irrespective whether copper is present or not. Although low, the hydrogen production rate is considerably larger than what would directly correspond to the amount of analysed copper oxidation products. Our analyses encompass the changes to the surface cleaned copper (99.9999%), the water phase and the Duran glass in contact with the water (ppt quality). We have used very sensitive methods (XPS, AES, ICP-MS, XRF) while keeping contamination risks to a minimum. We conclude that the oxidation rate of copper is very low, yielding only parts of a monolayer of Cu2O after 6 months of exposure at 50 degrees C together with an accompanying very low concentration of copper species (4-5 mu g L-1) in the water phase.
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| 2. |
- Lindgren, Mats, et al.
(författare)
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Methods for predicting corrosion on electronic products
- 2014
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Ingår i: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 49:7, s. 661-664
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Tidskriftsartikel (refereegranskat)abstract
- Surface insulation resistance (SIR) measurements have become necessary to perform, especially due to the introduction of lead free solders. It has been reported that SIR and other test methods have to be used for evaluating the reliability of printed wiring boards. This paper presents an investigation on how the SIR test environment influences the test results. The factors varied were temperature and humidity. The temperature was varied between 40 and 85°C, and the relative humidity was varied between 60 and 85%. Furthermore, the influence of different types of process chemicals on SIR was evaluated. Seven lead free solder pastes, of which five were no-clean and two were water soluble, were compared. The influence of using conformal coating was also studied. These solder pastes were used to verify the developed method. A proper test method for SIR measurements is suggested in the paper, as well as a recommendation for use of conformal coating.
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| 3. |
- Rosborg, Bo, et al.
(författare)
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Corrosion rate of pure copper in an oxic bentonite/saline groundwater environment
- 2011
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Ingår i: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 46:2, s. 148-152
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Tidskriftsartikel (refereegranskat)abstract
- The principal strategy for high level radioactive waste disposal in Sweden is to enclose the spent fuel in copper canisters that are embedded in bentonite clay similar to 500 m down in the Swedish bedrock. At this depth, the groundwater is reducing. However, oxic conditions are initially established in the repository during emplacement. The corrosion rate of pure copper in an oxic bentonite/saline groundwater environment has been followed by thin electrical resistance sensors placed in a bentonite test package that was kept at room temperature for 3 years. The corrosion potentials of the sensors have verified oxic conditions in the test package. The corrosion rate of pure copper in this environment has been found to slowly decrease to quite low but measurable values; from above 15 mu m/year down to similar to 1 mu m/year after 3 years of exposure. The measurements have verified a desired behaviour of copper in the environment.
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| 4. |
- Smart, N.R., et al.
(författare)
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Further studies of in situ corrosion testing of miniature copper-cast iron nuclear waste canisters
- 2011
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Ingår i: Corrosion Engineering Science and Technology. - 1478-422X. ; 46:2, s. 142-147
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Tidskriftsartikel (refereegranskat)abstract
- To ensure the safe disposal of spent fuel in Sweden, SKB is planning to use the copper-iron canister in a granitic deep geological repository, surrounded by a compacted bentonite engineered barrier. In order to develop a deeper understanding of the internal corrosion behaviour of the design should a leak occur in the outer copper canister, a set of model canisters was set up in the Äspöunderground laboratory in contact with bentonite with a range of densities. The environmental conditions and electrochemical corrosion behaviour were monitored using a range of techniques. Water analysis and electrochemical measurements indicated an increase in the corrosion rate of both iron and copper in contact with low density bentonite, and of iron only in experiments with no bentonite present. This behaviour may be attributable to microbial activity. The measured corrosion rate depends on the technique used and it will be necessary to confirm the measurements by removal and examination of weight loss coupons. © 2011 Institute of Materials, Minerals and Mining.
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| 5. |
- Smart, N.R., et al.
(författare)
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In situ evaluation of model copper-cast iron canisters for spent nuclear fuel: A case of microbiologically influenced corrosion (MIC)
- 2014
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Ingår i: Corrosion Engineering Science and Technology. - 1478-422X. ; 49:6, s. 548-553
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Tidskriftsartikel (refereegranskat)abstract
- © 2014 AMEC Nuclear UK Limited. The Swedish method for disposal of spent nuclear fuel in a deep geological repository (KBS-3) relies on the stability of the granitic bed-rock and two engineered barriers: a copper-cast iron canister and highly compacted bentonite clay. In order to develop a better understanding of the internal corrosion processes that could take place if a leak were to occur in the outer copper canister, five miniaturised copper cast iron canisters were installed at a depth of 450 m at the ä spö Hard Rock Laboratory, in Sweden. The experiments differed in the density of the surrounding bentonite buffer, as well as in the number and position of leak points that were introduced in the copper shell. Several electrochemical techniques (e.g. AC impedance, linear polarisation resistance and electrochemical noise) were used to monitor the corrosion of different components of the experiment. Copper specimens were installed for post-test evaluation of the rate of general corrosion, localised corrosion and stress corrosion cracking (SCC). In addition, mechanical and environmental parameters, such as surface strain, hydrostatic pressure, redox potential, pH, water chemistry, dissolved gases, and microbial numbers, diversity, and activity were measured regularly. After five years of in situ exposure one of the canisters was retrieved and analysed to characterise and evaluate the corrosion processes that had occurred during the experiment. Extensive sulphide production by sulphate reducing bacteria led to rapid corrosion of iron, and the formation of iron sulphide deposits on the copper and iron electrodes disturbed the electrochemical measurements. This paper describes the various analyses that were carried out on the model canister and summarises the conclusions that can be drawn.
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