Preparation Of Diamond-like Carbon Films Research Articles

Effect of local pressure difference caused by argon flow on properties of DLC films on rubber

The application of a diamondlike carbon (DLC) coating on rubber surfaces is a promising method to enhance the tribological properties of rubber and alleviate its poor wear resistance. However, in the preparation of DLC films, accurate pressure detection in the sputtering region is challenging due to the single detection position in common sputtering systems. In this paper, the direct current magnetic sputtering method was used to prepare DLC films on nitrile butadiene rubber (NBR). A set of Faraday beam detection device (FBDD) was employed to monitor the current density in the sputtering region. It was found that even if the pressure at the detection position of the vacuum gauge is consistent, the actual pressure in the sputtering region may be different under different rates of argon flow based on the detection results from the FBDD. The surface energy of DLC films was also calculated and researched. According to the results of FBDD, a series of analytical characterization methods were selected to explore the influence mechanism of changing the Ar flow rate on the properties of DLC films on NBR when the initial sputtering pressure remained consistent. The results of FBDD show that the density of the beam in the sputtering region increases with the increase in the Ar flow rate introduced into the vacuum chamber. The surface energy of DLC films was also calculated and evaluated by a contact angle tester. Raman and x-ray photoelectron spectroscopy results indicate that the increase in the Ar flow rate leads to an increase in pressure, which is conducive to the formation of sp3 in DLC films, and the increase in sp3 improves the surface energy of DLC films. The highest sp3 content and surface energy among as-prepared DLC films are observed when the argon flow rate was 40 SCCM. Ball-on disk friction experiment was used to characterize the tribological performance of DLC films on NBR rubber and the adhesion between DLC films and NBR rubber was evaluated by a nanoscratching test. Combining the results of tribology and nanoscratching testing, it can be inferred that the Ar flow rate plays an important role in improving the mechanical properties of DLC films on NBR rubber. Furthermore, the results of scanning electron microscopy confirmed that the sputtering atoms can effectively fill in the grooves of the rubber substrate. This finding is of significance for controlling the sputtering process of preparing DLC on rubber and improving the frictional properties of rubber.

Magnetic field enhanced radio frequency ion source and its application for Si-incorporation diamond-like carbon film preparation

Various ion sources are key components to prepare functional coatings, such as diamond-like carbon (DLC) films. In this article, we present our trying of surface modification on basis of Si-incorporation diamond-like carbon (Si-DLC) produced by a magnetic field enhanced radio frequency ion source, which is established to get high density plasma with the help of magnetic field. Under proper deposition process, a contact angle of 111° hydrophobic surface was achieved without any surface patterning, where nanostructure SiC grains appeared within the amorphous microstructure. The surface property was influenced by ion flow parameters as well as the resultant surface microstructure. The magnetic field enhanced radio frequency ion source developed in this paper was useful for protective film applications.

Microstructure and property evolution of diamond-like carbon films co-doped by Al and Ti with different ratios

Diamond-like carbon (DLC) films with weak carbide metal Al and carbide metal Ti co-doping (Al/Ti-DLC) were prepared by a hybrid ion beam deposition system. The atomic ratios of doped Al to Ti were tailored via designing the special Al/Ti combined sputtering target. The composition, microstructure, roughness, residual stress, hardness, toughness, and tribological behaviors of the deposited films were systematically evaluated to explore the dependence of structural properties on Al/Ti ratios. Results indicated that the high-throughput preparation of DLC films with different Al/Ti atomic ratios was achieved by tailoring the sputtering target and process parameters without the difference in both the film thickness and total Al/Ti content. With the Al/Ti ratios in the films decreased from 8.8 to 3.0, the residual stress, hardness, and toughness of Al/Ti-DLC films increased obviously, originating from the increased fraction of titanium carbide and the reduced Al content. However, the coefficient of friction and wear rate with decreasing the Al/Ti ratio were obviously improved, which was related with the transformation of underlying friction mechanism from the sliding interface graphitization to dangling bond-passivation. The present results not only suggest a high-throughput method to fabricate co-doped DLC films, but also promote the scientific understanding and engineering application of DLC films with high performance.

Diamond-like carbon film preparation using a high-repetition nanosecond pulsed glow discharge plasma at gas pressure of 1 kPa generated by a SiC-MOSFET inverter power supply

A high-repetition nanosecond pulsed glow discharge plasma at a gas pressure of 1 kPa was generated using a SiC-MOSFET inverter power supply for diamond-like carbon (DLC) film preparation. At a high repetition frequency above 50 kHz, the period of the nanosecond voltage pulse became shorter than the decay time of the afterglow plasma, and many ions and radicals remained in the gap space. The deposition rate was 0.1 µm/min, which was 5 times higher than that of a conventional plasma CVD process. An increase in hardness to 13 GPa and a decrease in hydrogen content in the DLC film were confirmed by increasing the repetition frequency to 200 kHz.

