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    骨科用选区激光熔化成形TC4钛合金表面仿生复合涂层的制备及性能

    Preparation and Performance of Biomimetic Composite Coating on Selective Laser Melting Forming TC4 Titanium Alloy Surface for Orthopedic Grade

    • 摘要: 在选区激光熔化成形TC4钛合金上通过氧化自聚合法生成聚多巴胺(PDA)膜层,随后电沉积羟基磷灰石(HA)形成PHA仿生复合涂层,通过三因素三水平正交试验,研究了电流密度(5,10,15 mA·cm−2)、沉积时间(5,10,15 min)和沉积温度(20,30,40 ℃)对涂层耐腐蚀性和耐磨性的影响,并对涂层显微组织和生物相容性进行表征。结果表明:均匀致密PDA膜层对HA的沉积具有促进作用,PHA复合涂层的黏结强度相比直接沉积HA涂层增加了41.18%;对PHA复合涂层自腐蚀电流密度和摩擦时间(电位变化区间经历的时间,表征耐磨性)的影响程度按由大到小排序均依次为电流密度、沉积温度、沉积时间;随着电流密度增加,涂层结构发生破坏,导致自腐蚀电流密度增大,摩擦时间缩短;随着沉积时间延长,涂层先趋向均匀致密后变疏松,自腐蚀电流密度先减小后增大,摩擦时间先延长后缩短;随着沉积温度升高,涂层趋向均匀致密,与基体结合力增大,自腐蚀电流密度先增大后减小,摩擦时间延长;最佳工艺参数组合为电流密度5 mA·cm−2、沉积时间10 min、沉积温度 40 ℃,此条件下制备涂层的自腐蚀电流密度最小,摩擦时间最长,腐蚀防护率高达98.2%,耐腐蚀性和耐磨性最好,表面黏附细胞数量和细胞伪足数量较多,生物相容性更好。

       

      Abstract: A polydopamine (PDA) film was prepared on laser selective melting froming TC4 titanium alloy by oxidation self-polymerization, and then hydroxyapatite (HA) was electrodeposited to form a PHA biomimetic composite coating. Through the three-factor three-level orthogonal experiment, the effects of current density (5, 10, 15 mA · cm−2), deposition time (5, 10, 15 min) and deposition temperature (20, 30, 40 ℃) on the corrosion resistance and wear resistance of the coating were studied. The microstructure and biocompatibility of the coating were characterized. The results show that the uniform and dense PDA film had a promoting effect on the deposition of HA. Compared with that of the directly deposited HA coating, the bonding strength of PHA composite coating increased by 41.18%. The influence degree on the self-corrosion current density and friction time (the time elapsed during the interval of potential change, for characterizing wear resistance) of PHA composite coating was ranked from large to small as current density, deposition temperature and deposition time. With the increase of current density, the coating structure was destroyed, resulting in an increase in the self-corrosion current density and shortening of the friction time. With the extension of deposition time, the coating tended to be uniform and dense first and then became loose, the self-corrosion current density decreased first and then increased, and the friction time extended first and then shortened. As the deposition temperature increased, the coating became more uniform and dense, the bonding force with the substrate was enhanced, the self-corrosion current density first increased and then decreased, and the friction time extended. The optimal process parameter combination was current density of 5 mA · cm−2, deposition time of 10 min and deposition temperature of 40 ℃. Under this condition, the self-corrosion current density of the coating was the smallest, the friction time was the longest, and the corrosion protection rate was as high as 98.2%; the corrosion resistance and wear resistance were the best. Meanwhile, a large number of adhered cells and pseudopodia on the surface of the PHA composite coating, shaving better biocompatibility.

       

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