负偏压对DLC薄膜结构和摩擦学性能的影响

采用离子束溅射沉积镀膜法制备了DLC薄膜,研究了偏压对薄膜性能的影响。通过原子力显微镜(AFM)和拉曼光谱对DLC薄膜的表面形貌以及内部结构进行了分析表征。并用UTM-2摩擦磨损仪对其摩擦学性能进行了测试。结果表明,利用离子束溅射沉积制备的DLC薄膜具有良好的减摩抗磨性能。随着偏压的增加薄膜的摩擦因数先减小后增加,在-150 V偏压时,薄膜的摩擦学性能最好。     

碳离子束注入辅助蒸发低温沉积DLC薄膜研究

采用碳离子束注入辅助蒸发技术低温沉积了DLC薄膜,对薄膜沉积的工艺参数进行了优化,并对该薄膜的摩擦学行为进行了探讨。研究发现:碳离子束注入辅助蒸发技术沉积的DLC薄膜在离子量为3.0×1017ions/cm2,沉积率为0.1nm/s时具有最小的摩擦因数(<0.1);电流为2.0mA比3.0mA条件下所沉积的DLC薄膜表面光滑;磨损试验后,DLC薄膜的表面只有轻微磨损的痕迹。     

脉冲偏压对PECVD制备DLC薄膜的结构及性能的影响

在不锈钢基材表面利用等离子体增强化学气相沉积技术(PECVD)改变脉冲偏压制备不同结构类金刚石薄膜(DLC)。分别采用表面轮廓仪、扫描电镜、拉曼光谱及电子探针分析薄膜的表面粗糙度、断面形貌、薄膜结构及成分,采用纳米压痕仪及划痕仪测试薄膜的纳米硬度、弹性模量和膜基结合力,采用球盘摩擦试验机测试薄膜在大气环境中的摩擦学性能。结果表明:脉冲偏压显著影响PECVD制备的DLC薄膜的表面粗糙度、微观形貌、膜基结合力、纳米硬度及摩擦学性能;随偏压的增大,DLC薄膜的表面粗糙度,摩擦因数及磨损量都先减小后增大,而膜基结合力则先增大后减小。其中2.0 k V偏压制备的DLC薄膜具有最强的膜基结合力,而1.6 k V偏压制备的DLC薄膜具有最低的表面粗糙度、最高的硬度和最优的减摩耐磨性能。     

不同温湿度下风电轴承表面防护DLC薄膜微动摩擦特性

针对湿热环境下风电绝缘轴承的微动磨损失效问题，采用等离子体增强化学气相沉积工艺在绝缘涂层Al₂O₃表面沉积类金刚石碳(DLC)薄膜，研究温湿度对其微动摩擦特性的影响。结果表明：DLC薄膜在适当高温下均具有良好的摩擦学性能，在湿度为80%RH时的平均摩擦因数较小；温湿度较高的环境有利于降低DLC薄膜的微动磨损程度，提高绝缘轴承的防护程度；对磨痕处进行拉曼光谱分析表明摩擦过程中DLC薄膜磨痕表面杂化键sp²/sp³比值均大幅上升，且薄膜发生了石墨化转变。DLC薄膜在高温下的低摩擦行为主要是由于DLC薄膜表面石墨化过渡层和磨损表面石墨化的协同作用。     

空心阴极放电制备金刚石薄膜及其性能研究

以石墨为电极，Ar气为辅助气体，利用空心阴极等离子体放电在载玻片上成功地制备了无氢类金刚石（DLC，diamond-likecarbon）薄膜。通过激光拉曼（Raman）光谱分析了所制备DLC薄膜的结构；利用扫描电子显微镜（SEM）和原子力显微镜（AFM）分析了薄膜的表面形貌；通过表面轮廓仪测量了薄膜的沉积速率；另外，试验中还利用摩擦磨损仪对薄膜的机械性能进行了研究。试验结果表明，制备的DLC薄膜比较致密均匀，粗糙度为8．1nm，有较好的耐磨性能。     

