80 results on '"Yaiza Gonzalez-Garcia"'
Search Results
2. Biodegradation of Oxide Nanoparticles in Apoferritin Protein Media: A Systematic Electrochemical Approach
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Ehsan Rahimi, Donghoon Kim, Ruben Offoiach, Roger Sanchis‐Gual, Xiang‐Zhong Chen, Peyman Taheri, Yaiza Gonzalez‐Garcia, Johannes M. C. Mol, Lorenzo Fedrizzi, Salvador Pané, and Maria Lekka
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apoferritin protein ,biodegradation ,CoFe2O4 ,CoFe2O4‐BiFeO3 core‐shell ,electrochemical monitoring ,electronic properties ,Physics ,QC1-999 ,Technology - Abstract
Abstract Functional oxide nanoparticles are extensively utilized in the last decades for biomedical purposes due to their unique functional properties. Nevertheless, their biodegradation mechanism by biological species, particularly by proteins at oxide/protein interfaces, still remains limited. Here, a systematic approaches is provided to investigate electrochemical behavior, electronic properties, and biodegradation mechanism of cobalt ferrite (CFO) and cobalt ferrite‐bismuth ferrite (CFO‐BFO) core‐shell nanoparticles in apoferritin‐containing media. Scanning Kelvin probe force microscopy results indicate that the presence of a thin shell (≈5 nm) of BFO on CFO causes a significant increase in surface potential. The potentiodynamic polarization measurements in different solutions showed higher anodic current densities for both samples when decreasing pH and increasing apoferritin concentration. Notably, CFO‐BFO exhibits lower anodic current densities than CFO due to a slightly higher flat band potential and lower donor density distribution on CFO‐BFO than on CFO, which results in lower electrochemical activity. Long‐term monitoring reveals that biodegradation of both nanoparticles is accelerated by high apoferritin concentrations and acidic media, resulting in the decrease of electrochemical potentials and impedance values, and enhancement of metal ion release. Thus, this systematic biodegradation study can help to predict the lifespan and toxicity of these functional nanoparticles in biological environments.
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- 2023
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3. Local changes in the microstructure, mechanical and electrochemical properties of friction stir welded joints from aluminium of varying grain size
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Marta Orłowska, Florian Pixner, Andreas Hütter, Agnieszka Kooijman, Cezary Jasiński, Yaiza Gonzalez-Garcia, Norbert Enzinger, and Małgorzata Lewandowska
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Aluminium ,Friction stir welding ,Ultrafine-grained microstructure ,Local characterization ,Mechanical properties ,Microcapillary ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The present study shows results of friction stir welded (FSW) samples after different plastic deformation routes. The welds were made of coarse-grained and ultrafine-grained commercially pure aluminium. As a plastic deformation method a new hybrid process has been chosen, which resulted in obtaining samples with different characteristics of microstructure, which also differed in dependance of the examined plane. Microstructure observations showed that, regardless of the base material, due to continuous dynamic recrystallization a stir zone was characterized by equiaxial grains with an average size of 3.5–5.0 μm. However, significant differences in the changes of the microstructure in thermomechanically affected and heat affected zones have been obtained between welds. Microhardness profiles revealed a decrease in the stir zones in comparison with the initially deformed samples, but an increase for the annealed samples. Tensile tests showed differences between the samples. In the deformed samples, the rupture occurred in a stir zone, while in the undeformed samples in the base material. In addition, due to the application of 3D digital image correlation, it was possible to observe deformation and local changes between the weld zones during the tensile test. Additionally, local electrochemical measurements were performed with two sizes of working electrode, which included the application of microcapillary technique. The results showed higher corrosion resistance in 3.5% NaCl in the stir zones.
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- 2021
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4. Role of Grain Size and Recrystallization Texture in the Corrosion Behavior of Pure Iron in Acidic Medium
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Satyakam Kar, Aytac Yilmaz, Konstantina Traka, Jilt Sietsma, and Yaiza Gonzalez-Garcia
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grain size ,crystallographic texture ,iron ,corrosion ,hydrogen evolution reaction ,EIS ,Mining engineering. Metallurgy ,TN1-997 - Abstract
This work investigates the role of grain size and recrystallization texture in the corrosion behavior of pure iron in 0.1 M sulfuric acid solution. Annealing heat treatment was applied to obtain samples with different average grain sizes (26, 53 and 87 µm). Optical microscopy, X-ray diffraction and electron backscatter diffraction techniques were used to characterize the microstructure. The EBSD data analysis showed ferrite phase with no inclusions and very low geometrically necessary dislocation density, indicating strain-free grains constituting all samples. The crystallographic texture analysis of the samples revealed that the 26 µm grain size sample had a high volume fraction of {111} oriented grains parallel to the sample surface, while other samples exhibited nearly random crystallographic texture. The electrochemical results from potentiodynamic polarization and electrochemical impedance spectroscopy showed a decrease in corrosion resistance from 87 µm to 53 µm grain size sample and then an increase for the 26 µm grain size sample. This increase was attributed to the dominant effect of recrystallization texture on the corrosion behavior of the sample. The cathodic hydrogen evolution reaction kinetics was found to play a decisive role in the corrosion behavior of iron.
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- 2023
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5. Fighting Antibiotic-Resistant Bacterial Infections by Surface Biofunctionalization of 3D-Printed Porous Titanium Implants with Reduced Graphene Oxide and Silver Nanoparticles
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Hongshan San, Marianne Paresoglou, Michelle Minneboo, Ingmar A. J. van Hengel, Aytac Yilmaz, Yaiza Gonzalez-Garcia, Ad C. Fluit, Peter-Leon Hagedoorn, Lidy E. Fratila-Apachitei, Iulian Apachitei, and Amir A. Zadpoor
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antibiotic-resistant bacteria ,reduced graphene oxide ,silver nanoparticles ,plasma electrolytic oxidation ,implant-associated infections ,titanium ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Nanoparticles (NPs) have high multifunctional potential to simultaneously enhance implant osseointegration and prevent infections caused by antibiotic-resistant bacteria. Here, we present the first report on using plasma electrolytic oxidation (PEO) to incorporate different combinations of reduced graphene oxide (rGO) and silver (Ag) NPs on additively manufactured geometrically ordered volume-porous titanium implants. The rGO nanosheets were mainly embedded parallel with the PEO surfaces. However, the formation of ‘nano-knife’ structures (particles embedded perpendicularly to the implant surfaces) was also found around the pores of the PEO layers. Enhanced in vitro antibacterial activity against methicillin-resistant Staphylococcus aureus was observed for the rGO+Ag-containing surfaces compared to the PEO surfaces prepared only with AgNPs. This was caused by a significant improvement in the generation of reactive oxygen species, higher levels of Ag+ release, and the presence of rGO ‘nano-knife’ structures. In addition, the implants developed in this study stimulated the metabolic activity and osteogenic differentiation of MC3T3-E1 preosteoblast cells compared to the PEO surfaces without nanoparticles. Therefore, the PEO titanium surfaces incorporating controlled levels of rGO+Ag nanoparticles have high clinical potential as multifunctional surfaces for 3D-printed orthopaedic implants.
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- 2022
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6. Corrosion and Microstructural Investigation on Additively Manufactured 316L Stainless Steel: Experimental and Statistical Approach
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Héctor Maicas-Esteve, Iman Taji, Marc Wilms, Yaiza Gonzalez-Garcia, and Roy Johnsen
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selective laser melting ,additive manufacturing ,316L SS ,pitting corrosion ,processing parameters ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The use of metal additive manufacturing (AM) has strongly increased in the industry during the last years. More specifically, selective laser melting (SLM) is one of the most used techniques due to its numerous advantages compared to conventional processing methods. The purpose of this study is to investigate the effects of process parameters on the microstructural and corrosion properties of the additively manufactured AISI 316L stainless steel. Porosity, surface roughness, hardness, and grain size were studied for specimens produced with energy densities ranging from 51.17 to 173.91 J/mm3 that resulted from different combinations of processing parameters. Using experimental results and applying the Taguchi model, 99.38 J/mm3 was determined as the optimal energy density needed to produce samples with almost no porosity. The following analysis of variance ANOVA confirmed the scanning speed as the most influential factor in reducing the porosity percentage, which had a 74.9% contribution, followed by the position along the building direction with 22.8%, and finally, the laser energy with 2.3%. The influence on corrosion resistance was obtained by performing cyclic potentiodynamic polarization tests (CPP) in a 3.5 wt % NaCl solution at room temperature for different energy densities and positions (Z axis). The corrosion properties of the AM samples were studied and compared to those obtained from the traditionally manufactured samples. The corrosion resistance of the samples worsened with the increase in the percentage of porosity. The process parameters have consequently been optimized and the database has been extended to improve the quality of the AM-produced parts in which microstructural heterogeneities were observed along the building direction.
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- 2022
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7. Passive Film Properties of Martensitic Steels in Alkaline Environment: Influence of the Prior Austenite Grain Size
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Aytac Yilmaz, Xiaolin Li, Sven Pletincx, Tom Hauffman, Jilt Sietsma, and Yaiza Gonzalez-Garcia
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martensitic steel ,grain-size ,passivity ,electrochemical impedance spectroscopy ,Mott-Schottky analysis ,X-ray photoelectron spectroscopy ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The role of prior austenite grain size (PAGS) on the passive layer properties of martensitic steels is studied. Electron backscatter diffraction analysis shows that PAGS between 5 and 66 µm were obtained after applying different heat treatments. The barrier properties of passive film deteriorate with grain refinement up to 28 µm, attributed to increased donor density and a decrease in the fraction of γ-Fe2O3 in passive films. However, the further refinement of PAGS to 5 µm leads to improvement in the barrier properties due to the changes within the martensite structure. This improvement stems from the increase in γ-Fe2O3 fraction.
