| 1. |
- Bartkowska, Aleksandra, et al.
(författare)
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Accelerated biodegradation of FeMn porous alloy coated with ZnO: Effect on cytocompatibility and antibiofilm properties
- 2023
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Ingår i: Surface and Coatings Technology. - 0257-8972. ; 471
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Tidskriftsartikel (refereegranskat)abstract
- Fe-based alloys are being studied as potential candidates for biodegradable implants; however, their degradation rates remain too slow. To accelerate biodegradation while simultaneously hindering biofilm formation, a ZnO coating was deposited onto porous equiatomic FeMn alloy discs by sol-gel method using dip coating. The effect of the ZnO coating on the microstructure, biodegradability, cytocompatibility, and antibacterial properties were investigated. Biodegradability experiments were performed by immersing the specimens in Hank's balanced salt solution and measuring ion release after up to 28 days of immersion. The experiments showed an increased degradation of the FeMn/ZnO sample due to Fe segregation towards the grain boundaries, formation of iron-manganese oxide, and limited formation of degradation products on ZnO. Further, indirect Saos-2 cell cytotoxicity testing in 24 h sample-conditioned media showed no significant cytotoxicity in concentrations equal to or below 50 %. In addition, the total biofilm biovolume formed by Staphylococcus aureus on the FeMn/ZnO surface was significantly reduced compared to the uncoated FeMn. Taken together, these results show that the ZnO coating on FeMn improves the degradation rate, maintains cytocompatibility, and reduces biofilm accumulation when compared to an uncoated FeMn alloy.
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| 2. |
- Bartkowska, Aleksandra, et al.
(författare)
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Biodegradable porous FeMn(-xAg) alloys: assessment of cytocompatibility, mechanical, magnetic and antibiofilm properties
- 2023
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Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 4:2, s. 616-630
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Tidskriftsartikel (refereegranskat)abstract
- In this work, porous FeMn(-xAg) alloys are fabricated through powder metallurgy methods. The effects of porosity and Ag addition on the microstructure, biodegradability, magnetic and mechanical properties of the alloys are investigated. Studies on the cytocompatibility, inflammatory cytokine response and antibacterial effect are also conducted. The fabricated alloys exhibit a macro- and nanoporous structure, with uniformly distributed silver particles. The biodegradability tests reveal that the release of Mn to the Hank's solution is higher than that of Fe, without significant differences between the alloys. The degradation products consist mainly of Fe, Mn, O and compounds enriched in Ca, P and Cl. As-sintered alloys show a low saturation magnetization value (below 1 emu g−1), which does not increase significantly with immersion time. The results on biocompatibility indicate that all tested alloys are non-cytotoxic, but the addition of Ag might interfere with cell proliferation. However, the ions released by the FeMn(-xAg) alloys do not induce an inflammatory response in macrophages. The obtained results on microbiological interactions reveal that although no significant bactericidal effect is observed at 4 h between FeMn control and FeMn-5Ag, a significant reduction in the total biofilm biomass of both live and dead bacteria is observed after 24 h in Ag containing FeMn-5Ag surfaces.
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| 3. |
- Eiler, Konrad, et al.
(författare)
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Oxygen reduction reaction and proton exchange membrane fuel cell performance of pulse electrodeposited Pt–Ni and Pt–Ni–Mo(O) nanoparticles
- 2022
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Ingår i: Materials Today Energy. - : Elsevier Ltd. - 2468-6069. ; 27
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Tidskriftsartikel (refereegranskat)abstract
- Proton exchange membrane fuel cells (PEMFCs) are an important alternative to fossil fuels and a complement to batteries for the electrification of vehicles. However, their high cost obstructs commercialization, and the catalyst material, including its synthesis, constitutes one of the major cost components. In this work, Pt–Ni and Pt–Ni–Mo(O) nanoparticles (NPs) of varying composition have been synthesized in a single step by pulse electrodeposition onto a PEMFC's gas diffusion layer. The proposed synthesis route combines NP synthesis and their fixation onto the microporous carbon layer in a single step. Both Pt–Ni and Pt–Ni–Mo(O) catalysts exhibit extremely high mass activities at oxygen reduction reaction (ORR) with very low Pt loadings of around 4 μg/cm2 due to the favorable distribution of NPs in contact with the proton exchange membrane. Particle sizes of 40–50 nm and 40–80 nm were obtained for Pt–Ni and Pt–Ni–Mo(O) systems, respectively. The highest ORR mass activities were found for Pt67Ni33 and Pt66Ni32–MoOx NPs. The feasibility of a single-step electrodeposition of Pt–Ni–Mo(O) NPs was successfully demonstrated; however, the ternary NPs are of more amorphous nature in contrast to the crystalline, binary Pt–Ni particles, due to the oxidized state of Mo. Nevertheless, despite their heterogeneous nature, the ternary NPs show homogeneous behavior even on a microscopic scale. © 2022 The Author(s)
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| 4. |
- Kovalska, Natalia, et al.
(författare)
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Electrodeposition of Soft Magnetic Fe-W-P Alloy Coatings from an Acidic Electrolyte
- 2023
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Ingår i: Coatings. - 2079-6412. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Fe-W-P coatings were deposited from a newly developed electrolytic bath. The effect of plating parameters, such as electrolyte current density and pH has been studied. It was found that the pH has a very strong effect on the phosphorous content of the coatings. Metallic-like, non-powdery alloys of Fe-W-P deposits with no cracks (lowly stressed) can be obtained at a lower pH (<3), exhibiting high phosphorus (up to 13 at.%) and low tungsten (6 at.%) contents. At a higher pH (>3), the composition changes to low phosphorus and high tungsten content, showing a matte, greyish, and rough surface. The applied current density also influences the morphology and the amount of phosphorous content. The deposits showed an amorphous structure for all samples with soft ferromagnetic properties.
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| 5. |
- Mulone, Antonio, 1989, et al.
(författare)
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Effect of heat treatments on the mechanical and tribological properties of electrodeposited Fe–W/Al2O3 composites
- 2020
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Ingår i: Wear. - : Elsevier BV. - 0043-1648. ; 448-449
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the influence of heat treatment on the mechanical and tribological properties of electrodeposited Fe–W/Al2O3 composite coatings is studied. The properties of the as-deposited and annealed composites are compared with those of electrodeposited hard chromium coatings. The amorphous structure of the Fe–W matrix transforms into a mixed amorphous-crystalline structure upon annealing at 600 °C for 1 h. The observed microstructural transformations result in a substantial increase of both the hardness and the reduced Young's modulus of the Fe–W/Al2O3 composite coatings, reaching values of 16.3 GPa and 191.7 GPa, respectively. The results on the wear resistance studied under dry friction using ball-on-disc sliding tests show that a low wear rate is obtained for both as-deposited and annealed composite coatings, i.e. ~1.5 × 10−6 mm3/Nm. In contrast, the heat treatments are detrimental for both the hardness and wear resistance of hard chromium coatings. As a consequence, the mechanical and wear properties of the electrodeposited Fe–W/Al2O3 composite coatings, especially after annealing, are superior to the properties of hard chromium coatings. Hence, Fe–W/Al2O3 composite coatings can be considered as a valid and sustainable alternative to hard chromium coatings, particularly in applications where these materials may be exposed to high temperatures.
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