氮离子注入及DLC涂层对Ti6Al7Nb合金在人工唾液中微动磨损性能的影响（英文）

通过往复滑动微动磨损实验研究Ti6Al7Nb合金、氮离子注入Ti6Al7Nb合金、DLC涂层Ti6Al7Nb合金在人工唾液环境下的磨损性能。运用X射线衍射分析、拉曼光谱分析、三维轮廓分析、扫描电镜形貌和摩擦动力学行为分析等方法,详细讨论了表面改性层的磨损特性。结果表明:随着氮离子浓度的增加,Ti6Al7Nb合金的抗微动磨损性能提高。具有DLC涂层的低氮离子注入Ti6Al7Nb合金显示出良好的抗微动磨损性。此外,由于其特殊的结构,DLC涂层组具有更好的耐腐蚀性能。在人工唾液环境下,DLC涂层Ti6Al7Nb合金组相比氮离子注入Ti6Al7Nb合金组具有更好的抗磨损性能。     

纯钛和钛合金在人工唾液中的复合微动磨损行为(英文)

在改进后的液压伺服双向微动磨损试验机上实现双向微动。在人工唾液环境中,对TA2纯钛和Ti6Al7Nb合金在6 mm/min的加载速度下以不同接触倾角(45°和60°)和不同最大外加载荷(200~400 N)条件下进行复合微动磨损实验。详细研究循环垂向力和倾斜角的影响。结合动力学分析与微观检测结果显示:磨痕和塑性变形累积呈现强烈的非对称性。在人工唾液环境中和相同实验参数下,Ti6Al7Nb合金比TA2纯钛具有更好的抗磨损性能,并随着倾斜角度的增加和外加载荷的降低,磨损相应减轻。TA2纯钛和Ti6Al7Nb合金在人工唾液环境中的复合微动磨损机制是磨粒磨损、氧化磨损和剥层。     

氮离子注入浓度对钛及其合金扭动微动磨损性能的影响（英文）

通过等离子体浸没离子注入,在纯钛及Ti6Al7Ni和Ti6Al4V合金表面进行不同剂量的氮离子注入处理。采用ZrO_2球与未处理和处理的钛及其合金平面摩擦副,以小牛血清溶液作为模拟生理介质,进行扭动微动磨损试验。研究氮离子注入处理后钛及其合金表面的特征以及注入剂量对材料扭动微动性能的影响。结果表明:氮离子注入浓度和角位移幅值显著影响钛及其合金的扭动微动运行和损伤行为。随着氮离子浓度增加,扭动微动运行边界向小角位移幅值滑移,中心轻微磨损区减少。钛及其合金的磨损机理为氧化磨损、磨粒磨损和剥层,磨粒磨损是离子注入层的主要磨损机理。     

Ti6Al4V 合金在Saline溶液中的扭动微动磨损

在球/面接触中存在四种微动模式,即切向、径向、转动和扭动微动,在生理介质中扭动微动是人工关节失效的主要原因之一。本文成功建立了一种可在恒温液体介质中实现球/面接触扭动微动的新的试验系统。利用该系统,在37℃的Saline溶液中进行了钛合金/二氧化锆陶瓷球的扭动微动试验,详细讨论了扭动微动的运行行为和损伤机理。结果表明,扭动微动动力学行为在很大程度上取决于扭动角位移振幅和周期数。研究建立了扭动微动运行工况图（RCFM）,包括3个区域,即：部分滑移区（PSR）,混合区（MFR）和完全滑移区（SR）。在部分滑移区,接触中心没有发现任何损伤,接触边缘上只观察到轻微的擦伤和磨损。在混合区,损坏区域从接触边缘向中心扩展,接触中心无损伤,接触边缘区域出现氧化磨损和损伤。在滑移区,整个接触区域均发生损伤,损伤机理主要是磨蚀磨损、氧化磨损、和粘着磨损。     

