1. Corrosion characterization and ion release in SLM-manufactured and wrought Ti6Al4V alloy in an oral environmentMirjam Bajt Leban, Tadeja Kosec, Matjaž Finšgar, 2022, original scientific article Abstract: As-produced and heat-treated TiAlV samples were prepared by selective laser melting and compared to wrought samples of identical chemical composition. Microstructural, corrosion, and spectroscopic studies of additively manufactured samples in artificial saliva at 37 °C, with NaF and at pH 2.3 were as a novelty combined with metal ion release during 42 days immersion. In artificial saliva higher amount of ions was released on SLM specimen when compared to wrought alloy. The total amount of ions released from SLM specimen in AS containing NaF was 10-times higher than in AS, while in AS with lactic acid it was 100-times higher.
Keywords: Ti6Al4V, SLM, corrosion, ion release, XPS, ToF-SIMS
Published in DKUM: 05.12.2024; Views: 0; Downloads: 3
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2. Flower-like superhydrophobic surfaces fabricated on stainless steel as a barrier against corrosion in simulated acid rainRegina Fuchs-Godec, 2022, original scientific article Abstract: Functionalisation of the metal surface of low-carbon ferritic stainless steel (from hydrophilic to hydrophobic properties) was achieved by flower-like hierarchical structures on a steel substrate prepared by a low-cost immersion method. The flower-like structured hydrophobic layers on the steel substrate were obtained by immersing the samples in an ethanolic solution of stearic acid with the addition of various concentrations of expired vitamin E ((+)α-tocopherol). The stability and corrosion-inhibiting effect of the hierarchically structured (such as natural cornflower) hydrophobic layers were studied systematically during short and long immersion tests, 120 h (five days) in an acidic environment (pH = 3) using potentiodynamic measurements, electrochemical impedance spectroscopy and chronopotentiometry. The surfaces of the samples, their wettability, surface morphology and chemical composition were characterised by contact angle measurements, SEM, ATR-FTIR and EDAX. After 120 h of immersion, the inhibition efficiency of the flower-like structured hydrophobic layers on the steel substrate in the selected corrosion medium remained above 99%, and the hierarchical structure (flower-like structure) was also retained on the surface.
Keywords: acid rain, corrosion, flower-like structure, inhibition, stainless steel
Published in DKUM: 05.12.2024; Views: 0; Downloads: 2
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3. ǂThe ǂcorrosion resistance of dental Ti6Al4V with differing microstructures in oral environmentsMirjam Bajt Leban, Tadeja Kosec, Matjaž Finšgar, 2023, original scientific article Abstract: The impact of the microstructural properties of a Ti6Al4V alloy on its electrochemical properties, as well as the effect of the α- and β-phases present within it, is still unclear. With the introduction of new, emerging technologies, such as selective laser melting and post heat treatments, the effect of the microstructure on an alloy's corrosion properties has become increasingly interesting from a scientific perspective. When these alloys are produced through different methods, despite an identical chemical composition they have diverse microstructures, and consequently display varying resistance to corrosion. In the present research study, Ti–6Al–4V alloy specimens produced by three different processes, leading to the formation of three different microstructures were investigated: heat treated specimen fabricated by selective laser melting, wrought and cast specimens. The impact of the microstructure of these alloys when immersed in artificial saliva was studied through the use of various electrochemical techniques, by microscopical examinations, and time-of-flight secondary ion mass spectrometry. Corrosion properties were investigated by the measurement of open circuit potential, linear polarization, and potentiodynamic curve measurements followed by microscopical examinations, and time-of-flight secondary ion mass spectrometry examination was conducted to reveal spatial distribution of alloying species on oxide film. It was found that the difference between specimens containing an α+β microstructure was small and not dependent on the aspect ratio of the β-phase, alloy grain size, and vanadium partitioning coefficient, but rather on the size, shape, and content of this phase.
