Abstract：
UNASSIGNED: This study aims to investigate the effect of coating time on the formation of hydroxyapatite (HA) coating layer on ZK60 substrate and understand the biodegradation behavior of the coated alloy for biodegradable implant applications.
UNASSIGNED: Biodegradable ZK60 alloy was coated by HA layer for different times of 0.5, 1, 2, and 4 h by chemical conversion method. After coating, all the coated specimens were used for immersion test in Hanks\' solution to understand the effect of coating time on the degradation behavior of the alloy. The degradation rate of the coated alloy was evaluated by Mg2+ ion quantification and pH change during immersion test. The microstructure of the coating layer was examined by scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDS) before and after immersion to understand the degradation behavior of the coated alloy.
UNASSIGNED: HA coating layers were formed successfully on surface of ZK60 specimens after 0.5, 1, 2, and 4 h with different microstructure. Optimal coating quality was observed at 1 or 2 h, characterized by well-formed and uniform HA layers. However, extending the coating duration to 4 h led to the formation of cracks within the HA layer, accompanied by Mg(OH)2. Specimens coated for 1 and 2 h exhibited the lowest degradation rates, while specimens coated for 0.5 and 4 h showed the highest degradation rates. Furthermore, analysis of degradation products revealed the predominance of calcium phosphates formed on the surface of specimens coated for 1 and 2 h. Conversely, specimens coated for 0.5 and 4 h exhibited Mg(OH)2 as the primary degradation product, suggesting a less effective corrosion barrier under these conditions.
UNASSIGNED: The HA layer formed after 2 h demonstrated as the most effective coating layer for enhancing the corrosion resistance of the ZK60 alloy for biomedical applications.
UNASSIGNED: Biodegradable ZK60 alloy was coated by HA layer for different times of 0.5, 1, 2, and 4 h by chemical conversion method. After coating, all the coated specimens were used for immersion test in Hanks\' solution to understand the effect of coating time on the degradation behavior of the alloy. The degradation rate of the coated alloy was evaluated by Mg2+ ion quantification and pH change during immersion test. The microstructure of the coating layer was examined by scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDS) before and after immersion to understand the degradation behavior of the coated alloy.
UNASSIGNED: HA coating layers were formed successfully on surface of ZK60 specimens after 0.5, 1, 2, and 4 h with different microstructure. Optimal coating quality was observed at 1 or 2 h, characterized by well-formed and uniform HA layers. However, extending the coating duration to 4 h led to the formation of cracks within the HA layer, accompanied by Mg(OH)2. Specimens coated for 1 and 2 h exhibited the lowest degradation rates, while specimens coated for 0.5 and 4 h showed the highest degradation rates. Furthermore, analysis of degradation products revealed the predominance of calcium phosphates formed on the surface of specimens coated for 1 and 2 h. Conversely, specimens coated for 0.5 and 4 h exhibited Mg(OH)2 as the primary degradation product, suggesting a less effective corrosion barrier under these conditions.
UNASSIGNED: The HA layer formed after 2 h demonstrated as the most effective coating layer for enhancing the corrosion resistance of the ZK60 alloy for biomedical applications.
摘要：
■本研究旨在研究涂覆时间对ZK60基材上羟基磷灰石（HA）涂层形成的影响，并了解用于可生物降解植入物应用的涂覆合金的生物降解行为。
■通过化学转化方法将可生物降解的ZK60合金用HA层涂覆0.5、1、2和4h的不同时间。涂层后,所有涂层试样在Hanks溶液中进行浸泡试验，以了解涂层时间对合金降解行为的影响。通过Mg2+离子定量和浸渍试验过程中的pH变化来评估涂层合金的降解速率。在浸入前后，通过配备了能量色散X射线光谱（EDS）的扫描电子显微镜（SEM）检查了涂层的微观结构，以了解涂层合金的降解行为。
■在0.5、1、2和4h后，在ZK60试样的表面上成功形成了具有不同微观结构的HA涂层。在1或2小时时观察到最佳涂层质量，其特征在于形成良好且均匀的HA层。然而,将涂层持续时间延长至4小时导致HA层内形成裂纹，伴随Mg(OH)2。涂覆1和2小时的样品表现出最低的降解率，而涂覆0.5和4小时的样品显示出最高的降解率。此外，降解产物的分析表明，在涂覆1和2小时的样品表面上形成的磷酸钙占优势。相反，涂覆0.5和4小时的样品表现出Mg(OH)2作为主要降解产物，在这些条件下，这表明了一种不太有效的腐蚀屏障。
■在2小时后形成的HA层被证明是用于增强用于生物医学应用的ZK60合金的耐腐蚀性的最有效的涂层。
■通过化学转化方法将可生物降解的ZK60合金用HA层涂覆0.5、1、2和4h的不同时间。涂层后,所有涂层试样在Hanks溶液中进行浸泡试验，以了解涂层时间对合金降解行为的影响。通过Mg2+离子定量和浸渍试验过程中的pH变化来评估涂层合金的降解速率。在浸入前后，通过配备了能量色散X射线光谱（EDS）的扫描电子显微镜（SEM）检查了涂层的微观结构，以了解涂层合金的降解行为。
■在0.5、1、2和4h后，在ZK60试样的表面上成功形成了具有不同微观结构的HA涂层。在1或2小时时观察到最佳涂层质量，其特征在于形成良好且均匀的HA层。然而,将涂层持续时间延长至4小时导致HA层内形成裂纹，伴随Mg(OH)2。涂覆1和2小时的样品表现出最低的降解率，而涂覆0.5和4小时的样品显示出最高的降解率。此外，降解产物的分析表明，在涂覆1和2小时的样品表面上形成的磷酸钙占优势。相反，涂覆0.5和4小时的样品表现出Mg(OH)2作为主要降解产物，在这些条件下，这表明了一种不太有效的腐蚀屏障。
■在2小时后形成的HA层被证明是用于增强用于生物医学应用的ZK60合金的耐腐蚀性的最有效的涂层。
