DLC薄膜改性钛合金的生物摩擦学研究

发布时间：2018-06-07 10:45

本文选题：DLC薄膜 + Ti6Al4V合金　；参考：《中国矿业大学》2016年博士论文

【摘要】：随着医用人体植入材料的迅速发展,人工关节置换技术逐渐成为恢复患者关节功能和解除患者痛苦的重要医疗手段。迄今为止,对人工关节的研究主要集中在髋、膝关节,颈椎关节的研究文献和数据较少,更缺少对其生物摩擦学行为和磨损机理的系统研究。随着颈椎病发病群体的日益年轻化,对人工颈椎间盘的使用寿命提出了更高的要求,因此,本文模拟人工颈椎间盘的屈/伸、侧弯和轴向旋转运动,系统的研究了人工颈椎间盘材料在不同运动形式下的生物摩擦学行为,探索不同运动形式间的交互作用机理,因此其研究具有重要的理论研究意义。本文采用非平衡磁控溅射与离子注入耦合技术,在Ti6Al4V合金基体表面沉积含氢类金刚石碳膜(DLC薄膜),对DLC薄膜的硬度、结构、形貌、润湿性等基本性能进行表征,利用多自由度材料磨损试验机对DLC薄膜在多种运动模式下的生物摩擦性能进行研究,并且结合有限元仿真模拟分析DLC薄膜的力学行为及磨损机理,获得了如下主要结论:采用高温热压成型方法制备超高分子量聚乙烯(UHMWPE)球冠,阳极型离子源结合非平衡磁控溅射复合技术与离子注入耦合的方法在Ti6Al4V合金表面沉积DLC薄膜。通过拉曼光谱和X射线光电子能谱分析薄膜特性,薄膜呈现出典型的类金刚石薄膜特征,DLC改性后的Ti6Al4V合金表面粗糙度从0.40μm降低到0.28μm,表面硬度提高了129%,表面接触角为37.41°,在小牛血清溶液中具有较好的浸润性。DLC薄膜与基体表面结合紧密,厚度均匀,达到2μm,未见明显的裂纹。模拟人工颈椎间盘的屈/伸和侧弯运动,开展摆动摩擦学试验,随着轴向载荷及摆动角位移的增加,DLC薄膜的摩擦系数逐渐增大,UHMWPE的磨损量及磨损表面的粗糙度也随之增加,与未改性的Ti6Al4V合金相比,DLC薄膜改性后的Ti6Al4V合金具有更好的耐磨性,接触界面间摩擦力降低了77.6%,磨损量降低了11.2%。未改性Ti6Al4V合金的磨损机制以严重的磨粒磨损为主,经DLC薄膜改性后的钛合金的磨损形式以磨粒磨损和粘着磨损为主,大载荷、大角位移条件下,DLC薄膜局部区域发生应力脆断,发生脆性剥落。模拟颈椎间盘的轴向旋转运动,开展转动摩擦学试验,随着轴向载荷、转动角位移的增大,摩擦扭转力矩、摩擦耗散能、磨损量均呈现出增大的趋势。与未改性的Ti6Al4V合金相比,DLC薄膜改性后的Ti6Al4V合金具有更好的耐磨性,进入完全滑移状态的时间缩短,接触界面间摩擦扭转力矩显著降低。未改性Ti6Al4V合金的磨损机制表现为严重的磨粒磨损,经DLC薄膜改性后的钛合金的磨损形式以应力集中产生的脆性剥落为主。DLC薄膜增大了对磨副UHMWPE的磨损,UHMWPE的磨损机制是粘着磨损和磨粒磨损综合作用的结果。与Ti6Al4V合金的摆-转复合摩擦对比,摆动摩擦系数低于复合摩擦系数,转动摩擦扭转力矩大于复合摩擦扭转力矩;不同摩擦状态下对磨副UHMWPE的磨损量呈现出摆动复合转动的趋势;摆动和转动表现为相互制约的关系。与DLC薄膜改性后Ti6Al4V合金的摆-转复合摩擦对比,摆动摩擦系数低于复合摩擦系数,转动摩擦扭转力矩大于复合摩擦扭转力矩;不同摩擦状态下对磨副UHMWPE的磨损量呈现出转动复合摆动的趋势。在低周、高周循环条件下,DLC薄膜的摩擦系数、扭转力矩和对磨副UHMWPE的磨损量均明显低于Ti6Al4V合金配副;DLC薄膜球窝中心区域的磨损机制为粘着磨损,球窝边缘区域的磨损机制则为磨粒磨损;Ti6Al4V合金球窝的磨损机制则均为磨粒磨损。有限元仿真结果表明,在摆动摩擦时,随着轴向载荷、摆动角位移的增大,摩擦剪切应力逐渐增大,DLC薄膜球窝的变形量随之增大,且平行于摆动摩擦方向的变形量大于垂直于摆动摩擦方向的变形量。DLC薄膜球窝中心区域的DLC薄膜易产生摩擦疲劳,最终引起DLC薄膜的破裂,局部区域发生脆性剥落。在转动摩擦时,DLC薄膜球窝的中心均出现粘着区,DLC薄膜球窝的旋转运动处于粘滑混合区,并且随着载荷、转动角位移的增大,相对滑移区域的面积增大,人工颈椎间盘接触界面间的接触应力及摩擦剪切应力逐渐增大,DLC薄膜球窝接触边缘的磨损愈加严重,导致材料的损失也愈加严重。
[Abstract]:With the rapid development of medical human implant materials, artificial joint replacement has gradually become an important medical means to restore the joint function and relieve the pain of the patients. So far, the research of artificial joints is mainly focused on the hip, knee joint and cervical joint. A systematic study of the mechanism of wear and tear. With the growing youth of the cervical spondylosis group, a higher requirement for the life of the artificial cervical disc is put forward. Therefore, this paper simulates the flexion / extension, lateral bending and axial rotation of the artificial cervical disc, and studies the biological tribological behavior of the artificial cervical disc material under different motion forms. In order to explore the interaction mechanism between different forms of motion, the research has important theoretical significance. In this paper, the hydrogen like diamond carbon film (DLC film) was deposited on the surface of Ti6Al4V alloy by non-equilibrium magnetron sputtering and ion implantation, and the basic properties of the hardness, structure, morphology and wettability of DLC thin films were carried out. A multi degree of freedom material wear test machine was used to study the biological friction properties of DLC film under a variety of motion modes, and the mechanical behavior and wear mechanism of DLC film were analyzed by finite element simulation. The following main conclusions were obtained: the high molecular weight polyethylene (UHMWPE) ball crown was prepared by high temperature hot pressing. The DLC film was deposited on the surface of Ti6Al4V alloy by the anode type ion source combined with the nonequilibrium magnetron sputtering composite technology and ion implantation. Through the Raman spectroscopy and X ray photoelectron spectroscopy, the film features a typical diamond like film. The surface roughness of the Ti6Al4V alloy after DLC modification is reduced from 0.40 to 0. The surface hardness of.28 mu m is increased by 129% and the surface contact angle is 37.41 degrees. The better infiltrative.DLC film in the calf serum solution is close to the surface of the matrix, the thickness is equal to 2 mu m, and no obvious crack is found. The motion of the flexion / extension and lateral bending of the artificial cervical intervertebral disc is simulated, and the swinging tribological test is carried out with the axial load and the swing