目的 研究负向电流密度对 TC4 钛合金在含 Ca-、P-的电解液体系中微弧氧化形成生物陶瓷膜的影响，为钛合金微弧氧化生物学改性提供参考。方法 采用交流脉冲微弧氧化技术在 TC4 合金表面制备生物陶瓷膜，通过 SEM、EDS、XRD、EIS 观察分析不同负向电流密度下微弧氧化膜的生长过程、膜层结构及化学组成，利用划痕实验表征了负向电流密度对膜/基结合强度的影响。结果 钛合金在含 Ca-、P-的电解液体系中微弧氧化时，陶瓷膜均由金红石 TiO2、锐钛矿 TiO2及少量的钙磷非晶态化合物组成，但随着负向电流密度的增加，膜层中 Ca、P 含量小幅提高，锐钛矿 TiO2 的占比逐渐减少，Ca/P 摩尔比则始终保持在 1.67 左右。负向电流的加入虽然会使膜层生长速率下降，但膜层表面的微裂纹明显减少，膜层与基体之间的结合强度有所提高。加入 3 A/dm2负向电流后，氧化膜开裂的临界载荷（Lc）由未加负向电流时的（15.1±0.5）N 增加至（19.9±0.5）N。结论 加入负向电流，可以提高膜/基界面结合强度，减少氧化膜中的裂纹缺陷，理论上更利于保证钛合金植入体与骨骼粘结成功。

The work aims to study the influence of negative current density on bioactivity coating formed by micro-arc oxidation (MAO) on TC4 alloy in the electrolyte with Ca(H2PO2)2 and Ca(CH3COO)2?H2O, which provides a reference for the biological modification of titanium alloy. The bio-ceramic coating was prepared on TC4 alloy by AC pulsed MAO technology. The growth process, structure and chemical composition of MAO coating formed under different negative current densities were analyzed by SEM, EDS, XRD and EIS. The scratch test was used to characterize the effect of negative current densities on the bond strength of the film/substrate. When titanium alloy was micro-arc oxidized in the electrolyte with Ca- and P-, the MAO ceramic coating was composed of rutile-TiO2, anatase-TiO2 and a small amount of Ca- or P- amorphous compounds. However, the content of Ca and P slightly increased and the relative proportion of anatase-TiO2 gradually decreased with the increase of negative current density. Meanwhile, the molar ratio of Ca/P always stayed around 1.67. Although the application of negative current would decrease the growth rate of MAO coating, the micro-cracks on the coating surface decreased obviously and the adhesive strength of coating/substrate increased greatly. The critical load (Lc) for the cracking of the coating increased from (15.1±0.5) N when 0 A/dm2 to (19.9±0.5) N when ?3 A/dm2 was used in MAO process. The application of negative current can increase the coating/substrate adhesive strength and decrease the micro-crack defects in the coating, which is more helpful to the bonding of titanium alloy implant and bone in theory.