Kim Verbeken - Academia.edu (original) (raw)
Papers by Kim Verbeken
Forschung im Ingenieurwesen
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Tecnologia em Metalurgia, Materiais e Mineração
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ACS Applied Materials & Interfaces
One of the leading causes of failure for any bone implant are implant associated infections. The ... more One of the leading causes of failure for any bone implant are implant associated infections. The implant-bone interface is in fact the crucial site of infection where both microorganisms and cells compete to populate the newly introduced implant surface. Most of the work dealing with this issue has focused on the design of implant coatings capable of preventing infection while ignoring cell proliferation or vice versa. The present study is therefore focused on investigating the antibacterial and biological properties of nanocomposite coatings based on an amorphous hydrocarbon (a-C:H) matrix containing silver nanoparticles (AgNPs). a-C:H coatings with varying silver concentrations were generated directly on medical grade titanium substrates using a combination of a gas aggregation source (GAS) and a plasma-enhanced chemical vapor deposition (PE-CVD) process. The obtained results revealed that the surface silver content increased from 1.3 at% to 5.3 at% by increasing the used DC magnetron current in the GAS from 200 to 500 mA. A series of in-vitro antibacterial assays also indicated that increasing the number of AgNPs in the nanocomposites led to excellent antibacterial activities resulting in a 6-log reduction of E. coli and a 4-log reduction of S. aureus after 24 hours of incubation. An MTT assay, fluorescence live/dead staining and SEM microscopy observations of MC3T3 cells seeded on the uncoated and coated Ti substrates also showed that increasing the amount of AgNPs in the nanocomposites had no notable impact on their cytocompatibility, while improved cell proliferation was especially observed for the nanocomposites possessing a low amount of Ag NPs. These controllable Ag/a-C:H nanocomposites on Ti substrates which simultaneously provide an excellent antibacterial performance and good biocompatibility could thus have promising applications in orthopedics and other biomedical implants.
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Materials
The service time of an industrial cracker is strongly dependent on the long-term coking behavior ... more The service time of an industrial cracker is strongly dependent on the long-term coking behavior and microstructure stability of the reactor coil alloy. Super alloys are known to withstand temperatures up to even 1400 K. In this work, several commercially available alloys have been first exposed to a long term oxidation at 1423 K for 500 h, so-called metallurgic aging. Subsequently, their coking behavior was evaluated in situ in a thermogravimetric setup under ethane steam cracking conditions (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, continuous addition of 41 ppmw S/HC of DMDS, dilution δ = 0.33 kgH2O/kgHC) and compared with their unaged coking behavior. The tested samples were also examined using scanning electron microscopy and energy diffractive X-ray for surface and cross-section analysis. The alloys characterized by increased Cr-Ni content or the addition of Al showed improved stability against bulk oxidation and anti-coking behavior after application of metallurgic agi...
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MRS Proceedings
ABSTRACTChemical solution deposition techniques are a very competitive low cost method to achieve... more ABSTRACTChemical solution deposition techniques are a very competitive low cost method to achieve coated conductors. Recently, fluorine-free CSD methods have made a great progress for the preparation of YBCO thin films and became a sustainable alternative for the well-known trifluoroacetate CSD approach. By elucidating the reaction mechanism behind this new approach, finally giving an answer to the question why it is possible to fabricate YBCO films without TFA, different processing routes were discovered giving rise to high superconducting YBCO films (>1MA.cm-2). Each route has it's own benefits. One specific route offers the opportunity to tune the crystallographic orientation. By changing one process parameter, a shift from complete c-axis to complete a-axis orientation is observed. This can be very useful for e.g. Josephson Junctions.We particularly investigated the fundamental reaction mechanism of each reaction route, with the focus on the corresponding barium compound....
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Journal of Alloys and Compounds
Abstract A model-based evaluation procedure by a trap-diffusion integrated finite element model (... more Abstract A model-based evaluation procedure by a trap-diffusion integrated finite element model (FEM) is used to interpret the experimentally measured thermal desorption spectra (TDS) of Fe-C-Ti alloys. Two material conditions are compared, i.e. as-quenched vs. quenched and tempered, in which TiC have precipitated. The discrepancy between measurement and simulation is found to be very small for all material conditions. The model shows high trapping energies of around 58 kJ/mol to 110 kJ/mol (0.61 eV–1.14 eV), when the materials are tempered. These traps could be related to carbon vacancies in TiC precipitates.
