多孔镁表面微弧氧化涂层和氟化学转化涂层的对比研究

Comparative Study of Micro-arc Oxidation Coating and Fluorine-conversion Coating on Porous Magnesium Surface

目的多孔镁具有生物可降解特性,降解过程中产生的碱性环境会促进新生骨形成,其多孔结构可以为新生骨长入提供通道,是一种理想的骨填充材料。与块体镁相比,多孔镁的降解速率更快,为了避免因快速降解引起局部环境碱性过高而可能导致的溶骨现象,需要通过表面改性来降低多孔镁的降解速率,使其降解速率与骨组织愈合速率相匹配。方法以块体镁表面防护涂层研究为基础,根据前期研究结果和前人的研究结果筛选出一种效果较好的微弧氧化和氟化学转化涂层制备方法对多孔镁进行表面改性,以降低多孔镁的降解速率。通过扫描电镜对多孔镁(带有微弧氧化涂层和带有氟化学转化涂层)的表面与孔隙内的形貌、涂层元素组成及涂层厚度进行表征,并采用浸泡法对涂层处理多孔镁的降解性能进行研究,分析浸泡后涂层形貌、涂层元素和涂层厚度的变化。结果多孔镁表面微弧氧化涂层具有多孔结构,涂层厚度在15μm左右,孔隙内同样被涂层覆盖,孔隙内的涂层厚度低于外表面涂层厚度。氟化学转化涂层致密、均匀,涂层厚度在2μm左右,孔隙内同样被涂层覆盖,孔隙内的涂层厚度比外表面的涂层厚度薄。与氟化学转化涂层相比,微弧氧化涂层对多孔镁的防护作用相对稳定,由于涂层的多孔结构,初期对基体的防护效果比氟化学转化涂层略差,但随着浸泡时间的延长,涂层变得相对致密,对多孔镁基体的防护作用也越来越明显。微弧氧化涂层处理的多孔镁在降解过程中引起的环境酸碱度变化更适宜骨细胞增殖。结论微弧氧化涂层与氟化学转化涂层均能有效降低多孔镁的降解速率。

Porous magnesium has feature of biodegradation,which will generate an alkaline environment to promote forming of bone tissues.In addition,the porous structure can provide access for new bone growth.So porous magnesium is an ideal bone filling material.Compared with bulk magnesium,the faster degradation rate of porous magnesium will lead to serious alkaline environment surrounding bone tissue,which may induce the osteolysis.To reduce the degradation rate,different surface modification methods are used to match the degradation rate with the healing rate of bone tissues.Based on the research of protective coating of bulk magnesium,and according to the results of previous studies,a new surface modification method for the preparation of micro-arc oxidation and fluorochemical-conversion coating with good effect was selected to reduce the degradation rate of porous magnesium.This paper characterizes the surface morphologies of outer profile and inner pore,cross-section morphology,element composition and thickness of coatings,studies the degradation properties of porous magnesium treated with two kinds of coatings by immersion method,and analyzes the changes of coating morphology,coating elements and coating thickness after immersion,so as to select a better coating treatment method to be more suitable for surface modification of porous magnesium.The fluoride-conversion coating was uniform and density on outer profile and inner pore surface,with the thickness of about 2μm,the inner pore thickness of the coating was thinner than the outer one;while the micro-arc oxidation coating was porous on outer profile and inner pore surface,with the thickness of about 15μm,the inner pore thickness of the coating was thinner than the outer one.In addition,the protective effect of the coating prepared by micro-arc oxidation on porous magnesium was relatively stable.Its initial protective effect of the coating on the matrix was slightly worse than that of the fluoride-conversion coating.However,as the immersion time increases,the coating becomes relatively dense,and its protective effect on the porous magnesium matrix becomes more and more obvious.The pH value during degradation of porous magnesium treated by micro-arc oxidation is suitable for bone cell proliferation.Both micro-arc oxidation coating and fluoride-conversion coating could decrease the degradation rate of porous magnesium effectively.