镁合金表面超疏水涂层的构建及其腐蚀行为

发布时间：2018-03-27 18:46

本文选题：镁合金　切入点：预处理　出处：《哈尔滨工业大学》2017年博士论文

【摘要】：镁合金作为生物医用可降解材料的研究逐渐成为近年来的研究热点,但是镁合金低的耐蚀性能限制了其在生物医用材料领域的广泛应用。为解决这一关键问题,本文采用阴极电沉积的方法在镁合金表面构建疏水/超疏水涂层以提高其耐蚀性能。同时为改善涂层与镁合金之间的界面结合,在镁合金表面进行先期预处理来调整合金表面状态。系统地研究了镁合金表面状态、涂层制备过程中阳极板材的选择、沉积溶液中阴离子的种类以及电沉积参数对涂层表面形态的影响,实现了对涂层表面状态的调控,并揭示了涂层的形成机制。详细研究了各工艺参数对涂层电化学腐蚀行为的影响规律,阐明了涂层在模拟体液中的腐蚀降解规律及其对镁合金的腐蚀抑制作用。研究发现,镁合金表面预处理强烈地影响疏水涂层的形貌、厚度以及润湿性,但并未影响涂层的物相组成。由于等离子体电解氧化层导电性差,疏水涂层不能直接沉积在等离子体电解氧化的镁合金表面,但疏水涂层易于在刻蚀的等离子体电解氧化、阳极氧化以及水热处理的镁合金基体表面沉积。预处理层对整个涂层体系的耐蚀性能有很大影响,经过刻蚀后的等离子体电解氧化预处理层为整个涂层体系提供了最好的耐蚀性能。这是由于该预处理在镁合金表面形成了一个致密的内层,且该预处理层厚度最大,从而提高了涂层/预处理层及预处理层/镁合金的界面稳定性,阻止了腐蚀介质中离子的渗入。无论在何种电沉积条件下制备涂层,电流密度随着沉积时间的延长均呈现出下降和保持不变两个阶段,分别对应于涂层在基体表面的形核与生长阶段。所制备的涂层表面形貌均表现出了微米纳米多级结构,这种结构的变化直接影响涂层的疏水/超疏水性能。涂层的制备工艺参数明显影响涂层的形貌、厚度以及疏水性能,但并未对涂层的相结构产生影响。涂层在模拟体液中是可降解的,浸泡后涂层的相组成由原来的C36H70Ca O4转变为C36H70Ca O4·H2O。涂层的制备工艺参数显著地影响它的耐蚀性能。当施加50V直流沉积电压,分别沉积15min、60min和120min时,涂层电化学交流阻抗谱在模拟体液浸泡过程中由两个时间常数演化为三个时间常数,出现第三个时间常数(电化学双电层)的时间分别为浸泡12h、24h和12h。此外,与其它沉积时间相比,沉积60min所制备的涂层具有最高的涂层电阻、阳极氧化层电阻以及电荷转移电阻,表明该涂层具有最好的耐蚀抗力。当施加脉冲电压(占空比为50%)沉积60min时,施加100V和20V沉积电压获得的涂层分别在浸泡1h和12h后出现了三个时间常数,施加50V电压所得涂层在48h后才出现第三个时间常数,说明该电压下获得的涂层能为基体提供最好的保护。涂层沉积过程中电压的加载方式强烈地影响涂层的耐蚀性能。当在相同的沉积电压(50V)下沉积60min时,直流方式加载获得涂层的电化学阻抗谱出现低频对应的电化学双电层的浸泡时间为24h,而脉冲方式加载时得到涂层出现电化学双电层的时间为48h。在相同沉积电压与沉积时间条件下加载脉冲电压时获得涂层耐蚀能力更强。无论是在直流电压还是脉冲电压下沉积涂层,涂层的耐蚀性能均随电压(或时间)的增加呈现先增加后降低的趋势,且当沉积时间为60min,沉积电压为50V时得到的涂层具有最优异的耐蚀性能。这主要是由于随沉积电压(或时间)的增加,涂层的表面形貌、厚度以及润湿性均会发生相应变化,它们的共同作用贡献于涂层的耐蚀性能。在生理环境中,阳极氧化预处理镁合金和超疏水涂层培养过程中生理溶液p H值变化和渗透压变化表现出了相似的规律,二者均表现出较高的降解抗力。与氧化层相比,超疏水涂层能为基体提供更好的降解抗力。预处理Mg O氧化层提高了成骨细胞的增殖,但并未增加其分化。相反,超疏水涂层减少了成骨细胞的增殖,但促进了成骨细胞的分化。
[Abstract]:Magnesium alloys as biomedical research on degradable materials has become a research hotspot in recent years, but the corrosion resistance of magnesium alloy low limit its application in the field of biomedical materials. To solve this key problem, this paper uses the method of cathodic electrodeposition on the surface of the magnesium alloy of hydrophobic / super hydrophobic coating to improve at the same time. In order to improve the corrosion resistance of magnesium alloy and the interface between the coating and the combination of pre treatment on the surface of magnesium alloy to adjust alloy surface. Systematic study of the state of the surface of magnesium alloy and preparation of coating anode plate in the process of selection, effect of anion in the deposition solution type and electrodeposition parameters on the coating surface morphology the implementation of the regulation of the state on the surface of the coating, and reveals the formation mechanism of the coating was studied. The effects of process parameters on the electrochemical corrosion behavior of the coatings. Law, clarify the corrosion degradation of coatings in simulated body fluid and its inhibitory effect on Corrosion of magnesium alloy. The study found that magnesium alloy surface pretreatment strongly influence the morphology of hydrophobic coating, thickness and wettability, but did not affect the coating phase composition. The plasma electrolytic oxidation layer of conductive, hydrophobic coating can not be directly deposited on the surface of magnesium alloy by plasma electrolytic oxidation, but the hydrophobic coating easily in plasma electrolytic oxidation etching, anodic oxidation and hydrothermal treatment of magnesium alloy surface deposition. Pretreatment have great influence on the corrosion properties of the coating system layer by etching after plasma electrolytic oxidation pretreatment layer for the entire coating system provides the best corrosion resistance. This is due to the pretreatment on the surface of magnesium alloy to form a dense inner layer, and the thickness of the pretreatment, from To improve the coating / pretreatment