过滤式阴极电弧沉积类金刚石薄膜的碳弧稳定性研究

介绍自行研制的一套过滤式阴极电弧沉积设备,并以石墨作为靶材进行类金刚石薄膜的沉积研究,碳弧本身的惰性限制了电弧的稳定性。电弧电压,磁场等对弧的稳定性有很大的作用。试验得到表面光滑的类金刚石薄膜,并对其进行了形貌分析。     

类金刚石薄膜纳米摩擦性能的试验研究

利用摩擦力显微镜(FFM),对由等离子体增强化学气相法沉积的类金刚石(DLC)薄膜的纳米摩擦性能进行了试验研究。用原子力显微镜(AFM)观察了DLC薄膜样品的表面形貌,同时测定了其粘附力值。从外加载荷、扫描速度和湿度的角度分析了薄膜的摩擦特性。     

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。     

ZnS基底沉积类金刚石薄膜研究

针对不能直接在红外光学材料ZnS基底上沉积类金钢石薄膜(下述简称DLC膜)的问题,介绍了在红外光学材料ZnS基底上沉积DLC膜的方法,指出了采用在ZnS基底表面镀制DLC膜的方法,来解决在ZnS基底表面上镀制高效增透膜后,其膜层耐磨强度不足以抵抗恶劣环境的缺点;同时,通过膜系优化设计,利用镀制组合膜层的方法来降低其单面反射率,可改善光学系统的成像质量。     

低压电化学合成类金刚石薄膜研究

采用液相电化学沉积方法,以乙醇为碳源,并加入含有KCl的去离子水溶液,在较低电压下（60V以下）,在铜基底上沉积出类金刚石（DLC）薄膜.用SEM表征薄膜表面形貌,用Raman光谱表征薄膜成份结构.结盟表明,少量KCI的加入,能够大幅降低沉积电压并提高DLC的沉积速率;沉积出的类金刚石膜均为连续,有较低的表面粗糙度;SP3碳键含量较高（约为30％）.     

过滤式阴极电弧沉积类金刚石 薄膜的碳弧稳定性研究

介绍自行研制的一套过滤式阴极电弧沉积设备,并以石墨作为靶材进行类金刚石薄膜的沉积研究。碳弧本身的惰性限制了电弧的稳定性。电弧电压、磁场等对电弧的稳定性有很大的作用。试验得到表面光滑的类金刚石薄膜,并对其进行了形貌分析。     

无氢类金刚石薄膜的过滤式阴极电弧沉积

研制了一套过滤式阴极电弧沉积设备 ,并利用该设备成功地获得了类金刚石薄膜。扫描电镜分析表明 :获得的薄膜在硅基片上是光滑和致密的。喇曼光谱研究表明 ,这种薄膜是典型的无氢类金刚石薄膜。膜层的摩擦试验表明 :无氢类金刚石薄膜的摩擦系数较低 ,是一种理想的耐磨材料     