接触载荷对7075铝合金扭转复合微动摩擦学行为的影响

在新型扭转复合微动试验机上,以7075铝合金平面/GCr15钢球配副为研究对象,研究不同接触载荷对7075铝合金扭转复合微动磨损行为的影响。在动力学特性分析的基础上结合磨痕形貌微观观察,研究7075铝合金扭转复合微动的磨损机理。结果表明:接触载荷明显地改变微动运行区域,随着接触载荷的增加,微动推迟进入混合区和滑移区,且混合区逐渐扩大;在相同的微动运行区域内,Ft/Fn系数随循环次数增加的变化趋势受接触载荷的影响不大,但Ft/Fn系数随着法向接触载荷的增加依次降低;在其它参量不变的情况下,接触载荷越大,微动更趋向于受扭动微动分量控制,表面损伤伴随着明显的剥落。扭转复合微动的磨损机制主要为磨粒磨损、氧化磨损和剥层。     

微动幅值对Ti-6Al-4V合金摩擦特性的影响

钛合金的微动磨损会加速裂纹萌生及扩展,甚至导致构件提前失效。为了在有限元建模过程中提供更加准确地反映钛合金摩擦特性的数据,更好地模拟微动磨损行为,对微动幅值为10~300μm时,球/平面接触Ti-6Al-4V合金的微动摩擦特性进行了研究,测量了不同微动幅值下的摩擦系数,对微动斑中心区域的表面形貌进行了表征,并对接触界面不同深度处的化学成分进行了检测。结果表明,微动幅值为100μm时摩擦系数最大,不同微动幅值下,摩擦系数的演变不一致,且摩擦系数的演变与微动模式有关;微动幅值的不同会导致表面形貌的差异,随着微动幅值的增大,磨屑颗粒逐渐减小,同时形状从块状逐渐向球形转变;此外,当微动幅值较大时,钛合...     

接触载荷对TC4钛合金微动磨损行为的影响

目的在不同的载荷和位移幅值下,结合微动图研究微动接触状态、滑移状态、损伤体积三者对微动摩擦磨损的影响以及不同微动接触状态和滑移状态下材料的损伤机理,为机械构件的微动磨损防护设计提供一定的理论支持。方法在相对湿度为50%、干摩擦条件下,运用SRV-V摩擦实验机,采用球/平面接触形式研究了TC4钛合金/GCr15钢球摩擦副的微动摩擦磨损行为。实验后,用原子力显微镜、纳米压痕仪、三维光学轮廓仪、场发射扫描电子显微镜及其自带的EDS,测试TC4试样的表面形貌及粗糙度、弹性模量与硬度、磨损体积与截面形貌和显微结构及磨斑、磨屑形貌成分等。结果在较低法向载荷下,完全滑移(GSR)占主导地位。磨粒磨损、粘着磨损、氧化磨损以及疲劳脱层是主要的损伤机理。另一方面,在较高法向载荷下,混合滑移(MSR)、部分滑移(PSR)占主导地位。损伤机制是由于高的应力集中,导致疲劳裂纹。此外,不同的微动运行条件下和材料损伤区域也不相同。完全滑移条件下,损伤主要集中在磨斑中心,而部分滑移条件下,损伤主要集中在磨斑边缘。结论切向摩擦力、微动振幅是影响微动磨损的重要因素。小位移幅值下,磨屑可以减缓接触面钛合金基体材料的微动磨损;而大位移幅值下,磨屑会加剧接触面基体材料的微动磨损。     

