Minderung von Reibung und Verschleiß von Bauteilen aus Aluminium mit diamantähnlichen Kohlenstoffschichten (DLC)

Reduction of friction and wear for parts made of aluminium by diamond-like carbon coatings Reduction of friction and wear of machine parts and tools is usually achieved by separating the participating surfaces. This is predominantly done by liquid lubricants. Solid lubricant coatings replace them where hydrodynamic lubrication is not possible or not active. Among the hard and friction reducing layers diamond-like carbon films (DLC) have distinguished themselves as the most interesting representatives. They are deposited on metallic and ceramic parts in a glow discharge of a hydrocarbon gas at temperatures between 150 and 200 °C. Those low deposition temperatures, their very low dry sliding friction coefficient of 0.05 to 0.1, and an elastic recovery of 90 % differentiate them from PVD coatings to a high degree. DLC can also be deposited on light metals with thicknesses of more than 30 μm. For closed films an outstanding protection against corrosion is established. Machining and forming of light metals can be done without cooling lubricants.     

Tribological performance of DLC coatings deposited by ion beam deposition under dry friction and oil lubricated conditions

Understanding the reaction between lubricant additives and diamond-like carbon coatings is imperative for the improvement of the friction and wear properties of mechanical parts with diamond-like carbon coatings. Diamond-like carbon coatings were deposited with ion beam deposition and the influence of lubricant additives on the friction coefficients and wear rates of diamond-like carbon coatings under the lubricated conditions was studied. It was revealed that the wear rates of diamond-like carbon coatings under unlubricated conditions are 1.5 × 10⁻¹⁴ m³/(Nm) while they are decreased to 3 × 10⁻¹⁷ m³/(Nm) to 1.7 × 10⁻¹⁶ m³/(Nm) when lubricated by PAO-4 base oil with three additives. The addition of molybdenum dithiocarbamate in PAO-4 base oil decreases the friction coefficients of diamond-like carbon coatings to 0.07, but increases the wear rate of diamond-like carbon coatings. The addition of zinc dialkyl dithiophosphate to PAO-4 can slightly decrease the friction coefficient of diamond-like carbon coatings and improve the wear resistance of diamond-like carbon coatings. The addition of amine sulfuric-phosphate diester in PAO-4 can greatly decrease the wear rate of diamond-like carbon coatings to 3 × 10⁻¹⁷ m³/(Nm) but has a negligible effect on the friction coefficients of diamond-like carbon coatings.     

Direct ion beam deposited carbon films and clusters

Carbon films and clusters have been formed by direct ion beam deposition. In all experiments crystalline n-Si 〈1 0 0〉 wafers with the 300 nm thermal SiO₂ film have been used as substrates. Effects of thermally microstructured Ni and substrate temperature were studied. Chemical structure of the carbon films was investigated using Raman spectroscopy. Surface morphology was studied by atomic force microscopy (AFM). Supplemental research on sheet resistance of the films has been performed. Rough diamond-like carbon film was grown onto the catalytic layer at 400 K temperature, and surface of the diamond-like carbon film deposited directly onto the SiO₂ layer at 400 K temperature was very smooth. At 750 K growth of the array of cylindrically shaped clusters was observed by AFM in the case of catalytically assisted deposition. Raman spectra of deposited films were typical for glassy carbon and/or carbon nanotubes with the carbonaceous deposits. Catalyticless deposition at 750 K temperature resulted in the formation of the conductive polymer-like carbon film with the graphite clusters in it.     

Field emission from diamond and diamond-like carbon films

Field emission from diamond and diamond-like carbon thin films deposited on silicon substrates has been studied. The diamond films were synthesized using hot filament chemical vapor deposition technique. The diamond-like carbon films were deposited using the radio frequency chemical vapor deposition method. Field emission studies were carried out using a sphere-to-plane electrode configuration. The results of field emission were analyzed using the Fowler-Nordheim model. It was found that the diamond nucleation density affected the field emission properties. The films were characterized using standard scanning electron microscopy, Raman spectroscopy, and electron spin resonance techniques. Raman spectra of both diamond and diamond-like films exhibit spectral features characteristic of these structures. Raman spectrum for diamond films exhibit a well-defined peak at 1333cm^?1. Asymmetric broad peak formed in diamond-like carbon films consists of D-band and G-band around 1550 cm^?1 showing the existence of both diamond (sp³ phase) and graphite (sp² phase) in diamond-like carbon films.     

