Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK.
IMDEA Materials Institute, C/Eric Kandel 2, Getafe 28906, Madrid, Spain; Department of Material Science and Engineering, Universidad Carlos III de Madrid, Leganes 28911, Madrid, Spain.
Acta Biomater. 2023 Jul 1;164:641-658. doi: 10.1016/j.actbio.2023.04.011. Epub 2023 Apr 15.
A phase-field model is developed to simulate the corrosion of Mg alloys in body fluids. The model incorporates both Mg dissolution and the transport of Mg ions in solution, naturally predicting the transition from activation-controlled to diffusion-controlled bio-corrosion. In addition to uniform corrosion, the presented framework captures pitting corrosion and accounts for the synergistic effect of aggressive environments and mechanical loading in accelerating corrosion kinetics. The model applies to arbitrary 2D and 3D geometries with no special treatment for the evolution of the corrosion front, which is described using a diffuse interface approach. Experiments are conducted to validate the model and a good agreement is attained against in vitro measurements on Mg wires. The potential of the model to capture mechano-chemical effects during corrosion is demonstrated in case studies considering Mg wires in tension and bioabsorbable coronary Mg stents subjected to mechanical loading. The proposed methodology can be used to assess the in vitro and in vivo service life of Mg-based biomedical devices and optimize the design taking into account the effect of mechanical deformation on the corrosion rate. The model has the potential to advocate further development of Mg alloys as a biodegradable implant material for biomedical applications. STATEMENT OF SIGNIFICANCE: A physically-based model is developed to simulate the corrosion of bioabsorbable metals in environments that resemble biological fluids. The model captures pitting corrosion and incorporates the role of mechanical fields in enhancing the corrosion of bioabsorbable metals. Model predictions are validated against dedicated in vitro corrosion experiments on Mg wires. The potential of the model to capture mechano-chemical effects is demonstrated in representative examples. The simulations show that the presence of mechanical fields leads to the formation of cracks accelerating the failure of Mg wires, whereas pitting severely compromises the structural integrity of coronary Mg stents. This work extends phase-field modeling to bioengineering and provides a mechanistic tool for assessing the service life of bioabsorbable metallic biomedical devices.
开发了一个相场模型来模拟体液中镁合金的腐蚀。该模型结合了镁的溶解和镁离子在溶液中的传输，自然预测了从激活控制到扩散控制的生物腐蚀的转变。除了均匀腐蚀外，所提出的框架还捕获了点蚀，并考虑了腐蚀性环境和机械载荷在加速腐蚀动力学方面的协同作用。该模型适用于任意 2D 和 3D 几何形状，无需对腐蚀前沿的演化进行特殊处理，腐蚀前沿的演化使用弥散界面方法来描述。进行了实验来验证模型，并与 Mg 线的体外测量结果吻合良好。通过考虑拉伸中的 Mg 线和承受机械载荷的生物可吸收冠状 Mg 支架的案例研究，证明了该模型在捕获腐蚀过程中机械化学效应的潜力。所提出的方法可用于评估基于 Mg 的生物医学设备的体外和体内使用寿命，并考虑机械变形对腐蚀速率的影响来优化设计。该模型有可能进一步推动将 Mg 合金作为生物医学应用的可生物降解植入材料的发展。
开发了一种基于物理的模型来模拟类似于生物流体的环境中生物可吸收金属的腐蚀。该模型捕获了点蚀，并纳入了机械场在增强生物可吸收金属腐蚀方面的作用。通过专门针对 Mg 线的体外腐蚀实验对模型预测进行了验证。通过代表性示例证明了模型捕获机械化学效应的潜力。模拟表明，机械场的存在会导致裂纹的形成，从而加速 Mg 线的失效，而点蚀则严重破坏冠状 Mg 支架的结构完整性。这项工作将相场建模扩展到生物工程领域，并提供了一种用于评估生物可吸收金属生物医学设备使用寿命的机械工具。