柴油机活塞环表面类金刚石薄膜在模拟工况下摩擦学性能

大缸径、长冲程的大功率柴油机的活塞环-缸套摩擦副易发生异常磨损,使柴油机动力性能丧失,甚至发生拉缸等重大事故,通过先进的表面处理技术可显著改善活塞环-缸套摩擦副的润滑条件,提高活塞环-缸套摩擦副的摩擦学性能。采用阴极电弧离子镀技术在铬-陶瓷复合镀(CKS)活塞环表面制备厚度为7 μm的DLC薄膜,研究CKS活塞环表面的DLC薄膜在柴油机模拟工况下的摩擦学性能。结果表明：在干摩擦、室温贫油和高温贫油的工况下,CKS活塞环表面的DLC薄膜可以显著减小活塞环-缸套摩擦副对摩的摩擦因数,降低缸套的磨损;摩擦过程中DLC薄膜与润滑油的协同润滑作用以及DLC薄膜的石墨化是改善活塞环-缸套摩擦副摩擦学性能的主要原因。     

类金刚石薄膜水润滑摩擦学特性研究进展

综述类金刚石薄膜水润滑摩擦学特性的研究进展,评述薄膜在水环境中的摩擦磨损特性,分析薄膜种类、元素掺杂、对摩材料以及微结构对DLC薄膜水润滑摩擦学特性的影响,并阐述DLC薄膜在水中的摩擦磨损机制。指出:DLC薄膜水润滑摩擦学特性受薄膜制备参数和摩擦试验环境影响,通过与微结构的耦合可以进一步改善类金刚石薄膜的摩擦学特性。同时还展望了类金刚石薄膜水润滑摩擦学未来研究方向。     

激光织构和碳基薄膜复合处理提高钛合金摩擦学性能研究

在重载滑动干摩擦条件下，对比不同织构密度的钛合金表面的摩擦学性能；在耐磨性最好的织构密度钛合金表面再制备碳基薄膜，并与直接在钛合金表面制备的碳基薄膜的摩擦学性能进行对比。结果表明：3种低织构密度条件下，TC4钛合金的摩擦因数减小、磨损率降低；随着织构密度的增大，钛合金材料的摩擦因数变化极小，磨损率有所增加；在织构密度5.95%的钛合金表面制备的碳基薄膜，因织构微凹处产生的小微湍流，减少了摩擦阻力，使得其摩擦因数相比直接在钛合金表面制备的碳基薄膜的摩擦因数有所减小。织构化碳基薄膜的磨损率比钛合金的磨损率降低了99.31%，比直接在钛合金表面制备碳基薄膜的磨损率也降低了约60%，这是因为高接触应力摩擦过程中触发石墨化转变，被磨损的石墨化颗粒碎片嵌入织构微凹中，抑制了摩擦接触界面的磨损行为。     

钨含量对WC/DLC复合薄膜摩擦学性能的影响

利用等离子体辅助化学气相沉积技术复合非平衡磁控溅射技术制备具有不同钨含量的WC/DLC复合薄膜。通过调节WC靶功率实现薄膜中钨含量的控制,用EDS能谱仪测量薄膜中的钨含量,采用SEM分析薄膜的表面形貌和结构,采用Raman光谱分析不同钨含量对薄膜结构的影响,采用纳米硬度测试仪测试薄膜的纳米硬度,在球-盘摩擦试验机上测试薄膜在大气环境中的摩擦学性能,研究薄膜的力学性能、摩擦学性能与薄膜中钨含量之间的关系。结果表明:薄膜中的钨含量随着WC靶功率的增加而增加;制备的薄膜具有典型的类金刚石碳膜结构,并且薄膜中的sp3键含量以及薄膜硬度都随着钨含量的增加而增大;摩擦因数和耐磨寿命随着钨含量的增加呈先减小后增加的趋势,薄膜的摩擦因数在钨原子质量分数为41.67%时最小,在此参数下的耐磨寿命也最优异。     

钢球表面制备复合碳基薄膜工艺研究

通过工装设计和工艺配合,在钢球表面制备非晶碳基薄膜,研究薄膜的结构、膜基结合力、摩擦学性能以及钢球表面制备非晶碳基薄膜的均匀性、表面粗糙度、膜层附着性和承载性。结果表明:薄膜由柱状的Cr N层和非晶态的碳基薄膜层组成;薄膜与基体之间的膜基结合力可达58 N;薄膜的摩擦因数较无膜基体降低80%,磨痕宽度减小约85%;在钢球表面制备的非晶碳基薄膜的均匀性较好,且能保持材料的纳米级光滑表面形貌,与基体的附着力能达到HF1级。经模拟工况测试可知,镀膜后钢球的抗压缩性能良好,完全满足使用需求。     

