Diamond-like Carbon Deposition Research Articles

Precise Deposition and Application of Diamond-like Carbon by Photo-excited Plasma

Precise Deposition and Application of Diamond-like Carbon by Photo-excited Plasma

Mechanical and tribological properties of diamondlike carbon-coated polycarbonate

To improve the mechanical and tribological properties of polycarbonate, diamondlike carbon (DLC) coating was deposited on its surface by pulsed vacuum arc deposition with different pulse repetition rates at low substrate temperature (not more than 80 °C). The surface hardness increased by 20–33 times, the plasticity index increased by 1.6–2.5 times, the resistance to plastic deformation increased by 50–200 times, and the wear rate decreased by 170–600 times compared to untreated polycarbonate depending on the pulse frequency in the process of coating deposition. It has been shown that decreasing the pulse frequency during DLC deposition from 3 to 1 Hz increases the content of sp3-hybridized carbon atoms and level of internal stresses in the coating and increases its hardness. However, this is accompanied by an increase in the number of microcracks in the coating. Deposition with an optimal pulse frequency formed a polycarbonate/DLC system with high hardness and wear resistance as well as a low number of microcracks.

Targeting Biomechanical Endurance of Dental-Implant Abutments Using a Diamond-Like Carbon Coating.

Abutment components (i.e., fixtures associated with oral implants) are essentially made of titanium (Ti), which is continuously exposed to the hash oral environment, resulting in scratching. Thus, such components need to be protected, and surface treatments are viable methods for overcoming long-term damage. Diamond-like carbon (DLC), an excellent protective material, is an alternative surface-treatment material for Ti abutments. Here, we demonstrate that a silicon interlayer for DLC film growth and the pulsed-direct current plasma-enhanced chemical vapor deposition (DC-PECVD) method enables the deposition of an enhanced protective DLC film. As a result, the DLC film demonstrated a smooth topography with a compact surface. Furthermore, the DLC film enhanced the mechanical (load-displacement, hardness, and elastic modulus) and tribological properties of Ti as well as increased its corrosion resistance (16-fold), which surpassed that of a bare Ti substrate. The biofilm formed (Streptococcus sanguinis) after 24 h exhibited an equal bacterial load (∼7 Log colony-forming units) for both the groups (Ti and DLC). In addition, the DLC film exhibited good cytocompatibility, owing to its noncytotoxicity toward human gingival fibroblast cells. Therefore, DLC deposition via DC-PECVD can be considered to be a promising protective and cytocompatible alternative for developing implant abutments with enhanced mechanical, tribological, and electrochemical properties.

Effects of power on tribological and mechanical properties of diamond-like carbon-film-modified rubber

This study aims to improve the wear resistance of nitrile butadiene rubber (NBR) by depositing diamond-like carbon (DLC) films using direct-current magnetron sputtering (DC-MS), a simple and cost-effective technique. DC-MS is a coating process that uses a direct current to generate an electric field and sputter conductive materials from a target to a substrate. A magnetic field enhances the plasma density and sputtering rate. This study examines the bonding force, surface morphology, tribological properties and mechanical strength of DLC. Scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy are used to characterize the cross-sectional morphology, structural features and chemical bonding species of DLC films and NBR substrates. The nanoindentation results show that varying the power has no significant effect on hardness and Young’s modulus. Tribological tests are conducted under ambient conditions using a ball-and-disk tribometer, with a fixed load of 0.3 N. The results indicate that the power of DLC films influences their tribological properties. Specifically, DLC films prepared at 120 W exhibit superior tribological properties, maintaining a stable coefficient of friction below 0.2 for the test duration. These findings have promising implications for application of DLC films.

