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2. Površinska kemija naravnih oksidnih plasti na uporabljenih in novih vzorcih stegneničnih komponent endoproteze kolka iz Ti-6Al-7Nb zlitine : diplomsko deloMatic Petrič, 2023, undergraduate thesis Keywords: kolčne endoproteze, aseptično omajanje, periprostetična okužba, titanov oksid, polimeri, titanove zlitine, XPS, SEM, EBSD, diplomsko delo
Published in DiRROS: 18.04.2025; Views: 3; Downloads: 1
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5. Reactive noble-gas compounds explored by 3D electron diffraction : XeF[sub]2–MnF[sub]4 adducts and a facile sample handling procedureKlemen Motaln, Kshitij Gurung, Petr Brázda, Anton Kokalj, Kristian Radan, Mirela Dragomir, Boris Žemva, Lukáš Palatinus, Matic Lozinšek, 2024, original scientific article Keywords: compounds, 3D electron diffraction
Published in DiRROS: 17.04.2025; Views: 42; Downloads: 7
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6. Surface engineering of aerospace aluminium alloys : understanding alloying effects on chemical pre-treatment and sol-gel coating adhesionJ.B.P. Van Dam, Urša Tiringer, Shoshan Abrahami, Ingrid Milošev, Herman Terryn, Janez Kovač, Johannes M. C. Mol, 2024, original scientific article Abstract: The sol–gel process is a chemical surface preparation method based on hydrolysis and polycondensation reactions for enhanced adhesion for metallic substrates in adhesive bonding and coating applications. This paper describes an investigation into the effect of the microstructural complexity of two commonly used aerospace aluminium alloys (AAs) 2024-T3 and 7075-T6, on the response to different surface pre-treatments before deposition of the sol-gel coating and subsequent adhesive bonding. Different surface pre-treatments, including two abrasive treatments and three chemical surface pre-treatments were used, and their effect on surface chemistry, wettability and roughness was assessed. Surfaces were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, profilometry and static contact angles. A hybrid silane sol-gel film was deposited on the differently pre-treated aluminium alloys, an epoxy adhesive was applied and the adhesion properties were evaluated using pull-off testing. The role of the altered physicochemical properties of the pre-treated surfaces was related to the adhesion strength of the sol–gel reinforced epoxy/aluminium interfaces. The microstructural complexity of the aerospace alloys caused non-uniform responses to the pre-treatments, proving the importance of compatibility between material and treatment conditions. Statistical analysis revealed that, despite that overall higher adhesion values were obtained on rougher surfaces, only a strong correlation exists between the surface hydroxyl fraction and adhesion strength. The relation of roughness and water contact angle to interfacial adhesion was found to be non-significant. The findings of this study underscore the critical role of surface pre-treatments and their impact on adhesion strength in aerospace aluminium alloys, providing valuable insights for the effective utilization of sol-gel coatings in adhesive bonding and coating processes.
Keywords: sol-gel, surface pre-treatment, surface morphology, wettability, adhesive
Published in DiRROS: 17.04.2025; Views: 36; Downloads: 7
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7. Complementary corrosion protection of cast AlSi7Mg0.3 alloy using Zr-Cr conversion and polyacrylic/siloxane-silica multilayer coatingsPeter Rodič, Barbara Kapun, Ingrid Milošev, 2024, original scientific article Abstract: Aluminium cast alloy AlSi7Mg0.3 is a lightweight metal commonly used in automotive, aeronautical and mechanical applications. It has good corrosion resistance but, under harsh operative conditions, would benefit from additional protection. In this study, a corrosion-protective multilayer coating system for AlSi7Mg0.3 based on hexafluoro-zirconated trivalent chromium coating (Zr-CrCC) and polyacrylic/siloxane-silica (PEHA-SS) coating was developed. The Zr-CrCC was formed by immersion of the substrate in a commercial conversion bath (SurTec® 650). PEHA-SS synthesis was based on organic precursors (2-ethylhexyl acrylate and [3-(methacryloyloxy)propyl]trimethoxysilane) and an inorganic precursor, tetraethyl orthosilicate. After deposition on AlSi7Mg0.3, each coating was first characterised individually, followed by the analysis of the multilayer using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The adhesion of the coatings was evaluated with a cross-hatch cut test. The corrosion studies in sodium chloride solution using electrochemical impedance spectroscopy and salt spray testing showed that the multilayer system is superior to individual Zr-CrCC and PEHA-SS coatings. After 4 months in 0.1 M NaCl, the multilayer-coated samples exhibited the impedance at 10 mHz in the range of GΩ cm2, while scribed samples withstood the corrosion attack in a salt spray chamber for one week. Thus, albeit only about 100 nm thick, the Zr-CrCC deposited between the substrate and a 9-micrometre thick barrier sol-gel PEHA-SS coating acts as an active corrosion protection interlayer and contributes to the overall protectiveness of the multilayer system.
