| 1. |
- Fazey, Ioan, et al.
(författare)
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Transforming knowledge systems for life on Earth : Visions of future systems and how to get there
- 2020
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Ingår i: Energy Research & Social Science. - : Elsevier. - 2214-6296 .- 2214-6326. ; 70
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Tidskriftsartikel (refereegranskat)abstract
- Formalised knowledge systems, including universities and research institutes, are important for contemporary societies. They are, however, also arguably failing humanity when their impact is measured against the level of progress being made in stimulating the societal changes needed to address challenges like climate change. In this research we used a novel futures-oriented and participatory approach that asked what future envisioned knowledge systems might need to look like and how we might get there. Findings suggest that envisioned future systems will need to be much more collaborative, open, diverse, egalitarian, and able to work with values and systemic issues. They will also need to go beyond producing knowledge about our world to generating wisdom about how to act within it. To get to envisioned systems we will need to rapidly scale methodological innovations, connect innovators, and creatively accelerate learning about working with intractable challenges. We will also need to create new funding schemes, a global knowledge commons, and challenge deeply held assumptions. To genuinely be a creative force in supporting longevity of human and non-human life on our planet, the shift in knowledge systems will probably need to be at the scale of the enlightenment and speed of the scientific and technological revolution accompanying the second World War. This will require bold and strategic action from governments, scientists, civic society and sustained transformational intent.
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| 2. |
- Fuertes, Nuria
(författare)
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Use of localised techniques to elucidate the influence of process variables on the corrosion of stainless steels
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Several factors during steel manufacture and fabrication can alter the passivity and corrosion behaviour of stainless steels. These include alloying, deformation, welding and heat treatments.In this work a combination of local techniques, such as Scanning Vibrating Electrode Technique (SVET) and Scanning Kelvin Probe Force Microscopy (SKPFM), and surface and microstructural analytical techniques, such as Electron Backscatter Diffraction (EBSD), Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) is used to elucidate the influence of process variables on the corrosion resistance of stainless steels. Different manufacturing processes, such as casting, rolling or additive manufacturing (AM) (Paper V), fabrication processes, such as welding (Paper III) and deformation (Paper I and IV), and post-processing, such as heat and high pressure treatments (Paper II and V) and post-weld cleaning (Paper II) are studied.The results showed that deformation can have a major impact on microstructure but a smaller impact on corrosion. Plastic deformation decreased irreversibly the Volta potential, whereas elastic deformation did not have any permanent effect. The potential was dependent on composition, passive film thickness and deformation but not on the crystallographic orientation. Thermal oxides formed after welding were detrimental to corrosion resistance. SVET showed anodic activity on the weld areas with oxides where pitting initiated, explained by the interplay between the composition and the thickness of the oxides. Brushing combined with pickling was recommended for restoring the corrosion resistance. Long-term ageing of a Cu-alloyed 2507 caused precipitation of Cu-rich ε particles which showed the lowest potential and were most severely pitted, plus nitrides which were the most noble. Intermetallic sigma phase observed in the AM 2507 after HIP heat treatment with slow cooling resulted in a decreased corrosion resistance. However, it was concluded that AM 2507 exhibits similar or even higher corrosion resistance than conventional 2507 if appropriate post-processing parameters are applied.This thesis provides scientific insights to facilitate the correct manufacturing, fabrication and use of stainless steels.
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| 3. |
- Gil, Harveth, 1978-
(författare)
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The initial atmospheric corrosion of copper and zinc induced by carboxylic acids : Quantitative in situ analysis and computer simulations
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Degradation of metals through atmospheric corrosion is a most important and costly phenomenon with significant effects on, e.g., the lifespan of industrial materials, the reliability of electronic components and military equipment, and the aesthetic appearance of our cultural heritage. Atmospheric corrosion is the result of the interaction between the metal and its atmospheric environment, and occurs in the presence of a thin aqueous adlayer. The common incorporation of pollutant species into this adlayer usually enhances the degradation process. During atmospheric corrosion indoors, low concentrations of organic atmospheric constituents, such as formic, acetic, propionic, butyric and oxalic acids, have found to play an accelerating role on a broad range of metals or their alloys, including lead, steel, nickel, copper, cadmium, magnesium and zinc. In this doctoral thesis the initial stages of the atmospheric corrosion of copper exposed to synthetic air, aiming at simulating representative indoor atmospheric environments, have been investigated both experimentally and through a computational method. The experiments have been based on a unique analytical setup in which a quartz crystal microbalance (QCM) was integrated with infrared reflection absorption spectroscopy (IRAS). This enabled the initial atmospheric corrosion of copper to be analyzed during ongoing corrosion in humidified air at room temperature and additions of 120 ppb (parts per volume billions) of acetic, formic or propionic acid. The main phases identified were copper (I) oxide (Cu2O) and various forms of copper carboxylate, and their amounts deduced with the different analytical techniques agree with a relative accuracy of 12% or better. Particular emphasis has been on the identification of different forms of copper (I) oxide generated