Tribological Properties of Diamond-Like Carbon Films in Low and High Moist Air

Diamond-like carbon (DLC) film was deposited on Si wafer by a plasma CVD deposition system using benzene. Tribological properties of the DLC film were evaluated using a ball-on-disk tribo-meter in low (RH 1720 %) and high humidity (RH 9095 %) conditions in air. The effect of sliding speed (4.2 mm/s to 25 mm/s) and load (1.06 N to 3.08 N) on friction and wear was investigated. The friction behavior of the DLC film was obviously different in low and high humidity. When tested under low humidity conditions, the friction coefficient decreased significantly with increasing speed, and increased with load. However, under high humidity conditions, the friction coefficient increased with the speed and decreased with increasing load. The wear of the DLC film was little influenced by the sliding speed, normal load and humidity; a level of 10^-8 mm³/Nm could be obtained in all tests. The formation of a uniform transfer layer would be the main factor which controlled the friction coefficient of the DLC films. Unlike the friction, the wear resistance of the DLC film is not so easy to discuss and may be affected mainly by the tribo-chemical reaction in all the test conditions.     

碳纤维增强热塑性聚酰亚胺的力学性能和摩擦磨损性能

用电子万能试验机和摩擦磨损试验机考察了短切碳纤维(CF)增强热塑性聚酰亚胺(PI)复合材料的力学性能和摩擦磨损性能,并通过扫描电镜(SEM)观察磨损面微观形貌,从而确定其主要磨损机理。结果表明:短切碳纤维可以提高复合材料的抗压强度,但对抗拉强度和抗弯强度的增强效果不明显,而冲击强度会有所下降。适量碳纤维的加入可以有效改善材料的摩擦磨损性能,其中10%碳纤维填充PI摩擦因数为0.12,仅为纯PI的44.4%,但随CF含量进一步增大(最大达到30%),摩擦因数趋于稳定;材料磨损率随CF加入下降了一个数量级,其中10%CF填充PI的磨损率最低,为1.83×10-8cm3.N-1.m-1。低含量碳纤维复合材料磨损机理以粘着磨损为主,而高含量时主要是磨粒磨损。     

Superlow Friction of Diamond-Like Carbon Films: A Relation to Viscoplastic Properties

Composition, structure, electrical, optical, mechanical properties and tribological behavior of diamond-like carbon films (DLC) are strongly dependent on the deposition system. Some hydrogenated amorphous carbon films (a-C:H) may exhibit superlow friction properties in ultra-high vacuum (UHV). The present paper compares tribological and mechanical properties of several DLC films prepared under different conditions. Friction coefficients were measured in an analytical ultra-high vacuum tribometer. The mechanical properties were evaluated from force-displacement curves using a nanoindentation instrument. Making use of continuous stiffness mode, Young's modulus and hardness were determined as a function of indentation depth. The measurements were performed at constant strain rates by special control of the load during indentation. We were, thus, able to determine the dependence of hardness on strain rate, characterizing a viscoplastic behavior. Many of the hydrogenated amorphous carbon films studied were significantly viscoplastic. The aim of this paper is to highlight the correlation between superlow friction and viscoplastic behavior.     

微波等离子体化学气相沉积法合成纳米碳管

长期以来等离子体化学气相沉积法广泛用于薄膜材料的合成。自纳米碳管被发现以后，该方法已成为纳米碳管合成的一种非常重要的手段。本研究以10X和13X分子筛为载体，在纳米钴颗粒的催化作用下，利用微波等离子体化学气相沉积法在较低的温度条件下合成了纳米碳管。     

Tribological Properties of Carbon Nanopearls Synthesized by Nickel-Catalyzed Chemical Vapor Deposition

The effect of an external electric field (EEF) on water-based thin films has been investigated. Some micro-bubbles emerging around the edge of the Hertz contact region in the films of deioned water and polyethylene glycols (PEG) aqueous solutions have been observed. A higher EEF intensity is needed at which the micro-bubbles begin to emerge after the EEF is applied on the liquid film, which is defined as the threshold EEF intensity. The threshold EEF intensity increases with the molecular weight of PEG solution at lower molecular weight. There is a maximum value when the molecular weight reaches 10,000 Da, beyond which the threshold EEF intensity tends to decrease. The threshold EEF intensity also increases with the concentration of PEG solution. Micro-bubble emerging at negative EEF is easier than at positive EEF. The micro-bubble emerging in the film of deioned water is sensitive to the variation of EEF intensity, and disappears eventually as time progresses.     