Keywords: corrosion-protective, aluminium, material
Published in DiRROS: 17.04.2025; Views: 30; Downloads: 6
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8. Development and characterization of gelatin-based hydrogels containing triblock copolymer and phytic acidNjomza Ajvazi, Ingrid Milošev, Romana Cerc Korošec, Peter Rodič, Bojan Đ. Božić, 2024, original scientific article Abstract: In recent research, significant interest has been directed towards gelatin-based hydrogels due to their affordable price, extensive availability, and biocompatibility, making them promising candidates for various biomedical applications. The development and characterization of novel hydrogels formed from varying ratios of gelatin, triblock copolymer Pluronic F-127, and phytic acid have been presented. Swelling properties were examined at different pH levels. The morphology of hydrogels and their thermal properties were analyzed using scanning electron microscopy (SEM), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Fourier-transform infrared (FTIR) analysis of the hydrogels was also performed. The introduction of phytic acid in the hydrogel plays a crucial role in enhancing the intermolecular interactions within gelatin-based hydrogels, contributing to a more stable, elastic, and robust network structure.
Keywords: hydrogels, phytic acid
Published in DiRROS: 17.04.2025; Views: 36; Downloads: 7
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9. Bilateral acrylic hip mold arthroplasty in a child with a revision 60 years after implantation : Clinical case and chemical analysis of endoprosthetic materialSamo Roškar, Ingrid Milošev, Rene Mihalič, Ema Žagar, Rihard Trebše, 2024, original scientific article Abstract: A 68-year-old man was referred due to bilateral hip pain and gradual deterioration of walking. He had mold arthroplasties on both hips at the age of 7 years and has been functioning well for more than 5 decades. However, the original data on operative report and the prostheses were missing. The radiological examination revealed bilateral broken prosthetic material. Thus, stage bilateral revision total hip arthroplasty was performed. A detailed chemical analysis of retrieved mold arthroplasty implants proved that the acrylic material was noted to be the same composition with the difference in appearance likely being related to different thermal treatments originally applied to the implants. As presented in our clinical case, even obsolete implants may have good survivorship. According to the case presented, total hip arthroplasty could be considered an effective option with the desired functional outcome when conservative and joint-preserving measures are exhausted
Published in DiRROS: 17.04.2025; Views: 38; Downloads: 4
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10. Enhanced mechanical properties and environmental stability of polymer-bonded magnets using three-step surface wet chemical modifications of Nd–Fe–B magnetic powderAna Damnjanović, Ingrid Milošev, Nataša Kovačević, 2024, original scientific article Abstract: This research focuses on the surface modification of Nd–Fe–B magnetic powder to enhance its thermal and oxidation resistance without compromising magnetic properties and to improve adhesion to the polymer binder for enhanced mechanical properties. A three-step surface modification process involving phosphatization treatment, tetraethyl orthosilicate (TEOS) application, and 3-aminopropyltriethoxysilane (APTES) grafting, was applied to the powder, which was then compounded with polyamide 12 and injection-moulded into cylinders and dog-bone-shaped tubes. The resulting magnets exhibited remanence (Br) of 487.6 mT, coercivity (Hci) of 727.7 kA/m, and energy product (BHmax) of 39.3 kJ/m3. The modified magnets demonstrated exceptional corrosion resistance and thermal stability, with less than 5% irreversible flux loss after exposure to hot water, temperature shock, and pressurised steam. Furthermore, the modified magnets displayed significantly higher tensile strength, elongation at break, and elastic modulus with improvements of 62%, 16.7%, and 19.9%, respectively, compared to the non-modified batch. Additionally, the modified batch showed a notable 52% increase in flexural stress during flexural testing. These findings underscore the potential of silane surface modifications in producing injection-moulded permanent magnets based on Nd–Fe–B alloy, extending their shelf life and enhancing their overall performance.
Published in DiRROS: 17.04.2025; Views: 28; Downloads: 5
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