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- 2022
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8. Properties of Passive Films Formed on Ferrite-Martensite and Ferrite-Pearlite Steel Microstructures
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Aytac Yilmaz, Can Ozkan, Jilt Sietsma, and Yaiza Gonzalez-Garcia
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HSLA steel ,dual-phase ,passivity ,EIS ,polarisation ,Mott–Schottky ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The effect of ferrite-pearlite and ferrite-martensite phase combinations on the passive layer properties of low carbon steel is investigated in a 0.1 M NaOH solution. Heat treatments were designed to obtain ferrite-pearlite and ferrite-martensite microstructures with similar ferrite volume fractions. Potentiostatic polarisation and electrochemical impedance spectroscopy (EIS) results demonstrated the lower barrier properties of passive films on ferrite-martensite microstructure compared to the ones formed on ferrite-pearlite microstructure. This was attributed to the higher donor density of the passive layer on ferrite-martensite samples, measured with Mott–Schottky analysis. This behaviour was explained by the complex microstructure morphology of the martensite phase that led to the formation of a more defective passive film.
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- 2021
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9. Morphological and Surface Potential Characterization of Protein Nanobiofilm Formation on Magnesium Alloy Oxide: Their Role in Biodegradation
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Ehsan Rahimi, Amin Imani, Maria Lekka, Francesco Andreatta, Yaiza Gonzalez-Garcia, Johannes M. C. Mol, Edouard Asselin, and Lorenzo Fedrizzi
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surface potential ,Surface Properties ,Surfaces and Interfaces ,Sodium Chloride ,Condensed Matter Physics ,Corrosion ,alloys ,adsorption ,Materials Testing ,oxides ,Electrochemistry ,Humans ,Magnesium ,General Materials Science ,Magnesium Oxide ,Spectroscopy - Abstract
The formation of a protein nanobiofilm on the surface of degradable biomaterials such as magnesium (Mg) and its alloys influences metal ion release, cell adhesion/spreading, and biocompatibility. During the early stage of human body implantation, competition and interaction between inorganic species and protein molecules result in a complex film containing Mg oxide and a protein layer. This film affects the electrochemical properties of the metal surface, the protein conformational arrangement, and the electronic properties of the protein/Mg oxide interface. In this study, we discuss the impact of various simulated body fluids, including sodium chloride (NaCl), phosphate-buffered saline (PBS), and Hanks' solutions on protein adsorption, electrochemical interactions, and electrical surface potential (ESP) distribution at the adsorbed protein/Mg oxide interface. After 10 min of immersion in NaCl, atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM) showed a higher surface roughness related to enhanced degradation and lower ESP distribution on a Mg-based alloy than those in other solutions. Furthermore, adding bovine serum albumin (BSA) to all solutions caused a decline in the total surface roughness and ESP magnitude on the Mg alloy surface, particularly in the NaCl electrolyte. Using SKPFM surface analysis, we detected a protein nanobiofilm (∼10-20 nm) with an aggregated and/or fibrillary morphology only on the Mg surface exposed in Hanks' and PBS solutions; these surfaces had a lower ESP value than the oxide layer.
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- 2022
10. Local changes in the microstructure, mechanical and electrochemical properties of friction stir welded joints from aluminium of varying grain size
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Florian Pixner, Norbert Enzinger, Małgorzata Lewandowska, C. Jasiński, Agnieszka Kooijman, Yaiza Gonzalez-Garcia, Andreas Hütter, and Marta Orłowska
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Digital image correlation ,Materials science ,Recrystallization (geology) ,Mining engineering. Metallurgy ,Friction stir welding ,Metals and Alloys ,TN1-997 ,Mechanical properties ,Microcapillary ,Microstructure ,Indentation hardness ,Ultrafine-grained microstructure ,Grain size ,Surfaces, Coatings and Films ,Biomaterials ,Ultimate tensile strength ,Ceramics and Composites ,Aluminium ,Local characterization ,Deformation (engineering) ,Composite material ,Tensile testing - Abstract
The present study shows results of friction stir welded (FSW) samples after different plastic deformation routes. The welds were made of coarse-grained and ultrafine-grained commercially pure aluminium. As a plastic deformation method a new hybrid process has been chosen, which resulted in obtaining samples with different characteristics of microstructure, which also differed in dependance of the examined plane. Microstructure observations showed that, regardless of the base material, due to continuous dynamic recrystallization a stir zone was characterized by equiaxial grains with an average size of 3.5–5.0 μm. However, significant differences in the changes of the microstructure in thermomechanically affected and heat affected zones have been obtained between welds. Microhardness profiles revealed a decrease in the stir zones in comparison with the initially deformed samples, but an increase for the annealed samples. Tensile tests showed differences between the samples. In the deformed samples, the rupture occurred in a stir zone, while in the undeformed samples in the base material. In addition, due to the application of 3D digital image correlation, it was possible to observe deformation and local changes between the weld zones during the tensile test. Additionally, local electrochemical measurements were performed with two sizes of working electrode, which included the application of microcapillary technique. The results showed higher corrosion resistance in 3.5% NaCl in the stir zones.
- Published
- 2021
11. Front Cover: Benchmarking the Electrochemical CO 2 Reduction on Polycrystalline Copper Foils: The Importance of Microstructure Versus Applied Potential (ChemCatChem 21/2022)
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Simone Asperti, Ruud Hendrikx, Yaiza Gonzalez‐Garcia, and Ruud Kortlever
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Inorganic Chemistry ,Organic Chemistry ,Physical and Theoretical Chemistry ,Catalysis - Published
- 2022
12. The Effect of Ambient Ageing on the Corrosion Protective Properties of a Lithium-Based Conversion Layer
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Ziyu Li, Axel Homborg, Yaiza Gonzalez-Garcia, Peter Visser, Mohammad Soleimani, and Arjan Mol
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Renewable Energy, Sustainability and the Environment ,Materials Chemistry ,Electrochemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
The influence of ageing under ambient conditions on the corrosion protective behaviour of a lithium-based conversion layer on AA2024-T3 is studied in this work. Conversion layers aged at ambient conditions for relatively short times (0 h and 4 h), show an initial high degree of corrosion inhibition but a much lower protectiveness after the inhibition stage terminates. Conversion layers with relatively long ageing times (24 h and 72 h) show a rather stable corrosion resistance which is higher than that of short-time aged samples. It is hypothesized that the freshly-formed conversion layer has trapped a certain amount of lithium ions and water molecules, leading to ongoing and heterogeneous growth of the conversion layer with time under ambient indoor conditions. Moreover, conversion layers with short ageing times show early-stage active corrosion protection by lithium-ion release.
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- 2023
13. Exploring the effect of the pH on the corrosion of multilayer nickel-chromium coatings
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Jesús Manuel Vega, Larraitz Ganborena, Yaiza Gonzalez-Garcia, Berkem Özkaya, Hans-Jürgen Grande, and Eva García-Lecina
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General Chemical Engineering ,General Materials Science ,General Chemistry - Published
- 2023
14. Evaluation of the formation and protectiveness of a lithium-based conversion layer using electrochemical noise
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Ziyu Li, Axel Homborg, Yaiza Gonzalez-Garcia, Ali Kosari, Peter Visser, and Arjan Mol
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Hexavalent chromium replacement ,Aluminium alloy ,General Chemical Engineering ,Electrochemistry ,lithium-based conversion layer ,Electrochemical noise ,Corrosion inhibition - Abstract
The formation process of a lithium-based conversion layer on AA2024-T3 and its corrosion protective behavior are studied using electrochemical noise (EN). Wavelet transform, as well as noise resistance analysis, have been employed to interpret the EN data. The EN data confirmed five different stages during the conversion layer growth, accompanied by anodic dissolution, increasing corrosion protection of the conversion layer, and adsorption, growth and desorption of hydrogen bubbles simultaneously. The detachment of hydrogen bubbles, localized and uniform corrosion generate different features in the EN signals with energy maxima in high, intermediate and low frequency bands, respectively. In addition, EN results show that the lithium-based conversion layer still provides efficient protection after re-immersion in a corrosive environment, even though localized damage occurs. Moreover, the EN data corresponds well with the morphological layer formation and breakdown observed with microscopy techniques. The results demonstrate that EN is a powerful tool to provide continuous time- and frequency-resolved information about inhibition efficiency.
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- 2022
15. Predicting the effect of droplet geometry and size distribution on atmospheric corrosion
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Nils Van den Steen, Yaiza Gonzalez-Garcia, Mol, J. M. C., Herman Terryn, YVES VAN INGELGEM, Faculty of Engineering, Materials and Chemistry, Materials and Surface Science & Engineering, and Electrochemical and Surface Engineering
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General Chemical Engineering ,General Materials Science ,General Chemistry ,Size distribution ,Atmospheric corrosion ,Droplet size distribution ,Droplet geometry ,Modelling - Abstract
A new approach is proposed to numerically predict and study atmospheric corrosion for ranging droplet size distributions and the influence of the droplet geometry. The proposed methodology allows for a corrosion prediction based on observed droplet size distributions and droplet contact angles. A mechanistic finite element model, including oxygen transport and Butler-Volmer kinetics, is solved in order to obtain the current density as a function of the droplet geometry. This is done for a range of both droplet radii and contact angles. The computed corrosion current densities are then used as input for imposed droplet size distributions. This allows for a calculated material loss estimation for different distributions and electrolyte configurations and shows the extent of the impact of the droplet size distribution on atmospheric corrosion.
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- 2022
16. Corrosion Behaviour of Electrodeposited Sn-Cu-Ni Alloys as Lead-Free Solders Using Direct and Pulse Plating in Choline Chloride Based Ionic Liquids
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Sabrina State, Stefania Costovici, Mirsajjad Mousavi, Yaiza Gonzalez Garcia, Caterina Zanella, Anca Cojocaru, Liana Anicai, Teodor Visan, and Marius Enachescu
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- 2022
17. Benchmarking the Electrochemical CO2 Reduction on Polycrystalline Copper Foils
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Simone Asperti, Ruud Hendrikx, Yaiza Gonzalez‐Garcia, and Ruud Kortlever
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Inorganic Chemistry ,CORR ,Organic Chemistry ,microstructure ,polycrystalline copper ,electrocatalysis ,applied potential ,Physical and Theoretical Chemistry ,Catalysis - Abstract
Copper is one of the most promising catalysts for the CO2 reduction reaction (CO2RR) due to its unique capability of producing multicarbon products in appreciable quantities. Most of the CO2RR research efforts have been directed towards the development of new electrocatalysts to either increase product selectivities or decrease overpotentials. In contrast, only a few studies have systematically tested or benchmarked CO2RR performances of electrocatalysts. In this paper, for the first time, the performances of five different polycrystalline copper foils purchased from different suppliers are benchmarked for their CO2RR performance. Their differences are characterized in terms of microstructural features and the effect that these microstructural properties have on the electrocatalytic behavior during potentiostatic CO2RR experiments are evaluated. It is shown that the potential applied is the dominant factor controlling CO2RR selectivities, leading to the conclusion that microstructural properties of polycrystalline copper electrodes have a negligible effect on the outcome of CO2RR experiments.