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Corrosion Reviews
In many industries and processes, heat exchangers are of vital importance as they are used to tra... more In many industries and processes, heat exchangers are of vital importance as they are used to transfer heat from one fluid to another. These fluids can be corrosive to heat exchangers, which are usually made of metallic materials. This paper illustrates that corrosion is an important problem in the operation of heat exchangers in many environments, for which no straightforward answer exists. Corrosion failures of heat exchangers are common, and corrosion often involves high maintenance or repair costs. In this review, an overview is given of what is known on corrosion in heat exchangers. The different types of corrosion encountered in heat exchangers and the susceptible places in the devices are discussed first. This is combined with an overview of failure analyses for each type of corrosion. Next, the effect of heat transfer on corrosion and the influence of corrosion on the thermohydraulic performances are discussed. Finally, the prevention and control of corrosion is tackled. Pre...
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Surface and Coatings Technology
Abstract Until now, several different chemical formulae are used to refer to the intermetallic θ-... more Abstract Until now, several different chemical formulae are used to refer to the intermetallic θ- and η-layers formed at the surface of hot-dip aluminized steel. To clear up the subsequent confusion, both layers were identified and characterized using several experimental techniques combined with DFT calculations. 1 EDX- and EBSD-mappings were performed on the cross section of a hot-dip aluminized steel and showed the presence of the two single-phased intermetallic layers, θ and η, just beneath the aluminum top-layer. The XRD-pattern of a sample of which the top aluminum layer was removed, confirmed the foregoing observations. The compositions of both layers were determined by APT and yield Fe 4 Al 13 and Fe 2 Al 5.6 . DFT calculations showed the stability of the Fe 4 Al 13 phase and predicted Fe 4 Al 13 to be the only stable composition in that area of the Fe-Al phase diagram. Based on the DFT results, the ILEEMS spectrum of the θ-layer could be successfully analyzed and, for the first time, fully interpreted in accordance with the crystallographic structure of Fe 4 Al 13 . Fe 4 Al 13 is suggested for referring to the composition of the θ-layer, instead of other formulae, e.g. FeAl 3 . The ILEEMS η-layer spectrum was best reproduced by a model-independent quadrupole splitting distribution, which supports the dis-ordered structure model for the η-layer. An analysis based on the results of the DFT calculations, confirmed this finding. Because of the partially dis-ordered structure of the η-layer and the width of the related region in Fe-Al phase diagrams, Fe 2 Al 5+x is suggested for referring to the composition of the η-layer.
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steel research international
Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycl... more Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycling or training is recognized to improve the shape memory effect. In the present work, different aspects of training are studied: the number of cycles, the amount of deformation and the annealing temperature. As the number of cycles increases, the epsilon martensite plates become thinner and within the different grains they tend to align in the same direction. Still, different variants are present. XRD measurements showed a strong increase in the E martensite volume from cycle 1 to cycle 2 and a slight decrease for further cycles. There exists an optimum deformation for obtaining stress induced E martensite which is reversibly transformable to austenite during annealing. When the amount of deformation is too low, the fraction of stress induced epsilon martensite is very low, therefore, the shape memory effect is small. If the deformation is too large, slip may occur and different E; martensite variants are formed, which hinders the reverse epsilon ->gamma transformation. The recovery annealing temperature is critical for obtaining a good shape memory, especially during training. The recovery annealing temperature of 400 degrees C is too low for completing the reverse transformation; annealing at 600 degrees C is most commonly used.
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Environmental science and pollution research international, Jan 14, 2017
Contamination of drinking water with arsenic causes severe health problems in various world regio... more Contamination of drinking water with arsenic causes severe health problems in various world regions. Arsenic exists predominantly as As(III) and As(V) depending on the prevailing redox conditions of the environment. Most of the techniques developed for treating As(V) are not very effective for As(III), which is more toxic and mobile than As(V). In this study, novel cerium-loaded pumice (Ce-Pu) and red scoria (Ce-Rs) adsorbents were developed to remove both As(III) and As(V) ions from water. The Ce-Pu and Ce-Rs adsorbents were characterized using ICP-OES, EDX, and SEM. The experimental equilibrium sorption data fitted well Freundlich and Dubinin-Radushkevich (D-R) isotherms. The adsorption was very fast and reached an equilibrium within 2 h. Both Ce-Rs and Ce-Pu showed high As(III) and As(V) removal efficiency in a wide pH range between 3 and 9, which is an important asset for practical applications. The Ce-Pu and Ce-Rs adsorbents can be recycled and used up to three adsorption cycle...
