电流密度对水热电化学沉积HA涂层性能的影响

在含0.15mol/L HF,2mol/L H_3PO_4的水溶液中对Ti6Al4V基体进行阳极氧化处理,然后在0.02mol/L CaCl_2,0.012mol/L K_2HPO_4·3H_2O,0.139mol/L NaCl的电解液中采用水热电化学沉积方法在预处理的Ti_6Al_4V基体表面制备羟基磷灰石(HA)涂层。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、台阶仪和万能材料试验机等研究沉积过程中电流密度大小对HA涂层物相、微观形貌、厚度、生物活性及结合强度的影响。结果表明:采用水热电化学沉积方法在不同电流密度下均制备出了HA涂层,涂层表现为分层生长,部分晶体呈花簇状。HA的厚度随电流密度的增加先增大后减小,在1.25mA/cm~2时达到最大为26.4μm,此时涂层最为致密,与基体的结合强度最高,约为20.0MPa。模拟体液(SBF)浸泡实验能较快诱导类骨磷灰石(CHA)的生成,最大直径达到7~8μm,表明涂层具有较好的生物活性。

Effect of Current Density on Properties of HA Coatings Fabricated by Hydrothermal-electrochemical Deposition

Ti6Al4V substrates were anodized in aqueous solution containing 0. 15mol/L HF + 2mol/L H3PO4. After that, hydroxyapatite coatings is deposited on the anodized Ti6Al4V substrates surface by hydrothermal-electrochemical method at a constant current in an electrolyte containing 0. 02mol/L CaCl2, 0. 012mol/L K2HPO4 · 3H2O and 0. 139mol/L NaCl. The influence of current density on the coating compositions, microstructure, thickness, bioactivity and bonding strength between the coating and substrate was investigated by XRD, SEM, EDS, step profiler and universal testing machine during deposition process. The results indicate that HA coatings can be successfully obtained on anodized Ti6Al4V surface by hydrothermal-electrochemical deposition with different current densities. The coatings appear a layered growth and parts of crystals are characterized by flower-shape. The thickness of the HA coatings increases firstly and then decreases with increasing current density. When the current density is 1. 25mA/cm2, the thickness of the HA coatings reaches the maximum 26. 4μm, the coating is the most dense and the bonding strength is near 20. OMPa. The simulated body fluid (SBF) immersion test can quickly promote the deposition of calcium phosphate with a maximum diameter of 7-8μm.