Effects of SiNx interlayer on characterisation of amorphous diamond-like carbon films

The magnetron sputtering amorphous diamond-like carbon film is successfully deposited by SiN_x interlayer approach. The scanning electron microscopy study reveals the creation of high uniform surface micrograph diamond-like carbon films with SiN_x interlayer. For comparison, diamond-like carbon films with different interlayers are also grown. The Raman spectra are analyzed in order to characterize the stressed induce peak shifts of the films. The interactions of C atom with Si(100) and SiN_x surface are studied by density functional theory simulation. The effects of interlayers on the films deposition and the considering deposition mechanism are discussed. It is suggested that the diamond-like carbon and SiN_x bilayer structure can help to render applications in protective coatings and high quality silicon on diamond related radiation tolerance devices.     

Nanocomposite tantalum–carbon-based films deposited by femtosecond pulsed laser ablation

Nanostructured coatings of metal (tantalum) containing diamond-like carbon (a-C:Ta) have been prepared by femtosecond pulsed laser deposition (PLD). The films, containing 15 at.% tantalum, have been deposited by ablating sequentially graphite and metallic tantalum in vacuum conditions with an amplified Ti:sapphire laser. The coatings have been investigated by X-ray photoelectron spectroscopy, grazing angle X-ray diffraction, energy filtered transmission electron microscopy, scanning and high resolution transmission electron microscopies. Evidence of metallic α-Ta and β-Ta particles (diameter in the 100 nm range) and smaller quasi-amorphous tantalum clusters embedded in the carbonaceous matrix have been shown. A thin tantalum carbide interface between the carbon matrix and the top surface of the tantalum nodules has also been identified. The ability of femtosecond pulsed laser deposition to synthetize nanocomposite carbon-based films and to control their nanostructure is discussed.     

The ion plating of carbon

Ion-plated coatings of carbon have been deposited on several metal substrates The coatings are very adherent and in contrast with vacuum-evaporated films have a highly graphitic crystal structure. They are wear resistant and have a low friction coefficient. The method of deposition and the crystallographic and tribological studies will be described.     

Investigation into the antibacterial property and bacterial adhesion of diamond-like carbon films

Diamond-like carbon films have unique properties for biological and medical applications due to their excellent biocompatibility, chemical inertness, and superior mechanical properties. In order to attend biomedical applications, there is an increasing interest in developing antibacterial coatings. In this paper, we investigated the bactericidal properties of diamond-like carbon films produced using plasma enhanced chemical vapor deposition. The films were deposited over 316L stainless steel substrates using a pulsed directly current discharge of methane gas. Diamond-like carbon structural quality was evaluated using Raman scattering spectroscopy. The bacterial adhesion and bactericidal activity of the coating was evaluated against Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Salmonella typhimurium ATCC 14028 and Staphylococcus aureus ATCC 25923. These tests show diamond-like carbon bactericidal activity ranged between 25 and 55%, depending on the kind of bacteria. The bacterial adhesion on diamond-like carbon surface was influenced by its structure, chemical bonds and hydrogen content. The low surface roughness did not have decisive effect on its antibacterial performance.     

Transport of vacuum arc plasma through an off-plane double bend filtering duct

A new magnetic macroparticle filter design consisting of an off-plane double-bend (OPDB) filter is described. The transport of the vacuum arc plasma through this OPDB filter is investigated using Langmuir and deposition probes. Films of amorphous hard carbon have been deposited using a 90° single bend and the OPDB filter and the macroparticle contents of the films are compared. The experimental results were found to be in good agreement with the simulations results based on an improved drift approximation model. The results demonstrate that OPDB filter has a relatively better transmission efficiency than the 90° single bend filter, lower macroparticle counts and is suitable for preparation of diamond-like carbon coatings with high quality.     

Nanostructured titanium/diamond-like carbon multilayer films: deposition, characterization, and applications

Titanium/diamond-like carbon multilayer (TDML) films were deposited using a hybrid system combining radio frequency (RF)-sputtering and RF-plasma enhanced chemical vapor deposition (PECVD) techniques under a varied number of Ti/diamond-like carbon (DLC) bilayers from 1 to 4, at high base pressure of 1 × 10(-3) Torr. The multilayer approach was used to create unique structures such as nanospheres and nanorods in TDML films, which is confirmed by scanning electron microscopy (SEM) analysis and explained by a hypothetical model. Surface composition was evaluated by X-ray photoelectron spectroscopy (XPS), whereas energy dispersive X-ray analysis (EDAX) and time-of-flight secondary ion mass spectrometer (ToF-SIMS) measurements were performed to investigate the bulk composition. X-ray diffraction (XRD) was used to evaluate the phase and crystallinity of the deposited TDML films. Residual stress in these films was found to be significantly low. These TDML films were found to have excellent nanomechanical properties with maximum hardness of 41.2 GPa. In addition, various nanomechanical parameters were calculated and correlated with each other. Owing to metallic interfacial layer of Ti in multilayer films, the optical properties, electrical properties, and photoluminescence were improved significantly. Due to versatile nanomechanical properties and biocompatibility of DLC and DLC based films, these TDML films may also find applications in biomedical science.     

