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Fusion reactions on the cathode surface of glow discharge deuterium–deuterium fusion neutron sources contribute significantly to the neutron production rate (NPR). While the NPR shows a linear relationship with current in the low current regime, a rise in cathode temperature in the high-current regime causes stagnation of the NPR. This tendency may be caused by high-temperature-induced desorption of deuterium on the cathode. This study aims to clarify the relationship between NPR and deuterium desorption. The present study utilized a water-cooling system to prevent deuterium desorption on the cathode. A stainless-steel 304 cathode and a diamond-like carbon (DLC)-coated cathode were tested. The cooling system kept the cathode temperature below 315 K throughout the experiment. In the case of the DLC-coated cathode, the water-cooling system improves the NPR in a high-current regime (30 mA or more in the present study). At 50 kV and 60 mA, the NPRs were 1.87 × 106 and 8.39 × 105 (n/s), with and without water cooling, respectively. Furthermore, without the cooling system, the NPR correlation with the cathode temperature indicates good agreement with the estimation model of deuterium desorption on the DLC-coated cathode. This study demonstrates that suppression of deuterium desorption in the cathode improves NPR, especially in the high-current regime. [ABSTRACT FROM AUTHOR]

We present diamond-like carbon (DLC) conversion surfaces to detect particles with energy below 2 keV. Conversion surfaces have been widely applied in measurements of low-energy particles by instruments onboard planetary and heliophysics missions. Their effectiveness is characterized by the efficiency in changing the charge state of the incident particles while maintaining a narrow angular distribution for the reflected particles. DLC as a conversion surface coating material has high conversion efficiency. We developed a conversion surface production process that provides ultra-smooth and ultra-thin DLC conversion surfaces. The process includes substrate preparation through precision cleaning, plasma immersion ion deposition of the DLC film, and diagnostics of the film parameters. The latter includes the measurement of the coating thickness, surface roughness, and the conversion efficiency for ion beams with energy below 2 keV. The process we developed provides the DLC conversion surface coating of repeatable parameters with a mean surface roughness of 3.4 ± 0.2 Å and a mean film thickness of 46.7 ± 0.8 nm uniform across the sample area. Ion beam measurements showed a negative ion yield of 1%–2% for hydrogen atoms and 8%–15% for oxygen atoms with an angular scatter distribution of 10°–20° at full width of half maximum. These results agree with those of other conversion surface coatings in the literature. The DLC conversion surfaces presented here are implemented in the conversion surface subsystem of the Interstellar Mapping and Acceleration Probe (IMAP)-Lo instrument of the IMAP mission scheduled for launch in 2025. [ABSTRACT FROM AUTHOR]

A model for the relationship between the healing time of the scratched diamond-like carbon (DLC) film and the localized corrosion incubation period of metal was established. Based on model calculations combined with experimental results, the scratched DLC film on 13Cr stainless steel was able to heal within 10–16 h in NaCl solution with an adsorbent-type corrosion inhibitor. However, the localized corrosion incubation time was 30–40 h. Healing of the scratched DLC film can be completed before localized corrosion occurs. This model provides a theoretical reference for the scratch-repassivation of inert films in corrosion inhibitors solutions. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC) coatings are celebrated for their exceptional mechanical properties, including high hardness, low friction and excellent wear resistance, making them indispensable in industrial applications. This study explores the influence of applied voltage on the structural evolution and properties of DLC films deposited on stainless steel 316L using micro-plasma at atmospheric pressure. Ethanol, in an argon environment, served as the carbon precursor, and five samples were processed for 5 min under varying voltage potentials ranging from 2.5 to 4.5 kV. The results reveal a clear correlation between increasing voltage and enhanced DLC deposition. X-ray diffraction (XRD) analysis confirmed the emergence of crystalline structures at higher voltages while scanning electron microscopy (SEM) highlighted the gradual transformation of DLC from an amorphous to a crystalline phase. Samples processed at 4.0–4.5 kV exhibited well-defined crystal growth along the peripheries. Mechanical characterization demonstrated a remarkable increase in hardness, exceeding 50 GPa at 4.5 kV, accompanied by a significant improvement in electrical conductivity as resistivity decreased consistently with voltage. These findings demonstrate that higher deposition voltages significantly enhance the structural and functional attributes of DLC coatings, unlocking new possibilities for their application in demanding industrial and biomedical environments. [ABSTRACT FROM AUTHOR]