钛合金表面MoS2-Ti/Cu-Ni-In多层固体润滑膜的制备及其抗微动磨损性能

目的改善钛合金表面抗微动磨损性能。方法利用非平衡磁控溅射技术在钛合金表面沉积MoS_2-Ti/Cu-Ni-In多层固体润滑膜,并与MoS_2-Ti与Cu-Ni-In单层固体润滑膜进行对比。利用扫描电镜、显微硬度计、摩擦磨损试验机、表面轮廓仪对固体润滑薄膜的形貌、硬度、抗微动磨损性能、磨痕形貌进行分析测试。结果所制备的Cu-Ni-In单层膜与MoS_2-Ti单层膜结构致密,与基体结合良好,MoS_2-Ti/Cu-Ni-In多层膜交替结构清晰,结构致密。MoS_2-Ti/Cu-Ni-In多层膜的硬度大于MoS_2-Ti及Cu-Ni-In单层膜,多层膜的平均微动系数为0.06,MoS_2-Ti单层膜的平均微动系数为0.102,Cu-Ni-In单层膜的平均微动系数大于1.0。在12 000个微动循环周期后,测得MoS_2-Ti/Cu-Ni-In多层膜的最终磨损总量为0.045 mm~3,Cu-Ni-In单层膜的最终磨损总量为37.79 mm~3,MoS_2-Ti单层膜的最终磨损总量为0.296 mm~3,即多层膜的抗微动磨损性能较Cu-Ni-In单层膜改善了2个数量级,较MoS_2-Ti单层膜改善了5倍以上。结论 MoS_2-Ti/Cu-Ni-In多层膜中的多个界面对单层晶粒生长起到了阻挡作用,从而致使交替结构中的单层晶粒得到细化,Cu-Ni-In膜的引入延缓了MoS_2-Ti膜的剥落及其转移,增加了不锈钢球与多层膜间第三体的润滑及减磨效果,多层膜表现出了优异的抗微动磨损性能。     

激光熔凝处理对NiTi形状记忆合金微动磨损性能的影响

采用高功率连续波固体Nd:YAG激光器,对NiTi形状记忆合金进行激光表面熔凝处理,利用SRVⅢ摩擦磨损试验机考察激光熔凝处理对NiTi形状记忆合金微动磨损性能的影响.采用扫描电子显微镜及能谱仪分析NiTi形状记忆合金表面磨痕形貌及磨损产物成分;用形貌仪测量样品表面磨痕深度,并对磨损体积进行计算.结果表明,与NiTi合金相比,熔凝层摩擦系数,磨损体积均显著降低,表明激光熔凝处理提高了Ni-Ti合金的耐微动磨损性能.NiTi合金微动磨损机理主要表现为氧化和磨粒磨损,而Ni-Ti合金激光熔凝层磨损机制主要以疲劳剥层理论及磨粒磨损为主.     

Ti6Al4V辉光等离子渗铝摩擦磨损性能研究

利用双层辉光等离子渗金属技术在Ti6Al4V上渗铝以提高材料的摩擦磨损性能,对渗铝层的相结构和显微硬度进行了测试.采用球盘滑动磨损试验机对渗层进行摩擦磨损性能测试.结果表明:渗铝后渗层由Al3Ti和Al组成,材料的硬度值较基体Ti6Al4V有了很大的提高;材料摩擦因数和磨损体积减小,耐磨性得到提高.通过磨痕形貌分析可知,渗层磨损机制为粘着磨损.可见采用辉光等离子渗铝技术改善了材料的摩擦磨损性能.     

Effect of N-ion implantation and diamond-like carbon coating on fretting wear behaviors of Ti6Al7Nb in artificial saliva

The tribology behaviors of Ti6Al7Nb, its alloy with N-ion implantation, and its alloy with diamond-like carbon (DLC) coating were investigated in artificial saliva. Fretting wear tests of untreated, N-ion implanted and DLC coated Ti6Al7Nb alloys plate against a Si₃N₄ ball were carried out on a reciprocating sliding fretting wear test rig. Based on the analysis of X-ray diffraction, Raman spectroscopy, 3-D profiler, SEM morphologies and frictional kinetics behavior analysis, the damage behavior of surface modification layer was discussed in detail. The results indicated that the fretting wear behavior of Ti6Al7Nb alloy with N-ion implantation was increased with the dose increase of the implanted nitrogen ions. Moreover, the DLC-coated Ti6Al7Nb alloy with low ion implantation could improve the fretting wear behavior greatly. In addition, the Ti6Al7Nb with DLC coating had better corrosion resistance due to the special compact structure. All results suggested that the Ti6Al7Nb with DLC coating had better wear resistance than that with N-ion implantation in artificial saliva.     