angle. With the increase of displacement, the friction coefficient of DLC film increases gradually, the wear amount of UHMWPE and the roughness of the worn surface also increase. Compared with the unmodified Ti6Al4V alloy, the Ti6Al4V alloy after the modified DLC film has better wear resistance, the friction force between the contact interfaces is reduced by 77.6%, and the wear amount of the 11.2%. unmodified Ti6Al4V alloy is reduced. The damage mechanism is mainly abrasive wear. The wear form of titanium alloy modified by DLC film is mainly abrasive wear and adhesion wear. Under large load and large angle displacement, the stress embrittlement and brittle exfoliation occur in the local area of DLC film. The axial rotation movement of the cervical intervertebral disc is simulated, the rotational tribological test is carried out, along with the axial load. The increase of the angular displacement, the torque torque, the friction dissipation energy and the wear amount all show an increasing trend. Compared with the unmodified Ti6Al4V alloy, the Ti6Al4V alloy modified by DLC film has better wear resistance, the time to enter the state of complete slip is shortened, and the torque torque between the contact interface is significantly reduced. The unmodified Ti6Al4V The wear mechanism of the alloy is characterized by serious abrasive wear. The wear form of the titanium alloy after the modification of the DLC film is mainly brittle exfoliation produced by the stress concentration in the.DLC film, which increases the wear of the grinding pair UHMWPE. The wear mechanism of the UHMWPE is the result of the combined effect of adhesion and abrasive wear. In contrast, the coefficient of swing friction is lower than the compound friction coefficient, and the torsion moment of rotational friction is greater than that of composite friction torsional moment; the wear of the grinding pair UHMWPE exhibits a trend of swinging compound rotation under different friction states; the relationship between swing and rotation is mutually restricted. The comparison of the pendulum and rotation friction between the DLC thin film and the Ti6Al4V alloy after the modification of the thin film is made. The coefficient of wobble friction is lower than the compound friction coefficient, and the torsion moment of rotational friction is greater than that of the composite friction torque. The wear of the grinding pair UHMWPE under different friction states shows a trend of rotational and compound oscillating. Under low cycle and high cycle conditions, the friction coefficient, torsional moment and wear of the grinding pair UHMWPE are obviously lower than Ti under the condition of low cycle and high cycle cycle. The wear mechanism of the center region of the DLC film is adhesive wear, and the wear mechanism of the edge area of the spherical dimple is abrasive wear, and the wear mechanism of the Ti6Al4V alloy ball socket is abrasive wear. The finite element simulation results show that the friction shear stress gradually increases with the increase of the axial load and the swing angle displacement during the swing friction. In addition, the deformation of the DLC film spherical dimple increases, and the deformation amount parallel to the direction of swinging friction is greater than that of the central region of the.DLC film's center area, which is perpendicular to the direction of the swinging friction. The DLC film of the center area of the spherical dimple of the.DLC film is easy to produce friction fatigue, which eventually causes the rupture of the thin film and the brittle exfoliation in the local region. In the rotational friction, the middle of the DLC film ball is in the middle. The rotation movement of the DLC film ball is in the stick slip zone, and with the load, the angular displacement increases and the area of the relative slip area increases. The contact stress and the friction shear stress between the contact interface of the artificial cervical disc increase gradually, and the wear of the contact edge of the DLC film ball is becoming more and more serious, leading to the material. The loss is getting worse.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG174.4;R318.08

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