With low friction and high hardness, diamond-like carbon (DLC) coatings are a prominent surface engineering solution for tribosystems in various applications. Their versatility stems from their varying composition, facilitated by different deposition techniques, which affect their properties. However, environmental impact is often overlooked in coating design. The objective of this paper is to assess the resource efficiency of four different common deposition techniques, thus identifying critical factors for sustainable DLC deposition. The coatings were deposited in one single chamber, enabling a direct comparison of the resource consumption of each technology. Expenditure of electric energy and consumables per volumetric output accounted for the environmental impact of manufacturing the coatings, which was evaluated across the indicators of damage to human health, damage to ecosystems, and resource scarcity. Electric energy use, dictated by deposition rate, was demonstrated to be the most significant factor contributing to the environmental impact. The environmental impact of PECVD and μW-PECVD was comparable and remarkably lower than that of dcMS and HiPIMS, the latter being the least energy efficient process, with the lowest output rate but highest energy expenditure. Thus, μW-PECVD could be considered the 'greenest' production method. These findings are consequential for coaters to efficiently produce good-quality DLCs with low environmental impact. [ABSTRACT FROM AUTHOR]

Diamond-like carbon coatings can be used to protect precision components in extreme marine environments from the coupling effects of tribocorrosion. However, the thickness of the diamond-like carbon coating is limited by residual stress. In this paper, a method combining filtered cathodic vacuum arc deposition and high-voltage pulsed technology is used to controllably release residual stresses to deposit high-quality thick diamond-like carbon coatings and to study their tribocorrosion mechanism and performance in extreme environments. The results showed that periodic energetic particles could disrupt the local carbon network structure with increasing frequency, thereby reducing the residual stress to 0.787 GPa in a diamond-like carbon coating of about 5 μm, and the release of residual stress prevented the formation of corrosion channels during corrosion of the diamond-like carbon coating. The high-quality diamond-like carbon coating was tested in a tribocorrosion test at 5 N and 10 N loads. The excellent corrosion resistance reduces the coupling effect of tribocorrosion on the coating. The high content of graphite-like structures inhibits the formation of microcracks, reducing the degree of wear of the diamond-like carbon coating in 3.5 wt% NaCl solution. The combination of high-voltage pulsed technology and filtered cathodic vacuum arc deposition can break through the limitation of residual stress on the thickness of diamond-like carbon coatings, which provides meaningful guidance for the application of thick diamond-like carbon coatings for surface protection of precision devices. [ABSTRACT FROM AUTHOR]

Precise and long-term electroanalysis at the single-cell level is crucial for the accurate diagnosis and monitoring of brain diseases. The reliable protection in areas outside the signal acquisition points at sharp ultramicroelectrode (UME) tips has a significant impact on the sensitivity, fidelity, and stability of intracellular neural signal recording. However, it is difficult for existing UMEs to achieve controllable exposure of the tip functional structure, which affects their ability to resist environmental interference and shield noise, resulting in unsatisfactory signal-to-noise ratio and signal fidelity of intracellular recordings. To address this issue, we chose a dense and electrochemically stable diamond-like carbon (DLC) film as the UME protection coating and developed a method to precisely control the exposed degree of the functional structure by directly fixed-point processing of the UME tip by the strong site-selectivity and good controllability of the atmospheric microplasma jet. By analyzing the interaction between the microplasma jet and the UME tip, as well as the changes in the removal length and microstructure of UME tips with processing time, the exposed tip length was precisely controlled down to the submicron scale. Biocompatibility experiments, electrochemical aging tests and real-time intracellular pH recording experiments have demonstrated that the DLC-UME with effective tip protection processed by microplasma jet has the potential to enable long-term detection of intracellular high-fidelity signals. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC) films on titanium alloy Ti6Al4V substrates were tested with nanoindentation and surface roughness to look at the hardness and roughness of the coating and substrate systems as well as their mechanical properties. The powdered titanium alloy Ti6Al4V used in the substrate specimen was produced using laser powder bed fusion, an additive manufacturing process. In this study, we investigated the influence of substrates on the nanoindentation and surface roughness of the DLC film layer with an estimated 2. 2 1 μ m thickness on Ti6Al4V substrates. The findings of the nanoindentation show that the reaction to the impact was more flexible than expected. Maximum load, residual nanoindentation depth, hardness, and modulus may influence mechanical properties. The DLC-film Ti6Al4V substrate materials' top surface roughness is measured. As a result of the increased load-carrying ability of DLC/Ti6Al4V, Ti6Al4V is a superior choice for substrate materials for DLC films, A DLC coating, measuring 2. 2 1 μ m in thickness, was applied to a Ti6Al4V substrate utilizing a 5-min chromium deposition process. The biocompatibility of the substrates plays a crucial role in determining the DLC films capacity to prolong the lifespan of bone implants. [ABSTRACT FROM AUTHOR]