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- 2022
18. Internal failure of anode materials for lithium batteries — A critical review
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Zhi Sun, Xiangqi Meng, Yaiza Gonzalez Garcia, Hongbin Cao, Pengge Ning, Yaolin Xu, Xiao Lin, and Yi Zhang
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Electrode material ,Materials science ,Renewable Energy, Sustainability and the Environment ,education ,lcsh:TJ807-830 ,lcsh:Renewable energy sources ,chemistry.chemical_element ,Failure prevention ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,Anode ,Molecular level ,chemistry ,lcsh:QH540-549.5 ,Lithium ,lcsh:Ecology ,Deformation (engineering) ,0210 nano-technology - Abstract
Prevention of mechanical and finally electrochemical failures of lithium batteries is a critical aspect to be considered during their design and performance, especially for those with high specific capacities. Internal failure is observed as one of the most serious factors, including loss of electrode materials, structure deformation and dendrite growth. It usually incubates from atomic/molecular level and progressively aggravates along with lithiation. Understanding the internal failure is of great importance for developing solutions of failure prevention and advanced anode materials. In this research, different internal failure processes of anode materials for lithium batteries are discussed. The progress on observation technologies of the anode failure is further summarized in order to understand their mechanisms of internal failure. On top of them, this review aims to summarize innovative methods to investigate the anode failure mechanisms and to gain new insights to develop advanced and stable anodes for lithium batteries. Keywords: Lithium battery, Anode materials, Internal failure
- Published
- 2020
19. Comparing Modelling and Experiments for Prediction of Atmospheric Corrosion Under Controlled Dynamic Thin Film and Droplet Electrolytes
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Herman Albert Terryn, Nils Van Den Steen, Keer Zhang, Ali Korsari, Bangalore Gangadharacharya Koushik, Yves Van Ingelgem, Yaiza Gonzalez-Garcia, and Arjan Mol
- Abstract
Corrosion prediction by multiscale modelling aims to achieve the required paradigm shift in the lifetime prediction of metals. Modelling of atmospheric corrosion, for example, based on Finite Element Modelling (FEM) requires an exact description of the boundary region between metal and electrolyte. This requires a radically different research approach for the electrolyte in contact with the metal surface. The critical issue is that most corrosion experiments in fundamental research are performed “in solution” under the assumption that the electrolyte layer is thick enough to approximate it as “infinite”, ignoring significant local effects introduced by dynamic electrolyte dimensions caused by droplets and puddles. In other words, a major part of the research in academia is not relevant to mimic the actual conditions encountered on the metal surface. To create accurate numerical models, we first and foremost needed to abandon this "infinite" and “stationary” approximation and consider dynamic and finite electrolyte dimensions. During atmospheric corrosion of metals, the evolution of the thin-film electrolyte thickness is the primary factor determining the corrosion rate. A full understanding the evolution of the electrolyte thickness and properties as a function of the key environmental parameters is yet to be achieved. A novel methodology has been developed to conduct experiments under a regulated environment to measure the film thickness evolution or individual droplets on an undisturbed metal surface [1]. Experimental results are compared with FEM models predicting both the electrolyte formation as well as the related corrosion. The heat transfer coefficient is noted as a critical parameter influencing both the film characteristics and the resulting corrosion rate. This model was tested in case of cut-edge corrosion of galvanized steel. Combining the in-house MiTReM (Multi ion Transfer Reaction electrochemical model) with the electrolyte film thickness model, we could see that the corrosion rates become very critical in the range of 20 µm [2]. The next step was to go into the dimension of droplets. A thorough literature review [3] was made and published around modelling of droplet formation and corrosion, forming a base for further progress and improvements. The literature study also highlighted that the topic of droplet formation is relatively new within the corrosion research community. A new approach [4] was proposed to numerically predict and study atmospheric corrosion under droplet size distributions. The proposed methodology allows for a corrosion prediction based on observed droplet size distributions and droplet contact angles. A mechanistic finite element model, including oxygen transport and Butler-Volmer kinetics, is solved to obtain the current density for the droplet geometry. This is done for a range of both droplet radii and contact angles. The computed corrosion current densities are then adapted onto imposed droplet distributions for a calculation of overall corrosion current. This allows for a calculated material loss estimation for different distributions and electrolyte configurations and shows the extent of the impact of the droplet distribution on atmospheric corrosion. This model is validated by comparing with experiments introducing droplet-induced corrosion in a lab scale reactor that allows monitoring in parallel droplet geometry and corrosion as function of induced thermal cycles in a controlled atmosphere. Keywords: Atmospheric corrosion, FEM modelling, thin electrolyte films, droplets References: [1] B.G. Koushik , N. Van den Steen, H. Terryn, Y. Van Ingelgem “Investigation of the importance of heat transfer during thin electrolyte formation in atmospheric corrosion using a novel experimental approach” Corrosion Science .vol 189, 2021.109542, https://doi.org/10.1016/j.corsci.2021.109542 [2] M. Saeedikhani, N. Van Den Steen, Nils, S. Wijesinghe, S. Vafakhah, , H. Terryn, D. Blackwood, Daniel “Moving Boundary Simulation of Iron-Zinc Sacrificial Corrosion under Dynamic Electrolyte Thickness Based on Real-Time Monitoring Data” Journal of Electrochemical Society Vol 167,4, 2020,1503. DOI: 10.1149/1945-7111/ab7368 [3] B.G. Koushik, N. Van den Steen, M. Haile Mamme, Y. Van Ingelgem, H. Terryn “Review on modelling of corrosion under droplet electrolyte for predicting atmospheric corrosion rate” Journal of Materials Science & Technology vol 62, 30 January 2021, 254. https://doi.org/10.1016/j.jmst.2020.04.061 [4] N. Van den Steen, Y. Gonzalez-Garcia, J.M.C Mol, H. Terryn, Y. Van Ingelgem “Predicting the effect of droplet geometry and size distribution on atmospheric corrosion” Corrosion Science (2022) https://doi.org/10.1016/j.corsci.2022.110308
- Published
- 2022
20. Effect of microstructural defects on passive layer properties of interstitial free (IF) ferritic steels in alkaline environment
- Author
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Yaiza Gonzalez-Garcia, Konstantina Traka, Sven Pletincx, Ahmet Yilmaz, Tom Hauffman, Jilt Sietsma, Faculty of Engineering, Materials and Chemistry, and Electrochemical and Surface Engineering
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Diffraction ,Materials science ,EIS ,020209 energy ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,SKP ,021001 nanoscience & nanotechnology ,Corrosion ,Dielectric spectroscopy ,X-ray photoelectron spectroscopy ,Microstructural defect density ,0202 electrical engineering, electronic engineering, information engineering ,Mott-Schottky analysis ,XPS ,General Materials Science ,Grain boundary ,passivity ,Dislocation ,Composite material ,0210 nano-technology ,Layer (electronics) ,Electron backscatter diffraction ,Ferritic steel - Abstract
The role of microstructural defects (dislocation density and grain boundary areas) on the passive film properties formed on cold- and hot-rolled interstitial free (IF) steels is investigated in 0.1 M NaOH solution. Electron backscattered diffraction (EBSD) shows higher microstructural defect density on cold-rolled samples. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) results exhibit the lower barrier properties of passive films with the increase in microstructural defects. This is attributed to the increase in donor density measured with Mott-Schottky analysis and the lower relative quantity of protective γ-Fe2O3 in passive films (composed of Fe3O4,γ-Fe2O3 and FeO(OH)) with the increase in microstructural defect density.
- Published
- 2021
21. Editors' Choice - Dealloying-Driven Cerium Precipitation on Intermetallic Particles in Aerospace Aluminium Alloys
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Pieter Visser, Frans D. Tichelaar, Herman Terryn, Majid Ahmadi, Ali Kosari, Henny W. Zandbergen, Johannes M. C. Mol, Yaiza Gonzalez-Garcia, Nanostructured Materials and Interfaces, Materials and Chemistry, Materials and Surface Science & Engineering, and Electrochemical and Surface Engineering
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Materials science ,Renewable Energy, Sustainability and the Environment ,Precipitation (chemistry) ,Metallurgy ,Intermetallic ,chemistry.chemical_element ,Condensed Matter Physics ,Electrochemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Corrosion ,Cerium nitrate ,chemistry.chemical_compound ,Cerium ,chemistry ,Aluminium ,Materials Chemistry ,Nanoscopic scale - Abstract
Cerium-based compounds have been studied for decades as non-toxic candidates for the protection of aerospace aluminium alloys (AAs) like AA2024-T3. However, the complex heterogeneous microstructure of these alloys has hindered a thorough understanding of the subsequent stages of corrosion protection provided by this class of inhibitors. Thus, this work is devoted to unravelling the interaction mechanisms of different intermetallic particles (IMPs) in AA2024-T3 with cerium nitrate at the nanoscopic scale. This has been fulfilled through detailed top-view and cross-sectional analytical TEM investigations along with electrochemical evaluations. In line with our recent findings, we here report dealloying of IMPs as the main factor governing the rate of local cerium precipitation in contrast to micro-galvanic corrosion between IMPs and the surrounding matrix. Furthermore, we discuss a connection between the electrochemical response of the AA2024-T3 system and the morphological and compositional evolutions of individual IMPs including Al2CuMg, Al2Cu, Al7Cu2Fe(Mn) and Al76Cu6Fe7Mn5Si6 at different stages of a 96-h exposure.