Effect of nitrogen ion implantation dose on torsional fretting wear behavior of titanium and its alloy

Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO₂ ball contact were performed on a torsional fretting wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The wear mechanisms of titanium and its alloys were oxidative wear, abrasive wear and delamination, with abrasive wear as the most common mechanism of the ion implantation layers.     

Torsional fretting corrosion behaviours of Ti6Al4V alloys in Hank’s simulated body fluid

ABSTRACT

Torsional fretting corrosion in a physiological medium is one of the main reasons that artificial joints fail. In this study, we carried out experiments on torsional fretting corrosion in Titanium alloys (Ti6Al4V) against Zirconium dioxide (ZrO₂) ceramic balls under 37°C in a Hank’s simulated body fluid. During the tests, we recorded electrochemical corrosion parameters using an electrochemical analysis system in real-time. We analysed the torsional fretting dynamics behaviours, damage mechanisms, and electrochemical corrosion behaviours in detail using the micro-examinations of a scanning electron microscope (SEM), an energy-dispersive X-ray (EDX), a profilometer, and an X-ray photoelectron spectrometer (XPS). The results showed that the dynamics behaviours strongly depended upon the torsional angular displacement amplitude and the number of cycles. The friction torque increased with increases in the torsional angular displacement amplitude and normal load. We established a running condition fretting map (RCFM), which included three fretting running regimes: a partial slip regime (PSR), a mixed fretting regime (MFR), and a slip regime (SR). We determined that the influences of torsional fretting on electrochemical corrosion behaviours were strongly correlated to the angular displacement amplitude. Under large angular displacement amplitudes, the corrosion of the Ti6Al4V alloys in Hank’s simulated body fluids were accelerated by torsional fretting, especially during the initial stage of the test. However, when the angular displacement amplitude was smaller than 1°, the corrosion potentials and corrosion currents were almost invariable during the entire duration of the test. The damage to the Ti6Al4V alloy was the result of wear and corrosion. The wear mechanisms were attributable to delamination and abrasive wear in the three fretting regimes. We observed almost no damage on the contact centre and only slight scratches and wear on the contact edge in the PSR. In MFR testing, the damage zone extended to the contact centre and the sticking zone (which exhibited no damage) contracted to the contact centre with increases in the number of cycles. Ultimately, in MFR and SR testing, the damage mechanisms were primarily the result of abrasive wear, oxidation wear, tribochemical reactions, adhesion wear, and electrochemical corrosion.     

Friction and wear properties of UHMWPE against ion implanted titanium alloy

In this study, a new two-step plasma immersion ion implantation technique was developed and applied for the modification of Ti6Al4V alloy; firstly ion implanting with nitrogen at high temperature and followed with oxygen in high dose. A graded titanium oxide-titanium nitride film was obtained on the surface of the Ti6Al4V alloy. The contact angle and the microhardness of the modified alloys were measured. The friction and wear properties of UHMWPE rubbing against the modified alloys under lubrication of distilled water were investigated using a pin-on-disc tribometer. The wettability and the microhardness of the alloy surfaces were found to be increased significantly after ion implantation. The friction coefficient decreased by nearly 5 times and the wear resistance of UHMWPE increased by about 40 times against the ion implanted Ti6Al4V alloy. Many deep furrows were found on the surface of the un-implanted alloy and were absent in the ion implanted surfaces of the alloy.     

