TiN-Ti-DLC等多层复合膜的摩擦学性能研究

在一台УВНИПА 1型双激发源等离子弧薄膜沉积装置上制取TiN Ti DLC、及其含有软金属Cu或PTFE覆盖膜的多层复合涂层。摩擦磨损试验在一台球 盘滑动磨损试验机上进行。结果表明,以TiN和DLC膜为主体的多层复合涂层具有较高的摩擦学特性,过渡金属钛层、软金属和聚四氟乙烯覆盖层可以降低摩擦系数33%～50%,对磨擦表面磨损减少90%。     

DLC层厚度对CNx/DLC多层膜结构及摩擦学性能的影响

采用直流磁控溅射法在硅基底上交替沉积类金刚石碳(DLC)和氮化碳(CNx)薄膜,制备了不同DLC层厚度的CNx/DLC纳米多层膜。使用X射线衍射、场发射扫描电子显微镜、X射线光电子谱、Raman光谱等测试手段表征了薄膜的微观组织形貌、化学成分和原子价键结构等。采用原位纳米压入技术、涂层附着力划痕仪、球盘式摩擦磨损试验机对薄膜的力学和摩擦学性能进行了测试。结果表明:所制备的CNx/DLC多层膜均为微晶或非晶结构,组织致密。随着DLC层厚度的减小,多层膜内sp3杂化键的含量先升高后下降,压应力由135 MPa增至538 MPa,结合力先上升后降低,而磨损率则呈相反变化趋势。多层膜在大气和真空中的摩擦因数约为0.17和0.15,DLC层厚度的影响很小。DLC层厚度为4.5 nm的多层膜的性能最佳,硬度可达44.1 GPa,最低磨损率为3.2×10-18m3/(N·m)。     

发动机挺柱沉积类金刚石薄膜的工艺及性能

采用磁控溅射法,以Cr、Ti和石墨为靶材,Ar、N2和CH4为溅射气体,在材料为20CrMo的发动机挺柱上利用多层梯度复合技术沉积了低摩擦类金刚石(DLC)薄膜复合层CrTi/CrTiN/CrTiC/DLC。该薄膜复合层的纳米压痕硬度高达13GPa,结合力为50N,表面粗糙度为0.398nm。在SRV-IV微动摩擦磨损试验机上进行耐磨损试验后,DLC复合薄膜挺柱的磨损率为渗碳挺柱的1/6。该研究技术具有自主知识产权,实现了挺柱批量化覆膜加工,并有望在发动机主要摩擦副上推广应用。     

掺硅类金刚石薄膜的制备及其微观机械性能研究

采用射频感应耦合离子源（ICP）在硅基底上沉积了DLC薄膜,并利用离子束溅射固体单晶石墨的方法掺入Si元素。通过原子力显微镜（AFM）和拉曼光谱对DLC薄膜的表面形貌及结构进行了分析表征。并用UTM-2摩擦磨损试验仪对薄膜进行了刻划测试,通过临界载荷的对比,分析了掺硅和纯DLC薄膜与基底的结合能力。结果表明,掺硅DLC薄膜具有良好的膜-基结合能力。     

类金刚石和硅氮类薄膜在人工关节表面的摩擦学性能

类金刚石(DLC)和Si–N薄膜都是具有两性分子特性的超硬薄膜,从薄膜的机械强度、摩擦系数、表面能态等方面分析了两类薄膜作为生物机械膜层的性能。Si–N薄膜在与胎牛血清模拟体液环境接触时,表面张力相对于DLC薄膜小,表现出极强的亲水性。Co合金被覆DLC和Si–N薄膜能使显微硬度分别提高7倍及3倍。DLC薄膜的被覆显著提高了钴合金的显微硬度,但在胎牛血清(FBS)中与超高分子量聚乙烯(UHMWPE)的摩擦磨损实验中,摩擦系数变化不大;钴合金被覆Si–N薄膜后在FBS中对磨UHMWPE摩擦系数低至0.02,Si–N薄膜有望成为新型的生物机械保护膜层。     

调制比对磁控溅射Ti/TiN多层膜组织结构和结合力的影响

通过固定薄膜厚度与调制周期,改变Ti与TiN调制比(分别为1∶3、1∶5、1∶9和1∶11),采用反应磁控溅射法在硅片上制备Ti/TiN多层膜,研究调制比对薄膜微观组织结构及薄膜与基体结合力的影响。用X射线衍射仪(XRD)分析薄膜的晶体结构,用扫描电镜(SEM)观察薄膜的形貌,用纳米压痕仪测试薄膜的硬度,用纳米划痕仪测试薄膜与基体之间的结合力。结果表明:多层膜中TiN出现(220)晶面择优取向,Ti/TiN薄膜为柱状晶方式生长。柱状晶的细化程度随调制比的变化而发生周期性变化,柱状晶组织细化程度高的样品具有更高的硬度,但结合力更低。     