Effect of pulse width on deposition of diamond-like carbon on high-power pulsed magnetron sputtering

A diamond-like carbon (DLC) film was deposited using high-power pulsed magnetron sputtering. The effect of pulse width on the deposition of DLC film was investigated under constant peak power density or average power density to clarify the densification mechanism of DLC film. The maximum hardness of 25 GPa analyzed by nanoindentation was obtained using Ar gas without negative substrate bias voltage at pulse width 30 μs and a peak power density of 1.5 kW cm−2. The flux and energy of C+ and Ar+ incident to the DLC film was evaluated by using energy-resolved and time-resolved mass spectrometry to clarify the relation between the input power to the target and the behavior of produced ions. The change in hardness is well correlated with the ion flux ratio C+/Ar+. This result indicates that a flux and energy of Ar+ as well as C+ is a key parameter to characterize the microstructure of DLC film.

Development of gas-injected pulsed plasma CVD method using Ar/C2H2 mixed gas for ultra-high-rate diamond-like carbon deposition

A diamond-like carbon (DLC) fabrication method with a greater deposition rate and simple equipment configuration facilitates to introduce DLC coating technology to industrial processes. In this study, a gas-injected pulsed plasma CVD method using a single plasma source is proposed as an ultra-high-rate deposition method for DLC films. A gas mixture of Ar and C2H2 was injected into a vacuum chamber through a gas nozzle, and plasma in the chamber was generated by applying a negative pulse voltage to the substrate stage. The gas velocity in the chamber was calculated using computational fluid dynamics simulations. DLC films with a nanoindentation hardness of 17.5 GPa were fabricated on a limited area of a Si substrate at a deposition rate of 2480 nm min−1. The deposition rate of the DLC films can be further improved by optimizing the conditions of the Ar partial pressure ratio, gas velocity, and stage applied voltage.

Effect of tail time of discharge current on film properties in diamond-like carbon deposition by high-frequency inclusion high-power impulse magnetron sputtering

Effect of tail time of discharge current on film properties in diamond-like carbon deposition by high-frequency inclusion high-power impulse magnetron sputtering

Influence of Electroless Nickel-DLC (Diamond-like Carbon) Multilayer Coating on the Mechanical Performance of the Heat-Treated AlSi10Mg Alloy Produced by Powder Bed Fusion-Laser Beam.

This study characterizes the mechanical performance of the AlSi10Mg alloy produced by powder bed fusion-laser beam (PBF-LB) subjected to two combined cycles consisting of multilayer coating deposition (electroless nickel (Ni-P) + diamond-like carbon (DLC)) and heat treatment. In particular, the DLC deposition phase replaces the artificial aging step in the T5 and T6 heat treatments, obtaining the following post-production cycles: (i) Ni-P + DLC deposition and (ii) rapid solution (SHTR) (10 min at 510 °C) before Ni-P + DLC deposition. Microstructural characterization shows no appreciable modifications in the morphology and dimensions of the hard Si-rich phase of the eutectic network and secondary spheroidal Si phase. However, overaging phenomena induced by DLC coating deposition and differences in elastic-plastic properties between the multilayer coating and the PBF-LB AlSi10Mg substrate lead to a reduction in tensile strength by up to 31% and a significant decrease in ductility by up to 58%. In contrast, higher resistance to crack opening thanks to improved surface hardness and residual compressive stresses of the coating and reduced defect sensitivity of the substrate increase the fatigue resistance by 54% in T5-coated alloy and 24% in T6R-coated alloy. Moreover, the coating remains well adherent to the substrate during fatigue testing, not becoming a source of fatigue cracks.

RADIATION-ACOUSTIC EFFECTS AT DIAMOND-LIKE COATING DEPOSITION FROM THE FLOW OF HYDROCARBON IONS AND THEIR INFLUENCE ON KINETIC PROCESSES

Based on the model of the nonlocal thermoelastic peak (NTP) the ion generalized to the case of the ion of polyatomic molecule, the acoustic effect of low-energy ion of a hydrocarbon molecule during plasma-ion deposition of diamond-like carbon coating is investigated. The generation of a stress wave takes place as a result of the combined action of mechanisms associated with the rapid transfer of energy, momentum, and additional volume to the NTP volume. The magnitude, shape, and spatial dependence of the stress pulse generated by CH4, C2H2, and C6H6 ions have been studied with absorption taken into account. The possibility of accelerating the diffusion of interstitial defects, as well as the possibility of brittle fracture of the coating at the interface with the substrate under the action of acoustic pulses from deposited hydrocarbon ions, is discussed.