钛合金表面离子束增强沉积MoS2基膜层及其性能

将离子束增强沉积（IBED）技术与离子束溅射的沉积技术相结合,在钛合金表面制备了MoS2,MoS2-Ti复合膜。研究了膜层的形态、结构、膜基结合强度、硬度、摩擦学性能及抗微动（fretting）损伤性能。结果表明;所获膜层较纯溅射膜结合强度高、致密性好,复合膜中允许的金属元素含量大。通过恰当地控制复合膜中Ti的含量,可获得以（002）基面择优取向的MoS2-Ti复合膜,该膜层有较好的减摩和抗磨综合性能,能够显著地改善钛合金的常规磨损、微动摩员（FW)和微动疲劳（FF）性能,特别是在磨损严重的大位移整体滑条件下,MoS2-Ti复合膜对钛合金FF抗力的提高作用可大于喷丸形变强化处理。     

等离子渗氮与喷丸强化复合改进钛合金抗微动损伤性能

利用直流脉冲等离子电源装置对Ti6A14V钛合金表面渗氮处理,研究了渗氮层的相组成、硬度分布、韧度及摩擦学性能,采用喷丸形变强化(SP)对渗氮层进行后处理,以达到联合提高钛合金微动疲劳(FF)抗力的目的.研究结果表明:脉冲电源等离子技术可在钛合金表面获得由TiN、Ti2N、Ti2A1N等相组成的渗氮层,该改性层能够显著地提高钛合金常规磨损和微动磨损(FW)抗力,但降低了基材的FF抗力.渗氮层的减摩和抗磨性能与SP引入的表面残余压应力协同作用,使钛合金FF抗力超过了SP单独作用.提高渗氮层韧度对改善钛合金FF和FW性能均十分重要.     

Cu/Ni多层膜对Ti811合金微动磨损和微动疲劳抗力的影响

在Ti811钛合金表面利用离子辅助磁控溅射沉积技术制备20～1200nm不同调制周期的Cu/Ni金属多层膜,分析多层膜的结构,测试膜基结合强度、膜层显微硬度和韧性,对比研究不同调制周期的Cu/Ni多层膜对钛合金基材常温下微动磨损性能和微动疲劳(FF)抗力的影响。结果表明:利用离子辅助磁控溅射技术可以获得致密度高、晶粒细化、膜基结合强度高的Cu/Ni多层膜,该类多层膜具有良好的减摩润滑作用,因而改善了Ti811钛合金常温下抗微动磨损和微动疲劳性能;Cu/Ni多层膜对钛合金FF抗力的改善程度随膜层调制周期呈现非单调变化趋势,调制周期为200nm的Cu/Ni多层膜对钛合金FF抗力的提高程度最大,原因归于该膜层具有良好的强韧和润滑综合性能。     

Friction and wear of 7075 aluminum alloy induced by torsional fretting

The torsional fretting wear tests of 7075 aluminum alloy flat against 52100 steel ball in dry condition were carried out on a new high-precision torsional fretting-wear tester.The kinetics behaviors and damage mechanism of 7075 aluminum alloy under different angular displacement amplitudes were investigated in detail.The results show that the torsional fretting running behaviors of 7075 aluminum alloy can be defined by three fretting regimes(i.e.partial slip regime(PSR),mixed fretting regime(MFR) and slip r...     

The relation between electrochemical tests and in vitro evaluation of titanium alloy biocompatibility

In this paper, the electrochemical behaviour of the titanium and Ti‐6Al‐7Nb alloy in artificial saliva (Tani&Zucchi and Carter–Brugirard), ion release tests and in vitro biocompatibility of human osteoblasts (HOB) were studied. Titanium and its implant Ti‐6Al‐7Nb alloy present self‐passivation and very stable passive films in Tani&Zucchi artificial saliva of pH = 2.5; 5; 6.7; 9; the total quantity of ions released in the artificial saliva and corrosion rates are very low, proving a very good corrosion resistance and very low toxicity. In undoped and doped Carter–Brugirard saliva, the open circuit potentials have highly electropositive values, denoting passive state and good stability; the open circuit potential gradients, simulating the non‐uniformity of the saliva composition, show very low values, no danger for the implant integrity. The in vitro cytotoxicity of Ti‐6Al‐7Nb alloy was evaluated on the basis of cell morphology and cell viability. The results obtained revealed a high biocompatibility between HOB and Ti‐6Al‐7Nb alloy.