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目的：镁合金在生物医学领域具有很好的应用前景，为消除其在人体环境中降解速度过快的不足，需在镁合金表面制备一层能够降低其腐蚀速度且具有很好生物相容性的防护涂层。方法采用电沉积法在AZ91D镁合金表面制备Ca-P生物涂层，沉积条件为：在Ca(NO3)2和NH4H2PO4浓度分别为0.1 mol/L和0.06 mol/L的电解液中，pH值4.5，沉积电压2 V，沉积时间分别为1、2、3和4 h。采用XRD、SEM/EDS分析Ca-P涂层的相结构、微观形貌和化学成分，测试Ca-P涂层在Hank，s模拟体液中的极化曲线。结果镁基体表面均获得物相为 DCPD(二水合磷酸氢钙)的生物涂层，但涂层表面形貌随沉积时间的不同变化明显，当沉积时间为3 h时，涂层颗粒尺寸均匀、细小，涂层钙磷比为1.324。极化曲线结果表明，沉积1 h时涂层对基体已有一定的防护作用，随着沉积时间的加长，涂层的腐蚀电压也呈增大趋势。相对镁基体，沉积3 h的涂层腐蚀电位升高了180 mV，腐蚀电流密度降低了3个数量级。结论当沉积时间为3 h时，涂层的耐蚀性最好。

ABSTRACT:Objective Magnesium alloy possesses a good potential application in the biomedical filed, to overcome its overly rapid degradation speed in human environment, a protective coating with good biological compatibility should be depo-sited on the surface of magnesium alloy.Methods Ca-P bioactive coatings were prepared on the surface of AZ91D magnesium alloy by electrodeposition method. The deposition conditions were: 0.1 mol/L of Ca (NO3)2, 0.06 mol/L of NH4H2PO4, pH=4.5, deposition voltage 2 V, and deposition time 1 h, 2 h, 3 h, 4 h, respectively. The phase structure, microstructure and chemical composition of Ca-P coating were analyzed by XRD and SEM/EDS, and the polarization curves of Ca-P coating in Hank’s solu-tion were tested.Results The results showed that DCPD coating was prepared on the surface of magnesium substrate by elec-trodepositon. The microstructure changed obviously with time and when the deposition time was 3 h, the particle size of the coating surface was the most uniform and fine, and the Ca-P ratio was 1.324. Polarization curve results showed that when the deposition time was 1 h the coating had produced protection for magnesium substrate. The corrosion voltage showed an in-creasing trend with prolongation of time, but the corrosion current reached the lowest. The corrosion potential of the coating was increased by 180 mV, and the corrosion current density was decreased by 3 orders of magnitude compared with the magnesium matrix.Conclusion The corrosion resistance of Ca-P coating was the best when the deposition time was 3 h in this paper.