Diamond-like carbon coatings for orthopaedic applications: an evaluation of tribological performance

A detailed investigation of the tribological behaviour of vacuum arc diamond-like carbon coated Ti–6Al–4V against a medical grade ultra-high molecular weight polyethylene is conducted in this work in order to investigate the potential use of diamond-like carbon coatings for orthopaedic appplications. Lubricated and non-lubricated wear experiments are performed using a standard pin-on-disc wear tester. The coefficient of friction is monitored continuously during testing and wear rate calculations are performed using surface profilometry measurements of worn disc surfaces. Sliding wear tests show the existence of two distinct friction and wear regimes distinguished by physically different mechanisms. In the first stages of wear, adhesion and abrasion are the dominant mechanisms of wear while fatigue processes are activated later in the tests. The effects of diamond-like carbon coating structure, surface roughness and lubrication on tribological behaviour are presented. Optimal process–structure–property design for vacuum arc plasma deposition is utilized in order to obtain strong adhesion to the titanium alloy substrate. Diamond-like carbon coatings significantly improve the friction and wear performance of the orthopaedic bearing pair and show exceptional promise for biomedical applications. © 1999 Kluwer Academic Publishers     

脉冲真空电弧离子镀在不锈钢上沉积类金刚石薄膜的研究

利用脉冲真空电弧离子镀技术在3Cr13不锈钢上制备了类金刚石(DLC)薄膜,通过Raman光谱分析了膜的结构特征,采用摩擦磨损试验机测试了薄膜在不同载荷下的摩擦系数,运用划痕仪研究了膜基的结合强度.结果表明:所镀制的薄膜具有典型类金刚石结构特征,膜中ID/IG为1.33;摩擦系数随着载荷的增大而减小,载荷为5 N,转速120 r/min时的摩擦系数为0.12;Ti过渡层的引入显著地提高了膜基结合力.     

Synthesis of fluorinated diamond films using a laser technique

A laser chemical vapour deposition process for growing fluorinated diamond thin films on two bearing materials, SiC and 440 C stainless steel, is described. The type of laser, carbon feedstock, laser-precursor gas interactions, and deposition conditions have been established. Raman spectroscopy analysis revealed that the films deposited on SiC consisted of a mixture of diamond and graphite, while the films on 440 C steel were composed of diamond, diamond-like carbon and graphite. The feasibility of diamond formation using laser light-gas interactions is explained.     

Wasserstofffreie amorphe Kohlenstoffschichten ‐ abgeschieden durch plasmaaktivierte Hochratebedampfung

Hydrogen free amorphous carbon coatings ‐ deposited with plasma‐activated high‐rate evaporation By using the technology of the plasmaactivated electron beam evaporation we deposited hydrogen free amorphous carbon coatings with deposition rates of up to 100 μm/h. The results of the mechanical and tribological investigations show the potential of these layers for the use in case of wear resistance. Hardnesses of up to 16GPa were proved. The actual state of the characterisation of the coatings is described and the outlook onto possibilities of further optimisation is given.     

Influence of the target composition on reactively sputtered titanium oxide films

Titanium dioxide thin films have many interesting properties and are used in various applications. High refractive index of titania makes it attractive for the glass coating industry, where it is used in low-emissivity and antireflective coatings. Magnetron sputtering is the most common deposition technique for large area coatings and a high deposition rate is therefore of obvious interest. It has been shown previously that high rate can be achieved using substoichiometric targets. This work deals with reactive magnetron sputtering of titanium oxide films from TiO_x targets with different oxygen contents.The deposition rate and hysteresis behaviour are disclosed. Films were prepared at various oxygen flows and all films were deposited onto glass and silicon substrates with no external heating. The elemental compositions and structures of deposited films were evaluated by means of X-ray photoelectron spectroscopy, elastic recoil detection analysis and X-ray diffraction. All deposited films were X-ray amorphous. No significant effect of the target composition on the optical properties of coatings was observed. However, the residual atmosphere is shown to contribute to the oxidation of growing films.     