钛基骨螺钉表面二氧化钛纳米管涂层的制备及力学性能

采用阳极氧化法在Ti6Al4V骨螺钉表面制备了二氧化钛纳米管(TNTs)涂层,针对TNTs涂层与基底结合强度较低的问题,通过磷酸阳极氧化在TNTs涂层和基底界面处制备了致密的氧化层,提高了TNTs涂层与基底的结合强度。借助场发射扫描电子显微镜、纳米压痕仪、微动摩擦磨损试验机以及拧入-旋出猪胫骨实验,分析了TNTs涂层的微观结构、力学性能、微动磨损性能及机械稳定性。结果表明,在骨螺钉表面制备的TNTs涂层结构紧凑、排列有序,改善了骨螺钉的力学性能,缓解了植入物植入后的应力屏蔽,并且显著提高了Ti6Al4V合金的微动磨损性能,有效避免了在植入过程中的分层和剥落。     

医用NiTi合金表面溶胶-凝胶法制备含磷TiO2薄膜

采用溶胶－凝胶法在医用NiTi形状记忆合金表面制备了含磷TiO2薄膜，原子力显微镜（AFM）分析表明，薄膜由微米级颗粒堆积而成，薄膜表面均匀平滑，通过阳极极化曲线测试对NiTi合金基体及其表面镀有含磷TiO2膜后在模拟体液中的腐蚀行为进行了研究，结果表明，含磷TiO2膜可作为NiTi合金的表面保护膜,使其抗腐蚀性显著提高，体外生物活性测试表明，含磷TiO2薄膜在模拟体液中能够诱导Ca,P沉积，具有一定的生物活性。     

氮氩流量比与基底温度对射频溅射TiN薄膜性能的影响

采用射频磁控溅射技术,以纯钛为靶材,氮气为反应气体,通过改变氮氩流量比与基底温度在304不锈钢及玻璃表面制备了不同的TiN薄膜.利用能谱仪、扫描电镜、台阶仪、四探针仪、划痕仪和纳米压痕仪对制备的所制薄膜的氮钛原子比、表面形貌、沉积速率、方块电阻、膜基结合力和纳米硬度进行表征.结果表明:随着氮氩流量比的增大,TiN的形貌先由四面锥体凸起结构逐渐过渡至柱状晶体堆积结构,然后转变为稀疏的液滴状颗粒结构,直至平整光滑,致密均匀.在氮气和氩气的流量分别为5.0 mL/min和50.0 mL/min的条件下,基底温度25～400°C范围内制备的TiN薄膜的结合力介于135.4 mN与210.2 mN之间.当基底温度为300℃时,薄膜的沉积速率最大,颜色最接近金黄色,氮钛原子比最接近1,结合力和纳米硬度也都最大.     

一种固液复合润滑材料的真空摩擦学性能

要利用磁控溅射设备在单晶硅表面制备了Ti掺杂的DLC薄膜。研究了类金刚石薄膜和磷酸二丁酯单丁胺离子液体组成的固液复合润滑体系在真空度约为10~(-5)Pa条件下的摩擦学性能,采用非接触式三维表面轮廓仪对薄膜表面形貌和磨痕形貌进行观察分析。结果表明:该体系在高真空下具有较低的摩擦系数和良好的抗磨损性能。相比于Ti掺杂的DLC薄膜,复合体系磨损率低近一个数量级。     

Blood compatibilities of carbon nitride film deposited on biomedical NiTi alloy

Carbon nitride (CNx) film, diamond-like carbon (DLC) film, and titanium nitride (TiN) film were deposited on biomedical NiTi alloy substrates using direct current magnetron sputtering, respectively. In order to improve the adhesive strength between the deposited hard film and the NiTi alloy, a Ti transition layer was pre-deposited firstly. We emphatically evaluated the blood compatibilities of the NiTi alloy substrate and the deposited hard films by haemolysis test and platelet conglutination test. It was shown that the blood compatibilities of NiTi alloy can be improved effectively by the deposition of hard films. In comparison with TiN and DLC film, CNx film had the best surface modification effects covering the minimum haemolysis ratio and the best anticoagulation property.     