- Published
- 2021
22. Corrosion Mechanism of Microporous Nickel-Chromium Coatings: Part II. SECM Study Monitoring Cu2+ and Oxygen Reduction
- Author
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Larraitz Ganborena, Yaiza Gonzalez-Garcia, Berkem Özkaya, Marta García, Eva García-Lecina, and Jesús Manuel Vega
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Renewable Energy, Sustainability and the Environment ,Materials Chemistry ,Electrochemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
The corrosion mechanism of microporous nickel-chromium multilayer coatings was studied at localised scale by Scanning Electrochemical Microscopy (SECM) after exposure to an aggressive electrolyte (chloride-based one at pH 3.1 containing cupric ions). The open circuit potential was initially monitored during 22 h, followed by a detailed characterisation using Glow Discharge-Optical Emission Spectroscopy and Field Emission Scanning Electron Microscope. Interestingly, Cu deposition occurs over the surface of the microporous nickel layer, and it is located on spots where micro-discontinuities (i.e., cracks and pores) of the outermost Cr layer are present. The application of different operation modes of the SECM (i.e., redox competition and surface generation/tip collection) not only reveals such copper deposits (which were identified after monitoring their catalytic capabilities for oxygen reduction reaction) but also confirms the stepwise reduction of Cu2+ to Cu0 (via intermediate species of Cu+) during the corrosion process. The impact of metallic copper particles in the local pH due to their catalytic activity could also explain why the microporous nickel layer is not corroded after exposure to such electrolyte.
- Published
- 2022
23. Molybdate as corrosion inhibitor for hot dip galvanised steel scribed to the substrate: A study based on global and localised electrochemical approaches
- Author
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Marie-Georges Olivier, E.B Fava, Leonardo Bertolucci Coelho, Yaiza Gonzalez-Garcia, and A.M. Kooijman
- Subjects
Materials science ,020209 energy ,General Chemical Engineering ,Sodium molybdate ,02 engineering and technology ,Molybdate ,engineering.material ,Electrochemistry ,Corrosion ,C. Neutral inhibition ,Corrosion inhibitor ,chemistry.chemical_compound ,symbols.namesake ,Coating ,C. Interfaces ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Composite material ,A. Mild steel ,C. Cathodic protection ,General Chemistry ,021001 nanoscience & nanotechnology ,Galvanization ,Galvanic corrosion ,chemistry ,engineering ,symbols ,0210 nano-technology ,A. Zinc - Abstract
The effect of sodium molybdate in inhibiting galvanic corrosion of Zn coating and mild steel is addressed. The inhibitor's performance was appraised by Zero Resistance Ammeter on HDG/mild steel galvanic coupling model in 0.05 M NaCl (+5 mM Na2MoO4) media. The effectiveness of Na2MoO4 was evaluated on HDG substrate mechanically scratched to reach the steel. Scanning Vibrating Electrode Technique was employed for assessing the distribution of j from scribed HDG surfaces. This local electrochemistry approach was repeated in NaCl solution to examine the behaviour of HDG when the Zn-coating is partially removed. Surface analysis supported all electrochemical results.
- Published
- 2020
24. Effect of surface roughness and chemistry on the adhesion and durability of a steel-epoxy adhesive interface
- Author
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J.P.B. van Dam, Herman Terryn, Yaiza Gonzalez-Garcia, Shoshan Tamar Abrahami, A. Yilmaz, and Johannes M. C. Mol
- Subjects
Materials science ,Polymers and Plastics ,General Chemical Engineering ,Surface treatment ,02 engineering and technology ,Surface finish ,Durability ,Biomaterials ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Adhesives ,Surface roughness ,Composite material ,Kelvin probe force microscope ,Araldite ,Bond strength ,030206 dentistry ,SKP ,021001 nanoscience & nanotechnology ,Silane ,chemistry ,Adhesion ,Adhesive ,Interfacial bonding ,0210 nano-technology - Abstract
This work focuses on the effect of surface roughness and surface chemistry on the initial adhesion strength and corrosive de-adhesion properties of adhesive bonds. The adherend used in this study is a S690 low-alloy steel whereas the adhesive is a 2-component epoxy-amine adhesive (Araldite 2015). The steel surface is subjected to different surface pre-treatment methods such as mechanical abrasion, grit blasting, zirconium conversion treatment and silane treatment. The effect of these different pre-treatments on the surface morphology, roughness and chemistry is addressed. Single-lap joint tests were performed at ambient conditions to assess the initial bond strength of the joint. Static wedge tests were performed in saltwater immersions to study the environmental ageing of the adhesive joints. Unloaded delamination of adhesive films from the steel surface was studied by means of scanning Kelvin probe (SKP) at high relative humidity. This unique combination of different techniques allows thorough evaluations of the bond performance under different environmental and loading conditions. Experimental results indicate that surface roughening plays an important role in the initial adhesion in the single-lap joint test but a minor role in the durability of the bonded steel surfaces. The improved initial adhesion is mainly attributed to the increased interfacial bond area at higher surface roughness. The presence of complex texture or morphology shows a more profound effect than the average roughness on both the initial adhesion and the durability of the interfacial adhesion. The results from the static wedge test show the large contribution of mechanical interlocking, caused by texturing of the surface, on the durability of the interfacial adhesion. In the absence of complex texture, surfaces with altered chemistry by zirconium- or silane treatment exhibit a significant increase of the initial bonding strength due to enhanced physicochemical interactions across the interface. Assessment of the interfacial delamination kinetics by SKP show that despite the absence of any surface topography, chemically altered surfaces prove to have higher resistance to delamination.
- Published
- 2020
25. Corrosion Protection in Chloride Environments of Nanosilica Containing Epoxy Powder Coatings with Defects
- Author
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Francisco Velasco, Beatriz Galiana, Yaiza Gonzalez-Garcia, Asunción Bautista, María Fernández-Álvarez, and Ministerio de Ciencia, Innovación y Universidades (España)
- Subjects
Absorption of water ,Materials science ,020209 energy ,02 engineering and technology ,engineering.material ,Chloride ,Corrosion ,Coating ,0202 electrical engineering, electronic engineering, information engineering ,Materials Chemistry ,Electrochemistry ,medicine ,Composite material ,Ball mill ,Kelvin probe force microscope ,Renewable Energy, Sustainability and the Environment ,Epoxy ,Química ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Dielectric spectroscopy ,visual_art ,engineering ,visual_art.visual_art_medium ,medicine.drug - Abstract
This paper describes the use of innovative, nanosilica containing epoxy powder coatings for the corrosion protection of steel. Two types of nanosilica particles (hydrophilic -HL- and hydrophobic -HB-) were mixed by ball milling with the powders (0.75 wt.%). The adequate homogeneity and embedding of nanoparticles were verified by transmission electron microscopy. The corrosion performance of the coatings as-received, and with HL and HB additions, were analyzed in 3.5 wt.% NaCl solutions. The mechanism and rate of delamination of defective coatings under drops simulating atmospheric conditions were analyzed by Scanning Kelvin Probe measurements for 30 d. The results show that the corrosion attack progresses through a cathodic delamination mechanism. Besides, fully-immersed samples, with and without defects, were monitored by electrochemical impedance spectroscopy. In defective coatings under these conditions, the occurrence of anodic undermining is proved. The results obtained reveal that the corrosion driven coating failure is delayed in the case of the epoxy coatings containing nanosilica. This delay is larger in the case of HB additions than HL additions in both atmospheric and immersion conditions. The corrosion mechanism observed is dependent upon exposure conditions. It is proposed that the nanoparticles delay water absorption, thus delaying corrosion attack. This work was supported by Interreg SUDOE, through the KrEaTive Habitat project (grant number SOE1/P1/E0307) and the Spanish Ministry of Science, Innovation and Universities (MICINN) through the project RTI2018-101020-B-100.
- Published
- 2020
26. Properties and performance of spin-on-glass coatings for the corrosion protection of stainless steels in chloride media
- Author
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Yaiza Gonzalez-Garcia, Per Møller, Annemette Hindhede Jensen, Rameez Ud Din, and Felix Lampert
- Subjects
Materials science ,thin film ,Corrosion resistance ,Oxide ,coatings ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Chloride ,Corrosion ,chemistry.chemical_compound ,Coating ,Coatings ,Materials Chemistry ,Pitting corrosion ,medicine ,Environmental Chemistry ,passivity ,Thin film ,Composite material ,Curing (chemistry) ,corrosion resistance ,Mechanical Engineering ,Metals and Alloys ,General Medicine ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry ,Polymerization ,Mechanics of Materials ,Passivity ,engineering ,0210 nano-technology ,medicine.drug - Abstract
Spin-on-glass deposition was investigated as viable alternative to increase the durability and performance of 316L steel in chloride environment. The buildup of a detrimental interface oxide was prevented by non-oxidative thermal curing of the coatings, which leads to a transformation to an inorganic, SiO2-like material. The degree of polymerization was found dependent on the curing temperature; however, even curing at the maximum investigated curing temperature of 800 °C led to still incomplete transformation, showing less SiO2-like character with respect to thermally grown oxide or fused silica. Electrochemical analysis by cyclic polarization indicated that the coatings behave as imperfect barrier coatings, which may enhance the passive properties of the substrates; however, there is still some statistical scatter in the quality of the coatings. While there is a tendency for an increase of the upper limit of the breakdown potential, there is also a decrease of the lower limit. It was found that such lower quality coatings showed, in association with substrate defects, unevenly distributed coating flaws, which may act as initiation points of pitting corrosion and decrease the corrosion resistance of coated substrates. Further, the films showed instability in aqueous environment due to imperfect polymerization.