Use of silane for the deposition of hard and oxidation resistant Ti–Si–N coatings by a hybrid cathodic arc and chemical vapour process

Ti–Si–N coatings were deposited on M2 steel substrates using a hybrid cathodic arc and chemical vapour deposition process. Silane was used as the silicon precursor. Whatever the films silicon content, only TiN grains were detected by X-ray diffraction. The mean grain size was estimated to be lower than 10 nm. The silicon content strongly influenced the TiN preferred orientation. Depth sensing indentation showed that films with Si/Ti = 0.08 exhibited a hardness close to 43 GPa. Silicon addition into TiN-based coatings induced an improvement of their oxidation resistance. The film properties were comparable to those obtained for Ti–Si–N coatings deposited using a Ti–Si target, indicating that the hybrid process was suitable for the deposition of hard and oxidation resistant Ti–Si–N coatings.     

Precursor gas effect on the mechanical and optical properties of ion beam deposited diamond-like carbon films

The effect of precursor gases on the diamond-like carbon (DLC) film deposition was investigated by the direct ion beam deposition method. DLC films were deposited using methane and benzene as the precursor gases. Ion energies for the deposition range from 100 to 700 eV were achieved by adjusting the beam voltage. The residual stresses, refractive indices and optical band gaps were compared at the same ion energy. We observed significant differences in residual stress and optical properties between these films. As in r.f. plasma-assisted CVD, the residual stresses of the films deposited from benzene show a characteristic behaviour of lower ion energy deposition than those deposited from methane. The present observations are discussed in terms of the difference in ion energy per carbon atom at the growth surface. We also observed that the Ar addition effect on the residual stress is strongly dependent on the precursor gases.     

Influence of bilayer period on the characteristics of nanometre-scale ZrN/TiAIN multilayers

In the last decade, considerable research effort was directed to the deposition of multilayer films with layer thicknesses in the nanometer range (superlattice coatings), in order to increase the performance of various cutting tools and machine parts. The goal of the present work was to investigate the main microstructural, mechanical and wear resistance characteristics of a superlattice coating, consisting of alternate multilayer ZrN/TiAIN films, with various bilayer periods (5 / 20 nm). The coatings were deposited by the cathodic arc method on Si, plain carbon steel and high speed steel substrates to be used as wear resistance surfaces. The multilayer structures were prepared by using shutters placed in front of each cathode (Zr and Ti+Al). The characteristics of multilayer structures (elemental and phase composition, texture, Vickers microhardness, thickness, adhesion, and wear resistance) were determined by using various techniques (AES, XPS, XRD, microhardness measurements, scratch, and tribological tests). A comparison with the properties of ZrN and TiAIN single-layer coatings was carried out.     

DEPOSITION OF DIAMOND-LIKE AND OTHER SPECIAL COATINGS BY PULSED LASER ABLATION AND THEIR POST-SYNTHESIS PROCESSING

Use of pulsed laser ablation technique for deposition of diamond-like and other special coatings is discussed here at length, establishing the correlation between the process parameters and the film quality. Process parameters dealt with sufficient detail are the laser wavelength, laser pulse width and energy density, nature of ambient and the corresponding partial pressure, substrate temperature and the electric field, if any, applied during deposition. The optimum parameter space for deposition of films having high performance features are identified in the case of diamond-like films and films of cubic boron nitride, titanium nitride and tungsten carbide. In this context, results on the characterization of the films deposited under different conditions are discussed. These include data obtained by Raman spectroscopy, IR spectroscopy, X-ray diffraction, ellipsometry, UV-VIS transmission, scanning electron microscopy. The post-synthesis of the laser deposited films using ion and laser beams from I he standpoint of enhancing their quality or etching of dielectric features therein are also discussed.     

超高分子量聚乙烯表面金属化及类金刚石薄膜沉积复合处理研究

采用超高分子量聚乙烯(UHMWPE)表面金属化及类金刚石薄膜沉积复合处理工艺,提高超高分子量聚乙烯的耐磨性.首先采用磁过滤阴极真空弧源沉积技术(FCVA)在UHMWPE表面制备约30nm钛金属层,使UHMWPE表面金属化,然后再沉积DLC薄膜,研究结果表明,UHMWPE表面金属化后,DLC薄膜沉积过程中,电荷累积效应消...