Preparation of Diamond-Like Carbon Films at Room Temperature for Ultraviolet Detecting Application

Preparation of Diamond-Like Carbon Films at Room Temperature for Ultraviolet Detecting Application

Preparation of diamond-like carbon films using reactive Ar/CH4 high power impulse magnetron sputtering system with negative pulse voltage source for substrate

Diamond-like carbon films were prepared using a reactive Ar/CH4 high-power impulse magnetron sputtering system with a negative pulse voltage source for the substrate, changing the CH4 fraction up to 15% in the total pressure range from 0.3 to 2 Pa. The magnitude of the negative pulse voltage for the substrate was also varied up to about 500 V. The hardness of films monotonically increased with increasing magnitude of the negative pulse voltage. The films with hardnesses between 16.5 and 23 GPa were prepared at total pressures less than 0.5 Pa and CH4 fractions less than 10% by applying an appropriate negative pulse voltage of 300–400 V. In X-ray photoelectron spectroscopy, the area ratio C–C sp3/(C–C sp2 + C–C sp3) in the C 1s core level was higher than 30% at pressures less than 0.5 Pa and CH4 fractions less than 15%. On the other hand, the films with hardnesses between 5 and 10 GPa were prepared with a relatively high growth rate at the partial pressures of CH4 higher than 0.1 Pa. However, the observation of the photoluminescence background in Raman spectroscopy indicated a relatively high hydrogen content.

Development of a polygonal barrel-plasma enhanced chemical vapor deposition method for preparing powdered materials with a diamond-like carbon film

A novel polygonal barrel-plasma enhanced chemical vapor deposition (PB-PECVD) method was developed to prepare powdered materials with diamond-like carbon (DLC) films. To investigate the effects of frequency on the DLC film preparation, frequency power supplies of 250kHz and 13.56MHz were used and a DLC film was successfully formed on an SiO2 glass plate at 250kHz. The PB-PECVD process was further examined by using polymethyl methacrylate (PMMA) powder sample. It was determined that a DLC film could be uniformly deposited onto the PMMA particles by rotating a hexagonal barrel including the PMMA sample during the PB-PECVD procedure while operating at 250kHz.

Preparation of Diamond-like Carbon Films by Plasma Source Ion Implantation with External Glow Discharge

Preparation of Diamond-like Carbon Films by Plasma Source Ion Implantation with External Glow Discharge

Direct hydrothermal electrochemical preparation of diamond-like carbon films on substrates

Direct hydrothermal electrochemical preparation of diamond-like carbon films on substrates

Influences of Film Deposition Condition on Friction of Diamond-Like Carbon Film: A Theoretical Investigation

We theoretically investigated influences of film deposition condition on a friction of diamond-like carbon (DLC) film using our developed molecular dynamics method. The method can deal with chemical reactions on the basis of our original stochastic equation. DLC slab model was firstly constructed, and carbon atoms were deposited onto its surface with various kinetic energies (1, 10 and 30 eV) to mimic physical vapor deposition process. Lower sp3 carbon concentration and density were obtained for the 1 eV case and “subplantation” phenomenon was found for each model. The dynamical friction of the deposited DLC film/iron oxide combination was also simulated. The friction coefficient for the deposited film with kinetic energy of 1 eV was much lower than that of 10 and 30 eV cases due to the friction-induced structural change. The simulations provided us an important insight on DLC film preparation to achieve low friction regime.

Preparation of diamond-like carbon films by cathodic micro-arc discharge in aqueous solutions

Diamond-like carbon films (DLC) and silicon doped diamond-like carbon films were deposited on Ni substrate by cathodic micro-arc discharge at room temperature in aqueous solutions. The deposit potential was 130 V. The structure of the films was characterized by a scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectra and XPS analysis demonstrated that the films were diamond-like carbon clearly. SEM observation showed that the DLC films were uniform and the thickness was about 200 nm. Potentiodynamic polarization curve indicated the corrosion resistance of the Ni substrate was markedly improved by DLC films.