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steel research international, 2006
ABSTRACT
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Water research, Jan 15, 2016
The increased use and criticality of platinum asks for the development of effective low-cost stra... more The increased use and criticality of platinum asks for the development of effective low-cost strategies for metal recovery from process and waste streams. Although biotechnological processes can be applied for the valorization of diluted aqueous industrial streams, investigations considering real stream conditions (e.g., high salt levels, acidic pH, metal speciation) are lacking. This study investigated the recovery of platinum by a halophilic microbial community in the presence of increased salt concentrations (10-80 g L(-1)), different salt matrices (phosphate salts, sea salts and NH4Cl) and a refinery process stream. The halophiles were able to recover 79-99% of the Pt at 10-80 g L(-1) salts and at pH 2.3. Transmission electron microscopy suggested a positive correlation between intracellular Pt cluster size and elevated salt concentrations. Furthermore, the halophiles recovered 46-95% of the Pt-amine complex Pt[NH3]4(2+) from a process stream after the addition of an alternative...
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Polymer Testing, 2016
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ABSTRACT The FeMnSi-based shape memory alloys (SMAs) have attracted much attention in the recent ... more ABSTRACT The FeMnSi-based shape memory alloys (SMAs) have attracted much attention in the recent time because of their low cost and excellent workability. In this work the deformation-induced defects and phase transformation is investigated by the positron annihilation lifetime spectroscopy (PALS) for Fe-Mn-Si-Cr-Ni samples with different deformation degrees (0%, 5% and 10% deformation). The positron-lifetime spectra were fitted using two components. The trapping component has a positron lifetime around 150 ps related to dislocations. The concentration of defects in the high deformed sample (10%) was found to be higher than the 5% deformation sample. The light optical microscopy (OM) is used to investigate the different phases in samples. The OM shows that the γ→ε martensite phase transformation in the 10% deformation is significantly higher than the one in the 5% sample.
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Corrosion Science, 2016
Abstract Passivation at grain boundaries was investigated on copper with Electrochemical Scanning... more Abstract Passivation at grain boundaries was investigated on copper with Electrochemical Scanning Tunneling Microscopy. The depth in intergranular regions was measured and its variation was discussed in terms of dissolution or passive film formation. The Cu(I) passive film is found to be thicker at grain boundaries than on grains but with a similar stoichiometry. A thicker Cu(I) passive film is observed at random grain boundaries than at coherent twins. No metal is preferentially consumed at grain boundaries by transient dissolution during Cu(I) passivation. Comprehensive comparison with Cu(I)/Cu(II) passivation shows that transient dissolution is a revelator of the grain boundary-type dependent behavior.
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International Journal of Electrochemical Science, 2012
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Mrs Proceedings, 2013
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Steel Research International, 2008
Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycl... more Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycling or training is recognized to improve the shape memory effect. In the present work, different aspects of training are studied: the number of cycles, the amount of deformation and the annealing temperature. As the number of cycles increases, the epsilon martensite plates become thinner and within the different grains they tend to align in the same direction. Still, different variants are present. XRD measurements showed a strong increase in the E martensite volume from cycle 1 to cycle 2 and a slight decrease for further cycles. There exists an optimum deformation for obtaining stress induced E martensite which is reversibly transformable to austenite during annealing. When the amount of deformation is too low, the fraction of stress induced epsilon martensite is very low, therefore, the shape memory effect is small. If the deformation is too large, slip may occur and different E; martensite variants are formed, which hinders the reverse epsilon ->gamma transformation. The recovery annealing temperature is critical for obtaining a good shape memory, especially during training. The recovery annealing temperature of 400 degrees C is too low for completing the reverse transformation; annealing at 600 degrees C is most commonly used.
