National Science Foundation Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A & T State University, Greensboro, NC 27411, USA; Key Laboratory of Advanced Technologies of Materials, Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.
National Science Foundation Engineering Research Center for Revolutionizing Metallic Biomaterials, North Carolina A & T State University, Greensboro, NC 27411, USA.
Acta Biomater. 2014 Dec;10(12):5213-5223. doi: 10.1016/j.actbio.2014.08.034. Epub 2014 Sep 6.
The aim of this work was to study corrosion behavior of magnesium (Mg) alloys (MgZnCa plates and AZ31 stents) under varied fluid flow conditions representative of the vascular environment. Experiments revealed that fluid hydrodynamics, fluid flow velocity and shear stress play essential roles in the corrosion behavior of absorbable magnesium-based stent devices. Flow-induced shear stress (FISS) accelerates the overall corrosion (including localized, uniform, pitting and erosion corrosions) due to the increased mass transfer and mechanical force. FISS increased the average uniform corrosion rate, the localized corrosion coverage ratios and depths and the removal rate of corrosion products inside the corrosion pits. For MgZnCa plates, an increase of FISS results in an increased pitting factor but saturates at an FISS of ∼0.15Pa. For AZ31 stents, the volume loss ratio (31%) at 0.056Pa was nearly twice that (17%) at 0Pa before and after corrosion. Flow direction has a significant impact on corrosion behavior as more severe pitting and erosion corrosion was observed on the back ends of the MgZnCa plates, and the corrosion product layer facing the flow direction peeled off from the AZ31 stent struts. This study demonstrates that flow-induced corrosion needs be understood so that Mg-based stents in vascular environments can be effectively designed.
本工作旨在研究血管环境中具有代表性的多种流体流动条件下镁（Mg）合金（MgZnCa 板和 AZ31 支架）的腐蚀行为。实验表明，流体动力学、流速和切向应力对可吸收镁基支架装置的腐蚀行为起着重要作用。由于传质和机械力的增加，流动诱导切向应力（FISS）加速了整体腐蚀（包括局部、均匀、点蚀和侵蚀腐蚀）。FISS 增加了平均均匀腐蚀速率、局部腐蚀覆盖率和深度以及腐蚀坑内腐蚀产物的去除率。对于 MgZnCa 板，FISS 的增加导致点蚀因子增加，但在约 0.15Pa 的 FISS 处饱和。对于 AZ31 支架，腐蚀前后在 0.056Pa 时的体积损失率（31%）几乎是在 0Pa 时（17%）的两倍。流动方向对腐蚀行为有显著影响，因为在 MgZnCa 板的后端观察到更严重的点蚀和侵蚀腐蚀，并且面向流动方向的 AZ31 支架支柱上的腐蚀产物层剥落。本研究表明，需要了解流动诱导腐蚀，以便能够有效地设计血管环境中的镁基支架。
