Deposition Of Diamond-like Carbon Films Research Articles

Temperature dependent erosion and Raman analyses of arc-deposited H free thick DLC coating on Cr/CrN coated plasma nitrided steel

Development of H and metal dopant-free single phase thick diamond like carbon (DLC) coating on metal nitride layer for automobile applications is still a challenging task due to internal stress developed during deposition of DLC films. A simple process was followed to deposit thick Cr/CrN/DLC (0.25/0.75/6 μm) coating on plasma nitrided steel using an un-filtered cathodic vacuum arc system without applying any high pulse bias voltage. In addition, the coating was deposited at room temperature and it showed very good adhesion on plasma nitrided steel surface and exhibited a very low coefficient of friction ~0.06 ± 0.005. Temperature dependent solid particle erosion tests were conducted according to ASTM-G-76-18 standards at an impinging angle of 45°. Erosion resistance of the coating is 33, 11, 7 and 6 times better than nitrided steel substrate at test temperatures of 25, 200, 300 and 400 °C, respectively. Better erosion resistance performance of a coating infers the long life of the coating on automobile components. A multi-wavelength Raman study gives a better understanding of the structural properties of DLC. So, the Raman spectra of the coating were recorded using three different laser wavelengths: 405 nm, 532 nm and 633 nm. The thermal stability of the coating was studied using temperature dependent Raman spectroscopy. The coating showed good thermal stability until a temperature of 425 °C.

HiPIMS pulse shape influence on the deposition of diamond-like carbon films

Two high-power impulse magnetron sputtering (HiPIMS) systems were used to prepare hard DLC films using two types of pulse shape, one normal HiPIMS pulse and the second with short multi-pulse HiPIMS. Similar DLC film performance was achieved, however, recurring to different substrate bias values showing that the pulse characteristics are one determinant factor to the film properties.

Design of thin DLC/TiO2 film interference coatings on glass screen protector using a neon–argon-based gas injection magnetron sputtering technique

This paper reports the results obtained from the deposition of diamond-like carbon (DLC) films on glass substrates by gas injection magnetron sputtering method. The conducted studies aimed to evaluate if the plasma discharge that is generated by varying the proportions of neon−argon (Ne−Ar) gases during pulsed injections (0%–100%) would promote the synthesis of DLC films with desirable sp3 phase by means of electron impact-induced plasma interactions. The obtained DLC films showed the presence of sp3 (CC) hybridized bonds along the Gaussian distribution curve, which revealed that a maximum sp3 content in the range of 32%–45% was obtained along the 40% injection of Ne gas, based on the analysis of the C1s core-level spectra and Raman spectroscopy. A 25% gain in hardness (H) and resistance to cracking (H3/E2) were also observed in the sp3-rich DLC sample (24.1 ± 4 GPa and 0.29 ± 0.04), thus promoting its use in various nanomechanical systems. The change in the sp3/sp2 fraction ratio, demonstrated in this research, corresponded well to a calculated model of graded optical bandgap in the range from 0.53 to 3.01 eV. However, to further minimize the parasitic reflectance from a significant share of sp2 (C=C) domains, thin titanium dioxide (TiO2) (8–36 nm) layers were deposited on the DLC surface, which provided maximum antireflective effect due to interference shift. A significant increase in visible–near-infrared transmittance (up to 87%) was observed as a result of such an interference in DLC/TIO2 bilayers. Our results have practical applications and aid in the design of functional nanocoating structures which are tremendously favored and required to improve the toughness of commercially available glass protectors in hostile environmental conditions.

Characterization of Diamond-like carbon films produced by electron- beam physical vapor deposition

Diamond-like carbon (DLC) films were deposited at 300 °C, 400 °C and 500 °C on 304 L stainless steel substrates by electron-beam physical vapor deposition. The obtained coatings were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy and X-ray photo electron spectroscopy (XPS). The FTIR results demonstrate the presence of sp3 and sp2 vibrations corresponding to a diamond-like carbon phase and graphite, respectively. Raman and XPS analysis confirm a presence of high quantity of CC bonds in sp3 state in the deposited DLC films. Increasing the substrate temperature from 300 °C to 500 °C led to a decreasing of the hardness from 4.5 GPa to 3.2 GPa.

Study of the influence of diamond-like carbon film deposition technology on the change of its physical and mechanical characteristics

The paper presents the results of testing the technology of deposition of diamond-like carbon films on the surface of stainless steel substrates at different process parameters, a quantitative assessment of the sp3 bond content and the physical and mechanical characteristics of the coatings obtained, a conclusion about the influence of the deposition process technological parameters on these characteristics is formulated.

