1. In vitro corrosion-fatigue behaviour of rare-earth containing magnesium WE43 in sterile complex cell culture mediumJulia Nachtsheim, Songyun Ma, Jaka Burja, Alexander Köppl, Jan-Marten Seitz, Bernd Markert, 2024, original scientific article Abstract: Rare-earth containing magnesium alloys are promising biomedical materials for a new generation of biodegradable orthopaedic implant systems due to their excellent biocompatibility, mechanical and biodegradation properties. However, chemo-mechanical interactions in aggressive physiological corrosion environments result in rapid degradation and early loss of mechanical integrity, limiting its broader application for orthopaedic implants. To date, only few studies have assessed the corrosion-fatigue behaviour of medical-grade magnesium alloys in an organic physiological corrosion environment, especially under sterile test conditions. In the present work, the corrosion-fatigue behaviour of fine-grained medical-grade magnesium alloy WE43MEO was systematically analysed under in vitro conditions using an organic physiological fluid DMEM. The experimental results showed that the fatigue strength of the alloy is nearly unaffected by a 1-day precorrosion, while a 7-day precorrosion resulted in a significant deterioration of mechanical integrity. In corrosion-fatigue experiments, the fatigue life was considerably reduced by interactions between corrosion and fatigue damages. The SEM analysis revealed that the mixed mode of intergranular and transgranular fracture in the crack propagation zone transits to intergranular cracking dominant mode under the corrosion-fatigue conditions due to hydrogen embrittlement.
Keywords: corrosion-fatigue behaviour, stress corrosion mechanisms, biodegradable magnesium alloys, WE43, DMEM
Published in DiRROS: 02.08.2024; Views: 131; Downloads: 90
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2. Microstructural, corrosion and mechanical properties of a WE43 alloy : conventional extrusion versus SPDAnna Dobkowska, Aleksandra Zielińska, Irena Paulin, Črtomir Donik, Milena Koralnik, Bogusława Adamczyk-Cieślak, Monika Wieczorek-Czarnocka, Dariusz Kuc, Jiří Kubásek, Tomasz Mikuszewski, Matjaž Godec, Jarosław Mizera, 2024, original scientific article Abstract: A hexagonal close-packed-structure WE43 alloy was extruded without any preheating of the initial billet using extrusion with an oscillating die to improve the corrosion and mechanical properties. The WE43 alloy was extruded at high ratios of R 1 5:1, R 2 7:1 and R 3 10:1. Electron back-scatter diffraction and transmission electron microscopy were used to determine the microstructural properties of the alloys. The influence of the extrusion method and the extrusion ratios on the corrosion and mechanical properties were investigated. Electrochemical tests were performed, and the corrosion damage was inspected. Tensile tests were made using micro specimens. When compared to conventional extrusion, the microstructural changes obtained with the KoBo method at R 5:1 increased the corrosion resistance, which was not only due to the grain refinement, but also due to the intensity of the texture. A decline in the corrosion resistance of the alloys deformed at higher extrusion ratios was observed. This was a result of the massive plastic strain imposed by the KoBo die. The room-temperature mechanical properties of the KoBo-extruded alloys were improved. However, at higher temperatures the mechanical properties decreased due to the solutioning of tiny triple precipitates.
Keywords: WE43, several plastic deformation, microstructure, corrosion, mechanical properties
Published in DiRROS: 23.07.2024; Views: 96; Downloads: 32
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3. An investigation into corrosion around voids at the steel-concrete interfaceMiha Hren, Tadeja Kosec, Andraž Legat, 2024, original scientific article Abstract: In this study, the influence of voids on corrosion process at the steel-concrete interface was investigated, as the exact influence of these features on corrosion processes under various environmental conditions is not entirely understood. Coupled multi electrode arrays and electrical resistance probes were implemented to monitor the evolution of corrosion under cyclic exposure to chlorides and carbonation. MicroCT was used to determine the location and volume of corrosion damage. It was found that, in most cases, corrosion damage initiated outside the voids. During initiation and the early propagation phase, the steel beneath the voids rarely participated in the redox reaction. In following phases, various kinds of corrosion evolution were observed. Specific corrosion mechanisms were proposed and discussed to explain these corrosion processes.
Keywords: microtomography, corrosion, coupled multi-electrode array, steel-concrete interface
Published in DiRROS: 06.06.2024; Views: 179; Downloads: 250
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4. Characterization of micro-threaded stem taper surface of cementless hip endoprosthesesDrago Dolinar, Boštjan Kocjančič, Klemen Avsec, Barbara Šetina, Aleksandra Kocijan, Matjaž Godec, Marko Sedlaček, Mojca Debeljak, John T. Grant, Timon Zupanc, Monika Jenko, 2024, original scientific article Abstract: We investigated micro-threaded stem taper surface and its impact on premature failures, aseptic loosening, and infection in cementless hip endoprostheses. Our study focused on the fretting, and crevice corrosion of micro-threaded tapers, as well as the characterization of the microstructure and surface properties of two new and three retrieved Zweymüller stem tapers. The retrieved samples were selected and examined based on the head–stem taper interface being the sole source of modularity with a metallic component, specifically between the Ti alloy taper stem and the ceramic head. To determine the surface chemistry and microstructures of both new and retrieved hip endoprostheses stem taper titanium alloy, scanning -electron microscopy (SEM) was employed for morphological and microstructural analyses. Energy dispersive spectroscopy (EDS) was utilized for characterizing chemical element distribution, and electron backscattered diffraction (EBSD) was used for phase analysis. The roughness of the micro-threated stem tapers from different manufacturers was investigated using an optical profilometer, with standard roughness parameters Ra (average surface roughness) and Rz (mean peak to valley height of the roughness profile) being measured. Electrochemical studies revealed no fretting corrosion in retrieved stem tapers with ceramic heads. Consequently, three retrieved tapers and two new ones for comparison underwent potentiodynamic measurements in Hank’s solution to determine the corrosion rate of new and retrieved stem taper surfaces. The results showed a low corrosion rate for both new and prematurely failed retrieved samples due to aseptic loosening. However, the corrosion rate was higher in infected and low-grade infected tapers. In conclusion, our study suggests that using ceramic heads reduces taper corrosion and subsequently decreases the incidence of premature failures in total hip arthroplasty.