T-shape filtered arc deposition system with built-in electrostatic macro-particle trap for DLC film preparation

A T-shape filtered arc deposition system (T-FAD) is a powerful tool to prepare high-quality diamond-like carbon (DLC) films. Most macro-particles (droplets) emitted from the graphite cathode are caught at the extension duct of the droplet catcher or collector facing the cathode, and then the clean plasma bent 90° is transported toward the substrate. However, further droplet reduction is still required in order to realize a higher quality film without droplet incorporation. In the present study, T-FAD employed an electrostatic droplet trap (ES-trap). A cylindrical ES-trap was placed in the extension duct part of the T-shape duct of an electromagnetic plasma transportation and droplet filter. The ion current at the exit of the T-filter duct and the current flowing to the ES-trap were measured as a function of the ES-trap bias voltage for various ES-trap positions. The deposition rate and number of droplets were also measured. As a result, it was found that the optimum voltage of the ES-trap was +35V and that it was better to place the ES-trap closer to the plasma beam in order to obtain fewer droplets on the film without an excessive decrease in the deposition rate. In the optimum condition, the number of droplets on the DLC film prepared with ES-trap was reduced to 1/3 of that without the ES-trap.

Preparation of super-hard coatings by pulsed laser deposition

Amorphous diamond-like carbon (DLC) films and nanocrystalline cubic boron nitride (c-BN) films were prepared by pulsed laser deposition. DLC films with 80 to 85% sp3 bonds prepared at a laser fluence above 6 J/cm2 and a substrate temperature below 100 °C show high compressive stresses in the range of 8 to 10 GPa. Those stresses can be completely removed by means of pulsed laser annealing, allowing the preparation of DLC films with several-micrometre thickness. c-BN films were prepared with additional ion-beam bombardment at a substrate temperature of 250 °C. The properties of DLC and c-BN films deposited at high growth rates up to 100 nm/min are presented .

Preparation and characterization of DLC films by twinned ECR microwave plasma enhanced CVD for microelectromechanical systems (MEMS) applications

Diamond-like carbon (DLC) films have recently been pursued as the protection of MEMS against their friction and wear. Plasma enhanced chemical vapor deposition (PECVD) technique is very attractive to prepare DLC coating for MEMS. This paper describes the preparation of DLC films using twinned electron cyclotron resonance (ECR) microwave PECVD process. Raman spectra confirmed the DLC characteristics of the films. Fourier-transform infrared (FT-IR) characterization indicates the carbon is bonded in the form sp3 and sp2 with hydrogen participating in bonding. The surface roughness of the films is as low as approximately 0.093 nm measured with an atomic force microscope. A CERT microtribometer system is employed to obtain information about the scratch resistance, friction properties, and sliding wear resistance of the films. The results show the deposited DLC films have low friction and good scratch/ wear resistance properties.

Laser Induced Fluorescence Measurement Of Plasma Plume During Pulsed Laser Deposition Of Diamond-Like Carbon

AbstractDynamics of carbon ablation plasma plume during the preparation of diamond-like carbon films by KrF excimer pulsed laser deposition was investigated using laser induced fluorescence (LIF) and optical emission spectroscopy. LIF signal from C2molecule (Swan band, d 3Φg – a3Φu) was detected using a photomultiplier tube and an intensified CCD camera. Temporal evolution and spatial distribution of C2 molecules in the ablated plume were measured as a function of laser energy density and ablation area. LIF intensity is found to be weaker in the central part of the plume than that at the periphery at incident energy greater than 6 J/cm2. It is conjectured that some of C2molecules are dissociated by collision with energetic species in central part of the ablation plume. Dynamics of ablation plasma plume is strongly dependent on the size of ablated area.

Optical emission study of ablation plasma plume in the preparation of diamond-like carbon films by KrF excimer laser

Optical emission study of the laser ablation plasma plume during the preparation of diamond-like carbon (DLC) films using KrF excimer (248 nm) pulsed laser deposition (PLD) has been carried out by means of a monochromator equipped with an intensified optical multichannel analyzer. In high vacuum (1×10−7 Torr), the emission lines from carbon ions of C+, C2+, and C3+ are observed in addition to atomic carbon emission lines, while no emission from the diatomic carbon molecule (C2) is observed. With increasing background nitrogen pressure up to 500 mTorr, the emission intensities of the C2 Swan band and the carbon nitride (CN) violet band increase. The diamond-like character of deposited DLC film degrades with background nitrogen pressure. The vibrational temperature of C2 and CN molecules decreases with the increasing of nitrogen pressure. The CN vibrational temperature for the first 2 μs after the laser pulse is very high and in agreement with the kinetic energy of monatomic carbon ions. The C2 vibrational temperature is as low as 0.6 eV and is consistent with the electron temperature of about 0.8–3.0 eV. It is conjectured that CN molecules are formed directly in reactions involving energetic ionic monatomic carbon, and that the formation of excited C2 molecules is the result of molecular recombinations of C atoms and ions. From the emission intensity measurements and the estimation of the vibrational temperature, it is suggested that the C2 molecule in the ablated plasma plume is not important, but energetic species, such as C+, are very important for producing high quality DLC films using PLD.