Deposition phenomena of diamond-like carbon coating on inner surface of circular metal tube by nanopulse plasma chemical vapor deposition

A method of depositing a diamond-like carbon (DLC) film on the inner surface of a circular metal tube by chemical vapor deposition using a nanopulse power source was developed. Because the nanopulse power source can supply rapidly rising and falling high-voltage nanopulses of nanosecond order, a stable plasma can be obtained even in small-diameter tubes by applying a high gas pressure of more than 100 Pa. DLC films were successfully deposited on the inner surfaces of metal tubes of 14 mm diameter and 300 mm length (21% aspect ratio), and of 40 mm diameter and 300 mm length. To understand the plasma state inside the tubes to determine appropriate DLC film deposition conditions, wavelength- and time-resolved optical emission spectroscopy of the plasma generated inside the tubes and numerical simulation were performed. Results of these investigations and characterization clarified that one nanopulse power source introduced to tubes generates glow and after-glow discharges at μs time intervals. It was further clarified that these discharges in combination with high-repetition pulses, suggested together contribute to the effective ionization of gas. Thus, the high speed and high source gas yield of DLC film deposition inside the tubes were confirmed.

Pulsed laser deposition of multilayer diamond-like carbon film grown on stainless steel

The amorphous SiC layers played an essential role of improving adhesive property in the pulsed laser deposition-grown multilayer DLC coating. Comparison of several experiments exhibited that the adhesive SiC layer enhanced the adhesive strength of the DLC layer on the transitional Ti layer. Meanwhile, the ‘inserted’ buffer thin SiC layers, which had strong binding force with the DLC layers, divided the thick DLC layer (about 1.2 μm) into several relatively thin layers. It's thought that the buffer SiC layers reduced accumulation of internal stress in each finite thickness and then prevented the cracking of the DLC layer. And the total thickness of optimized multilayer DLC coating reached to 2 μm. The multilayer DLC coating with the adhesive SiC layer and buffer SiC layers showed an excellent adhesive performance on the stainless steel. The similar tribological property of SiC layer to the DLC layer conferred this multilayer DLC coating a low friction coefficient and a low wear rate.

Effects of Substrate Bias Voltage on Structure of Diamond-Like Carbon Films on AISI 316L Stainless Steel: A Molecular Dynamics Simulation Study.

With the recent significant advances in micro- and nanoscale fabrication techniques, deposition of diamond-like carbon films on stainless steel substrates has been experimentally achieved. However, the underlying mechanism for the formation of film microstructures has remained elusive. In this study, the growth processes of diamond-like carbon films on AISI 316L substrate are studied via the molecular dynamics method. Effects of substrate bias voltage on the structure properties and sp3 hybridization ratio are investigated. A diamond-like carbon film with a compact structure and smooth surface is obtained at 120 V bias voltage. Looser structures with high surface roughness are observed in films deposited under bias voltages of 0 V or 300 V. In addition, sp3 fraction increases with increasing substrate bias voltage from 0 V to 120 V, while an opposite trend is obtained when the bias voltage is further increased from 120 V to 300 V. The highest magnitude of sp3 fraction was about 48.5% at 120 V bias voltage. The dependence of sp3 fraction in carbon films on the substrate bias voltage achieves a high consistency within the experiment results. The mechanism for the dependence of diamond-like carbon structures on the substrate bias voltage is discussed as well.

Structural, mechanical and tribological behavior of different DLC films deposited on plasma nitrided CF170 steel

In order to improve the surface hardness and tribological properties of CF170 steel, a duplex treatment including plasma nitriding and deposition of different diamond-like carbon (DLC) films was carried out on CF170 steel. The structural, mechanical and tribological properties of untreated, plasma nitrided and duplex-treated samples were investigated by methods of XRD, SEM, AFM, Raman spectroscopy, XPS, hardness tester, scratch tester and ball-on-disc tribometer, respectively. Raman spectroscopy and XPS revealed that the Ti/a-C/(ta-C) film had the highest amount of sp3 content, followed by Cr/WC/(a-C:H) and Cr/WC/(a-C:H:W) films. The hardness of duplex-treated samples was significantly higher than that of single plasma nitrided sample and the highest value was obtained from the Ti/a-C/(ta-C) film deposited on the plasma nitrided sample. The critical adhesion load (Lc3) of the Cr/WC/(a-C:H) film deposited on the plasma nitrided sample was obviously higher than that of the Ti/a-C/(ta-C) film deposited on the plasma nitrided sample. The duplex-treated samples showed a low friction coefficient. Both Cr/WC/(a-C:H) and Ti/a-C/(ta-C) films deposited on plasma nitrided samples had a low wear rate. The wear rate of the Cr/WC/(a-C:H) film deposited on the plasma nitrided sample was reduced by one (five) orders of magnitude compared to the plasma nitride (untreated) sample.

