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采用碱热处理＋电沉积＋碱热处理相结合的工艺,在Mg-4.0Zn-1.0Ca-0.6Zr合金板材表面制备羟基磷灰石（HA）涂层。利用X射线衍射和SEM对涂层的组织和形貌进行了分析,对合金板材及HA涂层板材在SBF溶液中的可降解性能进行了研究,结果表明：通过前碱热处理＋电沉积＋后碱热处理的方法在电沉积温度50℃,电压10 V条件下,在Mg-4.0Zn-1.0Ca-0.6Zr合金板材表面制备出了平整、致密的HA涂层,其Ca/P的比值（1.72）与人骨的（1.67）相近;HA涂层Mg-4.0Zn-1.0Ca-0.6Zr合金板材在SBF溶液腐蚀过程中,发现3 d时腐蚀液穿过HA涂层开始浸蚀基体。随着腐蚀时间的延长,部分点蚀的直径扩大,构成局部腐蚀;HA涂层Mg-4.0Zn-1.0Ca-0.6Zr合金板材在SBF溶液中的初始腐蚀速率低于未涂层的合金板材,其在SBF溶液中的初始pH值的变化低于未涂层的,随降解时间延长,pH变化幅度开始增大,10 d后pH值平均值约为9.2,随后逐步趋于稳定;HA涂层Mg-4.0Zn-1.0Ca-0.6Zr合金板材在SBF溶液中的初始自腐蚀电位与未涂层的相比正移200 mV以上,亦说明了其在SBF溶液中的初始腐蚀速率低于未涂层的,但是随着涂层的脱落将促使腐蚀速率增大。

Hydroxyapatite（HA） coatings on the surface of Mg-4.0Zn-1.0Ca-0.6Zr alloy sheet were prepared by a process of pre-treatment in hot alkali solution,electro-deposition and post-treatment in hot alkali solution.The microstructure and morphology of the coatings were observed and analyzed by means of X-ray diffraction and scanning electron microscopy,as well as its degradation behavior in SBF was examined.The results indicate that the dense HA coating on the magnesium alloy with the ratio of Ca and P of 1.72,which is close to that of the human bone tissue of 1.67,is obtained with the processing parameters of voltage of 10 V and temperature of 50 ℃.When Mg-4.0Zn-1.0Ca-0.6Zr alloy specimen with HA coatings is immersed in SBF,the HA coating is penetrated and the alloy substrate is found to be etched by SBF after 3 d.With increasing of corrosion time,the diameter of some pittings increases and becomes localized corrosion.Its initial corrosion rate in SBF is lower than that of the uncoated alloy sheet,as well as the change of its initial pH values is lower than that of the uncoated sheet and with increasing of time,the extent of pH value changes significantly.The average pH value is nearly 9.2 after 10 days and subsequently becomes stable gradually.The initial self-corrosion potential of the HA coated sheet compared with the uncoated sheet is shifted positively by 200 mV,which indicates that the initial corrosion resistance of the alloy sheet after HA coatings is improved,and the corrosion rate increases with flaking off of the HA coatings.