- Published
- 2018
27. Use of Local Electrochemical Methods (SECM, EC-STM) and AFM to Differentiate Microstructural Effects (EBSD) on Very Pure Copper
- Author
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Yaiza Gonzalez-Garcia, Philippe Marcus, Lorena H. Klein, Vincent Maurice, Iris De Graeve, Herman Terryn, Kim Verbeken, Leo A.I. Kestens, Linsey Lapeire, Arjan Mol, E. Martinez-Lombardia, Electrochemical and Surface Engineering, Materials and Chemistry, Architectural Engineering, In-Situ Electrochemistry combined with nano & micro surface Characterization, and Materials and Surface Science & Engineering
- Subjects
Materials science ,EBSD ,microstructure ,Metals and Alloys ,Nanotechnology ,Intergranular corrosion ,Microstructure ,Surfaces, Coatings and Films ,Corrosion ,law.invention ,Scanning electrochemical microscopy ,Chemical physics ,law ,copper ,Electrochemistry ,Materials Chemistry ,Grain boundary ,AFM ,Scanning tunneling microscope ,EC-STM ,SECM ,Dissolution ,Electron backscatter diffraction - Abstract
When aiming for an increased and more sustainable use of metals a thorough knowledge of the corrosion phenomenon as function of the local metal microstructure is of crucial importance. In this work, we summarize the information presented in our previous publications[1-3] and present an overview of the different local (electrochemical) techniques that have been proven to be effective in studying the relation between different microstructural variables and their different electrochemical behavior. Atomic force microscopy (AFM)[1], scanning electrochemical microscopy (SECM)[2], and electrochemical scanning tunneling microscopy (EC-STM)[3] were used in combination with electron backscatter diffraction (EBSD). Consequently, correlations could be identified between the grain orientation and grain boundary characteristics, on the one hand, and the electrochemical behavior on the other hand. The grain orientation itself has an influence on the corrosion, and the orientation of the neighboring grains also seems to play a decisive role in the dissolution rate. With respect to intergranular corrosion, only coherent twin boundaries seem to be resistant.
- Published
- 2017
28. A closer look at constituent induced localised corrosion in Al-Cu-Mg alloys
- Author
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Allan James Morton, Nick Birbilis, Anthony E. Hughes, Johannes M. C. Mol, M.A. Glenn, S.K. Kairy, Yaiza Gonzalez-Garcia, Jian Feng Nie, Yuman Zhu, Herman Terryn, Faculty of Sciences and Bioengineering Sciences, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
- Subjects
Materials science ,Intermetallics ,AA2024 ,020209 energy ,General Chemical Engineering ,pitting corrosion ,Intermetallic ,chemistry.chemical_element ,02 engineering and technology ,Corrosion ,Crystal ,Aluminium ,0202 electrical engineering, electronic engineering, information engineering ,Pitting corrosion ,General Materials Science ,stem ,Mg alloys ,Metallurgy ,General Chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Localised corrosion ,chemistry ,TEM ,0210 nano-technology - Abstract
The role of constituent intermetallic particles in the pitting corrosion of aluminium (Al) alloys is well recognised. A definitive quantification of the role of unique constituent particles has contributed towards an enhanced understanding of Al-alloy corrosion, however the complexity of Al-alloy microstructures warrants further attention. In the present work we identify a unique intermetallic type in contemporary versions of AA2024-T3, which has a two-phase structure, defined by two distinct crystal types, and distinct compositions. Detailed characterisation is used to unambiguously define this constituent, along with its role in localised corrosion.
- Published
- 2016
29. Active and passive protection of AA2024-T3 by a hybrid inhibitor doped mesoporous sol–gel and top coating system
- Author
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Yaiza Gonzalez-Garcia, Philippe Dubois, Farid Khelifa, Johannes M. C. Mol, Marie-Georges Olivier, Isaline Recloux, and Marie-Eve Druart
- Subjects
Materials science ,2024 aluminium alloy ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Corrosion ,chemistry.chemical_compound ,Scanning electrochemical microscopy ,Coating ,Materials Chemistry ,Thin film ,Polarization (electrochemistry) ,Benzotriazole ,Metallurgy ,Surfaces and Interfaces ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry ,Chemical engineering ,engineering ,0210 nano-technology ,Mesoporous material - Abstract
In the present investigation, a two-layer coating system was developed in order to protect 2024 aluminium alloy against corrosion. At the metal interface, a silica mesoporous thin film was used to offer storage and release functionalities for benzotriazole inhibitive molecules (active protection). An acrylic top coat was then applied as a barrier layer against corrosive species (passive protection). Various electrochemical techniques were employed to evaluate the anticorrosion performance of the coating system. Amongst them, the scanning vibrating electrode technique (SVET) and the scanning electrochemical microscopy (SECM) showed a slowdown of corrosion processes occurring within the damaged coating area. The acquisition of anodic polarization curves inside the scratch through the use of an electrochemical micro-cell allowed to correlate this enhancement in the corrosion protection with the formation of an inhibitive film. Upon a through-coating damage, the mesoporous reservoir comes into contact with the aggressive electrolyte and benzotriazole molecules are able to be released and to inhibit corrosion of the bare metal exposed in the scratch. The work demonstrates the potential of mesoporous films as reservoir for inhibitive species and its efficiency for controlled release of the inhibitor. Furthermore, the work demonstrates the added value of electrochemical micro-cell measurements to highlight active corrosion protection in coating defects due to inhibitor doped coating systems.
- Published
- 2016
30. In-situ study of corrosion of commercial SD memory card by local electrochemical techniques
- Author
-
Mirsajjad Mousavi, Arjan Mol, and Yaiza Gonzalez-Garcia
- Published
- 2019
31. Influence of inhibitor adsorption on readings of microelectrode during SVET measurements
- Author
-
Nico Scharnagl, Maria de Fátima Montemor, A. Yilmaz, Darya Snihirova, Yaiza Gonzalez-Garcia, Mikhail L. Zheludkevich, and Sviatlana V. Lamaka
- Subjects
Materials science ,General Chemical Engineering ,Inorganic chemistry ,Self-healing ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Reference electrode ,Corrosion ,chemistry.chemical_compound ,Mercaptobenzothiazole ,Electrochemistry ,Electroplating ,ddc:620.11 ,SVET ,Inhibitors ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Cerium nitrate ,Microelectrode ,Platinum black ,chemistry ,Electrode ,0210 nano-technology ,Platinum ,8-Hydroxyquinoline - Abstract
One of the main applications of SVET in corrosion research is the study of the corrosion inhibition effectiveness and the evaluation of the self-healing effect of inhibitor-containing coatings. The tip of the platinum/iridium vibrating electrode is electroplated with black platinum, which creates a large electrode surface and confers high capacitance to the tip. When studying organic inhibitors in aqueous solutions with SVET, inhibitor adsorption may occur at the tip, causing its contamination and the initial calibration conditions of the system might not be valid. This may lead to an incorrect interpretation of the results. This work is intended to study the effect of different inhibitors (cerium nitrate, 8-hydroxyquinoline, potassium 2,5-dimercapto-1,3,4-thiadiazolate, benzotriazole and mercaptobenzothiazole), typically used for corrosion protection of aluminum alloys, on the Pt probe signal during SVET measurements. The results reveal the detrimental effect of some corrosion inhibitors on the sensitivity of the vibrating probe, an effect that imposes a regular assessment of the electrode state during measurements. The increase of the signal noise was related to a decrease of the probe capacitance, while the false current density signal was a result of the potential drift between vibrating and reference electrodes.
- Published
- 2019
32. Mechanism of passive layer formation on AA2024-T3 from alkaline lithium carbonate solutions in the presence of sodium chloride
- Author
-
Johannes M. C. Mol, Herman Terryn, Peter Visser, Yaiza Gonzalez-Garcia, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Sodium ,Lithium carbonate ,Oxide ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,Electrochemical cell ,chemistry.chemical_compound ,Corrosion inhibitor ,chemistry ,Chemical engineering ,Materials Chemistry ,Leaching (metallurgy) ,0210 nano-technology - Abstract
This study focuses on the elucidation of the formation mechanism of passive layers on AA2024-T3 during the exposure to alkaline lithium carbonate solutions in the presence of sodium chloride. Under controlled conditions, in an electrochemical cell, a protective layer was generated comprising an amorphous inner layer and a crystalline outer-layer. In order to resolve the formation mechanism, the layers were characterized using surface analytical techniques to characterize the surface morphology, thickness and elemental composition of the layers at different stages of the formation process. In addition, electrochemical techniques were applied to link the electrochemical properties of the layers with the different stages of formation. The results demonstrate that the formation mechanism of these layers comprises three different stages: (I) oxide thinning, (II) anodic dissolution and film formation, followed by (III) film growth through a competitive growth-dissolution process. The passive properties of the layers are generated in the third stage through the densification of the amorphous layer. The combined results provide an enhanced insight in the formation mechanism and the development of the passive properties of these layers when lithium salts are used as leaching corrosion inhibitor for coated AA2024-T3.
