基材前处理活化时间对镍钛合金表面超声磷化膜组织及性能的影响

Effects of Pre-Treatment Activation Time on Morphology and Properties of Phosphating Film Prepared Under Ultrasonic Field on NiTi Alloy

为对镍钛合金在生物医用领域使用性能及生物相容性进行改善,对镍钛合金进行超声磷化处理,用扫描电子显微镜、X射线衍射仪、能谱仪、摩擦磨损仪及电化学工作站等对磷化膜表面的形貌、微观结构、成分、耐蚀性、耐磨性、镍离子释放量进行检测与分析,研究了重要参数基材前处理活化时间对磷化膜组织及性能的影响。结果表明:最佳活化时间为30 s,制得的磷化膜平直、致密、完整,其厚度约为18μm,其形貌为小细棒堆叠状,磷化膜的自腐蚀电位为-0.32 V,相比基材提高了0.40 V左右,自腐蚀电流密度较基材的降低了2个数量级,摩擦系数由基材的0.503 3降低到0.125 9左右;在模拟体液(SBF)中浸泡30 d,与基材的镍离子释放量1.847μg/m L相比,最优磷化膜的镍离子释放量减少到0.183μg/m L,下降了1.664μg/m L,显著提高了镍钛合金的表面生物相容性;最优活化时间下的超声磷化处理明显改善了镍钛合金表面的耐腐蚀性能、耐磨性能以及生物相容性。

To improve biocompatibility and usability on the surface of NiTi alloy in the biomedical fields, ultrasonic phosphating treatment was used to treat NiTi alloy. Morphology, microstructure, composition, corrosion resistance, abrasive resistance and release of nickel ions of the phosphating film were studied by scanning electron microscope （SEM） , X-ray diffractometer （XRD） , energy dispersive spectroscopy （EDS） , friction/wear meter, electro-chemical workstation, etc. The effects of activation time on the morphology and properties of phosphating film were studied. Results showed that the optimal activation time was 30 s. The uniform, compact and complete phosphating film with a thickness of about 18 μm was obtained, and the morphology was like tiny rods stacked. The self-corrosion potential of the phosphating sample were -0.32 V, which was positively shifted by about 0.40 V, compared with that of the substrate. Furthermore, the corrosion current density was also decreased by 2 orders of magnitude than that of the substrate. The friction coefficient was stable at around 0. 125 9, reduced a lot when compared with that of the substrate （0.503 3）. The releasing amount of nickel ion was O. 183 μg/mL from the phosphating sample after soaked in simulated body fluid （SBF） for 30 days, which was lower than that of the substrate （ 1.847 μg/mL）. Therefore, the biocompatibility of the phosphating sample was improved remarkably. Ultrasonic phosphating treatment with the optimized pretreatment activation time significantly improved the corrosion resistance, wear resistance and biocompatibility of NiTi alloy.