【作者】 周雪婧；

【导师】 冷永祥；

【作者基本信息】 西南交通大学 ， 材料科学与工程， 2010， 硕士

【摘要】 近年来,CoCrMo合金凭借其良好的生物相容性和力学性质逐渐成为骨科植入材料的首选,广泛应用在临床硬组织和器官的替换中,然而Co, Cr离子的潜在毒性在一定程度限制了它的临床应用。为了降低Co, Cr离子的释放,对CoCrMo进行表面改性研究引起了广大研究者的重视。本文采用等离子体浸没离子注入与沉积的方式对CoCrMo合金进行了低压高频氮化处理和类金刚石(DLC)薄膜的沉积。研究了不同氮气气压和射频功率对氮化层成分、结构和性能的影响；进一步研究了C2H2—Ar混合气体中的Ar含量以及基体偏压对类碳薄膜结构和性能的影响；最后对CoCrMo进行了等离子体氮化和DLC薄膜沉积复合处理,研究了复合处理后CoCrMo及其对偶件UHMWPE在25%小牛血清中的摩擦性能。利用X射线衍射谱(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)对氮化层的结构、成分及断面形貌进行了表征,采用电化学腐蚀实验检测氮化层的耐腐蚀性能；利用X射线光电子能谱(XPS)、激光拉曼光谱(Raman)测定了类碳薄膜的结构,使用维氏压痕和划痕法评价了膜基结合力,并用努氏显微硬度仪、销盘式摩擦磨损试验机对两种改性层的机械性能进行了表征。采用往复式摩擦磨损实验分析了经过复合处理的CoCrMo及其对偶件的摩擦性能,并用光镜和扫描电子显微镜观察磨损表面形貌。实验结果表明采用等离子体浸没离子注入与沉积的方式可以有效的对CoCrMo合金进行表面改性,并显著提高CoCrMo的表面性能。对Co合金进行低压高频等离子体浸没离子注入与氮化处理后,材料的机械性能得到一定程度的提高,但耐腐蚀性能明显下降,其表面成分以Cr2N、CrN以及Co2N为主,随着氮气气压的降低和射频功率的升高,氮化层的厚度逐渐增加,样品表面的机械性能呈递增趋势,即较低的气压和较高的功率更有利于氮化层机械性能的提高。在CoCrMo合金上制备DLC薄膜的结果显示,所有薄膜均具有典型类金刚石薄膜的特性,薄膜沉积明显提高了CoCrMo的耐腐蚀性能。随着混合气体中的Ar含量从20%增加到50%,薄膜中的sp3键含量逐渐增加,显微硬度提高,薄膜与基体的结合力和耐磨损性能降低,当Ar含量继续从50%增加到67%,薄膜中的sp3键含量减少,显微硬度相应降低,而薄膜与基体的结合力、耐磨损性能提高。基体偏压由15kV上升到25kV,促进了薄膜中sp3 C-C键向sp2C-C的转变,使硬度降低,膜基结合力和耐磨性能提高,而偏压对腐蚀性能影响不明显。经过复合处理的CoCrMo可显著降低其本身和UHMWPE的磨损程度。更多还原

【Abstract】 CoCrMo alloy has been extensively used in orthopedic implants for its excellent biocompatibility and mechanical property, but its application is limitied for the potential toxiticy of Co and Cr ions. Thus, CoCrMo alloy surface modifications have attracted a lot of researcher’s attention in order to reduce the Co and Cr ions releaseIn this study, CoCrMo was modificated by the high frequency and low voltage ionic nitriding, and DLC were deposited on CoCrMo alloy by plasma immersion ion implantation and deposition. The effect of different gas pressure and the power of radio frequency were considered in the study. The effect of the Ar content of the C2H2—Ar mixed gas and the voltage on the structures and properties of DLC films have been investigate. Finally, DLC film was fabricated on the nitrided CoCrMo, and the biotribological behaviors of CoCrMo and counter part UHMWPE were investigated in bovine synovia lubrication.After the nitriding process, the microstructure and composition were characterized with X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The thickness of the modified diffusion layer was investigated by scanning electron microscopy (SEM). The corrosion resistance of nitriding layer was characterized by electrochemical corrosion test. Raman spectroscopy and X-ray photoelectron spectroscopy were ultilized to characterize the structure of the DLC film. The adhesion strength were examined by WS-97 scratch tester. Surface hardness and wear resistance of the two modificated layers were performed by HXD-1000 microhardness meter and CSEM ball-on-disk-type equipment. The wear tracks of DLC/UHMWPE pairings in biotribological behaviors were acquired by optical micrographs and SEM.It was found that surface property of the CoCrMo alloy could be extensively improved through plasma immersion ion implantation and deposition. Plasma nitriding on CoCrMo can enhance mechanical properties apparently but decrease corrosion resistance. The micro compositons of the nitrided layers were Cr2N、CrN and Co2N. The thickness of nitriding layer increased with the increasing of the gas pressure and radio power, and mechanical properties enhanced, in other words, lower gas pressure and higher radio power were of great benefit to the property of the nitriding layer. The results also indicted that, Ar fraction in the C2H2-Ar gas mixture and the base voltage have important effects on the structure and the adhesion of the a-C:H films, and DLC films can improve corrosion resistance. When Ar fraction in the C2H2-Ar gas mixture is less than 50%, the a-C:H film microstructure transfer from graphite-like to diamond-like which contains higher sp binding, the adhesion strength and wear resistance decreased but the hardness decreased with the increment of Ar fraction. However, when Ar fraction in the C2H2-Ar gas mixture is beyond 50%, the film will contain more sp2 bonding and exhibit higher adhesion strength and wear resistance but lower hardness with the increment of the Ar fraction. With the increase of the bias voltage, C-C bonds were promoted from sp3 to sp2 due to the bombardme(?) of ion, as a result, hardness decreased and the adhesion strength, but little effects on corrosion resistance due to bias-voltage. The CoCrMo treated both nitriding and depositing DLC can decrease wear abrasion for both of the pairings.更多还原