- Published
- 2018
33. Additively manufactured biodegradable porous iron
- Author
-
Behdad Pouran, Jie Zhou, P. Pavanram, Y. Li, A. Yilmaz, M.A. Leeflang, Harrie Weinans, Holger Jahr, Karel Lietaert, Yaiza Gonzalez-Garcia, Amir A. Zadpoor, L.I. Fockaert, Johannes M. C. Mol, and RS: CAPHRI - R3 - Functioning, Participating and Rehabilitation
- Subjects
Bone Regeneration ,Compressive Strength ,Biocompatible Materials ,02 engineering and technology ,01 natural sciences ,Biochemistry ,Absorbable Implants ,Materials Testing ,Electrochemistry ,Magnesium ,Titanium ,Tissue Scaffolds ,MECHANICAL-PROPERTIES ,General Medicine ,021001 nanoscience & nanotechnology ,FE-PD ,medicine.anatomical_structure ,Compressive strength ,Biodegradation ,Biocompatibility ,0210 nano-technology ,Cancellous bone ,Porosity ,Biotechnology ,Materials science ,Additive manufacturing ,Direct metal printing ,Simulated body fluid ,Iron ,Biomedical Engineering ,chemistry.chemical_element ,ORTHOPEDIC IMPLANTS ,Zinc ,010402 general chemistry ,Biomaterials ,Cell Line, Tumor ,BIOMEDICAL IMPLANTS ,medicine ,Alloys ,Humans ,Bone regeneration ,Molecular Biology ,Mechanical property ,Iron scaffolds ,IN-VITRO DEGRADATION ,Elasticity ,0104 chemical sciences ,STENT APPLICATION ,CELL-DEATH ,Chemical engineering ,chemistry ,Stress, Mechanical ,PURE IRON ,Diamond - Abstract
Additively manufactured (AM) topologically ordered porous metallic biomaterials with the proper biodegradation profile offer a unique combination of properties ideal for bone regeneration. These include a fully interconnected porous structure, bone-mimicking mechanical properties, and the possibility of fully regenerating bony defects. Most of such biomaterials are, however, based on magnesium and, thus, degrade too fast. Here, we present the first report on topologically ordered porous iron made by Direct Metal Printing (DMP). The topological design was based on a repetitive diamond unit cell. We conducted a comprehensive study on the in vitro biodegradation behavior (up to 28 days), electrochemical performance, time-dependent mechanical properties, and biocompatibility of the scaffolds. The mechanical properties of AM porous iron (E = 1600-1800 MPa) were still within the range of the values reported for trabecular bone after 28 days of biodegradation. Electrochemical tests showed up to approximate to 12 times higher rates of biodegradation for AM porous iron as compared to that of cold-rolled (CR) iron, while only 3.1% of weight loss was measured after 4 weeks of immersion tests. The biodegradation mechanisms were found to be topology-dependent and different between the periphery and central parts of the scaffolds. While direct contact between MG-63 cells and scaffolds revealed substantial and almost instant cytotoxicity in static cell culture, as compared to Ti-6A1-4V, the cytocompatibility according to ISO 10993 was reasonable in in vitro assays for up to 72 h. This study shows how DMP could be used to increase the surface area and decrease the grain sizes of topologically ordered porous metallic biomaterials made from metals that are usually considered to degrade too slowly (e.g., iron), opening up many new opportunities for the development of biodegradable metallic biomaterials. Statement of Significance Biodegradation in general and proper biodegradation profile in particular are perhaps the most important requirements that additively manufactured (AM) topologically ordered porous metallic biomaterials should offer in order to become the ideal biomaterial for bone regeneration. Currently, most biodegradable metallic biomaterials are based on magnesium, which degrade fast with gas generation. Here, we present the first report on topologically ordered porous iron made by Direct Metal Printing (DMP). We also conducted a comprehensive study on the biodegradation behavior, electrochemical performance, biocompatibility, and the time evolution of the mechanical properties of the implants. We show that these implants possess bone-mimicking mechanical properties, accelerated degradation rate, and reasonable cytocompatibility, opening up many new opportunities for the development of iron-based biodegradable materials. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
- Published
- 2018
34. pH-responsive nanostructured polyaniline capsules for self-healing corrosion protection: The influence of capsule concentration
- Author
-
Johannes M. C. Mol, N. Pirhady Tavandashti, Akbar Shojaei, Herman Terryn, Mohammad Ghorbani, Yaiza Gonzalez-Garcia, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
- Subjects
Materials science ,corrosion protection ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Corrosion ,chemistry.chemical_compound ,Coating ,Coating system ,Polyaniline ,organic coating ,Engineering(all) ,General Engineering ,Capsule ,Epoxy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Dielectric spectroscopy ,chemistry ,Chemical engineering ,Self-healing ,visual_art ,MBT corrosion inhibitor ,visual_art.visual_art_medium ,engineering ,Nanostructured polyaniline capsules ,0210 nano-technology - Abstract
Nanostructured hollow polyaniline (PANI) capsules are good candidates for encapsulation of corrosion inhibitors and pH-responsive release when incorporated into organic coatings. In previous studies, the corrosion protection performance of PANI capsules, containing organic inhibitor 2-Mercaptobenzothiazole (MBT), was demonstrated. The present work studies the influence of capsule concentrations (i.e., 0.3, 1, and 2 wt%) on the corrosion protection properties of the coating system. Anti-corrosion properties of different coatings were compared by means of Electrochemical Impedance Spectroscopy (EIS) and Scanning Vibrating Electrode Technique (SVET). MBT loaded PANI capsules in epoxy ester coating on AA2024-T3 substrate allow for a self-healing effect to be obtained during the corrosion process. The results showed that the concentration of MBT loaded PANI capsules greatly influences the corrosion protection properties of the coatings, and the best corrosion protection performance was observed for the coating system containing 1 wt% PANI capsules. The impedance value of the scratched area of this coating after 7 days of immersion was one order of magnitude higher than that of the control sample.
- Published
- 2017
35. Electrochemical evaluation of corrosion inhibiting layers formed in a defect from lithium-leaching organic coatings
- Author
-
Johannes M. C. Mol, Yaiza Gonzalez-Garcia, Herman Terryn, Peter Visser, Mats Meeusen, Faculty of Engineering, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
- Subjects
Materials science ,Scanning electron microscope ,020209 energy ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,Electrochemistry ,Corrosion ,Coating ,Aluminium ,0202 electrical engineering, electronic engineering, information engineering ,Materials Chemistry ,Composite material ,corrosion ,Renewable Energy, Sustainability and the Environment ,aluminium ,coating ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrochemical scanning tunneling microscope ,inhibition ,Dielectric spectroscopy ,Electronic, Optical and Magnetic Materials ,Surfaces, Coatings and Films ,leaching ,chemistry ,lithium ,engineering ,Leaching (metallurgy) ,0210 nano-technology - Abstract
This work presents the electrochemical evaluation of protective layers generated in a coating defect from lithium-leaching organic coatings on AA2024-T3 aluminum alloys as a function of neutral salt spray exposure time. Electrochemical impedance spectroscopy was used to study the electrochemical properties on a macroscopic scale. An electrochemical model allowed to quantitatively link the electrochemical behavior with the physical model of the layer in the damaged area as studied by scanning electron microscopy. Local potentiodynamic polarization curves obtained from micro-cell measurements showed an increase of the passive range in the defect area due to the formation of a robust protective layer. Scanning vibrating electrode technique measurements confirmed the non-reversible long-term corrosion protection of these generated layers in the coating defect.
- Published
- 2017
36. Corrosion resistance of AISI 316L coated with an air-cured hydrogen silsesquioxane based spin-on-glass enamel in chloride environment
- Author
-
Rameez Ud Din, Per Møller, Alexander Bruun Christiansen, Felix Lampert, and Yaiza Gonzalez-Garcia
- Subjects
Materials science ,020209 energy ,General Chemical Engineering ,02 engineering and technology ,engineering.material ,Chloride ,Corrosion ,Stainless steel ,chemistry.chemical_compound ,Oxide coatings ,Coating ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,General Materials Science ,Composite material ,Oxide Coatings ,Hydrogen silsesquioxane ,Curing (chemistry) ,Polarisation ,IR Spectroscopy ,EIS ,Metallurgy ,General Chemistry ,Stainless Steel ,021001 nanoscience & nanotechnology ,Dielectric spectroscopy ,Polymerization ,chemistry ,IR spectroscopy ,engineering ,Passivity ,Chemical stability ,0210 nano-technology ,medicine.drug - Abstract
The efficiency of thin hydrogen silsesquioxane (HSQ) −based corrosion barrier coatings on 316L substrates after oxidative thermal curing at 400–550 °C in air was investigated. Infrared spectroscopy and electrochemical impedance spectroscopy showed that an increasing curing temperature leads to progressing coating densification, accompanied by decreasing barrier properties. Cyclic polarization measurements indicated that defects due to substrate oxidation are detrimental for the substrate passivity. Insufficiently polymerized coatings showed poor chemical stability in neutral salt spray testing and the chemical coating stability increased with curing temperature. Oxidative curing was found inadequate as polymerization treatment of HSQ-based corrosion barrier coatings on 316L substrate.
- Published
- 2017
37. Oxygen consumption upon electrochemically polarised zinc
- Author
-
Miao Chen, Ivan S. Cole, Johannes M. C. Mol, Nick Birbilis, Yaiza Gonzalez-Garcia, Herman Terryn, Sebastian Thomas, and Mustafa Musameh
- Subjects
Passivation ,General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,Zinc ,Electrochemistry ,Redox ,Oxygen ,Corrosion ,Metal ,chemistry ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Limiting oxygen concentration - Abstract
A Pt microelectrode was used to measure the oxygen consumption by redox reduction (ORR) on electrochemically polarised zinc in the redox competition mode. Zinc was polarised in the active and passive state, using a pH 7 and pH 13 solution, respectively. At pH 7, the oxygen concentration measured at a distance of 50 μm from the zinc surface, using the Pt microelectrode, is 15–60 % of the bulk oxygen concentration. Therefore, correspondingly, the oxygen consumption by zinc (due to ORR) is 40–85 % of the bulk oxygen concentration. At pH 13, where zinc undergoes passivation, the oxygen consumption by zinc is 70–80 % of the bulk oxygen concentration. The ORR rate on the surface of zinc passive films (ZnO/Zn(OH)2) is thus significant when compared to that on bare/actively corroding zinc. The influence of the electrode kinetics of zinc corrosion, on oxygen diffusion towards the metal surface has been investigated in this study.
