镁合金表面层层组装PSS/PAH膜诱导钙磷涂层

目的镁合金具有良好的生物相容性和可降解性,作为生物医用材料具有广泛的应用前景。有效地提高镁合金的耐蚀性能,对镁合金作为医用材料具有重要意义。方法利用浸泡法在AZ31镁合金基体表面层层组装制备聚苯乙烯磺酸钠(PSS)、聚丙烯胺盐酸盐(PAH)多层膜,并将获得的样品采用水热法在Ca(NO)_3、NaH_2PO_4、Na_2CO_3溶液中诱导钙磷涂层(羟基磷灰石)的形成。利用高分辨扫描电子显微镜、傅里叶红外光谱、X射线光电子能谱对Ca-P/(PAH/PSS)5/Mg复合膜层的表面形貌、化学成分进行了表征,通过析氢和电化学实验(包括极化曲线及阻抗谱)研究了Ca-P/(PAH/PSS)5/Mg涂层的耐腐蚀性能。结果Ca-P/(PAH/PSS)5/Mg膜层厚度约为7.67μm,表现为立体叶草状,在镁合金表面紧密排列。Ca-P/(PAH/PSS)5/Mg涂层耐蚀性提高一个数量级,其腐蚀电流密度从镁合金AZ31的3.69×10–5 A/cm2降低到1.61×10–6 A/cm~2,同时析氢速率降低。结论该涂层可以有效地提高镁合金的耐蚀性能,其成因则主要归功于组装的两种聚电解质的类生物矿化作用。这种诱导所得钙磷膜层对镁合金在生物医用领域的应用提供了新的思路。

Induction Effect of Layer-by-Layer Assembled PAH/PSS Multilayers to Construct Ca-P Coating on Magnesium Alloy

As biomedical materials,magnesium alloys have a wide application prospect due to their excellent biocompatibility and biodegradability.Effectively improving corrosion resistance of magnesium alloy was of great importance to biomedical materials.PSS/PAH multilayer films were prepared on the surface of AZ31 substrate based on layer-by-layer assembly by virtue of dip-coating method,then the modified samples were hydrothermal treated in the solution of Ca(NO)3,NaH2PO4 and Na2CO3 to induce the formation of Ca-P coating (HA).The surface morphology and chemical composition of the films were characterized by using high resolution scanning electron microscopy,Fourier infrared spectrometer and X-ray photoelectron spectroscopy.Hydrogen evolution and electrochemical experiment (including potentiodynamic polarization and electrochemical impedance spectroscopy) were conducted to study corrosion resistance of Ca-P/(PAH/PSS)5/Mg coating.The Ca-P coating was approximately 7.67 μm thick,in presence of leaf-like shape,randomly and densely arranged on the alloy.With Ca-P/(PAH/PSS)5/Mg coating thickness increased by one order of magnitude,the corrosion current density decreased from 3.69÷ 10-5 to 1.61÷ 10-6 A/cm2,so did the hydrogen evolution rate.The corrosion resistance of the magnesium alloy can be improved effectively by the Ca-P coating,which can be ascribed to biological mineralization of the two assembled polyelectrolytes.The Ca-P coating obtained by induction provides a new idea application of magnesium alloy in biomedical field.