脉冲多弧离子镀制备类金刚石薄膜的力学特性

利用脉冲多弧离子镀技术在硅基底上沉积类金刚石薄膜。分析了类金刚石薄膜的硬度和工艺参数的关系 ,讨论了薄膜的耐磨性和化学稳定性。     

Effect of Water Adsorption on Microtribological Properties of Hydrogenated Diamond-Like Carbon Films

Microtribological properties of diamond-like carbon (DLC) films in the presence of water molecule have been studied. The amount of water adsorbed on DLC films was measured by the quartz crystal microbalance (QCM), while microtribological properties of the film were evaluated by an environment-controlled microtribometer. The hydrogenated-DLC showed an advancing water contact angle of 97°, indicating a relatively hydrophobic surface. No hysteresis in adsorption and desorption isotherms were observed. This suggests an absence of micropores at the DLC surface. The greatest adhesion and friction forces between a W-tip and DLC films deposited onto QCM were observed at a water coverage of 2-3 monolayers, which corresponds to a relative humidity of 70-80%. This abrupt increase in adhesion was explained by the generation of a meniscus from the condensed water between tip and DLC surface. The atomically flat DLC surface showed maximum adhesion and friction forces at lower humidity than those of DLC on OCM, implying the importance of surface texturing, which reduces the effect of water condensation.     

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。     

类金刚石膜的性质及应用

介绍了类金刚石膜（Diamond—like Carbon films，DLC films）的结构、制备方法和发展现状。综述了DLC膜的机械、电子、光学和医学等性能以及在这些领域中的应用状况。     

类金刚石膜的力学性能及其工具应用

阐述了类金刚石膜的力学性能和类金刚石膜工具的应用及研究现状。     

偏压对掺钨含氢类金刚石碳膜摩擦学性能的影响

利用非平衡磁控溅射技术在单晶硅片及9Cr18基体表面制备不同偏压下的掺钨含氢类金刚石碳膜。采用Ra-man光谱分析薄膜结构,采用纳米硬度测试仪和纳米划痕仪研究薄膜的纳米硬度、弹性模量和膜基附着力,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,研究薄膜的摩擦学性能与偏压的关系。结果表明:制备的薄膜样品均具有典型的类金刚石碳膜结构;基体偏压强烈影响薄膜的力学和摩擦学性能,薄膜硬度和弹性模量在0～150 V范围内随着偏压增加而增大,薄膜的摩擦因数在偏压为100 V时最小,在此参数下的耐磨寿命也最长。     

W-C-S-Mo复合薄膜的制备及力学和摩擦学性能

利用磁控溅射与磁过滤阴极真空电弧（MS/FCVA）复合沉积法,在不同偏压下在单晶Si基体上制备W-C-S-Mo四元复合薄膜;分析沉积偏压对薄膜纳米硬度、弹性模量和膜基结合力等力学性能的影响;在潮湿大气、真空环境下研究偏压对薄膜摩擦学性能的影响。结果表明,薄膜硬度、弹性模量和附着力随着沉积负偏压的增大呈现先增大后减小的趋势,在偏压-100 V时薄膜力学性能最好;负偏压-100 V下制备的W-C-S-Mo四元复合薄膜样品在潮湿大气和真空环境下均具有较好的摩擦学性能,拉曼测试发现,W-C-S-Mo复合薄膜在潮湿大气环境中的润滑作用主要由DLC提供,而在真空环境中薄膜中的软质相MoS2晶粒起润滑作用。     

CVD催化法合成碳纳米管

用CVD催化法在镍催化剂上合成多壁碳纳米管，分析对比了各种工艺条件下的试验结果，讨论了碳纳米管的生长机理。结果表明，试验条件下，最佳反应温度为750℃，C2H2、H2的最佳气体流量分别为10-20ml／min和600-800ml／min，最佳反应时间为60-70min。     

Effect of Humidity on the Tribological Properties of Carbide-Derived Carbon (CDC) Films on Silicon Carbide

The effect of humidity on the tribological behavior of carbide-derived carbon (CDC) films prepared by high-temperature chlorination of silicon carbide was examined. Pin-on-disk tribological tests indicate that CDC, unlike graphite or glassy carbon, performs better in dry nitrogen (less than 0.05 friction coefficient at 0% humidity) than in humid air. This versatility is explained by the onion-like structure of the nanoporous CDC coating.     