- Published
- 2014
38. Scanning electrochemical microscopy to study the effect of crystallographic orientation on the electrochemical activity of pure copper
- Author
-
Kim Verbeken, E. Martinez-Lombardia, Yaiza Gonzalez-Garcia, Herman Terryn, Johannes M. C. Mol, Linsey Lapeire, I. De Graeve, and Leo A.I. Kestens
- Subjects
Materials science ,General Chemical Engineering ,chemistry.chemical_element ,Microstructure ,Copper ,Crystal ,Scanning electrochemical microscopy ,Crystallography ,chemistry ,Electron diffraction ,Electrochemistry ,Erosion corrosion of copper water tubes ,Single crystal ,Electron backscatter diffraction - Abstract
The local electrochemical reactivity of high purity copper as a function of the grain orientation in the microstructure has been investigated. The different crystal orientations were determined by means of Electron backscatter diffraction (EBSD) followed by in-situ Scanning electrochemical microscopy (SECM) measurements operating in feedback mode across the very same copper surface. With this procedure it is possible to characterize in-situ the reactivity of selected grains in the polycrystalline microstructure of the copper. The study is focused on monitoring differences in the electrochemical response on //ND and //ND oriented grains. The behaviour of these selected orientations was studied under two surface conditions: passive state of copper after the formation of an anodic oxide layer, and corrosion or active state of the copper by immersion in chloride solution. In the case of the passivated copper it was observed that the grain with an orientation closer to //ND shows a lower reactivity compared to the grain where the orientation is nearer to //ND, which confirmed that grain orientation has an influence on the electrochemical reactivity of the passive layer formed on the metal. It was found that for the copper in the active state, the reactivity of a //ND oriented grain is higher when compared to a //ND oriented grain, which is contrary to the expected behaviour. This discrepancy could be explained by possible neighbouring effects between both grains.
- Published
- 2014
39. Inhibitor-loaded conducting polymer capsules for active corrosion protection of coating defects
- Author
-
Herman Terryn, Akbar Shojaei, Mohammad Ghorbani, Yaiza Gonzalez-Garcia, N. Pirhady Tavandashti, Kitty Baert, Johannes M. C. Mol, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
- Subjects
animal structures ,Materials science ,General Chemical Engineering ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Corrosion ,Corrosion inhibitor ,chemistry.chemical_compound ,Coating ,Polyaniline ,Aluminium ,General Materials Science ,Composite material ,Polymer ,Conductive polymer ,EIS ,Organic coatings ,General Chemistry ,Epoxy ,Surface-enhanced Raman spectroscopy ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Dielectric spectroscopy ,chemistry ,Chemical engineering ,visual_art ,embryonic structures ,visual_art.visual_art_medium ,engineering ,0210 nano-technology - Abstract
This work presents the synthesis of nanostructured hollow polyaniline (PANI) capsules and their application for encapsulation of corrosion inhibitor 2-Mercaptobenzothiazole (MBT). The pH-triggered release of MBT from the capsules was evidenced using UV–vis and Surface Enhanced Raman Spectroscopy (SERS). Incorporation of MBT loaded PANI capsules into epoxy ester coating on AA2024-T3 resulted in a protective system with self-healing ability confirmed by Electrochemical Impedance Spectroscopy (EIS) and Scanning Vibrating Electrode Technique (SVET). The results showed that the incorporation of MBT-loaded PANI capsules into the coating has significantly improved its corrosion protection performance due to the interesting smart characteristics of PANI capsules.
- Published
- 2016
40. pH responsive Ce(III) loaded polyaniline nanofibers for self-healing corrosion protection of AA2024-T3
- Author
-
Mohammad Ghorbani, N. Pirhady Tavandashti, Herman Terryn, Akbar Shojaei, Johannes M. C. Mol, Yaiza Gonzalez-Garcia, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
- Subjects
Materials science ,General Chemical Engineering ,Inorganic chemistry ,Self-healing ,chemistry.chemical_element ,Polyaniline (PANI) ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Corrosion ,chemistry.chemical_compound ,Corrosion inhibitor ,Polyaniline ,Materials Chemistry ,Polyaniline nanofibers ,Organic Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Dielectric spectroscopy ,Cerium nitrate ,Cerium ,pH-triggered release ,chemistry ,Chemical engineering ,Nanofiber ,0210 nano-technology - Abstract
Cerium nitrate loaded polyaniline (PANI) nanofibers were synthesized in this work via a chemical route. PANI nanofibers act as a host structure for the corrosion inhibitor, forming a Ce(III)-PANI complex. This complex is pH sensitive, and a change of pH can cause breaking of the complex and releasing of Ce(III). The Ce(III) loaded PANI nanofibers were embedded into epoxy ester coating and the self-healing corrosion protection ability was investigated by Scanning Vibrating Electrode Technique (SVET) and Electrochemical Impedance Spectroscopy (EIS). The results showed that by embedding of Ce(III) loaded PANI nanofibers into the coatings a superior corrosion protection and self-healing performance is obtained. Local change of pH due to corrosion stimulates the release of Ce(III) from PANI nanofibers. The released Ce(III) precipitates out as insoluble cerium hydroxides at regions of local high pH, which results in slowing down the cathodic reaction and reducing further corrosion. Accordingly, a synergistic effect of Ce(III) corrosion inhibitor together with PANI nanofibers was observed as additives for epoxy ester coating.
- Published
- 2016
41. The Role of Lithium Salt Concentration in the Active Corrosion Protection of Aluminium Alloys
- Author
-
Emmanouela Michailidou, Peter Visser, Johannes M. C. Mol, and Yaiza Gonzalez-Garcia
- Abstract
It has been demonstrated previously that lithium salts containing organic coatings offer effective active corrosion protection on AA2024-T3 alloys when exposed to neutral salt spray test for 168 hours [1, 2]. In the presence of a coating defect the lithium salts leach from the organic coating to the exposed metal substrate increasing the local pH to moderate alkaline conditions followed by the formation of a protective layer within the defect site [2, 3]. The lithium accumulation at the defect site and hence the formation of the protective layer is influenced by the inhibitor loading and solubility in the coating as well as the coating defect size. Three different surface compositions of the lithium protective layer have been recently identified as lithium-based layered double hydroxide (Li-LDH), lithium mixed pseudo-boehmite (Li-PB) and pseudo-boehmite (PB) each depending on the lithium leaching rate and the coating defect size [4]. For small defect sizes a high lithium concentration is hypothesized to result in the generation of Li-LDH. Furthermore, Li-PB is identified within moderate defect sizes and moderate inhibitor concentration and PB is generated within large defect sizes where low lithium concentrations are expected. On this basis, this paper describes the lithium active corrosion protection on aerospace aluminium alloys as a function of the inhibitor concentration. In doing so, commercial AA2198-T8 and AA2024-T3 aluminium alloys are immersed for 24 hours in lithium salt containing aqueous solutions at systematically varied lithium salts concentration from 10-6 M to 10-1 M. The alloys are then transferred to 10-1 M aqueous NaCl solution at near neutral pH conditions and either LPR measurements are performed as a function of time over 100 hours or anodic polarization is performed. The surface composition of the alloys after 24 hours immersion in lithium containing aqueous solution is also characterized. The surface composition and the electrochemical characteristics of each lithium passive layer generated is determined as a function of the lithium concentration. The surface composition of the passive layer ranges from PB to Li-PB and Li-LDH with increasing inhibitor concentration. The polarization resistance obtained as a function of time is correlated to the corrosion rate of each generated passive layer thus demonstrating the corrosion protection performance of Li-LDH, Li-PB and PB. The generation and corrosion protection performance of each passive layer is also demonstrated under relatively thin electrolyte layers mimicking the exposure of a coating defect and the leaching of lithium salt from the coating matrix under atmospheric conditions. Visser, P., et al., Study of the formation of a protective layer in a defect from lithium-leaching organic coatings. Progress in Organic Coatings, 2016. 99: p. 80-90. Visser, P., et al., Electrochemical Evaluation of Corrosion Inhibiting Layers Formed in a Defect from Lithium-Leaching Organic Coatings. Journal of The Electrochemical Society, 2017. 164(7): p. C396-C406. Visser, P., et al., Mechanism of Passive Layer Formation on AA2024-T3 from Alkaline Lithium Carbonate Solutions in the Presence of Sodium Chloride. Journal of The Electrochemical Society, 2018. 165(2): p. C60-C70. Visser, P., et al., The chemical throwing power of lithium-based inhibitors from organic coatings on AA2024-T3. Corrosion Science, 2019. 150: p. 194-206.
- Published
- 2019
42. Scanning Kelvin force microscopy study at the cut-edge of aluminum rich metal coated steel
- Author
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K. Van den Bergh, A. Alvarez-Pampliega, Yaiza Gonzalez-Garcia, Herman Terryn, and J. De Strycker
- Subjects
Kelvin probe force microscope ,Materials science ,Scanning electron microscope ,Mechanical Engineering ,Metals and Alloys ,Analytical chemistry ,General Medicine ,Conductive atomic force microscopy ,Scanning capacitance microscopy ,Surfaces, Coatings and Films ,Galvanic series ,Mechanics of Materials ,Microscopy ,Materials Chemistry ,Scanning ion-conductance microscopy ,Environmental Chemistry ,Volta potential - Abstract
This work aims to characterize the electrochemical behaviour of the phases observed on the cross-sections of different hot dip aluminum-rich metal coatings on steel. In this framework, scanning Kelvin probe coupled with atomic force microscopy was used to establish the differences of Volta potential on the cross-sections as function of the chemical composition of the different phases present on each system. Chemical analysis of the cross-sections was carried out with scanning electron microscope coupled with energy dispersive X-ray analysis. Then the differences in nobility among the different layers have been reported here and a galvanic series of the different sublayers has been established.
- Published
- 2013
43. Electrochemical Techniques for the Study of Self Healing Coatings
- Author
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Yaiza Gonzalez-Garcia, Johannes M. C. Mol, and Santiago J. Garcia
- Subjects
Materials science ,020209 energy ,Nanotechnology ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Electrochemistry ,Corrosion ,Dielectric spectroscopy ,Characterization (materials science) ,Corrosion inhibitor ,chemistry.chemical_compound ,chemistry ,Self-healing ,0202 electrical engineering, electronic engineering, information engineering ,0210 nano-technology - Abstract
Diverse and complementary methods are required to predict and control the rate of corrosion processes, and also to evaluate the efficiency of corrosion protection methods. Because of the electrochemical nature of the corrosion processes, electrochemical methods are powerful tools to study and evaluate protection methods although their combination with optical and spectroscopic techniques is becoming more prelevant. This chapter describes the conventional electrochemical techniques and the latest advances in local electrochemical methods for the evaluation and characterization of novel protection approaches based on the self-healing concept.
