【作者】 谢东；

【导师】 黄楠；

【作者基本信息】 西南交通大学 ， 材料学， 2011， 博士

【摘要】 人工关节置换是治疗严重骨关节疾病最终最有效的方法。目前由UHMWPE制成的人工关节臼配合金属或陶瓷制成的关节头已成为临床最普遍使用的人工关节摩擦副。然而在人工关节的长期活动中,UHMWPE人工关节臼,会因磨损产生磨屑,而磨屑会刺激人体内的生物反应,引起组织发炎,发生无菌松动,并最终导致人工关节的远期失效及其它并发症。在现有的技术和医疗水平下,UHMWPE的使用还将持续一段相当长的时间,因此通过物理或化学的手段对UHMWPE进行各种改性,提高其表面硬度和耐磨损性能是解决人工关节无菌松动与远期失效的一种有效手段。本文对UHMWPE的表面改性正是为了提高其耐磨性能,达到延缓和减少UHMWPE磨屑之目的。本文对UHMWPE的表面改性,包含“低温等离子体活化／强化预处理”和“DLC薄膜沉积”的双重改性,低温等离子体处理和DLC薄膜沉积均采用微波ECR等离子体技术。全文首先研究了微波ECR等离子体处理对UHMWPE表面成分与结构、表面形貌、表面能、表面力学性能及表面摩擦学性能的影响；然后通过正交实验详细研究了微波ECR等离子过程参数对沉积DLC结构的影响；在此基础上最后通过ECR-PECVD方法在UHMWPE表面沉积DLC薄膜,并对DLC的结构、力学性能及摩擦学性能进行了研究。为了降低DLC与UHMWPE基体间弹性模量的不匹配程度以及UHMWPE在等离子成膜时的电荷累积效应,本文还研究了金属过渡层(Ti)对沉积DLC结构和性能的影响。全文主要结果如下：(1)经等离子体处理,UHMWPE表面生成了含氧基团和反式乙烯基基团,同时UHMWPE的表面交联度和结晶度也都得到了提高。活性基团的引入改善了UHMWPE的表面能(润湿性能),特别是氧等离子体处理,对UHMWPE表面能的改善最为显著；而交联度和结晶度的变化则提高了UHMWPE的表面力学性能。经等离子体处理,UHMWPE表面硬度、抗塑性变形能力都不同程度得到提高,其中经O或N等离子体处理其表面综合力学性能提高最大(适宜的硬度和韧性等)。(2)经等离子体处理,UHMWPE表面形貌产生了明显变化。其中经O、H、Ar等离子体处理,UHMWPE表面粗糙度都增加,但差别不明显；经N等离子体处理UHMWPE其表面粗糙度略有降低。(3)经等离子体处理,UHMWPE的摩擦学性能产生明显变化。经等离子体处理后,UHMWPE的摩擦系数都有所增大,但其体积磨损率却不同程度的有所下降。特别是经N或O等离子体处理,UHMWPE磨损率最低。在等离子体的表面改性效果中,对UHMWPE磨损率影响最大的因素是UHMWPE的表面力学性能和表面能(润湿性)。UHMWPE的磨损率随着UHMWPE表面力学性能(硬度、抗形变能力)和表面能的增加而降低。(4)采用ECR-PECVD技术制备DLC薄膜时,不同过程参数对沉积DLC中sp3/sp2键比例影响的重要性次序为：微波功率>气体流量比>基底偏压>沉积室压强。其中sp3/sp2随着微波功率的增大而减少；随着C2H2/Ar中Ar分量的增大而增大；随着基底偏压的增加而略为增加；随着沉积室压强的增加而略为降低。ECR-PECVD技术中不同过程参数对沉积DLC中氢含量影响的重要性次序为：基底偏压>气体流量比>沉积室压强>微波功率。其中氢含量随微波功率增大而增大；随着真空室压强的增大而增大；随着C2H2/Ar中Ar分量的增大而增大；但是随着基底偏压的增加,DLC中氢含量逐渐减少。(5)利用ECR-PECVD技术在等离子体活化后的UHMWPE表面成功制备出一种含氢DLC薄膜。UHMWPE经等离子体活化提高了其表面能和表面粗糙度,增强了与DLC间的膜基结合强度。DLC薄膜的沉积,进一步提高了UHMWPE的表面硬度、表面抗擦伤能力和耐磨损能力。(6) UHMWPE表面金属过渡层的引入,提高了DLC薄膜的沉积速率和薄膜中sp3键的含量,进一步提高了UHMWPE的耐磨损性能概况起来,本文采用的“低温等离子体活化／强化预处理+DLC薄膜沉积”的双重表面改性技术对提高UHMWPE的耐磨性来说将起到双重保障作用。将该技术应用于UHMWPE人工关节臼的表面改性具有潜在的重要应用价值。更多还原