Corrosion,wear and wear–corrosion behavior of graphite-like a-C:H films deposited on bare and nitrided titanium alloy

This work presents a comparative wear, corrosion and wear–corrosion (the last one in a simulated physiological solution) study of graphite-like a-C:H (GLCH) films deposited on bare and nitrided Ti6Al4V alloy. Films, deposited by r.f. PACVD, presented low porosity and promoted high corrosion resistance. The friction coefficient of the films was very low with appreciable wear resistance at room conditions. However, due to the simultaneous action of both load and the corrosive environment in wear–corrosion tests a marked reduction in the coating lifetime was observed. Unexpectedly, films deposited on the nitrided alloy presented a lifetime at least ten times shorter than that of films on bare alloy. We explain such a result in terms of film/substrate interaction. The weak GLCH/nitrided alloy interaction facilitates fluid penetration between the film and the substrate which leads to a fast film delamination. Such an interpretation is supported by force curve measurements, which show that the interaction between GLCH and nitrided alloy is four times weaker than that between GLCH and bare alloy.     

Study on the diamond-like carbon multilayer films for tribological application

In this paper, DLC multilayer films consisting of alternating layers of soft and hard carbon films were deposited on Si wafer by a plasma CVD deposition system. Different DLC multilayer films were prepared by varying the sub-layer thickness (from 1000 to 25 nm) and the ratio of hard to soft sub-layer (H/S) thickness (from 1:1 to 4:1). By using a ball-on-disk tribo-tester, the friction and wear properties of the DLC multilayer films were measured in vacuum, O₂ and dry-air environments respectively. By comparing with single-layer DLC film, the change of the multilayer structure has little influence on friction coefficient of the multilayer films. However, the wear rate of the DLC multilayer films is restricted effectively by constructed the multilayer structure in the film. The wear rate of the multilayer films is lower than that of the single film in reactive (O₂ and dry-air) environments. An DLC multilayer film with excellent wear resistance, approximately in the level of 10⁻⁸ mm³/Nm in different environments (dry-air, O₂ and vacuum), is obtained as the DLC multilayer film at a certain sub-layer thickness and ratio.     

Nano-texture for a wear-resistant and near-frictionless diamond-like carbon

The effect of nano-scale surface texture on wear resistance of diamond-like carbon (DLC) films was studied using a reciprocating ball-on-flat tribometer in dry, humid, and liquid water environments. The nano-scale surface texture was produced by depositing ∼1 μm thick DLC films onto silicon substrates pre-textured with pyramidal wells and polystyrene spheres. The surface roughness of the textured DLC films was about 50 nm in both cases. The friction and wear behavior of the flat and nano-textured DLC films were tested with AISI 440C-grade stainless steel balls at a contact load creating about 360 nm deep Hertzian deformation which is significantly larger than the surface roughness. At this condition, nano-texturing did not affect the friction coefficient, but it significantly reduced the wear of DLC films in dry and humid nitrogen compared to flat DLC. In dry nitrogen, the nano-textured DLC films showed the ultra-low friction without substantial wear of DLC and deposition of thick transfer films onto the counter-surface. The wear reduction appeared to be related to the stress relief in the nano-textured DLC film. In liquid water, surface features on the nano-textured DLC films were diminished due to tribochemical oxidation and material removal at the sliding interface.     

Exceptional improvement in the wear resistance of biomedical β-type titanium alloy with the use of a biocompatible multilayer Si/DLC nanocomposite coating

A silicon/diamond-like carbon (Si/DLC) multilayer nanocomposite coating (MNC) was applied to the Ti–29Nb–13Ta?4.6Zr (TNTZ) alloy to improve its wear resistance and durability. The Si/DLC MNC on the TNTZ alloy demonstrated an extremely low wear rate of 6.2 × 10^?10 mm³N^?1mm^?1. Moreover, the wear track depth after one million wear cycles was found to be only 220 nm, while the thickness of the entire coating was 370 nm. Furthermore, cell culture tests demonstrated that the Si/DLC MNC samples exhibited better biocompatibility than the TNTZ alloy samples. A quantitative comparison of the cell adhesion behavior of the TNTZ and Si/DLC MNC samples indicated that 60% of the surface of the Si/DLC MNC sample was covered with cells, which was approximately twice the surface of the TNTZ alloy sample covered with cells. In addition, no dead cells were observed on the Si/DLC MNC samples, indicating that the Si/DLC MNC samples exhibited no toxic effects against the MC3T3 cells. These results indicate that the Si/DLC MNC enhances the wear resistance of the TNTZ alloy and improves its biofunctionality, thus making it a potential candidate for use in long-term implant applications.     