Keywords: Ti6Al4V, dental alloy, microstructure, corrosion resistance, heat treatment, ToF-SIMS
Published in DKUM: 07.05.2024; Views: 198; Downloads: 13
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4. In Vitro Bioelectrochemical Properties of Second-Generation Oxide Nanotubes on Ti–13Zr–13Nb Biomedical AlloyAgnieszka Stróż, Thomas Luxbacher, Karolina Dudek, Bartosz Chmiela, Patrycja Osak, Bożena Łosiewicz, 2023, original scientific article Keywords: anodizing, corrosion resistance, oxide nanotubes, Ti–13Zr–13Nb alloy, zeta potential
Published in DKUM: 04.04.2024; Views: 193; Downloads: 7
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5. High-Order Fiber Bragg Grating Corrosion Sensor Based on the Detection of a Local Surface ExpansionVedran Budinski, Matej Njegovec, Simon Pevec, Boris Macuh, Denis Đonlagić, 2023, original scientific article Abstract: This paper presents a fiber optic sensor for the detection of corrosion processes that occur on metal surfaces. In the proposed sensor design, a sensing fiber with an inscribed high-order Bragg grating is attached to the observed metal surface. A broadening of high-order Bragg grating spectral characteristics is observed and used to detect small and highly localized longitudinal strain variations that occur along the fiber as a result of corrosive rust flakes' formations beneath the sensing fiber. The proposed approach provides a straightforward fabrication method, the possibility for unobtrusive mounting, including mounting of the sensor beneath the corrosion-protective layers, and consistent corrosion detection yields.
Keywords: optical fiber sensors, corrosion, impact of corrosion, optic sensors
Published in DKUM: 09.02.2024; Views: 320; Downloads: 23
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6. Electrochemical and surface analysis of 2-phenylimidazole adsorbed on copper from chloride solutionMatjaž Finšgar, Klodian Xhanari, 2018, original scientific article Abstract: The electroanalytical and surface characterization of copper immersed in 3 wt.% NaCl solution containing 1 mM of 2-phenylimidazole (2PhI) is presented. It was proven that 2PhI can be employed as corrosion inhibitor for copper using various electrochemical analyses, such as cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy, and potentiodynamic curve measurements. The adsorption of 2PhI on copper was further analyzed by 3D-profilometry, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements, and scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. This system was therefore comprehensively described by various analytical approaches.
Keywords: corrosion inhibitor, copper, electrochemical impedance spectroscopy, EIS, cyclic voltammetry, attenuated total reflectance Fourier transform infrared, ATR-FTIR
Published in DKUM: 17.01.2019; Views: 2084; Downloads: 392
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7. Corrosion mechanisms for cemented soils in three different sulfate solutionsPengju Han, Chao Ren, Xiaohong Bai, Frank Chen, 2015, original scientific article Abstract: In order to simulate and study the corrosion effects on the compressive strength of cemented soils that could be exposed in a polluted environment, a series of tests were conducted on cemented soil blocks cured with different concentrations of H2SO4, MgSO4, and Na2SO4 solutions. The test results show that the corrosion degree generally increases with the corrosion time and the solution concentration, while the compressive strength decreases with the increasing corrosion degree. The corrosion degree is highest for the Na2SO4 solution, followed by the MgSO4 and H2SO4 solutions. Namely, when the SO4 2- ion exists in a solution, the corrosion degree for the positive ions follows this descending order: Na+, Mg2+, and H+. X-ray diffraction (XRD) phase analyses were performed for the cemented soil samples after corrosion and ionic concentrations. The results show that the compressive strength decreases with an increase of the Mg2+ concentration in the MgSO4 solution and the Na+ concentration in the Na2SO4 solution. At the same time, the strength increases with an increase of the pH value of the H2SO4 solution. Based on the chemical analysis results, the corrosion of H2SO4 or MgSO4 solutions on cemented soils is deemed as a composite action involving the combined resolving and crystallizing corrosion processes. Furthermore, the corrosion of the Na2SO4 solution of cemented soil is a composite action consisting of dissolving and crystallizing.