类金刚石薄膜厚度的测量

采用真空等离子休沉积法沉积了类金刚石膜,采用椭圆偏振光测量法测定了薄膜的厚度,在测量薄膜厚度的同时也可知道所沉积膜的均匀性情况。     

沉积功率对金刚石薄膜质量和结合性能的影响

借助ＳＥＭ、ＸＲＤ和Ｒａｍａｎ光谱等分析方法对不同沉积功率条件不合成的金刚石膜形貌、结构和质量进行了表征,并采用压痕试验法评定了金刚石膜与基体的结合性能。     

The role of hydrogen on the friction mechanism of diamond-like carbon films

The structure, properties and tribological behavior of DLC films are dependent on the deposition process, the hydrogen concentration and chemical bondings in the films. The present paper reports selected tribological experiments on model DLC films with different hydrogen contents. The experiments were performed in ultrahigh vacuum or in an atmosphere of pure hydrogen or argon in order to elucidate various friction mechanisms. Two typical friction regimes are identified. High steady-state friction in UHV (friction coefficient of 0.6) is observed for the lowest hydrogenated and mostly sp²-bonded DLC film. Superlow steady-state friction (friction coefficient in the millirange) is observed both for the highest hydrogenated film in UHV, and for the lowest hydrogenated film in an atmosphere of hydrogen (10 hPa). The high steady-state friction in UHV, observed for the lowest hydrogenated film with a dominant sp² carbon hybridization, is associated with a –^* sub-band overlap responsible for an increased across-the-plane chemical bonding with a high shear strength similar to what is observed with unintercalated graphite in the same UHV conditions. Superlow friction is correlated with a hydrogen saturation across the shearing plane through weak van der Waals interactions between the polymer-like hydrocarbon top layers. This regime is observed during the steady-state period if the film contains enough hydrogen incorporated during deposition. If this condition is not satisfied (i.e., for the film with the lowest hydrogen content), the limited diffusion of hydrogen from the film network towards the sliding surfaces seems to be responsible for a superlow running-in period. The superlow friction level can be reached over longer time periods by suitable combinations of temperature and molecular hydrogen present in the surrounding atmosphere during friction.     

Small amplitude reciprocating wear performance of diamond-like carbon films: dependence of film composition and counterface material

Small amplitude (50 μm) reciprocating wear of hydrogen-containing diamond-like carbon (DLC) films of different compositions has been examined against silicon nitride and polymethyl-methacrylate (PMMA) counter-surfaces, and compared with the performance of an uncoated steel substrate. Three films were studied: a DLC film of conventional composition, a fluorine-containing DLC film (F-DLC), and silicon-containing DLC film. The films were deposited on steel substrates from plasmas of organic precursor gases using the Plasma Immersion Ion Implantation and Deposition (PIIID) process, which allows for the non-line-of-sight deposition of films with tailored compositions. The amplitude of the resistive frictional force during the reciprocating wear experiments was monitored in situ, and the magnitude of film damage due to wear was evaluated using optical microscopy, optical profilometry, and atomic force microscopy. Wear debris was analyzed using scanning electron microscopy and energy dispersive spectroscopy. In terms of friction, the DLC and silicon-containing DLC films performed exceptionally well, showing friction coefficients less than 0.1 for both PMMA and silicon nitride counter-surfaces. DLC and silicon-containing DLC films also showed significant reductions in transfer of PMMA compared with the uncoated steel. The softer F-DLC film performed similarly well against PMMA, but against silicon nitride, friction displayed nearly periodic variations indicative of cyclic adhesion and release of worn film material during the wear process. The results demonstrate that the PIIID films achieve the well-known advantageous performance of other DLC films, and furthermore that the film performance can be significantly affected by the addition of dopants. In addition to the well-established reduction of friction and wear that DLC films generally provide, we show here that another property, low adhesiveness with PMMA, is another significant benefit in the use of DLC films.     

飞秒脉冲激光沉积类金刚石膜实验研究

期望用类金刚石膜作为硅的红外保护/增透膜,采用波长为800nm,脉宽50fs,重复频率1KH z的T i:Sapph ire飞秒激光器及石墨靶材在单晶S i片上沉积了约0.7μm~1μm厚的类金刚石膜(d iam ond-like carbon film s,DLC),获得了光滑致密,硬度显著提高,红外透过率有一定增加的样品。通过对薄膜拉曼光谱和X射线光电子能谱等的测试,发现单脉冲能量在0.4m J~1.6m J范围内变动时,单脉冲能量0.8m J获得的类金刚石膜综合性能最佳,其对应的焦斑功率密度计算值为1.4×1014W/cm2。     

Wear of metal-containing diamond-like carbon coatings

Four commercial metal-containing DLC coatings were tested with a ball-on-disk tribomete to examine their modes of wear. Although all were sputter-deposited, the coatings differed in their compositions, thicknesses, and surface finish. The tests showed certain common wear modes. In each case the films wore away at constant rates until they were worn through. In this sense, interface adhesion was not an important issue. Since the nominal contact areas increased significantly during the course of the test, while the wear rates were constant, the wear rate was not controlled by the nominal average contact stress. Our data are consistent with the model of Greenwood and Williamson.     

