Effect of parameters of micro-arc oxidation process on Ti-6Al-4V ELI for dental implants

ABSTRACT In order to study the variation effect of some parameters of micro-arc oxidation process (MAO) on Ti-6Al-4V samples for dental implants, several treatments were carried out under different conditions of current density, exposure time and electrolyte chemical composition. These processes resulted in generated bioactive titanium oxide surface coatings enriched in calcium and phosphorus. The MAO treatment was perfomed from two starting surface conditions: machining and blasting. After each MAO treatment, an alkali treatment was performed to evaluate its influence on the bioactivity of the coating obtained. The surfaces were characterized by means of topographic analysis with scanning electron microscopy, coating adhesion from Rockwell-C standard test and bioactivity in a simulated body fluid test (SBF). The best results (uniform and bioactive coatings with satisfactory performance in the adhesion assay) were attained with longer treatment times and in phosphoric-sulfuric and potassium diacid phosphate electrolytes. Furthermore, the results showed that the blasting treatment previous to MAO process enhanced the coating adhesion while a subsequent alkaline treatment improved MAO bioactivity.摘要 为探究微弧氧化（micro-arc oxidation，MAO）工艺的多项参数对牙科种植体用Ti-6Al-4V试样的影响效应，本研究通过调控电流密度、处理时长与电解液化学成分三类工艺参数，设置多组不同工况开展实验。各实验组均成功制备出富钙磷的生物活性二氧化钛表面涂层。本实验分别以机加工和喷砂两种表面预处理状态作为起始条件开展MAO处理；每组MAO处理完成后，均增设碱处理工序，以评估其对所得涂层生物活性的影响。采用扫描电子显微镜（scanning electron microscopy）进行表面形貌分析、通过洛氏C（Rockwell-C）标准试验测试涂层附着力，并借助模拟体液试验（simulated body fluid test，SBF）评估涂层生物活性。实验结果显示，当采用更长的处理时长，并选用磷硫酸与磷酸二氢钾电解液时，可获得最优涂层：其形貌均匀且具备生物活性，附着力测试结果表现优异。此外，研究表明MAO处理前的喷砂预处理可有效提升涂层附着力，而后续的碱处理则可强化MAO涂层的生物活性。