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%0 Thesis %A Nachtsheim, Julia Alessandra %T In vitro corrosion behaviour of biodegradable magnesium implants %V 25 %N 25 %I Rheinisch-Westfälische Technische Hochschule Aachen %V Dissertation %C Aachen %M RWTH-2025-08712 %M 25 %B Report. Institute of General Mechanics / Institut für Allgemeine Mechanik (IAM) %P 1 Online-Ressource : Illustrationen %D 2025 %Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University %Z Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2025 %X Biodegradable magnesium implants can potentially resolve major challenges of conventional implant technologies. They provide mechanical support to the fracture site and gradually degrade within the body. This can eliminate the need for an implant-removal surgery, which is beneficial to the patient and to healthcare systems. Magnesium alloys are especially suitable for bone fracture treatments, as they are highly biocompatible and possess mechanical properties similar to those of native bone. Their similar elastic moduli improves load transfer. Thereby, the recovering bone is continuously subjected to physiological stresses. This reduces the risk of stress-shielding and pathological tissue development. Their broad application, however, is limited by their fast material degradation in physiological conditions, which can cause harmful side effects and can result in catastrophic implant failure. In this context, research and development efforts are required to establish in-depth understanding of the relevant degradation processes and to derive strategies to overcome these limitations. The aim of this thesis is to systematically study the in vitro corrosion behaviour of a biodegradable magnesium alloy WE43, which is currently under development for load-bearing implant applications. The material is alloyed with rare-earth elements, and a PEO coating is applied for an improved protection against corrosion. For this purpose, experimental in vitro studies were conducted to assess the degradation behaviour of the material under different external load protocols. In service conditions, the implant is exposed to considerable mechanical loadings and aggressive physiological corrosion environments. This combination triggers adverse mechano-chemical interactions, which accelerate material degradation. Hence, understanding the underlying mechanisms is particularly important. The experimental results reveal a localised corrosion process of WE43, which can be attributed to the fine and evenly dispersed secondary phases. The barrier effect of the coating fully preserves the mechanical integrity for 14 days and delays the degradation process for longer periods. Under constant loadings, a critical stress level is identified, which leads to a high probability of failure in the short term. The protection of the coating against material degradation is limited to its undamaged state. High local stresses trigger coating damage, which adds another source for material failure. Under very slow and continuously increasing straining in slow strain rate testing, the material suffered significant embrittlement. Synergetic mechanisms of corrosion and crack propagation are revealed on fracture surfaces. In corrosion-fatigue experiments, the fatigue performance is considerably reduced and the failure mode changes in comparison to the pristine alloy. The experimental findings provide valuable information on the environmentally assisted mechanisms. Based on the experimental results, strategies for further improving the material’s functionality are derived and some findings can be translated into recommendations for therapeutic strategies. %F PUB:(DE-HGF)11 ; PUB:(DE-HGF)3 %9 Dissertation / PhD ThesisBook %R 10.18154/RWTH-2025-08712 %U https://publications.rwth-aachen.de/record/1020004