工艺条件对类金刚石薄膜在不同介质环境下摩擦学性能的影响研究

考察了基底负偏压对类金刚石薄膜(DLC)在无水和有水环境下摩擦性能的影响。利用电子回旋共振等离子体化学气相方法沉积制备DLC薄膜,利用激光拉曼(Raman)、原子力显微镜(AFM)和纳米硬度计表征了其结构特征,用UMT型多功能摩擦磨损实验机考察了其摩擦性能,并用光学显微镜分析了磨痕特征。结果表明:随着基底偏压的增加,表面粗糙度减小;在无水条件下,基底偏压较低的DLC薄膜摩擦因数较高,并存在一定的波动性,基底偏压较高时,摩擦因数较低。在有水条件下,基底偏压对摩擦因数影响不大。总体来说,加水后薄膜磨损较为严重。     

Tribological Performance of Diamond and Diamondlike Carbon Films at Elevated Temperatures

In this study, the authors investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a reciprocating wear machine in open air (20 to 30% relative humidity) and under a 10 N load using SiC pins. For the test conditions explored, the steady-state friction coefficients of test pairs without a diamond or DLC film were 0.7 to 0.9 and the average wear rates of pins were 10^?5 to 10^?7 mm³/N·m, depending on ambient temperature. DLC films reduced the steady-slate friction coefficients of the test pairs by factors of three to five and the wear rates of pins by two to three orders of magnitude. Low friction coefficients were also obtained with the diamond films, but wear rates of the counterface pins were high due to the very abrasive nature of these films. The wear of SiC disks coated with either diamond or DLC films was virtually unmeasurable while the wear of uncoated disks was substantial. Test results showed that the DLC films could afford low friction up to about 300° C. At higher temperatures, the DLC films graphitized and were removed from the surface. The diamond films could withstand much higher tempera-lures, but their tribological behavior degraded. Raman spectroscopy and scanning electron microscopy were used to elucidate the friction and wear mechanisms of both films at high temperatures.     

Tribological properties of nanostructured DLC coatings deposited by C60 ion beam

The frictional and wear characteristics of nanostructured DLC films were investigated. The coatings were deposited on silicon substrates by irradiation of a mass-separated C₆₀ ion beam with 5 keV of energy and a deposition temperature ranging from 100 to 450 °C. The effects of deposition temperature on the surface morphology, nano-structure, mechanical properties and tribological characteristics of the coatings were assessed. Results showed that deposition temperature strongly affects the nanostructure and surface morphology of the coatings. Coatings deposited at temperatures exceeding 350–400 °C exhibited an increase in surface roughness as well as compressive stress due to the formation of graphite, which led to a significant increase in the friction coefficient and wear rate. Coatings deposited at 300 °C showed the best tribological properties.     

Mechanical and Tribological Properties of Diamond-Like Carbon Films Deposited by Electron Cyclotron Resonance Microwave Plasma Chemical Vapor Deposition

Mechanical and tribological properties of diamond-like carbon (DLC) films deposited by electron cyclotron resonance microwave plasma chemical vapor deposition were analyzed by nanoindentation, nanoscratch and ball-on-disk sliding tests. As the results, hardness and residual stress which depended on the substrate bias voltage had combined effects on the scratch resistance of the films. In sliding friction tests, the transferred layer on the surface of the counterpart accounts for the decrease of friction coefficient with increasing sliding distance. Atomic force microscopic images of the DLC films and the counterpart Si₃N₄ ball surfaces indicate that the sliding friction process could be treated as a periodical scratching process with many indenters.     

Tribochemical reaction of hydrogenated diamond-like carbon films: a clue to understand the environmental dependence

Tribological behavior of hydrogenated diamond-like carbon (DLC) films and Si incorporated DLC (Si-DLC) films deposited on Si (100) wafer by r.f.-plasma assisted chemical vapor deposition were investigated by ball-on-disk type tribometry in various environments. The friction tests were performed in ambient air of relative humidity ranging from 0% to 90% or dry oxygen environment. We focused on the tribochemical reactions by analyzing chemical composition, chemical bond structure and agglomerated shape of the debris. High and unstable friction behavior was observed in both humid air and dry oxygen environments. In these environments, Auger spectrum analysis showed that the debris contained large amounts of Fe. Significant incorporation of Fe in the debris resulted from the wear of the steel ball, which might be enhanced by the surface oxidation of the ball. These results show that the humidity dependence of friction coefficient is not an inherent tribological property of DLC films but results from the surface reaction of the steel ball in humid environments. Two possible reasons for the Fe rich debris affecting the friction behavior are presented. Reduced dependence of the friction coefficient on the relative humidity observed for Si-DLC films is discussed in terms of the two possible reasons.     