Diamond-like carbon film preparation and surface coatings of oxide superconducting and ferroelectric films

Diamond-like carbon (DLC) films as well as amorphous carbon films are investigated as possible passivation and environment protection for YBa 2Cu 2O 7 − x (YBCO) oxide superconducting and Pb(Zr x Ti 1 − x )O 3 (PZT) ferroelectric thin films. The pulsed laser deposition (PLD) technique was employed to prepare the perovskite oxide films of YBCO and PZT. These film surfaces were coated by the DLC films prepared using the excimer laser ablation method. Optimum deposition condition of the PLD process for the YBCO, PZT and DLC was investigated. In the case of DLC coatings, a graphite target was ablated using a KrF excimer laser of 2–9 J cm −2 in 200–800 mTorr hydrogen ambient gas. An optical band gap of 2.0 eV was attained on room temperature substrate and high quality superconductivity of the DLC coated YBCO films was kept over 1 month. The PZT film encapsulated by the DLC layer showed no degradation due to aging over 30 days.

Preparation of diamondlike carbon films by high-intensity pulsed-ion-beam deposition

Diamondlike carbon (DLC) films were prepared by high-intensity pulsed-ion-beam ablation of graphite targets. A 350 keV, 35 kA, 400 ns beam, consisting primarily of hydrogen, carbon, and oxygen ions was focused onto a graphite target at a fluence of 15–45 J/cm2. Amorphous carbon films were deposited at up to 30 nm per pulse, corresponding to an instantaneous deposition rate greater than 1 mm/s. Electrical resistivities were between 1 and 1000 Ω cm. Raman spectra indicate that diamondlike carbon is present in most of the films. Electron-energy-loss spectroscopy indicates significant amounts of sp3-bonded carbon, consistent with the presence of DLC. Scanning electron microscopy showed most films contain 100 nm features, but micron size particles were deposited as well. Initial tests revealed favorable electron field-emission behavior.

Diamond-like carbon film preparation by laser arc

The method of laser-induced, laser-pulsed and laser-guided vacuum are evaporation (laser arc) was used to prepare diamond-like carbon (DLC) films. The deposition was carried out with an arc repetition frequency of 100 Hz, a peak current of 450 A and a pulse duration of about 37 μs. At a deposition rate of 1 nm s-1 films were deposited up to a thickness of 1 μm. It will be shown that, using this controlled arc deposition, characterized by plasma-sustained ion bombardment, DLC films can be prepared on silicon wafers, quartz, glass, ZnSe and NaCl or KCl substrates with an increased adhesion in comparison with earlier experiments. The frictional behaviour of films prepared at different temperatures (50°C–500°C) was studied. The refractive index was estimated by ellipsometry and varied between 2.0 and 2.4 with an extinction coefficient below 0.2 at a wavelength of 633 nm. The optical band gap has been found to be of the order of 1.3 eV.

DLC film preparation by LASER-ARC and properties study

The LASER-ARC was used to prepare diamond-like carbon (DLC) films up to a thickness of about 1 μm on different substrate materials. The laser-induced, laser-pulsed and laser-guided vacuum are evaporation is a precisely controlled pulsed plasma source for which the film deposition is characterized by plasma sustained ion bombardment. At a deposition rate of 1 nm/s DLC films were prepared on Si(111)-wafers, quartz, glass, ZnSe and NaCl or KCl substrates with an increased adhesion allowing wear tests. Mechanical, optical and electrical properties of the films were studied depending on the substrate deposition temperature (500 °C> T > 25 °C) and on substrate bombardment with Ar + ions. Film-substrate interfaces were analyzed by secondary ion mass spectrometry. Unlubricated friction measurements in air were carried out with a ball-on-disk machine using hardened steel and Al 2O 3 balls. The friction coefficient varied depending on deposition conditions from 0.1 to 0.5. The optical properties of the films were estimated both by ellipsometry (λ = 633nm) and spectral reflection and transmission measurements. The refractive index varied between 2.3 and 1.8 with an extinction coefficient from 0.2 to 1.1, corresponding to substrate deposition temperature of 25 °C to 500 °C. The optical band gap (Tauc-gap) was of the order of 1.3 eV at 25 °C and 0.3 eV at 500 °C.