Diamond-Like Carbon - Coated Silicon Nanowires as a Supercapacitor Electrode in an Aqueous LiClO4 Electrolyte

Silicon nanowires (SiNWs) were successfully coated by uniform, adherent, and homogenous films of diamond-like carbon (DLC) using electrophoretic method. The coating was performed in an organic dimethylsulfoxide (DMSO) solution at 70 °C for 60 min with an applied voltage of 150 V. The as prepared samples of SiNWs and DLC/SiNWs were characterized by a scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Raman spectroscopy techniques. The SEM micrographics showed that the films were uniformly deposited on the whole of SiNWs surface and composed of compact and small spherical grains with uniform distribution. Raman spectroscopy indicates that the coating films were DLC in nature. These results were well confirmed by the EDX and XRD techniques. The electrochemical investigation including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, showed that the electrochemical behavior of SiNWs was clearly enhanced after coating with a DLC film. Indeed, the latter showed a specific capacitance of 400 mF/cm2at scan rate of 5 mV/s in an aqueous 0.5 M LiClO4 solution with capacitance retention of 90% after 16,000 cycles. Thus, the deposition of DLC film onto silicon nanowires (SiNWs) substrate can be considered as a simple and economical method to fabricate a high-performance electrode for supercapacitors.

Deposition of DLC films on the inner wall of U-type pipes by hollow cathode PECVD

There are many defects in the bending part of U-type pipe, which will directly affect its safety and service life. DLC (Diamond Like Carbon) film is considered as an effective protective film because of its excellent properties. However, it is very difficult to deposit DLC films on the inner wall of U-type pipes with double stress. The purpose of this paper is to deposit DLC film with high hardness, wear resistance and corrosion resistance on the inner wall of U-type pipes by hollow cathode PECVD. The microstructure, mechanical properties, tribological and corrosive behaviors were characterized by the Raman spectroscopy, ATR-FTIR, SEM, nano-indention, polarization, electrochemical impedance spectroscopy and ball-on-disk tribological tests. Results indicates that the U-type pipe inner DLC films shows the lower stress level. Compared with the bare substrate, it presents the higher hardness (7– 14 GPa), elastic factor (>0.1) and plastic factor (>0.1) and the above DLC film exhibits the lower corrosion current density, which is about 1–2 orders of magnitude lower than the bare substrate. Moreover, the DLC films also possesses the lower friction coefficient (0.04– 0.06) and wear rate (2.67– 5.93E-7 mm3N−1 m−1). Therefore, the DLC films exhibits the greater mechanical, tribological and anti-corrosion performance, indicating that the above DLC films effectively protects U-shaped pipe and prolongs its service life.

Electrochemical Deposition of DLC Films Embedded with Crystalline Graphite and Multilayer Graphene

Diamond-like carbon (DLC) films embedded with crystalline graphite and multilayer graphene have been fabricated on silicon substrates by a simple electrochemical route from methanol and C60-1, 2-ethylenediamine (C2H8N2) derivatives as an incorporating reagent at atmospheric pressure. The structure and sheet resistivity of the as-obtained films were characterized by x-ray photoelectron spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and four-point probe measurements, respectively. The structure of the as-prepared films with crystalline graphite and multilayer graphene consisted of sp2 C, sp3 C, C–N, C–H, and N–H bonds. After introducing crystalline graphite and multilayer graphene, the conductivity of the DLC films was evidently improved and the sheet resistivity drastically decreased from 108 Ω cm to about 80 Ω cm.

