DLC膜对NiTi合金表面性能的影响

Effect of the DLC Coating on the Surface Properties of the NiTi Alloys

采用新型等离子浸没离子注入和沉积(PIIID)法以C2H2为等离子源对NiTi合金进行表面改性。利用Raman光谱分析膜层结构;采用纳米压痕和光电子能谱(XPS)分析涂层前后NiTi合金的表面力学性能和表面成分,利用电化学阻抗谱和动电极化测试涂层前后基体的耐腐蚀性能。结果表明:NiTi合金表面的膜层是DLC;经过PIIID处理后,基体表面由原先的TiO2转变为DLC;纳米硬度和杨式模量得到提高;耐腐蚀性能获得明显改善。

Diamond-like carbon （DLC） film was fabricated on NiTi alloys surface adopting novel plasma immersion ion implantation and deposition （PIIID） at room temperature, using C2H2 as plasma source. Film structure was characterized by Raman spectroscopy. Film structure and hardness were characterized by nano-indentation, and XPS were used to study the surface mechanical properties and composition of the DLC coated and uncoated sample, respectively. The corrosion resistance in Hank＇s solution was evaluated by mean of potentiodynamic polarization tests and electrochemical impedance spectroscopy （EIS）. The results show that the carbon coating on TiNi alloy surface is diamond-like carbon, and the elastic modulus and hardness of the alloys are increased by DLC coating. The surface composition of the NiTi alloys is changed from the TiO2 to DLC due to the novel PIIID treatment. The corrosion resistance of the NiTi alloys is improved greatly.