layer and interface stability of pretreatment of magnesium alloy layer / prevent ion corrosion medium infiltration. No matter what the electrodeposition coating was prepared under the condition of current density, with the increase of the deposition time were decreased and maintained two stages unchanged, respectively corresponding to the coating on the substrate the surface of the nucleation and growth stage. The surface morphology of coatings showed the micro nano hierarchical structure, the change of the structure directly affect the coating hydrophobic / super hydrophobic properties. The process parameters for preparing coating significantly affected the morphology of the coatings, and the thickness of the hydrophobic properties, but not on the phase structure of coating effect of coating is biodegradable. After soaking in SBF, the coating phase composition of the preparation parameters changed from C36H70Ca O4 to C36H70Ca O4 H2O. the influence of the coating corrosion resistance significantly. When applying it With 50V DC deposition voltage, deposition of 15min and 120min respectively, 60min coating, electrochemical impedance spectroscopy in the SBF process by two time constants for the evolution of three time constants, third time constants (electrochemical double layer) time respectively for 12h, 24h and 12h., in addition, compared with the other the deposition time, deposition of 60min coatings prepared with the highest resistance coating, anodic oxidation layer resistance and charge transfer resistance, corrosion resistance shows that the coating has the best. When the applied pulse voltage (50% duty cycle) deposition of 60min, 100V and 20V applied coating deposition voltage obtained by immersion in 1H and 12h respectively after the three time constants, 50V voltage is applied to the coating of third time constants appeared in 48h after coating the voltage to provide the best protection to the matrix. The coating deposition voltage sink The loading modes strongly affect the corrosion resistance of the coatings. When the deposition voltage (50V) under the same deposition 60min, DC load for electrochemical impedance spectrum of double coating immersion time frequency corresponding to the electrodeposition layer is 24h, and the pulse load is obtained when the coating layer of the electric double layer time the corrosion resistance of 48h. coating is stronger at the same deposition voltage and deposition time under the condition of loading. When the pulse voltage in the DC voltage or under voltage pulse deposited coatings, the corrosion resistance of coatings increases with the voltage (or time) increased with the increased first and then decreased, and when the deposition time of 60min coating deposition voltage 50V has been the most excellent corrosion resistance. This is mainly due to the deposition voltage (or time) increases, the surface morphology of the coating thickness and wettability are corresponding changes, The corrosion resistance of their interactions contribute to the coating. In physiological environments, anodic oxidation pretreatment of magnesium alloy and super hydrophobic coating during the culture solution of P H changes and physiological change of osmotic pressure in exertedoxidation, two showed higher degradation resistance. Compared with the oxide layer, super hydrophobic the coating can provide better degradation resistance as the matrix. Pretreatment of Mg O oxide layer improves the proliferation of osteoblasts, but did not increase its differentiation. On the contrary, the super hydrophobic coating reduces the proliferation of osteoblasts, but promoted osteoblast differentiation.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG174.4

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