微弧氧化镁表面构建β-硅酸二钙基玻璃陶瓷水泥涂层及其长效耐蚀行为

The rapid corrosion and lower bioactivity of magnesium and its alloys as a hard tissue replacement and repair materials in physiological environment has limited their clinical applications. In the project, the β-dicalcium silicate-based bioglass ceramic cement /micro-arc oxidation coating is prepared on the surface of Mg by micro-arc oxidation and a dipping-pulling method. The effect of the process parameters on composition and corrosion resistant of the coatings have been investigated systematically. And the coating which possessed the excellent performance was built. By analysis of the decay law of mechanical properties and the corrosion behavior of the coating after soaking in SBF solution for different time. The corrosion failure mechanism of the MAO coating was study. This project will reveals mechanism that the degradation rate and strength degradation of the Mg is controlled by β-C2S-based bioglass ceramic cement coating. The biological activity controllable degradation mechanism of β-C2S-based bioglass ceramic cement coating will be preliminarily explored through the in vitro and in vivo experiments. And the mechanism of β-C2S-based bioglass ceramic cement coating on the growth of new bone was study. This study will effective control the degradation rate of magnesium in implantation stage, increase the biological activity and osteoinduction, and it provides a theoretical basis and experimental data for the further development and practical applications of the magnesium and its alloys materials for biomedical application.

镁在生理环境下过快的降解速率和较差的生物活性限制了其作为硬组织替换和修复材料在临床上的应用。本项目拟通过微弧氧化法、负压提拉浸渍封孔处理等手段在镁表面构建微弧氧化陶瓷膜层/β-硅酸二钙基玻璃陶瓷水泥涂层。拟系统研究微弧氧化技术和β-硅酸二钙基玻璃陶瓷水泥涂层制备的主要工艺参数对涂层组成及耐蚀性能的影响规律，综合优化构建表面涂层。通过对涂层在模拟体液中不同时期的耐蚀行为和力学强度衰变规律的分析，探索微弧氧化膜层的腐蚀失效机制，揭示水泥涂层组织结构对镁基体的可调控降解机制和力学强度退化的抑制效应与作用机理。拟通过体内外模拟实验，研究水泥涂层的生物活性以及对骨磷灰石诱导能力，揭示涂层激发新骨生成的形成机制。本项目的研究将有效控制医用镁在植入服役期的腐蚀降解速率，提高其生物活性和骨诱导性，为具有高经济附加值、高性能生物医用镁及镁合金材料的研制和应用提供重要的实验数据和理论基础。

本项目通过微弧氧化法、液相沉积法在镁表面构建微弧氧化陶瓷膜层/磷酸八钙涂层，通过对不同微弧氧化工艺参数及钙磷溶液pH值及沉积时间处理后的样品进行微观结构表征、耐蚀性能及体外生物活性测试，以探讨涂层对镁基体长效耐蚀性能和生物矿化性能的影响。.通过对不同微弧氧化（MAO）电解液，电压及时间处理后的纯镁试样进行测试发现最优电解液成分为九水硅酸钠，氢氧化钠，六偏磷酸钠，在450V、300s条件下微弧氧化镁的物相为Mg2SiO4和MgO，厚度可达14μm，其腐蚀电流密度为1.63×10-6低于纯镁2个数量级，在模拟体液浸泡7天后其腐蚀电流密度与浸泡前相比增加了4倍，14天后试样表面出现大量腐蚀坑较纯镁样品出现时间延长一倍。通过对85℃下pH为4.5的钙磷溶液处理不同时间的纯镁试样进行测试发现，沉积时间为3h的Ca-P涂层样品的体外生物活性及耐腐蚀性能优于24h试样。通过对85℃下不同pH值Ca-P溶液处理3h后的纯镁试样进行测试发现pH5.7条件下得到的钙磷涂层性能较优，5.7 Ca-P涂层由类菜花状晶簇外层和类片状晶体内层组成，厚度为6μm，其主要物相组成为磷酸八钙。5.7Ca-P / MAO涂覆镁在模拟体液中浸泡7天后的腐蚀电流密度低于纯镁的3倍。在模拟体液浸泡55天后镁基体依然完整，并且5.7Ca-P涂层能够诱导类骨磷灰石（HA）层沉积到样品表面，厚度可达85μm。该结果表明MAO层作为中间过渡层在体外模拟体液浸泡初期和中期阶段起到主要抗腐蚀作用，而OCP层和其诱导不断沉积的HA层在浸泡后期阶段起主要抗腐蚀作用。微弧氧化陶瓷膜层/磷酸八钙双层涂层能够提高纯镁在模拟生理环境下的持久耐蚀性、延缓其降解速率并提高其生物活性。.因此，本工作可为具有高经济附加值、高性能生物医用镁及镁合金材料的研制和应用提供重要的实验数据和理论基础。