【Abstract】 Ultra-high molecular weight polyethylene (UHMWPE) paired with a metal or ceramic are the most common combination of materials used in artificial joint replacement. However, the polymeric nature of UHMWPE makes it susceptible to wearing, releasing micro particles into the joint capsule, causing chronic inflammation and osteolysis which leads to aseptic loosening and eventual failure of the implant. Therefore, many efforts are being carried out to reduce the wear rate of UHMWPE by physical or chemical methodes. In this paper, UHMWPE was modified by plasma pretreating and DLC coating. Plasma was generated by microwave electron cyclotron resonance (ECR), and the DLC films was prepared with the method of microwave electron cyclotron resonance plasma chemical vapor deposition (ECR-PECVD).Firstly, the effect of plasma treating on the UHMWPE, which includes the component and structure, surface morphology, surface energy and surface mechanical property of UHMWPE were investigated. Then, these effects on the tribological property of UHMWPE were further analysed. Secondly, the effect of the process parameters of ECR-PECVD on the structure of DLC based on an orthogonal experimental design and analysis method were studied. Lastly DLC were deposited on UHMWPE, and its structure, mechanical proptery and tribologycial proptery were characterized. The main resulsts of this paper are as follows:(1) Treated by plasma, oxygen containing groups and trans vinylene groups were introduced into the UHMWPE, and the surface crosslinking degree and crystallinlity degree of UHMWPE also increased. The polar groups increased the surface engergy of UHMWPE. And the increased crosslinking degree or crystallinlity degree can improve the surface mechnical propery of UHMWPE, including hardess and anti-plastic deformation. Specially treated by oxygen or nitrogy plasma, UHMWPE has best comprehensive mechanical properties (proper hardness and toughness).(2) The roughness of UHMWPE has been increased after it was treated by oxygen, hydrogen or argon plasma, but the deference of roughness was not clear among different plasmas. However, the roughness of UHMWPE has been little decreased after it was treated by nitrogen plasma. (3) The tribology propery of UHMWPE can be changed by plasma treating. The friction coefficient of UHMWPE increased, but the volume wear rate decreased after plasma treating. The sample treated by nitrogen or oxygen has the lowest wear rate. The main factor of improvement in wear resistance should attribute to the improved mechanical properties and increased surface engery of UHMWPE when it was modified by plasma.(4) When the DLC films were prepared by ECR-PECVD, the importance of each process parameter on the sp3/sp2 bonding ratio of DLC is in the following order:microwave power > C2H2/Ar gas flow ratio > substrate bias voltage > deposition pressure. The sp3/sp2 decreased with the rise of microwave power or deposition pressure, and that increased with the rise of Ar fraction in C2H2/Ar mix gas or substrate bias voltage.The importance of each parameter on the hydrogen content in DLC films is in the following order:substrate bias voltage > C2H2/Ar gas flow ratio > deposition pressure > microwave power. The hydrogen content in DLC films decreased with the rise of substrate bias voltage, and it increased with the rise of microwave power, operating pressure and Ar fraction in C2H2/Ar gas mixture.(5) Typical DLC films were deposited on UHMWPE successfully. The hardness, wear-resistance and anti-scratch of UHMWPE can be significantly improved by the DLC films coating.(6) With the introduction of thin metal transition films, the deposition rate, hardness and sp3/sp2 bonding ratio of DLC deposited on UHMWPE can be increased, And the wear-resistance of UHMWPE can be further improved.更多还原