1. 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: 66; Downloads: 0 |
2. 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: 159; Downloads: 65
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4. A critical appraisal of the use and properties of nickel–titanium dental alloysPetra Močnik, Tadeja Kosec, 2021, review article Abstract: Nickel–titanium (NiTi) archwires are used in dentistry for orthodontic treatment. NiTi alloys have favourable mechanical characteristics, such as superelasticity and shape memory, and are also known as a corrosion-resistant alloy. In specific cases, an archwire could be attacked by certain types of corrosion or wear degradation, which can cause the leaching of metal ions and a hypersensitive response due to increased concentrations of Ni in the human body. A systematic search of the literature retrieved 102 relevant studies. The review paper focuses on three main fields: (i) electrochemical properties of NiTi wires and the effect of different environments on the properties of NiTi wires (fluoride and low pH); (ii) tribocorrosion, a combination of chemical and mechanical wear of the material, and (iii) the biocompatibility of NiTi alloy and its subsequent effect on the human body. The review showed that corrosion properties are affected by microstructure, pH of saliva and the presence of fluorides. A high variation in published results should be, therefore, interpreted with care. The release of nickel ions was assessed using the same unit, showing that the vast majority of metal ions were released in the first few days of exposure, then a stable, steady state was reached. In tribocorrosion studies, the increased concentrations of Ni ions were reported.
Keywords: NiTi alloy, archwires, corrosion, NI ion release
Published in DiRROS: 23.02.2024; Views: 195; Downloads: 66
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5. Mechanisms of premature fracture in modular neck stems made of CoCrMo/Ti6Al4V and Ti6Al4V/Ti6Al4V alloyDrago Dolinar, Miro Gorenšek, Klemen Avsec, Barbara Šetina, Matej Hočevar, Matjaž Godec, Borut Žužek, Mojca Debeljak, Monika Jenko, John T. Grant, Boštjan Kocjančič, 2023, original scientific article Abstract: In this paper, we present the mechanisms of premature fracture of modular neck stems in two case studies: (I) when the neck and stem are both made of the same Ti6Al4V alloy, and (II) when the neck and stem are made from two different alloys, CoCrMo and Ti6Al4V alloy. Our study integrates two orthopedic patients who have undergone primary uncemented THA for usual indications in two orthopedic centers (Community Health Centre and University Medical Centre). Both centers are part of the national public health care system. Both surgeries were performed by two skilled orthopedic surgeons with more than 10 years of experience in THA. The survivorship of the modular neck of cast CoCrMo alloy was 24 months. The survivorship of the modular neck from Ti6Al4V alloy was 84 months. Multivariate analyses were performed to assess the differences in the fretting, corrosion, and fatigue of the two prematurely failed modular neck stems: stereo light microscopy (SLM), scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). Patient demographic information, including sex, age, body mass index, survivorship of implants, and reason for the revision, was collected from medical records. We found that fretting and fatigue occurred on both neck-stem retrievals due to additional galvanic corrosion, but the CoCrMo/Ti6Al4V alloy system suffered more corrosion due to additional galvanic corrosion and fractured earlier than the Ti6Al4V/Ti6Al4V metal alloy system. Both metallic alloy systems used in this application are known to be highly corrosion-resistant, but the bio-tribo-corrosion processes need to be understood in detail and characterized so that appropriate improvements in design and materials can be made.
Keywords: total hip arthroplasty, modular neck, Ti6Al4V alloy, CoCrMo alloy, corrosion
Published in DiRROS: 07.02.2024; Views: 229; Downloads: 126
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6. Dispersoids in Al-Mg-Si alloy AA 6086 modified by Sc and YFranc Zupanič, Sandi Žist, Mihaela Albu, Ilse Letofsky-Papst, Jaka Burja, Maja Vončina, Tonica Bončina, 2023, original scientific article Keywords: aluminium alloy, heat treatment, microstructure, dispersoids, dilatometry, DSC, hardness
Published in DiRROS: 02.02.2024; Views: 142; Downloads: 77
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7. Solidification behavior of Fe-6.5Si alloy powder for AM-SLM processing, as assessed by differential scanning calorimetryDarja Steiner Petrovič, Črtomir Donik, Irena Paulin, Matjaž Godec, Maja Vončina, Martin Petrun, 2023, original scientific article Keywords: soft magnetic alloy, differential scanning calorimetry, oxygen, high-temperature phase, microstructure, eutectics
Published in DiRROS: 02.02.2024; Views: 143; Downloads: 68
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8. Influence of oil viscosity on the tribological behavior of a laser-textured Ti6Al4V alloyMarjetka Conradi, Aleksandra Kocijan, Bojan Podgornik, 2023, original scientific article Abstract: Laser texturing with a dimple pattern was applied to modify a Ti6Al4V alloy at the micro level, aiming to improve its friction and wear resistance in combination with oil lubrication to optimize the performance in demanding industrial environments. The tribological analysis was performed on four different dimple-textured surfaces with varying dimple size and dimple-to-dimple distance and under lubrication with three different oils, i.e., T9, VG46, and VG100, to reflect the oil viscosity’s influence on the friction/wear of the laser-textured Ti6Al4V alloy. The results show that the surfaces with the highest texture density showed the most significant COF reduction of around 10% in a low-viscosity oil (T9). However, in high-viscosity oils (VG46 and VG100), the influence of the laser texturing on the COF was less pronounced. A wear analysis revealed that the laser texturing intensified the abrasive wear, especially on surfaces with a higher texture density. For low-texturing-density surfaces, less wear was observed for low- and medium-viscosity oils (T9 and VG46). For medium-to-high-texturing densities, the high-viscosity oil (VG100) provided the best contact conditions and wear results. Overall, reduced wear, even below the non-texturing case, was observed for sample 50–200 in VG100 lubrication, indicating the combined effect of oil reservoirs and increased oil-film thickness within the dimples due to the high viscosity.
Keywords: oil lubrication, surface modification, Ti-based alloy, tribology
Published in DiRROS: 01.02.2024; Views: 179; Downloads: 73
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9. The impact of Al2O3 particles from grit-blasted Ti6Al7Nb (alloy) implant surfaces on biocompatibility, aseptic loosening, and infectionBoštjan Kocjančič, Klemen Avsec, Barbara Šetina, Darja Feizpour, Matjaž Godec, Veronika Kralj-Iglič, Rok Podlipec, Andrej Cör, Mojca Debeljak, John T. Grant, Monika Jenko, Drago Dolinar, 2023, original scientific article Keywords: Ti6Al7Nb implant alloy cementless hip endoprostheses, roughness, Al2O3 grit blasting, surface and subsurface implant contamination, cytotoxicity, aseptic loosening, infection, osseointegration
Published in DiRROS: 01.02.2024; Views: 170; Downloads: 71
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10. Effects of variated final temperature and workpiece thickness for hot rolling of aluminum alloy EN AW-8011Jakob Kraner, Peter Cvahte, Primož Šuštarič, Tomaž Šuštar, Črtomir Donik, Irena Paulin, Shae K. Kim, Kjung Il Kim, 2023, original scientific article Keywords: aluminum alloy, hot rolling, simulations, metallography, mechanical properties
Published in DiRROS: 01.02.2024; Views: 143; Downloads: 77
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