Pulsed laser deposition of high-quality diamond-like carbon films under an inhomogeneous magnetic field

High-quality diamond-like carbon film was deposited on silicon substrate by magnetic field-enhanced pulsed laser deposition. The motion tracks of carbon ions in the inhomogeneous magnetic field were simulated. The thickness and surface morphology of carbon film were characterized by surface profilometer and atomic force microscopy, respectively. Mechanical property was evaluated by an indenter. The results showed that the deposition rate of the carbon film prepared under the magnetic field increased 1.7 times than that of the carbon film without magnetic field. The surface of the carbon films constructed of columnar particle arrays with the size ranging from 20 nm to 30 nm was improved and the roughness was decreased from 3.22 nm to 0.93 nm. The nano-hardness of the carbon film was 53.4 GPa, which increased by 18.1% than that of carbon film deposited without magnetic field. The experiment and simulation on the magnetic field-enhanced pulsed laser deposition proved that the new method of film preparation by magnetic filtration laser plasma deposition is feasibility.

Effect of nitrogen (N2) flow rate over the tribological, structural and mechanical properties diamond-like carbon (DLC) thin film

In this article, nitrogen (N2) doped diamond-like carbon (N-DLC) coatings are deposited by Atmospheric pressure chemical vapor deposition (APCVD) technique at varying N2 flow rates and are investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, nanoindentation (NI) and nano scratch (NS) characterization. The wear rate (WR) and coefficient of friction (μ) of the N-DLC thin films increase from 1.32 × 10−4 to 3.11 × 10−4 μm2 and 0.05 to 0.15 with the increase of load from 40 to 70 mN at 70 sccm N2 flow rate. The results showed that there is a significant improvement in the tribological and mechanical properties of the APCVD synthesized DLC film as compare to the other PVD deposited DLC film.

Improved Thermal Resistance and Electrical Conductivity of a Boron-Doped DLC Film Using RF-PECVD

Diamond-like carbon (DLC) film doped with boron has unique properties and displays higher thermal resistance, lower internal stress, and better electrical conductivity than un-doped DLC film; this makes it is suitable for various applications, especially in outer space. Radio-frequency plasma-enhanced chemical vacuum deposition of boron-doped DLC film was performed to determine the optimal percentage of boron for improving thermal resistance. Additional heat treatment and 40% B2H6/CH4 yielded the best electrical conductivity. X-ray photoelectron spectroscopy, thermal gravimetric analysis, Raman spectroscopy, and the four-point probe method were utilized to analyze the properties of boron-doped DLC film. The boron-doped DLC film displayed outstanding performance in terms of thermal resistance and electrical conductivity.

The structure and properties of amorphous diamond-like carbon films deposited by helicon wave plasma chemical vapor deposition

The diamond-like carbon (DLC) films have been synthesized on silicon substrates by using chemical vapor deposition assisted with a high-density m=+1 mode helicon wave-excited plasma in Ar/CH4 gas mixtures. The structure and morphology of the DLC films are characterized by scanning electron microscopy (SEM), Raman spectroscopy and atomic force microscopy (AFM). The surface energies of the DLC films are calculated by the the Owens–Wendt–Rabel–Kaelble (OWRK) method. SEM results show that the surfaces of DLC films are found to be very uniform and dense, and the deposition rate of the film can reach up to 45 μm/h. The Young's modulus of the DLC films reaches the maximum (11 GPa) value at 25 sccm CH4 flow rate. With the increase of CH4 flow rate from 5 sccm to 35 sccm, the surface energy and friction coefficient of the DLC films decrease from 73.5 to 37.6 mJ m − 2 and from 0.56 to 0.25, respectively. It indicates that the deposited DLC films have good friction properties.The Young's modulus value is obtained here using AFM [48]. The results show that the Young's modulus increases from 4.1 to 10. 77 GPa, as the CH4 flow rate increases from 5 to 25 sccm. However, with further increasing the CH4 flow rate, the Young's modulus decreases gradually. This is consistent with the trend of sp3 bond content in Raman results. According to literature [49], CC sp3 bond of DLC films has a certain influence on Young's modulus. The result shows that the CC sp3 content reaches its maximum when the CH4 flow rate reaches 25 sccm. Moreover, the RMS results of DLC films show that the smoother the film is, the higher the Young's modulus is, likewise the rougher the DLC film is, the lower the Young's modulus is. It can be inferred that when DLC film is rough, the accumulated carbon polymer sp3 content in DLC film is low.