Keywords: total hip arthroplasty, stem micro-threaded taper, taper surface morphology, microstructure, corrosion, Ti implant alloy
Published in DiRROS: 06.06.2024; Views: 198; Downloads: 196
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6. Tuning the long-term corrosion behaviour of biodegradable WE43 magnesium alloy by PEO coatingJulia Nachtsheim, Songyun Ma, Jaka Burja, Barbara Šetina, Bernd Markert, 2023, original scientific article Keywords: long-term degradation, in vitro corrosion mechanisms: biodegradable, magnesium, DMEM fluid, hydrogen evolution, PEO coating
Published in DiRROS: 20.05.2024; Views: 222; Downloads: 126
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7. Microstructure and properties of an AZ61 alloy after extrusion with a forward-backward oscillating die without preheating of the initial billetAnna Dobkowska, Aleksandra Zielińska, Irena Paulin, Črtomir Donik, Maciej Łojkowski, Milena Koralnik, Bogusława Adamczyk-Cieślak, Krystian Paradowski, Marek Tkocz, Dariusz Kuc, Jiří Kubásek, Matjaž Godec, Wojciech Święszkowski, 2023, original scientific article Keywords: magnesium alloys, severe plastic deformation, microstructure, mechanical properties, corrosion, extrusion, high deformation ratio
Published in DiRROS: 17.05.2024; Views: 250; Downloads: 168
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8. Bioresorbability dependence on microstructure of additivelly- manufactured and conventionally-produced Fe-Mn alloysMatjaž Godec, Jakob Kraner, Danijela Anica Skobir Balantič, Irena Paulin, Damjana Drobne, Veno Kononenko, Aleksandra Kocijan, Paul J. McGuiness, Črtomir Donik, 2024, original scientific article Keywords: Fe-Mn alloy, laser powder bed fusion, bioresorbable, microstructure, corrosion behaviour, biocompatibility
Published in DiRROS: 06.05.2024; Views: 301; Downloads: 223
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9. The impact of urban rain on the changes of bare and artificially patinated bronze during 9-year exposureTadeja Kosec, Mirjam Bajt Leban, Polonca Ropret, Matjaž Finšgar, 2024, original scientific article Abstract: Atmospheric pollutants in the air form acid rain which interacts with bronze surfaces exposed in urban outdoor environment. In this study, different types of patinas on bronze were investigated during and after 9 years of exposure to urban environment in moderately polluted continental city. Natural bronze patina and artificial brown sulphide, green chloride, and green–blue nitrate patinas were investigated. Visual assessment was carried out at defined periods. After 9 years of exposure, an electrochemical study was performed to investigate the electrochemical activity of the patinas in artificial urban rain. Additionally, the patinas were characterised using a variety of techniques, including metallographic examination, scanning electron microscopy/energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray diffraction analysis, X-ray-photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry to analyse the surface morphology, chemical composition, and stratigraphic features of the patinas. Evolution of the patinas was shown to be a result of both, the composition of the acid rain and the hydrophobicity of the patinated surfaces.
Keywords: bronze, bronze, corrosion, patina characterization
Published in DiRROS: 29.04.2024; Views: 281; Downloads: 528
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10. Bioresorbability dependence on microstructure of additivelly- manufactured and conventionally-produced Fe-Mn alloysMatjaž Godec, Jakob Kraner, Danijela Anica Skobir Balantič, Irena Paulin, Damjana Drobne, Veno Kononenko, Aleksandra Kocijan, Paul J. McGuiness, Črtomir Donik, 2024, complete scientific database of research data Abstract: The dataset supports the results shown in the tables and figures in the article entitled “Bioresorbability Dependence on Microstructure of Additivelly-Manufactured and Conventionally-Produced Fe-Mn Alloys” (doi.org/10.1016/j.jmrt.2024.04.097). It contains measurements of corrosion resistance of Fe-Mn samples, phase analysis of samples A, B and C, surface and depth profiling XPS, EDS measurements of a cross-section of Fe-Mn powder particles and viability measurements results.
Keywords: Fe-Mn alloy, laser powder bed fusion, bioresorbable, microstructure, corrosion behaviour, biocompatibility
Published in DiRROS: 12.04.2024; Views: 410; Downloads: 251
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