生物医用镁合金表面电沉积硅烷改性研究

发布时间：2019-04-21 09:42

【摘要】：镁合金具有优异的力学相容性、生物相容性和可降解性,在临床医学领域中有广阔的应用前景,但过快的腐蚀速度严重制约了其医学应用。金属表面硅烷化是近年来迅速发展起来的一种绿色环保型腐蚀防护技术,在不锈钢、铝合金及镁合金等多种金属材料表面已成功应用。本文采用电化学辅助沉积(电沉积)方法对AZ31B镁合金进行硅烷化处理,通过电化学工作站、扫描电子显微镜、能谱仪等仪器设备及体外模拟降解实验,研究了KH-560、KH-570和BTSE三种硅烷在沉积过程中的最佳添加量,并横向比较了相同电沉积工艺下三种硅烷膜对镁合金耐蚀性能的影响；在三种硅烷各自最佳添加量的基础上,分别添加纳米二氧化硅颗粒和铈盐离子对三种硅烷膜进行改性,研究了改性前后硅烷膜耐蚀性能的变化。经研究发现：采用电沉积方法在AZ31B镁合金表面成功制备出了KH-560、KH-570和BTSE三种硅烷膜。48h体外模拟体液浸泡降解实验表明,三种硅烷膜均能有效延缓镁合金的降解速率,硅烷膜优先发生点腐蚀,其中KH-570硅烷膜厚度最大、结构致密且较为均匀,其耐蚀性能最佳。动电位极化曲线测试表明,镁合金表面电沉积三种硅烷膜后,自腐蚀电位提高,自腐蚀电流密度大幅度下降。KH-560、KH-570和BTSE三种硅烷在镁合金表面电沉积处理过程中存在最佳添加量,分别为6ml、8ml、4ml。镁合金经KH-560、 KH-570和BTSE三种硅烷电沉积处理后具有相似阻抗谱特征：在Nyquist图中,高频区和中低频区各有一个容抗弧,前者半径更大,而最低频段裸镁合金所具有的感抗弧消失；在阻抗-频率Bode图中,硅烷化处理后低频阻抗值大幅增大,耐蚀性能有效提升；在相位角-频率Bode图中,三种硅烷在各自最佳添加量下低频相位角值较大,峰值趋向于低频范围,而在中频区和高频区,硅烷化使得相位角值稳定提升,表明膜层中Si-O-Si键和Mg-O-Si键结合紧密。采用ZSimpWin电化学分析软件建立了表面硅烷化镁合金的等效电路模型(ECM),发现最佳添加量下,KH-570硅烷膜层C。值稳定在10-7 F.cm-2量级,硅烷膜层厚度最大,耐蚀性能最佳。添加纳米二氧化硅颗粒或铈盐离子改性物质,能够进一步提升KH-560、KH-570和BTSE三种硅烷膜对AZ31B镁合金耐腐蚀性能的改进效果。与纳米二氧化硅颗粒相比,铈盐离子具有更显著的改性作用,其可以通过电化学辅助沉积与硅烷膜起到协同作用,使硅烷膜层具有一定的自修复能力,有效增加膜层厚度、降低膜层孔隙率。
[Abstract]:Magnesium alloys have excellent mechanical compatibility, biocompatibility and biodegradability, and have broad application prospects in the field of clinical medicine. However, the rapid corrosion rate seriously restricts its medical application. Silanization is a green and environmentally friendly corrosion protection technology which has been developed rapidly in recent years. It has been successfully applied on stainless steel, aluminum alloy and magnesium alloy and so on. In this paper, AZ31B magnesium alloy was silanized by electrochemical assisted deposition (ECD) method. KH-560, was studied by electrochemical workstation, scanning electron microscope, energy spectrometer and other instruments, and simulated degradation experiments in vitro. The optimum addition of KH-570 and BTSE in the deposition process were compared. The effects of three silanes films on the corrosion resistance of magnesium alloy were compared in the same electrodeposition process. On the basis of adding nano-silica particles and cerium ions, three kinds of silane membranes were modified by adding nano-silica particles and cerium ions respectively, and the changes of corrosion resistance of silane films before and after modification were studied. It was found that three kinds of KH-560,KH-570 and BTSE silicane films were successfully prepared on the surface of AZ31B magnesium alloy by electrodeposition. 48 h simulated humoral immersion degradation experiments showed that all of them could effectively delay the degradation rate of magnesium alloys. Among them, the thickness of KH-570 silicone film is the largest, its structure is dense and uniform, and its corrosion resistance is the best. The potentiodynamic polarization curves show that the corrosion potential increases and the corrosion current density decreases greatly after electrodeposition of three kinds of silanes on the surface of magnesium alloy. KH-560, The best addition amount of KH-570 and BTSE is 6ml, 8ml and 4ml respectively in the electrodeposition process of magnesium alloy surface. Magnesium alloys have similar impedance spectra after electrodeposition of KH-560, KH-570 and BTSE. In the Nyquist diagram, there is a capacitive arc in the high frequency region and the low frequency region, and the radius of the former is larger than that in the low frequency region. However, the induction arc of bare magnesium alloy in the lowest frequency band disappears. In the impedance-frequency Bode diagram, the low-frequency impedance value increases greatly after silylation treatment, and the corrosion resistance is improved effectively. In the phase angle-frequency Bode diagram, the low-frequency phase angle of the three silanes is larger and the peak value tends to the low-frequency range, but in the medium-frequency region and the high-frequency region, the phase angle is steadily increased by silanization, and the phase angle is increased steadily by silanization in the medium-frequency region and high-frequency region. The results show that the Si-O-Si bond and the Mg-O-Si bond are closely bound in the film. The equivalent circuit model of magnesium silanide alloy surface was established by means of ZSimpWin electrochemical analysis software. It was found that under the optimal addition of KH-570 silane film C. The value is stable in the order of 10 ~ 7 F.cm-2, the thickness of silane film is the largest, and the corrosion resistance is the best. The addition of nano-silica particles or cerium ions can further improve the corrosion resistance of AZ31B magnesium alloy with KH-560,KH-570 and BTSE silicone films. The results show that the corrosion resistance of AZ31B magnesium alloy can be improved by adding nano-Sio _ 2 particles or cerium ions. Compared with nano-silica particles, cerium ion has more obvious modification effect. It can cooperate with silane film by electrochemistry-assisted deposition, so that the silicone film layer has certain self-repairing ability, and the thickness of the film can be increased effectively. The porosity of the film was decreased.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG174.4;R318.08

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