Diamond-like carbon is used to increase the resistance to wear of components due to its physical and chemical similarity to diamond. The use of this coating, due to its low friction coefficient, in various industries such as aerospace, precision tools, automotive, and cutting tools helps reduce production costs and increase the lifespan of components. In this study, articles published from 1985 to 2022 were extracted from the Scopus database and analyzed using VOSviewer software. A total of 2977 articles were published, of which 1337 (45%) were related to the past 10 years and the highest number of published articles was related to 2022 with 152 articles. The highest number of published articles was related to the United States with 481 articles. In the past ten years, India and China had the highest compound annual growth rate (CAGR) with 25 and 12%, respectively, and Slovenia and the United States had the highest CAGR decline rate among leading countries in this field with 9.5 and 3.17%, respectively. [ABSTRACT FROM AUTHOR]

Abstract In this study, for the first time, the optimization of applied pressure for achieving the one of the best tribological properties of diamond-like carbon (DLC) coating on graphite surface using plasma-enhanced chemical vapor deposition (PECVD) method was investigated. Raman spectroscopy and microscopy methods were used to characterize the applied coating. Additionally, the mechanical properties of the coating were investigated through nanoindentation testing. The wear resistance of coating has been tested as functional test. The results indicated that with increasing gas pressure, the sp3 hybridization percentage decreases, while the ID/IG ratio increases. The average roughness values for the uncoated sample and the coated samples at working pressures of 25, 30, and 35 mTorr were obtained as 1.6, 5.1, 3, and 2.4 nm, respectively. The results of hardness and wear tests showed that these properties were optimized by reducing the applied gas pressure. The highest hardness was 11.59 GPa, and the best sample in terms of the mechanical properties of the coating was the sample applied at a gas pressure of 25 mTorr. Results show that the optimal sample in tribological performance is the one applied at a working pressure of 25 mTorr. Because this sample demonstrates the lowest coefficient of friction, and wear depth.

The iron-based parts with different densities were prepared by powder metallurgy, and then were densified by ultrasonic shot peening. The diamond-like carbon (DLC) self-lubricating coatings were deposited on the sintered and shot peening samples with different densities by physical vapor deposition, and the binding force and tribological properties of DLC coatings were studied. The results show that the matrix with high density has the better binding force with coatings, and the matrix treated with shot peening shows much better binding force, which is about 28.0 N. However, in the process of ultrasonic shot peening, the surface layers of the matrix produce huge compressive stress, and the accumulation of residual stress in the matrix and the coatings may lead to the premature failure of coatings. To reduce the stress accumulation caused by ultrasonic shot peening process, the samples are annealed after shot peening, and show much higher binding force between the matrix and coatings, about 54.5 N. The frictional properties of samples with DLC coating are greatly improved, the friction coefficient of the samples without coatings is about 0.60, and that of the sintered samples with DLC coatings is about 0.15. Compared with the DLC coatings on the matrix after shot peening (friction coefficient 0.13 ~ 0.17), the lubricity of DLC coatings on the annealed matrix is more stable (friction coefficient 0.13).

Electrospun poly(ε-caprolactone) (PCL)-based scaffolds are widely used in tissue engineering. However, low cell adhesion remains the key drawback of PCL scaffolds. It is well known that nitrogen-doped diamond-like carbon (N-DLC) coatings deposited on the surface of various implants are able to enhance their biocompatibility and functional properties. Herein, we report the utilization of the pulsed vacuum arc deposition (PVAD) technique for the fabrication of thin N-DLC coatings on the surface of electrospun PCL scaffolds. The effect of N-DLC coating deposition under various nitrogen pressures on the morphological, mechanical, physico-chemical, and biological properties of PCL scaffolds was investigated. It was established that an increase in nitrogen pressure in the range from 5 × 10−3 to 5 × 10−1 Pa results in up to a 10-fold increase in the nitrogen content and a 2-fold increase in the roughness of the PCL fiber surface. These factors provided the conditions for the enhanced adhesion and proliferation of human mesenchymal stem cells (MMSCs) on the surface of the modified PCL scaffolds. Importantly, the preservation of N-DLC coating properties determines the shelf life of a coated medical device. The elemental composition, tensile strength, and surface human MMSC adhesion were studied immediately after fabrication and after 6 months of storage under normal conditions. The enhanced MMSC adhesion was preserved after 6 months of storage of the modified PCL-based scaffolds under normal conditions. [ABSTRACT FROM AUTHOR]

