Abstract Corrosion behaviour of polymer coated Mg alloy screw is compared with a laboratory coupon with emphasis on the adhesion of coating to surface features such as threads. The corrosion behaviour of poly (e-caprolactone) (PCL) coated commercial pure Mg (CP Mg) and Mg-4Zn-0.2Ca alloy in simulated body fluid (SBF) is investigated. CP Mg with a high corrosion rate (8.426 mmyr− 1) formed large amount of corrosion products on the surface which pushed out the PCL layer. In contrast the Mg-4Zn-0.2Ca alloy with a corrosion rate of 2.481 mmyr− 1 held the PCL coating intact for up to 72 h. Fully and partially threaded screws of the Mg-4Zn-0.2Ca alloy were fabricated and coated with PCL. It was found that pH variation of the medium depends on PCL adhesion to screw, which was better in the threaded regions than in smoother areas. As a result, the fully threaded screws showed slower pH rise than partial threaded ones. The crests and troughs of the threads act as anchoring points for the polymer. It was found in the current study that the increased adhesion of PCL coating to threaded Mg alloy substrate dominates over the increased corrosion rates of threaded surface.

中文翻译：

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植入物涂层：研究镁基实验室试样和最终组件的 PCL 涂层之间的异同

摘要 聚合物涂层镁合金螺杆的腐蚀行为与实验室试样进行了比较，重点是涂层对螺纹等表面特征的附着力。研究了聚（ε-己内酯）（PCL）涂层商业纯镁（CP Mg）和 Mg-4Zn-0.2Ca 合金在模拟体液（SBF）中的腐蚀行为。具有高腐蚀速率 (8.426 mmyr−1) 的 CP Mg 在表面形成大量腐蚀产物，将 PCL 层推出。相比之下，腐蚀速率为 2.481 mmyr-1 的 Mg-4Zn-0.2Ca 合金使 PCL 涂层保持完整长达 72 小时。Mg-4Zn-0.2Ca 合金的全螺纹和部分螺纹螺钉被制造并涂有 PCL。发现介质的 pH 值变化取决于 PCL 对螺钉的附着力，在螺纹区域比在光滑区域更好。因此，全螺纹螺钉比部分螺纹螺钉显示出更慢的 pH 值上升。螺纹的波峰和波谷充当聚合物的锚固点。在目前的研究中发现，PCL 涂层对螺纹镁合金基材的附着力增加超过了螺纹表面腐蚀速率的增加。