Feasible power for DLC deposition on alumina by RF-biased inductively coupled plasma: Effect of atmospheric parameters

The high density and controllability of radio frequency (RF)-biased inductively coupled plasma offer significant potential for diamond-like carbon (DLC) deposition on alumina. However, the effects of power and atmospheric parameters on DLC deposition have been understudied due to multiple constraints, such as discharge conditions and carbon source requirements. In this study, considering the dual requirements of ion flux and ion kinetic energy for deposition, an RF-biased inductively coupled plasma-enhanced DLC deposition method was proposed. A total of 273 deposition experiments designed by response surface methodology were performed over wide parameter ranges to explore the influence of atmospheric parameters, such as gas pressure and Ar/H2 auxiliary gas fractions, on feasible power. The results showed that there was a power threshold for DLC deposition on alumina, which increased with gas pressure and slightly decreased with auxiliary gas addition. The effect of auxiliary gas on DLC deposition exhibited duality due to changes in the dominance of ion etching and methane dissociation. The feasible power region for DLC deposition in multicomponent atmosphere was jointly constrained by the power threshold and etching action. This research contributed to the DLC modification of alumina substrate in batches.

Carbon ion self–sputtering attained by sublimation of hot graphite target and controlled by pulse injection of a neon–helium gas mixture

The operation of graphite targets with an increased temperature (HT – hot target) is studied for the case of gas injection magnetron sputtering (GIMS) of: 1) diamond–like carbon (DLC), and 2) carbon–silicon carbide (C–SiC) films. A purposely–thinned graphite target with a reduced thermal conductivity is applied for DLC deposition, extending its high temperature sputtering range up to 1636 °C. For the purpose of C–SiC synthesis four sockets with a silicon carbide powder are designed within graphite target. In this approach, the C–SiC target surface can be heated up to 1443 °C due to a greater energy input from impulse plasma, in the range 322–932 J. The HT sputtering is energy–controlled by a pulsed injection of a neon–helium gas mixture. High–energy Ne+ and He+ ions extend the length of pulsed GIMS discharge due to the self–sputtering effect observed during the deposition of DLC and C–SiC films. These conditions result in an almost 5–fold increase in the film growth rate (up to 185 nm/min) with respect to the operation with a cold target, which is due to the assisting vapour sublimation from custom–designed graphite–based targets. The temperature boosted HT GIMS discharge, proves to be an efficient tool for reaching relatively high (∼35 %) sp3–hybridized C content in both carbon–based materials. It also allows for tailoring the energy bandgap of DLC–based optical structure, in the range from 1.7 to 2.75 eV, due to the formation of the (CC) and (CO) bonds. Higher content of silicon oxide (SiO2-x) and silicon carbide (SiC) phases (15 – 23 %) in the case of C–SiC films results in hardness increase from 21.8 to 30.1 GPa.

Diamond-like carbon graphene nanoplatelet nanocomposites for lubricated environments

The tribological behaviour of diamond-like carbon (DLC) and graphene nanoplatelets (GNP) nanocomposite has not been previously explored in a lubricated environment, with some previous studies reporting only on graphene materials on the surface of the DLC. In this study DLC-GNP nanocomposite films with various GNP coverages were synthesised by a 3 step process: spin coating a GNP suspension, heat treatment, and DLC deposition. In this study, the effect of the GNP coverage on the mechanical properties, and tribological response of the DLC-GNP nanocomposite film were studied at elevated temperatures against a cast iron pin in a base-oil lubricated environment. The study shows decrease in friction and wear of the DLC-GNP nanocomposites as the GNP coverage increased, with the lowest friction (COF ∼0.03) and wear (∼1.6 × 10−19 m3/Nm−1) achieved with a 4.5% coverage. This study reports the addition of GNP into the DLC matrix reduced both friction and wear by creating a highly graphitic transfer film on the counter-body, but for higher GNP coverages agglomeration during the spin coating of GNP islands were recorded, leading to removal of the GNP during sliding wear negating the friction reduction effect of the GNP.