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ABSTRACT
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International journal of electrochemical science
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Forschung im Ingenieurwesen
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Tecnologia em Metalurgia, Materiais e Mineração
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ACS Applied Materials & Interfaces
One of the leading causes of failure for any bone implant are implant associated infections. The ... more One of the leading causes of failure for any bone implant are implant associated infections. The implant-bone interface is in fact the crucial site of infection where both microorganisms and cells compete to populate the newly introduced implant surface. Most of the work dealing with this issue has focused on the design of implant coatings capable of preventing infection while ignoring cell proliferation or vice versa. The present study is therefore focused on investigating the antibacterial and biological properties of nanocomposite coatings based on an amorphous hydrocarbon (a-C:H) matrix containing silver nanoparticles (AgNPs). a-C:H coatings with varying silver concentrations were generated directly on medical grade titanium substrates using a combination of a gas aggregation source (GAS) and a plasma-enhanced chemical vapor deposition (PE-CVD) process. The obtained results revealed that the surface silver content increased from 1.3 at% to 5.3 at% by increasing the used DC magnetron current in the GAS from 200 to 500 mA. A series of in-vitro antibacterial assays also indicated that increasing the number of AgNPs in the nanocomposites led to excellent antibacterial activities resulting in a 6-log reduction of E. coli and a 4-log reduction of S. aureus after 24 hours of incubation. An MTT assay, fluorescence live/dead staining and SEM microscopy observations of MC3T3 cells seeded on the uncoated and coated Ti substrates also showed that increasing the amount of AgNPs in the nanocomposites had no notable impact on their cytocompatibility, while improved cell proliferation was especially observed for the nanocomposites possessing a low amount of Ag NPs. These controllable Ag/a-C:H nanocomposites on Ti substrates which simultaneously provide an excellent antibacterial performance and good biocompatibility could thus have promising applications in orthopedics and other biomedical implants.
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Materials
The service time of an industrial cracker is strongly dependent on the long-term coking behavior ... more The service time of an industrial cracker is strongly dependent on the long-term coking behavior and microstructure stability of the reactor coil alloy. Super alloys are known to withstand temperatures up to even 1400 K. In this work, several commercially available alloys have been first exposed to a long term oxidation at 1423 K for 500 h, so-called metallurgic aging. Subsequently, their coking behavior was evaluated in situ in a thermogravimetric setup under ethane steam cracking conditions (Tgasphase = 1173 K, Ptot = 0.1 MPa, XC2H6 = 70%, continuous addition of 41 ppmw S/HC of DMDS, dilution δ = 0.33 kgH2O/kgHC) and compared with their unaged coking behavior. The tested samples were also examined using scanning electron microscopy and energy diffractive X-ray for surface and cross-section analysis. The alloys characterized by increased Cr-Ni content or the addition of Al showed improved stability against bulk oxidation and anti-coking behavior after application of metallurgic agi...
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MRS Proceedings
ABSTRACTChemical solution deposition techniques are a very competitive low cost method to achieve... more ABSTRACTChemical solution deposition techniques are a very competitive low cost method to achieve coated conductors. Recently, fluorine-free CSD methods have made a great progress for the preparation of YBCO thin films and became a sustainable alternative for the well-known trifluoroacetate CSD approach. By elucidating the reaction mechanism behind this new approach, finally giving an answer to the question why it is possible to fabricate YBCO films without TFA, different processing routes were discovered giving rise to high superconducting YBCO films (>1MA.cm-2). Each route has it's own benefits. One specific route offers the opportunity to tune the crystallographic orientation. By changing one process parameter, a shift from complete c-axis to complete a-axis orientation is observed. This can be very useful for e.g. Josephson Junctions.We particularly investigated the fundamental reaction mechanism of each reaction route, with the focus on the corresponding barium compound....
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Journal of Alloys and Compounds
Abstract A model-based evaluation procedure by a trap-diffusion integrated finite element model (... more Abstract A model-based evaluation procedure by a trap-diffusion integrated finite element model (FEM) is used to interpret the experimentally measured thermal desorption spectra (TDS) of Fe-C-Ti alloys. Two material conditions are compared, i.e. as-quenched vs. quenched and tempered, in which TiC have precipitated. The discrepancy between measurement and simulation is found to be very small for all material conditions. The model shows high trapping energies of around 58 kJ/mol to 110 kJ/mol (0.61 eV–1.14 eV), when the materials are tempered. These traps could be related to carbon vacancies in TiC precipitates.