Friction of diamond-like carbon films in different atmospheres

Diamond-like carbon (DLC) films constitute a class of new materials with a wide range of compositions, properties, and performance. In particular, the tribological properties of these films are rather intriguing and can be strongly influenced by the test conditions and environment. In this paper, a series of model experiments are performed in high vacuum and with various added gases to elucidate the influence of different test environments on the tribological behavior of three DLC films. Specifically, the behavior of a hydrogen-free film produced by a cathodic arc process and two highly hydrogenated films produced by plasma-enhanced chemical-vapor deposition were studied. Flats and balls used in these experiments were coated with DLC and tested in a pin-on-disc machine under a load of 1 N and at constant rotational frequency. With a low background pressure, in the 10⁻⁶ Pa range, the highly hydrogenated films exhibited a friction coefficient of less than 0.01, whereas the hydrogen-free film gave a friction coefficient of approximately 0.6. Adding oxygen or hydrogen to the experimental environment changed the friction to some extent. However, admission of water vapor into the test chamber caused large changes: the friction coefficient decreased drastically for the hydrogen-free DLC film, whereas it increased slightly for one of the highly hydrogenated films. These results indicate that water molecules play a prominent role in the frictional behavior of DLC films—most notably for hydrogen-free films but also for highly hydrogenated films.     

Tribochemical interactions of Si-doped DLC film against steel in sliding contact

This study concerns the effects of tribochemical interactions at the interface of Si-DLC (silicon-doped diamond-like carbon) film and steel ball in sliding contact on tribological properties of the film. The Si-DLC film was over-coated on pure DLC coating by radio frequency plasma-assisted chemical vapor deposition (r.f. PACVD) with different Si concentration. Friction tests against steel ball using a reciprocating type tribotester were performed in ambient environment. X-Ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES) were used to study the chemical characteristics and elemental composition of the films and mating balls after tests. Results showed a darkgray film consisting of carbon, oxygen and silicon on the worn steel ball surface with different thickness. On the contrary, such film was not observed on the surface of the ball slid against pure DLC coating. The oxidation of Si-DLC surface and steel ball was also found at particular regions of contact area. This demonstrates that tribochemical interactions occurred at the contact area of Si-DLC and steel ball during sliding to form a tribofilm (so called transfer film) on the ball specimen. While the pure DLC coating exhibited high coefficient of friction (∼0.06), the Si-DLC film showed a significant lower coefficient of friction (∼0.022) with the presence of tribofilm on mating ball surface. However, the Si-DLC film possesses a very high wear rate in comparison with the pure DLC. It was found that the tribochemical interactions strongly affected tribological properties of the Si-DLC film in sliding against steel.     

Effect of Surface Roughening of Substrate Steel on the Improvement of Delamination Strength and Tribological Behavior of Hydrogenated Amorphous Carbon Coating Under Lubricated Conditions

The adhesion strength of diamond-like carbon (DLC) coatings is an obstacle in efforts to improve the reliability of coated products. It is generally believed that the roughening of the substrate surface improves the adhesion between a substrate and coating. The effect of surface roughening of the substrate on the delamination strength of DLC coating and the tribological behavior under lubrication were studied. Five types of roughened substrates were prepared by a wet blast device with differing materials, shapes, and sizes of the shot particles. A hydrogenated DLC film was deposited using plasma-enhanced chemical vapor deposition on the roughened substrates. The tribological properties were investigated under air and lubrication with pure water or n-decane. It was found that the delamination strength of the DLC coating could be improved by roughening the substrate surface, especially by spherical particles. It was also found that slight polishing of either the DLC surface deposited on the rough substrate or the roughened substrate before deposition significantly reduced the wear of the counter surface. The remaining chemical element of alumina particles on the roughened surface affected the delamination strength of the DLC coating.