Biomimetic Diamond-like Carbon Coating on a Lumen of Small-diameter Long-sized Tube Modified Surface Uniformly with Carboxyl Group using Oxygen Plasma

Silicone tubing is used in small-diameter long-sized tubes for medical applications, such as urinary catheters. However, bacteria in urine adhere to the catheters, forming colonies and biofilms and resulting in blockages and urinary tract infections. Therefore, we have reported a method of AC high-voltage plasma chemical vapor deposition to prevent bacterial adhesion by depositing diamond-like carbon (DLC) on a lumen of a silicone catheter and smoothing the surface. However, the sp3/sp2 structure of DLC on the lumen surface is unresolved, and biomimetic DLC with a functionalized surface has not been investigated. Therefore, we analyzed a flexible membrane structure that can deform as the resin tube deforms. In addition, we developed a lumen surface-modification method using an AC high-voltage burst oxygen plasma processing to bring the DLC surface closer to the in vivo environment. We succeeded in creating biomimetic DLC and introducing carboxyl groups. Using this technology, the surface functionalization of medical tube materials is biocompatible with various protein-adsorption properties.

Optimizing diamond-like carbon coatings - From experimental era to artificial intelligence

Diamond-like carbon (DLC) coatings are widely used for numerous engineering applications due to their superior multi-functional properties. Deposition of good quality DLC is governed by energy per unit carbon atom or ion and plasma kinetics, which are independent parameters. Translating independent parameters to dependent parameters to produce a best DLC is subjected to deposition method, technology, and system configurations which may involve above 50 combinations of bias voltage, chamber pressure, deposition temperature, gas flow rate, etc. Hence DLC coatings are optimized to identify the best parameters which yield superior properties. This article covers DLC introduction, the role of independent parameters, translation of independent parameters to dependent parameters, and discussion of four generations of DLC optimization. The first-generation of DLC optimization experimentally optimizes the parameter-to-property relationship, and the second-generation describes multi-parameter optimization with a hybrid of experimental and statistical-based analytical methods. The third generation covers the optimization of DLC deposition parameters with a hybrid of statistical methods and artificial intelligence (AI) tools. The ongoing fourth generation not only performs multi-parameter and multi-property optimization but also use AI tools to predict DLC properties and performance with higher accuracy. It is expected that AI-driven DLC optimizations and progress in virtual synthesis of DLC will not only assist in resolving DLC challenges specific to emerging markets and complex environments, but will also become a pathway for DLC to enter a digital-twin era. • DLC quality is a function of carbon ion energy, an independent parameter. • Translating independent to dependent parameters make above 50 experimental combinations. • New DLC markets need robust optimizations for fabrication and properties. • AI/ML optimizations have ability to provide optimal solutions for new DLC markets.

Tribological CCF-PEEK transfer film growth on cutting tool coating

ABSTRACT To show transfer film growth of continuous carbon fibre reinforced thermoplastic poly-ether-ether-ketone (CCF-PEEK) on cutting tool coating, dry-sliding tribological behaviours of single-layer diamond-like carbon (DLC), titanium nitride (TiN), titanium aluminium nitride (TiAlN) and diamond deposited on cobalt-based cemented carbide (WC-Co) against CCF-PEEK were studied at atmospheric room temperature, respectively. CCF-PEEK showed little affinity to DLC, but continuous CCF-PEEK transfer films with micron-level thickness grew on TiN, TiAlN and diamond, and raising load facilitated the growth. Deposition of DLC significantly lowered the friction of WC-Co whereas TiN, TiAlN and diamond exhibited higher friction than WC-Co. Much larger amounts of CCF-PEEK wear debris were produced on diamond than on TiAlN, TiN and DLC. Formation mechanisms of CCF-PEEK transfer films and the effect on friction are discussed. This study suggests that DLC can be used as countermate surfaces of CCF-PEEK composite with low friction and little CCF-PEEK wear debris.