during these exposures. An electrochemically based model has been proposed to describe how copper oxides, formed in the presence of acetic acid, are electrochemically reduced in neutral solution. The model includes the electrochemical reduction of copper (II) oxide (CuO), amorphous copper (I) oxide (Cu2O)am, intermediate copper (I) oxide (Cu2O)in, and crystalline copper (I) oxide (Cu2O)cr. A good agreement is obtained between the model and experimental data, which supports the idea of a reduction sequence which starts with copper (II) oxide and continues with the reduction of the three copper (I) oxides at more negative potentials. The quantified analytical data obtained in this doctoral study on corrosion products formed on copper, and corresponding data on zinc reported elsewhere, were used as the starting point to develop a computational model, GILDES, that describes the atmospheric corrosion processes involved. GILDES considers the whole interfacial regime in which all known chemical reactions have been considered which are assumed to govern the initial atmospheric corrosion of copper or zinc in the presence of carboxylic acids. The model includes two separate pathways, a proton-induced dissolution of cuprous ions or zinc ions followed by the formation of either copper (I) oxide or zinc (II) oxide, and a carboxylate-induced dissolution followed by the formation of either copper (II) carboxylate or zinc (II) carboxylate. The model succeeds to predict the two main phases in the corrosion products and a correct ranking of aggressiveness of the three acids for both copper and zinc. The ranking has been attributed to differences in acid dissociation constant and deposition velocity of the carboxylic acids investigated.
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| 4. |
- Herting, Gunilla, 1975-
(författare)
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Bioaccessibility of Stainless Steels : Importance of Bulk and Surface Features
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With increasing environmental awareness, the desire to protect human beings and the environment from adverse effects induced by dispersed metals has become an issue of great concern and interest. New policies, such as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) within the European Community, have been implemented to reduce hazards posed by the use of chemicals on producers and downstream users. The generation of exposure assessment data and relevant test procedures able to simulate realistic scenarios are essential in such legislative actions. This doctoral study was initiated to fill knowledge gaps related to the metal release process of stainless steels. A wide range of stainless steel grades, fourteen in total, were investigated. They cover a very broad range of applications, and the focus in the thesis was to simulate a few selected exposure scenarios: precipitation, the human body and food intake. Comparisons were made between metal release from stainless steel alloys and the pure metals that constitute each stainless steel in order to explore the differences between alloys and pure metals, and to provide quantitative data on metal release rates of different alloy constituents. Because of similar surface properties between stainless steel and pure chromium, this metal exhibits similar release rates, whereas iron and nickel exhibit significantly lower release rates as alloy components than as pure metals. Detailed studies were also performed to elucidate possible relations between metal release and steel surface properties. Key parameters turned out to be chromium enrichment of the self-passivating surface film, surface roughness, the electrochemically active surface area and the microstructure of the steel substrate. The degree of metal release increased with decreasing chromium content in the surface oxide, increasing surface roughness, and increasing presence of inhomogeneities in the bulk matrix. More detailed studies were initiated to possibly correlate the nucleation of metastable pits and the extent of metal release. Evidence was given that metastable pits exist even when the stainless steel is passive, and may cause extremely short-lived bursts of released metal before the surface film repassivates again.
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| 5. |
- Zhou, Nian
(författare)
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Surface integrity and corrosion behavior of stainless steels after grinding operations
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stainless steels are widely used in applications where both the mechanical properties of steels and high corrosion resistance are required. There is continuous research to enable stainless steel components to be produced in a more economical way and be used in more harsh environments. A way to achieve this is to correlate the service performance with the production processes.The central theme of this thesis is surface integrity and corrosion, especially the stress corrosion cracking behavior, after grinding processes. Controlled grinding parameters, including abrasive grit size, machine power and grinding lubricant, were used and the resulting surface properties studied for austenitic 304L and duplex 2304 stainless steels. The abrasive grit size effect was found to have a larger influence. Surface defects, a highly deformed surface layer and the generation of a high level surface tensile residual stresses along the grinding direction were observed as the main types of damage. The effect of grinding on stress corrosion cracking behavior of austenitic 304L, ferritic 4509 and duplex 2304 stainless steels in chloride-containing environments was also investigated. The abrasive grit size effect on corrosion behavior for the three grades was compared. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks on the ground surface for 304L and 2304; for 4509, grinding-induced grain fragmentation was considered as the main factor for the initiation of extensive micro-pits. For duplex 2304, the microstructure and micro-notches in the as-ground surface also had significant influence. Depending on the surface conditions, the actual loading by four-point bending was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. The knowledge obtained from this work can provide guidance for choosing appropriate stainless steel grades and grinding parameters; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.
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| 6. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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