电化学沉积羟基磷灰石过程晶体生长行为

采用恒电流电化学沉积方法从含钙与磷盐水溶液中直接在纯金属钛电极表面沉积纳米羟基磷灰石涂层,运用EDS、SEM、XRD、FTIR等方法对其进行表征. 重点考察了一种典型制备条件下钙磷沉积层的形貌、结构及组分随沉积时间的变化,进而探讨相应条件下电化学沉积羟基磷灰石涂层晶体生长过程的基本规律. 研究表明电化学沉积法可用于在医用金属表面直接涂覆含钙离子缺陷的纳米羟基磷灰石涂层,典型条件下涂层的生长规律为: (1)沉积过程中羟基磷灰石晶粒以c轴方向沿沉积面法线方向择优生长,且这一趋势延续整个沉积过程; (2)内层晶粒的生长受到外层晶粒生长的抑制, 对于同层的晶粒,当晶粒分布密集时,晶粒生长可能发生相互制约; (3)随沉积时间的延长,沉积量增加,而膜层的化学组成基本不发生变化.

The Crystal Growth Behavior of Hydroxyapatite Coating on Titanium Substrate under Electrochemical Deposition Conditions

A nano-hydroxyapatite coating on titanium substrate was directly prepared by electrochemical deposition method and was characterized by EDS,SEM, XRD and FTIR. It was observed that under a wide range of deposition conditions calcium-deficient hydroxyapatite coatings with different topographies can be prepared. Under a representative preparation condition, i.e. a titanium substrate was used as working electrode with a Pt electrode as counter electrode, the electrolyte was composed of 4.2×10－4 mol•L－1 Ca(NO3)2 , 2.5×10－4 mol•L－1 NaH2PO4 and 0.9％ NaCl, with a pH adjusted to be 6.0, and galvanostatic mode with 1 mA•cm－2 cathodic current density was applied at the temperature of 100 ℃, a series of hydroxyapatite coatings under different deposition durations (15, 30, 60, 120 and 240 min) were prepared and characterized to investigate the coating growth behavior. Following laws of coating growth were observed: (1) preferential growth with the c-axis of the hydroxyapatite crystal perpendicular to working surface is always detected in the XRD measurements with the peak of (002) crystal face being greatly intensified; (2) the growth of grains at inner layer is impeded by the growth of those at outer layer; when grains are packed closely, competition between the growths of grains at the same layer takes place; (3) the amount of deposited coating increases with deposition time while the chemical composition almost keeps the same.