- Published
- 2016
44. A combined redox-competition and negative-feedback SECM study of self-healing anticorrosive coatings
- Author
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Johannes M. C. Mol, Santiago J. Garcia, Yaiza Gonzalez-Garcia, and Anthony E. Hughes
- Subjects
Materials science ,Nanotechnology ,engineering.material ,Redox ,Chloride ,Corrosion ,lcsh:Chemistry ,Scanning electrochemical microscopy ,lcsh:Industrial electrochemistry ,lcsh:QD1-999 ,Coating ,Negative feedback ,Self-healing ,Electrochemistry ,Immersion (virtual reality) ,medicine ,engineering ,Composite material ,lcsh:TP250-261 ,medicine.drug - Abstract
In this paper, the long-term anticorrosive efficiency of a damaged self-healing coating is studied for the first time using scanning electrochemical microscopy (SECM). In the study an epoxy-coating with embedded-capsules containing a silyl-ester is employed. The properties of the silyl-ester as a healing-agent for the protection of AA2024-T3 were evaluated by complementary SECM experiments operating in negative-feedback and redox-competition modes. The experimental approach here presented allowed for monitoring the early-stages of corrosion activity and subsequent healing mechanisms offered by the release of silyl-ester into a relatively large coating defect. This result was observed by detecting the transition of the oxygen reduction response from a redox-competition mode to a negative-feedback behavior. These measurements demonstrated that the silyl-ester is released efficiently after capsules break upon coating damage, covering relatively large areas and gradually healing the damaged-site hindering the corrosion processes and providing an effective protection for at least one month of immersion in chloride solution. Keywords: Self-healing coating, Silyl-ester, Encapsulation, Corrosion, Scanning electrochemical microscopy
- Published
- 2011
45. Scanning electrochemical microscopy for the investigation of localized degradation processes in coated metals: Effect of oxygen
- Author
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Ricardo M. Souto, Yaiza Gonzalez-Garcia, Juan José Santana, Sergio González, and Luis Fernández-Mérida
- Subjects
Materials science ,General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,Ultramicroelectrode ,General Chemistry ,Oxygen ,Corrosion ,Ion ,chemistry.chemical_compound ,Scanning electrochemical microscopy ,chemistry ,Degradation (geology) ,General Materials Science ,Limiting oxygen concentration ,Hydrogen peroxide - Abstract
The effect of oxygen content on the corrosion reactions inside a holiday in a polymer-coated metal substrate was studied by SECM without adding a redox mediator. The system was mild steel coated by polyurethane in KCl. By selecting different values for the potential applied to the ultramicroelectrode tip, local concentrations of species involved in the degradation process are monitored, namely Fe(II) ions, hydrogen peroxide and oxygen. The results show a variation in both the shape and the magnitude of the scan lines measured over the holiday. A critical oxygen concentration was found below which the corrosion reaction is not observed.
- Published
- 2011
46. Self-healing anticorrosive organic coating based on an encapsulated water reactive silyl ester: Synthesis and proof of concept
- Author
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James I. Mardel, Yaiza Gonzalez-Garcia, Johannes M. C. Mol, Anthony E. Hughes, Santiago J. Garcia, Hartmut Fischer, and P.A. White
- Subjects
Materials science ,Silylation ,General Chemical Engineering ,Organic Chemistry ,engineering.material ,Surfaces, Coatings and Films ,Catalysis ,Corrosion ,Dielectric spectroscopy ,Metal ,Coating ,Chemical engineering ,Self-healing ,visual_art ,Materials Chemistry ,engineering ,visual_art.visual_art_medium ,Organic chemistry ,Fourier transform infrared spectroscopy - Abstract
In this paper a self-healing anticorrosive organic coating based on an encapsulated water reactive organic agent is presented. A reactive silyl ester is proposed as a new organic reactive healing agent and its synthesis, performance, incorporation into an organic coating and evaluation of self-healing capabilities is described. Such silyl esters are good candidates to be used in self-healing anticorrosive organic coating systems since they present the capability to react with water/humidity and metallic substrates, removing thus the need of presence of a crosslinker or catalyst in the system unlike traditional encapsulated approaches. In order to prove the self-healing ability and reactivity of the presented silyl ester encapsulated system, Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET) were used, showing the high capability of these techniques to be used in the development and evaluation of self-healing anticorrosive organic coatings and the good results in corrosion protection offered by the proposed silyl ester healing agent.
- Published
- 2011
47. SECM study of defect repair in self-healing polymer coatings on metals
- Author
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B. Van Mele, Herman Terryn, Johannes M. C. Mol, G. Van Assche, Thibault Muselle, I. De Graeve, G. Scheltjens, Yaiza Gonzalez-Garcia, Electrochemical and Surface Engineering, and Materials and Chemistry
- Subjects
chemistry.chemical_classification ,Materials science ,Metallurgy ,Alloy ,coating ,Polymer ,engineering.material ,Corrosion ,Cathodic protection ,lcsh:Chemistry ,Scanning electrochemical microscopy ,lcsh:Industrial electrochemistry ,lcsh:QD1-999 ,Coating ,chemistry ,Self-healing ,Electrochemistry ,engineering ,Composite material ,Self-healing material ,polymers ,lcsh:TP250-261 - Abstract
In this paper the local healing efficiency of shape-memory polymers as a new alternative for the protection against corrosion of damaged coated metals is studied by scanning electrochemical microscopy (SECM). These measurements allowed us to evaluate the local corrosion activity at a damaged self-healing polymer coating on an aluminum alloy before and after the thermally healing process of the shape-memory polymer film. SECM operating in redox-competition mode is applied to monitor in situ the reduction of oxygen as a cathodic process in the corrosion onset at a coating defect as a function of exposure time in 0.05 M NaCl solution. It is proven that the physical repair of the film in the defect leads to a recovery of the local barrier properties of the coated system and subsequent protection of the aluminum alloy. Keywords: Self-healing, Scanning electrochemical microscopy, Organic coatings, Shape-memory polymer
- Published
- 2011
48. Imaging the Origins of Coating Degradation and Blistering Caused by Electrolyte Immersion Assisted by SECM
- Author
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G.T. Burstein, Sergio Rodríguez González, Yaiza Gonzalez-Garcia, and Ricardo M. Souto
- Subjects
Materials science ,Metallurgy ,Nucleation ,Blisters ,Electrolyte ,engineering.material ,Chloride ,Analytical Chemistry ,Microelectrode ,Coating ,Electrochemistry ,Immersion (virtual reality) ,medicine ,engineering ,Degradation (geology) ,medicine.symptom ,Composite material ,medicine.drug - Abstract
A new method to image the origins of coating degradation and the nucleation and subsequent growth of blisters by using SECM in the feedback mode is proposed. The unique role of chloride ions towards coating performance has been established at a very early stage following immersion of the sample. We believe this to show the earlier stages of blistering in a coated metal system ever recorded. The method allowed for the first time to detect the nucleation and to monitor quantitatively the growth process of an individual blister, because it effectively advanced towards the microelectrode when scanned at constant height over the sample.
- Published
- 2009
49. Characterization of coating systems by scanning electrochemical microscopy: Surface topology and blistering
- Author
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Sergio Rodríguez González, Yaiza Gonzalez-Garcia, and Ricardo M. Souto
- Subjects
Aqueous solution ,Materials science ,General Chemical Engineering ,Organic Chemistry ,Inorganic chemistry ,Nucleation ,Ionic bonding ,Electrolyte ,engineering.material ,Electrochemistry ,Chloride ,Surfaces, Coatings and Films ,Scanning electrochemical microscopy ,Coating ,Materials Chemistry ,medicine ,engineering ,medicine.drug - Abstract
Operation of the scanning electrochemical microscope used in feedback mode over a coated metal allows changes in the state of the coating surface to be monitored during immersion in aqueous electrolytes. This paper reports changes in the coating induced by specific anions in the electrolyte in situ during immersion. Significant surface roughening is observed for immersion times shorter than 1 day when the electrolyte contains chloride ions. This effect is also observed when the oxygen dissolved in the electrolytic phase is employed as redox mediator for SECM imaging. The coated system exposed to chloride-free electrolytes containing sulphate or nitrate maintains a featureless topography within the same time scale. The observed features are due to the nucleation and growth of blisters at the metal/coating interface induced by chloride ions in the environment. The implication is that ionic migration occurs simultaneously with the absorption of water by the coating already from the beginning of exposure to the aqueous environment. The unique role of chloride ions compared with sulphate or nitrate ions towards coating performance has been established at a very early stage following immersion of the sample.
- Published
- 2009
50. Evaluation of the corrosion performance of coil-coated steel sheet as studied by scanning electrochemical microscopy
- Author
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Yaiza Gonzalez-Garcia, Sergio Rodríguez González, and Ricardo M. Souto
- Subjects
Materials science ,General Chemical Engineering ,Metallurgy ,chemistry.chemical_element ,Blisters ,General Chemistry ,Zinc ,Electrolyte ,engineering.material ,Chloride ,Galvanization ,Corrosion ,Scanning electrochemical microscopy ,symbols.namesake ,chemistry ,Coating ,medicine ,engineering ,symbols ,General Materials Science ,medicine.symptom ,Composite material ,medicine.drug - Abstract
This work focuses on the investigation of the very early stages of the degradation of coil-coated galvanized steel sheet through swelling and blistering during exposure to chloride-containing aqueous solutions and the possible effect of the zinc-based metallic coating on the degradation at these very early stages. Three types of coil-coated steel whose difference was in the zinc-based metallic coating, namely galvanized, galfan and aluzinc, were considered. Scanning electrochemical microscopy (SECM) operating in the feedback mode was employed to image topographic changes when the samples were left at their spontaneous open circuit potential. Swelling of the coating and nucleation of blisters were observed for all the samples when they were exposed to naturally aerated 0.1 M KCl solution within 24 h exposure. Conversely, featureless and flat surfaces were found when the samples were either exposed to 0.1 M K2SO4 or to 10 mM KCl. For chloride concentrations of 0.1 M and above the chloride ions were observed to promote coating degradation nearly immediately upon immersion in the electrolyte.
- Published
- 2008
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