类金刚石薄膜摩擦机理及其摩擦学性能影响因素的研究现状

类金刚石薄膜(DLC)具有十分优异的减摩耐磨性能,是一种极具发展潜力的固体润滑材料。但其摩擦学性能受到很多因素的影响,这些因素主要可以分为两大类:固有因素和外在因素。在不同的固有因素和外界因素影响下DLC薄膜的摩擦学性能会产生较大差异,这大大制约了人们对其摩擦学行为及摩擦机理的认识,限制了其应用范围的扩展。总结了目前有关DLC薄膜摩擦机理的三种理论,即转移膜理论、滑行界面石墨化理论和化学吸附钝化悬键理论,并在此基础上概括分析了各固有因素和外界因素对DLC薄膜摩擦学性能的影响及其机理,提出未来可以从基础理论和相关技术两方面对DLC薄膜的摩擦学性能展开深入研究。     

碳纳米管及石墨烯协同增强尼龙6摩擦学性能的分子动力学模拟

为研究碳纳米管（CNT）和石墨烯片(GNS)协同增强尼龙6（PA6）复合材料摩擦学及力学性能的微观机制,利用分子动力学方法模拟PA6及其复合材料的拉伸过程及摩擦学行为,分析CNT、GNS对PA6复合材料力学及摩擦学性能的影响。建立Fe原子与纯PA6和PA6/ CNT、PA6/GNS、PA6/GNS/CNT复合材料组成的摩擦学模型,并对模型进行几何优化、退火及动力学平衡,通过对Fe原子施加0.2 GPa应力及0.01 nm/ps速度进行摩擦模拟。研究结果发现,PA6/GNS/CNT复合材料摩擦因数在所有材料中最低为0.252;相比其他3种材料,PA6/GNS/CNT复合材料的抗剪切性能最好,且弹性模量及剪切模量均有提高。通过对比分析4种材料的径向分布函数、摩擦界面温度、材料总势能揭示了CNT和GNS协同增强PA6摩擦学及力学性能的作用机制,指出加入的CNT/GNS通过范德华及静电力作用降低了PA6与Fe原子摩擦副之间的相互作用,此外一维CNT与二维GNS通过π-π堆叠杂化作用形成了3D杂交堆叠体系,协同增强了PA6的摩擦学性能。     

Tribological Behavior of Nickel-Doped Diamond-Like Carbon Thin Films Prepared on Silicon Substrates via Magnetron Sputtering Deposition

In this study, nickel-doped diamond-like carbon (Ni-DLC) thin films were deposited on silicon (Si) substrates using a magnetron cosputtering system by varying DC power density applied to a Ni target at a fixed DC power density applied to a carbon (C) target. Their tribological properties were systematically investigated using a ball-on-disc microtribometer. The tribological results showed that increasing the DC power density applied to the Ni target more than 0.49 W/cm² significantly increased the friction and wear of the Ni-DLC films due to the degraded sp³-bonded cross-linking structures of the films. However, the much lower friction and wear of the Ni-DLC-coated Si samples than those of the uncoated Si sample implied that the Ni-DLC films could effectively prevent their Si substrates from wear. It could be concluded that the Ni-DLC films could be used as high wear-resistant coatings for micromold applications because their tribological properties were significantly influenced by the DC power density applied to the Ni target.     

类金刚石碳基薄膜在1-乙基-3-甲基咪唑四氟硼酸盐中的摩擦学性能

利用射频等离子体增强化学气相沉积技术,以甲烷为气源,在单晶硅(P(001))衬底上制备类金刚石碳基薄膜(DLC);利用高速往复摩擦磨损试验机分别测试DLC薄膜/Al2O3球摩擦副在大气环境下和1-乙基-3-甲基咪唑四氟硼酸盐离子液润滑下的摩擦磨损性能;利用光学显微镜,X射线光电子能谱和三维轮廓仪分别对磨痕、磨痕表面元素和磨损率进行考察。实验结果表明:DLC薄膜在离子液润滑时,在低载荷下减摩作用明显,但在较高载荷下摩擦因数较无离子液润滑时高,且不随载荷增加而变化,推测是离子液形成了边界润滑膜;XPS分析表明这层边界润滑膜可能是由离子液物理吸附在摩擦接触面上形成的,并且对DLC薄膜有很强的抗磨作用。     

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。     

ECR结合中频磁控溅射制备掺Cu类金刚石膜工艺及性能研究

为改善DLC膜的内应力及导热问题,采用ECR微波等离子体化学气相沉积及中频磁控溅射的方法制备掺Cu类金刚石膜,研究溅射电流对薄膜中Cu含量、薄膜表面形貌、结构及机械性能的影响.结果表明:改变溅射电流能有效地控制类金刚石膜中金属含量,拉曼光谱显示,制备的薄膜为典型的类金刚石薄膜结构;Cu的掺入使得类金刚石膜的硬度和耐磨损性能下降,但在一定溅射电流下可得到薄膜结构及机械性能均较好的掺Cu类金刚石膜.