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.

Coatability of diamond-like carbon on 316L stainless steel printed by binder jetting

Diamond-like carbon (DLC) coatings are efficient in improving surface properties of functional components and parts. For conventionally manufactured materials and products, the DLC coatings are on a high level of development and industrially well established. However, with the advent of additive manufacturing technologies and the unique microstructure of the produced parts, so far the properties of the DLC coatings on these surfaces have not been extensively investigated. Additively manufactured materials possess process-related structural characteristics, such as residual porosity or an anisotropic material behavior, thereby leading to distinguished properties of the substrate/coating system compared to conventionally fabricated substrate materials. Therefore, 316L substrates are produced with an intended residual porosity and different building directions by binder jetting and subsequently coated with DLC in a magnetron sputtering process. Conventionally manufactured 316L substrates were also coated to evaluate the manufacturing effects on the DLC properties. Based on the analysis of DLC coated open pores, a model is developed to describe the growth mechanisms of thin PVD coatings on open pores of different size. The thin DLC coating entirely covers residual porosity when the pore size (opening diameter) is smaller than or equal to the coating thickness of ~3 µm. Independently of the residual porosity or building orientation, the DLC coating provides a high hardness of 24 GPa and reveals a high adhesion strength to all binder jetted 316 L substrates. Compared to conventional manufacturing routes, the combination of additive manufacturing and DLC deposition is a competitive approach to fabricate complex-shaped components and parts with enhanced surface properties.

Development of DLC-Coated Solid SiAlON/TiN Ceramic End Mills for Nickel Alloy Machining: Problems and Prospects

The study is devoted to the development and testing of technological principles for the manufacture of solid end mills from ceramics based on a powder composition of α-SiAlON, β-SiAlON, and TiN additives, including spark plasma sintering powder composition, diamond sharpening of sintered ceramic blanks for shaping the cutting part of mills and deposition of anti-friction Si-containing diamond-like carbon (DLC) coatings in the final stage. A rational relationship between the components of the powder composition at spark plasma sintering was established. The influence of optimum temperature, which is the most critical sintering parameter, on ceramic samples’ basic physical and mechanical properties was investigated. DLC coatings’ role in changing the surface properties of ceramics based on SiAlON, such as microrelief, friction coefficient, et cetera, was studied. A comparative analysis of the efficiency of two tool options, such as developed samples of experimental mills made of SiAlON/TiN and commercial samples ceramic mills based on SiAlON, doped with stabilizing additives containing Yb when processing nickel alloys (NiCr20TiAl alloy was used as an example). DLC coatings’ contribution to the quantitative indicators of the durability of ceramic mills and the surface quality of machined products made of nickel alloy is shown.

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.

Combined Use of Surface Texturing, Plasma Nitriding and DLC Coating on Tool Steel

In cold rolling, a textured roll can be used to imprint a desired surface topography onto the sheet during rolling. This work proposes the use of diamond-like carbon (DLC) coatings to protect the surface topography of the rolls in replacement of the carcinogenic hard chrome. For that, hydrogenated amorphous carbon (a-C:H) was deposited on plasma nitrided tool steel, both for ground and textured specimens. Changes in surface topography due to DLC coating were assessed using a confocal microscope. Coating adhesion was evaluated using the method VDI 3198. The specimens were characterized using X-ray diffraction (XRD), microhardness test and scanning electron microscopy (SEM). The coating was characterized using Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS). The results showed a soft multilayer coating consisting of a plasma nitrided layer for load support, a Si-rich interlayer to improve adhesion and an a-C:H top layer. DLC deposition reduced the roughness of the textured specimens. The coating resulted in relatively stable friction and good durability, with small damage and negligible wear even under dry sliding.