镁表面Ca-P生物涂层在腐蚀与磨损协同作用下降解机理研究

Magnesium has been suggested as a revolutionary biodegradable metal for use as an orthopaedic material. However, the degradation of magnesium is a little rapid. Therefore, it is necessary to control the degradation rates of the materials to match the rates of bone healing. In response, calcium phosphate coatings by microarc oxidation(MAO) technology have been suggested as a means to control these degradation rates. However, the synergism between corrosion and wear of Ca-P coating on Mg alloy in simulated body fluid need to be investigated systematically. In this project, Ca-P coating will be prepared on Mg alloys using MAO under appropriate electrical parameters, electrolyte composition and concentration, and oxidation time. Surface analysis technology is employed to determine the composition, chemical state of elements, surface morphology, thickness, hardness and adhesion of the Ca-P coatings, at the same time, the influence of MAO parameters on the surface characteristics is investigated. The wear-corrosion properties are studied on a tribocorrosion tester under various loads and sliding distance . The degradation mechanism under synergism between corrosion and wear is discussed and explored through the analysis of corrosion and wear products, and a physical model will be further established. The expected results will provide theoretical foundation and application instructions for the use of Ca-P coating as orthopaedic devices in vivo applications.

镁及其合金作为骨修复固定器件的金属材料在生物医学上的应用越来越受研究人员的亲睐，但镁的降解速度过快，因此必须控制镁的降解速率用以匹配骨愈合率。微弧氧化钙磷酸盐（Ca-P）涂层是一种控制镁降解速率的有效手段。然而，镁合金Ca-P涂层在仿生液中在腐蚀与磨损协同作用下的降解机理尚不深入和全面。本项目以AZ31镁合金为研究对象，采用微弧氧化技术，配制合适浓度和成分的钙源和磷源电解液，选择合适的过程参数制备Ca-P涂层；采用表面分析技术确定涂层的成分，元素的化学态，表面形貌，厚度，硬度及结合力，考察参数对Ca-P涂层性能的影响；在仿生液里进行不同载荷及滑动距离的腐蚀与磨损协同作用规律研究，通过腐蚀和磨损产物的表面形貌及成分探讨镁合金Ca-P涂层在腐蚀与磨损协同作用下的降解机理，并建立其物理模型。预期研究成果对镁合金Ca-P涂层作为骨固定器件在人体里的降解行为提供理论依据与应用指导。

镁及其合金具有优良的生物相容性和生物降解性，因此作为骨修复固定器件材料有着明显的性能优势和广阔的应用前景。但镁合金的可降解性是一把双刃剑，降解速度过快阻碍了镁合金在临床上的应用。本项目针对镁合金表面Ca-P涂层在腐蚀和磨损共同作用下的降解机理进行了研究，取得了一系列成果，发表论文11篇，其中被SCI/EI收录6篇。本项目采用微弧氧化技术，在AZ31镁合金基体上，配制合适浓度和成分的钙源和磷源电解液，选择合适的过程参数制备了Ca-P涂层；采用表面分析技术确定了涂层的成分，元素的化学态，表面形貌，厚度，硬度及结合力，考察了参数对Ca-P涂层性能的影响；获得了结合力强，均匀微观表面形貌的Ca-P涂层；在不同PH值的仿生液里进行了不同载荷、频率和时间的磨损作用规律研究，初步分析了磨损机理；采用电化学工作站对涂层进行了动电位极化曲线和电化学阻抗的研究，确定了不同参数下制备的Ca-P涂层的腐蚀电流密度、腐蚀电位和电化学阻抗，对其腐蚀规律进行了研究。还研究了其在磨损状态下的腐蚀特性，分析了不同的表面处理对磨损腐蚀的影响规律；再结合腐蚀和磨损产物的表面形貌及成分探讨了镁合金Ca-P涂层在腐蚀与磨损协同作用下的降解机理，并建立了其物理模型。