Bookmarks Related papers MentionsView impact
Corrosion Reviews
In many industries and processes, heat exchangers are of vital importance as they are used to tra... more In many industries and processes, heat exchangers are of vital importance as they are used to transfer heat from one fluid to another. These fluids can be corrosive to heat exchangers, which are usually made of metallic materials. This paper illustrates that corrosion is an important problem in the operation of heat exchangers in many environments, for which no straightforward answer exists. Corrosion failures of heat exchangers are common, and corrosion often involves high maintenance or repair costs. In this review, an overview is given of what is known on corrosion in heat exchangers. The different types of corrosion encountered in heat exchangers and the susceptible places in the devices are discussed first. This is combined with an overview of failure analyses for each type of corrosion. Next, the effect of heat transfer on corrosion and the influence of corrosion on the thermohydraulic performances are discussed. Finally, the prevention and control of corrosion is tackled. Pre...
Bookmarks Related papers MentionsView impact
Surface and Coatings Technology
Abstract Until now, several different chemical formulae are used to refer to the intermetallic θ-... more Abstract Until now, several different chemical formulae are used to refer to the intermetallic θ- and η-layers formed at the surface of hot-dip aluminized steel. To clear up the subsequent confusion, both layers were identified and characterized using several experimental techniques combined with DFT calculations. 1 EDX- and EBSD-mappings were performed on the cross section of a hot-dip aluminized steel and showed the presence of the two single-phased intermetallic layers, θ and η, just beneath the aluminum top-layer. The XRD-pattern of a sample of which the top aluminum layer was removed, confirmed the foregoing observations. The compositions of both layers were determined by APT and yield Fe 4 Al 13 and Fe 2 Al 5.6 . DFT calculations showed the stability of the Fe 4 Al 13 phase and predicted Fe 4 Al 13 to be the only stable composition in that area of the Fe-Al phase diagram. Based on the DFT results, the ILEEMS spectrum of the θ-layer could be successfully analyzed and, for the first time, fully interpreted in accordance with the crystallographic structure of Fe 4 Al 13 . Fe 4 Al 13 is suggested for referring to the composition of the θ-layer, instead of other formulae, e.g. FeAl 3 . The ILEEMS η-layer spectrum was best reproduced by a model-independent quadrupole splitting distribution, which supports the dis-ordered structure model for the η-layer. An analysis based on the results of the DFT calculations, confirmed this finding. Because of the partially dis-ordered structure of the η-layer and the width of the related region in Fe-Al phase diagrams, Fe 2 Al 5+x is suggested for referring to the composition of the η-layer.
Bookmarks Related papers MentionsView impact
steel research international
Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycl... more Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycling or training is recognized to improve the shape memory effect. In the present work, different aspects of training are studied: the number of cycles, the amount of deformation and the annealing temperature. As the number of cycles increases, the epsilon martensite plates become thinner and within the different grains they tend to align in the same direction. Still, different variants are present. XRD measurements showed a strong increase in the E martensite volume from cycle 1 to cycle 2 and a slight decrease for further cycles. There exists an optimum deformation for obtaining stress induced E martensite which is reversibly transformable to austenite during annealing. When the amount of deformation is too low, the fraction of stress induced epsilon martensite is very low, therefore, the shape memory effect is small. If the deformation is too large, slip may occur and different E; martensite variants are formed, which hinders the reverse epsilon ->gamma transformation. The recovery annealing temperature is critical for obtaining a good shape memory, especially during training. The recovery annealing temperature of 400 degrees C is too low for completing the reverse transformation; annealing at 600 degrees C is most commonly used.
Bookmarks Related papers MentionsView impact
Environmental science and pollution research international, Jan 14, 2017
Contamination of drinking water with arsenic causes severe health problems in various world regio... more Contamination of drinking water with arsenic causes severe health problems in various world regions. Arsenic exists predominantly as As(III) and As(V) depending on the prevailing redox conditions of the environment. Most of the techniques developed for treating As(V) are not very effective for As(III), which is more toxic and mobile than As(V). In this study, novel cerium-loaded pumice (Ce-Pu) and red scoria (Ce-Rs) adsorbents were developed to remove both As(III) and As(V) ions from water. The Ce-Pu and Ce-Rs adsorbents were characterized using ICP-OES, EDX, and SEM. The experimental equilibrium sorption data fitted well Freundlich and Dubinin-Radushkevich (D-R) isotherms. The adsorption was very fast and reached an equilibrium within 2 h. Both Ce-Rs and Ce-Pu showed high As(III) and As(V) removal efficiency in a wide pH range between 3 and 9, which is an important asset for practical applications. The Ce-Pu and Ce-Rs adsorbents can be recycled and used up to three adsorption cycle...