Effects of Polyurethane Substrate Pre-Treatment on Pulsed Cathodic Arc Deposited DLC Films

Diamond-like carbon (DLC) films were deposited by means of pulsed cathodic arc deposition on pretreated polyurethane (PU) rubber substrates. Tetrachloroethylene was chosen as a dissolution method to remove the plasticizer added in the PU substrates. Scanning electron microscopy (SEM) and Raman spectroscopy were applied to observe and characterize the surface morphologies and compositions of the deposited films, respectively. The tribological behaviours of uncoated and coated rubbers were investigated with ring-on-disc tribo experiments under dry sliding conditions. The coefficients of friction (COFs) of the coated rubbers were 40% lower than those of uncoated rubber and the COFs of different samples decreased first and then increased slightly with the increase in temperature and the time of ultrasonic treatment under dry friction. Based on the above experiments, ultrasonic treatment with tetrachloroethylene contributes to the increase in the wear resistance of DLC films deposited on PU rubbers. The most suitable temperature and time of ultrasonic treatment with tetrachloroethylene is 50 °C for 15 min.

Effect of methane content and the oscillating electric field between electrodes on atmospheric Ar/methane plasma jet and DLC coating deposition

In this work, the effects of the methane gas flow and the internal oscillating electric field between electrodes on radio-frequency (RF) atmospheric pressure argon/methane plasma jet and process of diamond-like carbon (DLC) film deposition have been investigated. Properties of RF atmospheric Ar/methane plasma jet such as active species density, length, electron temperature, appearance and ionization process of argon/methane plasma jet are changed due to the changing of methane flow content and electric field vector and its gradient. With increasing methane flow, the formation of C2 hydrocarbon and CH band content is decreased because injected electrical energy to a mixture of Ar/methane gases is insufficient to stabilize the ionization process of methane gas and the electrical-chemical reaction rate is decreased. With shortening the gas gap between two electrodes, electric field strength and its gradient are increased leading to more energy injection to the electron. Electrical-chemical reactions are strengthened leading to increasing the CH band content. These phenomena introduce the Ar/methane plasma jet in different modes causing to deposit the DLC film with different structures and properties. With using quartz glass and alumina ceramic as dielectric barriers tubes, RF atmospheric pressure Ar/methane plasma jet has been used to deposit DLC coating in different modes. Increasing methane content and shortening the gas gap leads to decreasing sp3 bonded content and the quality of the deposited film.

A Strategy for Alleviating Micro Arcing during HiPIMS Deposition of DLC Coatings.

In this work, we investigate the use of high power impulse magnetron sputtering (HiPIMS) for the deposition of micrometer thick diamond like carbon (DLC) coatings on Si and steel substrates. The adhesion on both types of substrates is ensured with a simple Ti interlayer, while the energy of impinging ions is adjusted by using RF (Radio Frequency) biasing on the substrate at −100 V DC self-bias. Addition of acetylene to the working Ar+Ne atmosphere is investigated as an alternative to Ar sputtering, to improve process stability and coatings quality. Peak current is maintained constant, providing reliable comparison between different deposition conditions used in this study. The main advantages of adding acetylene to the Ar+Ne gas mixture are an increase of deposition rate by a factor of 2, when comparing to the Ar+Ne process. Moreover, a decrease of the number of surface defects, from ~40% surface defects coverage to ~1% is obtained, due to reduced arcing. The mechanical and tribological properties of the deposited DLC films remain comparable for all investigated gas compositions. Nanoindentation hardness of all coatings is in the range of 25 to 30 GPa, friction coefficient is between 0.05 and 0.1 and wear rate is in the range of 0.47 to 0.77 × 10−6 mm3 N−1m−1.

Deposition of diamond-like carbon films on insulating substrates by plasma source ion implantation

Plasma source ion implantation (PSII) is a technique that is suitable for implantation as well as film deposition. Since it involves a high voltage that is applied to the sample holder to attract ions from the plasma to the sample, an influence can be expected in case that either the whole substrate or a part of it is nonconductive. Diamond-like carbon (DLC) films were deposited by PSII, using C2H2 as precursor. The substrates were silicon samples that were placed on a large, horizontally oriented conductive sample holder in three different ways: 1) directly on the holder, 2) with an alumina block of 5 mm height between holder and sample, and 3) with an alumina block of 12 mm height between holder and sample. A high voltage (pulse or DC) was applied directly to the sample holder. The plasma was generated by this voltage or, in some experiments, by an additional RF signal, which was applied to a plate that was oriented parallel to the sample holder in a distance of 100 mm. The investigation of the effect of the presence of the insulating alumina block on the film properties focused on the deposition rate, the hydrogen content and film structure, the surface roughness, the hardness and the friction coefficient of the films.