Keywords: cemented soil, compressive strength, corrosion mechanism, sulfate, pollution, solution
Published in DKUM: 15.06.2018; Views: 1757; Downloads: 178
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8. The influence of $Ce^{3+}$ ions on the corrosion rate of stainless steel in acidic solutions of different pH-valuesAljana Petek, Sebastijan Kovačič, 2014, original scientific article Abstract: The corrosion resistance of AISI 420 stainless steel in 0.1 mol $L^{−1}$ $H_2SO_4$ + 0.1 mol $L^{−1}$ $Na_2SO_4$ solutions at different pH-values and the inhibiting effect of $Ce^{3+}$ ions was studied using electrochemical polarization methods. The results reveal decreasing of the corrosion rate with an increasing the pH of the solution, which demonstrates the progressive protective character of the inhibitor used. At pH lower than 3.33, the corrosion inhibition was most probably a result of the competitive adsorption of $Ce^{3+}$ with $H^+$ ions on the cathodic sites of the electrode surface, and it was found to be dependent on the relative concentration of $H^+$/$Ce^{3+}$. The peroxide generated from the oxygen reduction reaction at pH 3.33 was found to be capable oxidize trivalent cerium (Ce) to the tetravalent state. As obtained hydroxide precipitates act as diffusion barrier hindering the corrosion processes, whereafter a spontaneous passivity occurs on the steel surface at this pH.
Keywords: acid corrosion, green corrosion inhibitor, stainless steel, electrochemical techniques
Published in DKUM: 24.07.2017; Views: 1416; Downloads: 376
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9. Novel chitosan/diclofenac coatings on medical grade stainless steel for hip replacement applicationsMatjaž Finšgar, Amra Perva, Janja Stergar, Lidija Gradišnik, Uroš Maver, 2016, original scientific article Abstract: Corrosion resistance, biocompatibility, improved osteointegration, as well the prevention of inflammation and pain are the most desired characteristics of hip replacement implants. In this study we introduce a novel multi-layered coating on AISI 316LVM stainless steel that shows promise with regard to all mentioned characteristics. The coating is prepared from alternating layers of the biocompatible polysaccharide chitosan and the non-steroid anti-inflammatory drug (NSAID), diclofenac. Electrochemical methods were employed to characterize the corrosion behavior of coated and uncoated samples in physiological solution. It is shown that these coatings improve corrosion resistance. It was also found that these coatings release the incorporated drug in controlled, multi-mechanism manner. Adding additional layers on top of the as-prepared samples, has potential for further tailoring of the release profile and increasing the drug dose. Biocompatibility was proven on human-derived osteoblasts in several experiments. Only viable cells were found on the sample surface after incubation of the samples with the same cell line. This novel coating could prove important for prolongation of the application potential of steel-based hip replacements, which are these days often replaced by more expensive ceramic or other metal alloys.
Keywords: corrosion, corrosion resistance, chitosan, biocompatibility, biomaterials, biomedical materials, coatings, stainless steel
Published in DKUM: 23.06.2017; Views: 2073; Downloads: 391
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10. Morphology and corrosion properties PVD Cr-N coatings deposited on aluminium alloysDarja Kek-Merl, Ingrid Milošev, Peter Panjan, Franc Zupanič, 2011, original scientific article Abstract: The attempt to find an alternative coating for corrosion protection of Al- alloys was made. PVD coatings are one of the possible alternatives for replacement of ecological unfriendly chromate coatings. Chromium-nitride (Cr-N) and Ni/Cr-N coatings were sputtered on aluminium substrates (AA7075 and cladded AA2024). Surface and sub-surface characterizations were performed by AFM and SEM. Special attention was given to defects incorporated into coatings, since they play important role in the corrosion protection of the coating/substrate systems. The cross-sections through the typical defects were performed by ion beam milling incorporated into the SEM. The Vickers hardness of the Cr-N with and without layer of Ni on both substrates was determined. After the coatings deposition, the values of Vickers hardness (10 mN load) increase for 10 to 100-fold compared to the substrates. The corrosion behaviour of Cr-N and Ni/Cr-N thin films was investigated in near neutral 0.1 M solution of NaCl using potentiodynamics electrochemical measurement. Cr-N and Ni/Cr-N coatings shift the corrosion potentials to more positive values. The best corrosion resistance among the tested coating/substrate systems were found for Ni/Cr-N on AA7075 substrate.
Keywords: Al-alloys, corrosion properties, CrN films, FIB, PVD coatings
Published in DKUM: 17.03.2017; Views: 1359; Downloads: 95
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