@article{HornbergerKisselStriegletal., author = {Hornberger, Helga and Kissel, Hannah and Striegl, Birgit and Kronseder, Matthias and Vollnhals, Florian and Christiansen, Silke H.}, title = {Bioactivity and corrosion behavior of magnesium barrier membranes}, series = {Materials and Corrosion}, volume = {73}, journal = {Materials and Corrosion}, number = {1}, publisher = {Wiley}, doi = {10.1002/maco.202112385}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-24499}, pages = {8 -- 19}, abstract = {In the current research, magnesium and its alloys have been intensively studied as resorbable implant materials. Magnesium materials combine their good mechanical properties with bioactivity, which make them interesting for guided bone regeneration and for the application as barrier membranes. In this study, the in vitro degradation behavior of thin magnesium films was investigated in cell medium and simulated body fluid. Three methods were applied to evaluate corrosion rates: measurements of (i) the gaseous volume evolved during immersion, (ii) volume change after immersion, and (iii) polarization curves. In this comparison, measurements of H2 development in Dulbecco's modified Eagle's medium showed to be the most appropriate method, exhibiting a corrosion rate of 0.5 mm·year-1. Observed oxide and carbon contamination have a high impact on controlled degradation, suggesting that surface treatment of thin foils is necessary. The bioactivity test showed positive results; more detailed tests in this area are of interest.}, language = {en} } @article{KloiberSchultheissSoteloetal., author = {Kloiber, Jessica and Schultheiß, Ulrich and Sotelo, Lamborghini and Sarau, George and Christiansen, Silke and Gavras, Sarkis and Hort, Norbert and Hornberger, Helga}, title = {Corrosion behaviour of electropolished magnesium materials}, series = {Materials Today Communications}, journal = {Materials Today Communications}, edition = {Journal Pre-proof}, publisher = {Elsevier}, doi = {10.1016/j.mtcomm.2023.107983}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-68254}, abstract = {Although magnesium and its alloys are promising candidates as biodegradable implant materials, the tendency for localized corrosion mechanism in physiological environment limit their biomedical application. Electropolishing is an attractive strategy for improving the corrosion behaviour of metals, but it is still largely unexplored in magnesium materials. In this study, the characterization of electropolished surfaces of AM50 and pure magnesium was performed, focussing on their in vitro degradation behaviour in cell medium. Corrosion rates were evaluated using potentiodynamic polarisation. The surface morphology before and after the onset of corrosion was investigated by scanning electron microscopy and confocal laser scanning microscopy. The presented electropolishing process led to improved surface performances, observable by significantly lower corrosion rates (0.08 mm·year-1 in Dulbecco's modified Eagle's medium), lower arithmetical mean height (0.05 µm), lower water contact angle (25-35°) and lower micro hardness (35-50 HV 0.1) compared to mechanically and chemically treated surfaces. MgO/Mg(OH)2 could be detected on electropolished surfaces. The localized corrosion mode could be reduced, but not entirely prevented. Electropolishing shows great potential as post-treatment of magnesium-based components, but detailed tests of the long-term corrosion behaviour are an important area of future research.}, language = {en} } @article{TezelSchultheissHornbergeretal., author = {Tezel, Tugce and Schultheiss, Ulrich and Hornberger, Helga and Kovan, Volkan}, title = {Operational wear behaviour of 3D-printed lightweight metal gears: EDS and oil analysis comparison}, series = {Materials Testing}, volume = {66}, journal = {Materials Testing}, number = {6}, publisher = {de Gruyter}, issn = {0025-5300}, doi = {10.1515/mt-2023-0222}, pages = {830 -- 834}, abstract = {Additive manufacturing (AM) has come to the fore in recent years among manufacturing techniques. This technique, which has different advantages than traditional ones such as casting, forging and machining, is expected to be widely used in producing machine parts like gears in the coming years. Therefore, experimental data on AM parameters for lightweight metal gears are important for industrial production. In this study, a wear test was applied to AlSi10Mg and Ti6Al4V gears under operational conditions, and the wear behaviour of conventionally and additively manufactured gears was compared. The amount of abrasion elements was determined by analysing the oil in the gearbox. In addition, gear surfaces were analysed using scanning electron microscopy and an energy-dispersive spectrometer before and after wear. Thus, the wear behaviour of gears produced by conventional and AM under service conditions was demonstrated comparatively.}, language = {en} }