Load-carrying capacity evaluation of coating/substrate systems for hydrogen-free and hydrogenated diamond-like carbon films

Diamond-like carbon (DLC) coatings have shown excellent tribological properties in laboratory tests. The coatings have also been introduced to several practical applications. However, the functional reliability of the coatings is often weakened by adhesion and load-carrying capacity related problems. In this study the load-carrying capacity of the coating/substrate system has been evaluated. The DLC coatings were deposited on stainless steel, alumina and cemented carbide with two different deposition techniques: the tetrahedral amorphous carbon (ta-C) coatings were deposited by a pulsed vacuum arc discharge deposition method and the hydrogenated carbon (a-C:H) films by radio frequency (r.f.) plasma deposition method. The load-carrying capacity of the coated systems was evaluated using a scratch test, Rockwell C-indentation test and ball-on-disc test. The effect of substrate material, substrate hardness, coating type and coating thickness was studied. An increase in substrate hardness increased the load-carrying capacity for the coated systems, as expected. The two coating types exhibited different performance under load due to their different physical and mechanical properties. For the load-carrying capacity evaluations the ball-on-disc configuration was found to be most suitable. This revised version was published online in July 2006 with corrections to the Cover Date.     

The respective role of oxygen and water vapor on the tribology of hydrogenated diamond-like carbon coatings

The tribological behavior of diamond-like carbon coatings (DLC) strongly depends on the chemical nature of the test environment. The present study proposes to explore the influence of water vapor and oxygen on the friction behavior of a hydrogenated DLC coating exhibiting ultralow friction in ultrahigh vacuum (friction coefficient below 0.01). Using a UHV tribometer, reciprocating pin-on-flat friction tests were performed in progressively increasing or decreasing partial pressures of pure oxygen and pure water vapor. The maximum gaseous pressures of oxygen and water vapor were 60 hPa and 25 hPa (1 hPa = 100 Pa), respectively, the second value corresponding to a relative humidity (RH) of 100% at room temperature. It was found that, for the pressure range explored, oxygen does not change the ultralow friction behavior of DLC observed in UHV. Conversely, water vapor drastically changes the friction coefficient at pressures above 0.5 hPa (RH = 2%), from about 0.01 to more than 0.1. Electron energy loss spectroscopy and in situ Auger electron spectroscopy have been performed to elucidate the friction mechanisms responsible for the tribological behaviors observed with the two different gaseous environments. In all cases no significant oxidation has been observed either inside the wear scars or in the wear debris particles. Ultralow friction is systematically associated with a homogeneous carbon-based transfer film. The higher friction observed at partial pressure of water vapor higher than 0.5 hPa, is associated with a thinner transfer film. Consequently friction seems to be controlled by the transfer film whose kinetics of formation strongly depends on the partial pressure of water vapor. This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparation,characterization and investigation of molecular films coated on diamond-like carbon substrate

For the successful application of boundary lubrication, detailed investigations about the influence of preparation process on molecular films are needed. In this paper, a specially designed device was used for the film preparation. The scanning electron microscope (SEM) combined with atomic force microscope (AFM) was employed to characterize the surface morphology and nanotribological behavior of molecular films. After the liquid phase deposition, molecular films are randomly and densely distributed over Ti-doped diamond-like carbon (Ti-DLC) substrates. Through rigorous surface treatments, island-like molecular films were finally achieved on substrate surfaces. The surface friction of molecular films is obviously lower than that of Ti-DLC surfaces. Then, pin-on-disk tribotests were performed to study the macrofriction behavior of molecular films under different preparation parameters. Based on the orthogonal experiment, the effect of five preparation parameters (solution weight percent, smearing force and processing time of three smearing steps) on initial friction coefficient of molecular films was investigated. The results indicated that the order of significance levels is as follows: processing time of the second smearing step > solution weight percent > processing time of step 1 > processing time of step 3 > smearing force. For the purpose of friction reduction, the appropriate level ranges are 0.75% (Solution), 2.5 N–15 N (Force), 1 min–10 min (Step 1), 1 min–2 min (Step 2) and 1 min, 2 min, 5 min and 15 min (Step 3). The initial friction coefficient under the optimized conditions is around 0.112, and the equilibrium friction coefficient is around 0.162, which is lower than that of unlubricated Ti-DLC substrates.     

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.     

XPS表征类金刚石膜探讨

介绍X射线光电子能谱(XPS)分析类金刚石(DLC)膜的原理与方法,探讨分峰拟合计算时参量设定对分析结果的影响,改进拟合方法,拟合结果更准确,结果的一致性好。