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steel research international, 2006
ABSTRACT
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Water research, Jan 15, 2016
The increased use and criticality of platinum asks for the development of effective low-cost stra... more The increased use and criticality of platinum asks for the development of effective low-cost strategies for metal recovery from process and waste streams. Although biotechnological processes can be applied for the valorization of diluted aqueous industrial streams, investigations considering real stream conditions (e.g., high salt levels, acidic pH, metal speciation) are lacking. This study investigated the recovery of platinum by a halophilic microbial community in the presence of increased salt concentrations (10-80 g L(-1)), different salt matrices (phosphate salts, sea salts and NH4Cl) and a refinery process stream. The halophiles were able to recover 79-99% of the Pt at 10-80 g L(-1) salts and at pH 2.3. Transmission electron microscopy suggested a positive correlation between intracellular Pt cluster size and elevated salt concentrations. Furthermore, the halophiles recovered 46-95% of the Pt-amine complex Pt[NH3]4(2+) from a process stream after the addition of an alternative...
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Polymer Testing, 2016
Bookmarks Related papers MentionsView impact
ABSTRACT The FeMnSi-based shape memory alloys (SMAs) have attracted much attention in the recent ... more ABSTRACT The FeMnSi-based shape memory alloys (SMAs) have attracted much attention in the recent time because of their low cost and excellent workability. In this work the deformation-induced defects and phase transformation is investigated by the positron annihilation lifetime spectroscopy (PALS) for Fe-Mn-Si-Cr-Ni samples with different deformation degrees (0%, 5% and 10% deformation). The positron-lifetime spectra were fitted using two components. The trapping component has a positron lifetime around 150 ps related to dislocations. The concentration of defects in the high deformed sample (10%) was found to be higher than the 5% deformation sample. The light optical microscopy (OM) is used to investigate the different phases in samples. The OM shows that the γ→ε martensite phase transformation in the 10% deformation is significantly higher than the one in the 5% sample.
Bookmarks Related papers MentionsView impact
Corrosion Science, 2016
Abstract Passivation at grain boundaries was investigated on copper with Electrochemical Scanning... more Abstract Passivation at grain boundaries was investigated on copper with Electrochemical Scanning Tunneling Microscopy. The depth in intergranular regions was measured and its variation was discussed in terms of dissolution or passive film formation. The Cu(I) passive film is found to be thicker at grain boundaries than on grains but with a similar stoichiometry. A thicker Cu(I) passive film is observed at random grain boundaries than at coherent twins. No metal is preferentially consumed at grain boundaries by transient dissolution during Cu(I) passivation. Comprehensive comparison with Cu(I)/Cu(II) passivation shows that transient dissolution is a revelator of the grain boundary-type dependent behavior.
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International Journal of Electrochemical Science, 2012
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Mrs Proceedings, 2013
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Steel Research International, 2008
Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycl... more Shape recovery in iron-based shape memory alloys is known to be incomplete. Thermomechanical cycling or training is recognized to improve the shape memory effect. In the present work, different aspects of training are studied: the number of cycles, the amount of deformation and the annealing temperature. As the number of cycles increases, the epsilon martensite plates become thinner and within the different grains they tend to align in the same direction. Still, different variants are present. XRD measurements showed a strong increase in the E martensite volume from cycle 1 to cycle 2 and a slight decrease for further cycles. There exists an optimum deformation for obtaining stress induced E martensite which is reversibly transformable to austenite during annealing. When the amount of deformation is too low, the fraction of stress induced epsilon martensite is very low, therefore, the shape memory effect is small. If the deformation is too large, slip may occur and different E; martensite variants are formed, which hinders the reverse epsilon ->gamma transformation. The recovery annealing temperature is critical for obtaining a good shape memory, especially during training. The recovery annealing temperature of 400 degrees C is too low for completing the reverse transformation; annealing at 600 degrees C is most commonly used.
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ABSTRACT
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International journal of electrochemical science
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