1. 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: 59; Downloads: 48
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2. 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: 135; Downloads: 123
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3. 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: 188; Downloads: 124
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4. Processing aluminium EN AW 7075 alloy using selective laser meltingNejc Velikajne, Jože Medved, Matjaž Godec, Irena Paulin, complete scientific database of research data Abstract: Selective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be designed and manufactured with high accuracy and little post processing. Currently, different types of steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop a new alloy which is more suitable for the SLM process for the wide used aluminium alloy EN AW 7075. But before that, gas-atomized powder material was characterized in terms of statistical distribution. A wide range of process parameters and different pre-heating temperatures were selected to optimize the process in terms of optimum volume density and reducing the effect of hot cracking. However, all laser-melted parts exhibited hot cracks which typically appear in aluminium alloy EN AW 7075.
Keywords: EN AW 7075, aluminium alloy, hot cracks, relative density, selective laser melting (SLM)
Published in DiRROS: 22.04.2024; Views: 165; Downloads: 0 |
5. 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: 287; Downloads: 151
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6. A coupled convective-diffusive model of heat transfer and melt-pool dynamics in additive manufacturingTijan Mede, Matjaž Godec, 2024, treatise, preliminary study, study Keywords: additive manufacturing, selective laser melting, laser powder-bed fusion, melt-pool, heat transfer, convection
Published in DiRROS: 05.04.2024; Views: 190; Downloads: 0 |
7. Effect of post-treated low-temperature plasma nitriding on the wear and corrosion resistance of 316L stainless steel manufactured by laser powder-bed fusionMatjaž Godec, Črtomir Donik, Aleksandra Kocijan, Bojan Podgornik, Danijela Anica Skobir Balantič, 2020, original scientific article Keywords: austenitic stainless steel, powder bed fusion, low-temperature plasma nitriding, wear and corrosion behaviour, dislocation cell structure
Published in DiRROS: 25.03.2024; Views: 174; Downloads: 89
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8. Use of plasma nitriding to improve the wear and corrosion resistance of 18Ni-300 maraging steel manufactured by selective laser meltingMatjaž Godec, Bojan Podgornik, Aleksandra Kocijan, Črtomir Donik, Danijela Anica Skobir Balantič, 2021, original scientific article Keywords: selective laser melting, 18Ni-300 maraging steel, heat treatment, plasma nitriding, retained and reverted austenite, wear and corrosion behaviour
Published in DiRROS: 25.03.2024; Views: 182; Downloads: 79
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9. Evolution of microstructure and embrittlement during the tempering process in SiCrCu medium-carbon steelsPavel Salvetr, Aleksandr Gokhman, Črtomir Donik, Zbyšek Nový, Jakub Kotous, Matjaž Godec, 2023, original scientific article Keywords: medium-carbon steel, tempering martensite embrittlement, microstructure, mechanical properties
Published in DiRROS: 08.03.2024; Views: 165; Downloads: 91
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10. Characterisation of the microstructure and defects during the direct energy deposition of hybrid Ti6Al4V in a low-quality atmosphereSimon Malej, Črtomir Donik, Matej Balažic, Matija Bizjak, Marko Kač, Matjaž Godec, 2023, original scientific article Keywords: direct energy deposition, Ti6Al4V, protective atmosphere
Published in DiRROS: 08.03.2024; Views: 182; Downloads: 84
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