We elaborate a method for determining the 0D–1D nanostructure size by photoluminescence (PL) emission spectrum dependence on the nanostructure dimensions. As observed, the high number of diamond-like carbon nanocones shows a strongly blue-shifted PL spectrum compared to the bulk material, allowing for the calculation of their top dimensions of 2.0 nm. For the second structure model, we used a sharp atomic force microscope (AFM) tip, which showed green emission localized on its top, as determined by confocal microscopy. Using the PL spectrum, the calculation allowed us to determine the tip size of 1.5 nm, which correlated well with the SEM measurements. The time-resolved PL measurements shed light on the recombination process, providing stretched-exponent decay with a τ0 = 1 ns lifetime, indicating a gradual decrease in exciton lifetime along the height of the cone from the base to the top due to surface and radiative recombination. Therefore, the proposed method provides a simple optical procedure for determining an AFM tip or other nanocone structure sharpness without the need for sample preparation and special expensive equipment. [ABSTRACT FROM AUTHOR]

DLC film is considered to be one of the most promising film materials for improving the abrasion resistance and operation life of pump plungers draw upon its low friction and high hardness, but the friction characteristics and mechanism of the doping element Ti on pump plungers under the petroleum extraction environment are still unclear. In this paper, the friction performance and mechanism of the doping Ti for DLC film on the appearance of the pump plunger under the petroleum extraction environment were investigated at the microscopic scale by using the reactive molecular dynamics. The outcome shows that the Ti-DLC displays a reduction in average friction force of 78.82 % and a decrease in average temperature of 40.33 % in the oil extraction environment, thus improving the abrasion resistance of the pump plunger. Moreover, with the increase of Ti content, the friction will gradually decrease, and significantly low friction behavior can be even materialized without lubrication. It is found that the main reason for the low friction of Ti-DLC film is that the layered structure determined by Ti concentration is formed on the appearance of friction pair, which inhibits the formation of interfacial carbon bond and reduces the shear stress on the contact surface. [ABSTRACT FROM AUTHOR]

Hydrogenated diamond‐like carbon (H‐DLC) films are limited by their poor thermal stability, which significantly affects the tribological applications and needs improvement. Accordingly, nanodiamond (ND) and hexagonal boron nitride (h‐BN) are used to address this issue. When the H‐DLC surface is deposited using ND+h‐BN mixture with mass ratio of 1:1 and a concentration of 0.1 mg mL−1 and vacuum‐heated at 200 °C and 1 × 10−5 Pa, a superlow friction coefficient of 0.0015 can be obtained, with a reduction of 98.33% as compared to pure H‐DLC. Correspondingly, the wear rates of wear scar and wear track decreased by 81.95% and 24.83%, respectively. High vacuum thermal treatment can purify the adsorbed species on the surfaces of ND and h‐BN, and produce newly‐exposed dangling bonds. Simultaneously, new bonds of C‐N are formed between ND and h‐BN, and the nanoparticles adhere together to form a polymer‐like structure under friction. Furthermore, the ND can support h‐BN and reduce its agglomeration. Under the action of tribochemical reaction, the layer spacing of hexagonal boron nitride is increased to obtain a better shear slip. The combination of these factors resulted in ultra‐low friction. This study paved the way for developing functional anti‐friction additives for durable and high‐performance lubrication. [ABSTRACT FROM AUTHOR]

In this study, a novel periodic multilayered DLC coating, which was composed of a Si interlayer and a Si/N co-incorporated DLC layer (Si/(Si, N)-DLC) per period, was deposited; the corrosion behavior under the neutral, acidic, or alkaline coal mine water environment and its periodic number dependence, especially the fundamental corrosion mechanism, were systemically explored. Results suggest that compare to the substrate, the introduction of multilayered Si/(Si, N)-DLC coating presents a dramatic enhancement in the corrosion resistance under coal mine water environment. However, with increasing the periodic number, the corrosion resistance of the multilayered coating strongly depends on the working environment, which exhibits an enhancement in neutral and alkaline environments while a degeneration in acidic environment. This is attributed to not only the prolongation of the corrosion path caused by the multilayered structure but also the formation of an insulating silicon oxide layer in neutral and alkaline environments. However, in acidic environments, the strong permeability of H+ with the smallest ionic radius easily infiltrates the inherent defects of the coating. This not only weakens the protective properties of the multilayer structure but also leads to hydrogen-induced cracking, ultimately diminishing corrosion resistance. These findings theoretically guide the development of the DLC coatings with excellent corrosion resistance for coal mine applications. [ABSTRACT FROM AUTHOR]