Relationship between interlayer hardness and adhesion and pin-on-disc behaviour for fast atom beam source diamond-like-carbon films

The effect of interlayers of Ti, and Ti(C,N) on the adhesion, hardness and friction coefficient of DLC films deposited using a Fast Atom Beam (FAB) source has been studied. Values obtained for DLC films on top of interlayers were compared with those of DLC films directly deposited on Co-Cr substrates by both the FAB source and RF CVD techniques. The scratch test adhesion of such coatings can be classified in the following ascending order: DLC/Ti, DLC/no interlayer, DLC/Ti(C,N). The surface composite hardness is greatly improved by a Ti(C,N) interlayer. However, DLC films deposited on Ti(C,N) failed during the pin-of-disc test whilst those on Ti and without an interlayer exhibited low friction coefficients and excellent wear performance. An explanation is developed in order to explain the causes of film failure during the pin-on-disc test. For a given interlayer hardness, an adhesion threshold is required to survive the pin-on-disc test. The higher the hardness, the greater the required adhesion threshold, as interfacial shear stresses induced by the pin-on-disc are greater for hard surfaces, due to the smaller contact area.     

Effect of diamond-like carbon (DLC) on the properties of the NiTi alloys

NiTi alloy has found wide application in the biomedical field due to its unique shape memory effect, superelasticity and biocompatibility. However, the materials are vulnerable to surface corrosion and the most serious issue is out-diffusion of toxic Ni ions from the substrate into body tissues and fluids. In this paper, NiTi alloys were coated with diamond-like carbon (DLC) fabricated by plasma immersion ion implantation and deposition (PIIID) to improve their corrosion resistance and blood compatibility without sacrificing their shape memory effect and superelasticity. The structure of the films and the depth profiles between the films and substrate were studied using Raman spectroscopy and XPS, respectively. The phase transformation temperature, superelasticity, anticorrosion behavior and Ni ions release of the coated and uncoated sample were investigated by DSC, tensile tests, potentiodynamic polarization and AAS, respectively. The hemocompatibilty of the coated and uncoated samples was measured using clotting time and platelet adhesion. The results shows that the films is DLC accompanying with the formation of the mixing layer, and the DLC films can markedly improve the corrosion resistance and the hemocompatibility, obviously increase the ratio of albumin-to-fibrinogen and effectively block the Ni ions release of the NiTi alloys without sacrificing its superelasticity and changing its phase transformation temperature. The research results suggest DLC films prepared by PIIID could improve the in vivo performance of NiTi alloys implanted into the human body.     

电流密度对Ti 6Al 4V微弧氧化膜形貌和性能的影响

采用NaAlO2-Na3PO4-NaF溶液体系,研究了电流密度对Ti 6Al 4V合金微弧氧化膜厚度、生长速率、表面形貌、粗糙度、组成相以及氧化膜耐蚀性、耐磨性等影响.结果表明,(1)在试验的电流密度范围内,氧化膜的厚度随电流密度的增大呈线性增大,但氧化膜的粗糙度却几乎呈指数增大,表面质量变差;(2)在质量分数为3.5%的NaCl溶液中显示了比Ti 6Al 4V钛合金更好的耐蚀性;(3)在干摩擦条件下,氧化膜的摩擦系数高于基体的,氧化膜的磨损机制为脆性断裂.     

A study of biotribological behavior of DLC coatings and its influence to human serum albumin

Diamond-like carbon (DLC) coatings has been synthesized on NiTi alloy substrates by arc enhanced magnetic sputtering (AEMS) system using graphite targets. The tribological behavior indicates that the friction coefficient and wear rate of DLC coatings deposited on NiTi alloy substrates is relatively higher in ambient air than that in simulated body fluid (SBF). In human serum albumin (HSA) solution, though the friction coefficient is higher than that in SBF, but it has quite low wear rate. The Raman spectrum shows that the low friction coefficient of DLC coatings is due to the graphitization during sliding, and the degree of graphitization is relatively lower in both SBF and HSA solution than them in ambient air. The friction mechanism of DLC coatings at different environments is then proposed. On the other hand, the kinematic viscosity and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) measurements show that the DLC coatings cannot induce the thermal and mechanical denaturation of HSA during sliding.