Freeform carbon fibres were 3D-printed from CH3OH:H2O mixtures using hyperbaric-pressure laser chemical vapour deposition (HP-LCVD). The experiment overlapped a region of known diamond growth, with the objective of depositing diamond-like carbon without the use of plasmas or hot filaments. A high-pressure regime was investigated for the first time through the precursor's critical point. Seventy-two C-fibres were grown from 13 different CH3OH:H2O mixtures at total pressures between 7.8 and 180 bar. Maximum steady-state axial growth rates of 14 µm/s were observed. Growth near the critical point was suppressed, ostensibly due to thermal diffusion and selective etching. In addition to nanostructured graphite, various carbon allotropes were synthesised at/within the outer surface of the fibres, including diamond-like carbon, graphite polyhedral crystal, and tubular graphite cones. Several allotropes were oversized compared to structures previously reported. Raman spectral pressure–temperature (P-T) maps and a pictorial P-T phase diagram were compiled over a broad range of process conditions. Trends in the Raman ID/IG and I2D/IG intensity ratios were observed and regions of optimal growth for specific allotropes were identified. It is intended that this work provide a basis for others in optimising the growth of specific carbon allotropes from methanol using HP-LCVD and similar CVD processes. [ABSTRACT FROM AUTHOR]

This article compares the properties of the diamond-like carbon (DLC) coating with those of ZrN and (Zr,Hf)N coatings deposited on the Ti-6Al-4V titanium alloy substrate. To improve substrate adhesion during the deposition of the DLC coating, preliminary etching with chromium ions was conducted, ensuring the formation of a chromium-saturated diffusion surface layer in the substrate. A Si-DLC layer followed by a pure DLC layer was then deposited. The hardness of the coatings, their surface morphology, fracture strength in the scratch test, and tribological properties and wear resistance in the pin-on-disk test in contact with Al2O3 and steel indenters were investigated. The structure of the DLC coating was studied using transmission electron microscopy, and its corrosion resistance in an environment simulating blood plasma was also investigated. In the pin-on-disk test in contact with Al2O3 and AISI 52100 indenters, the DLC-coated sample demonstrates a much lower friction coefficient and significantly better wear resistance compared to the nitride-coated and uncoated samples. Both nitride coatings—(Zr,Hf)N and ZrN—and the DLC coating slow down the corrosive dissolution of the base compared to the uncoated sample. The corrosion currents of the (Zr,Hf)N-coated samples are 37.01 nA/cm2, 20% higher than those of the ZrN-coated samples. The application of (Zr,Hf)N, ZrN, and DLC coatings on the Ti-6Al-4V alloy significantly inhibits dissolution currents (by 30–40%) and increases polarization resistance 1.5–2.0-fold compared to the uncoated alloy in 0.9% NaCl at 40 °C. Thus, the DLC coating of the described structure simultaneously provides effective wear and corrosion resistance in an environment simulating blood plasma. This coating can be considered in the manufacture of medical products (in particular, implants) from titanium alloys, including those functioning in the human body and subject to mechanical wear (e.g., knee joint endoprostheses). [ABSTRACT FROM AUTHOR]

During shearer operation, the piston rod is susceptible to wear from the invasion of pollutants, thus ruining the sealing ring in the hydraulic cylinder. This work attempts to conduct a systematic investigation of Cu-doped diamond-like carbon (Cu-DLC) film to improve the seal performance. The failure process of the cylinder was analyzed, and relevant parameters were determined. Several Cu-DLC films were deposited on the substrate of the piston rod in a multi-ion beam-assisted system, and their structures and combined tribological performances were investigated. The hardness of the film ranges from 27.6 GPa to 14.8 GPa, and the internal stress ranges from 3500 MPa to 1750 MPa. The steady-state frictional coefficient of the film ranges from 0.04 to 0.15; the wear rate decreases first and then increases, and it reaches its lowest (5.0 × 10−9 mm3/N·m) at 9.2 at.% content. a:C-Cu9.2% film presents optimal combined tribological performances in this experiment. The modification mechanism of Cu-DLC film for the seal performance may come from the synergistic effects of (i) the contact force and friction-heat-induced film graphitization, (ii) Cu doping improves the toughness of the film and acts as a solid lubricant, and (iii) the transfer layer plays a role in self-lubrication. [ABSTRACT FROM AUTHOR]

In the field of industrial lubrication, solid–liquid composite lubrication (SLCL) techniques based on diamond-like carbon (DLC) coatings and lubricating oils are emerging recently, which may be applied in many fields in the near future, especially automotive industries. The tribological behaviors of SLCL systems depend strongly on the compatibility between DLC coatings and oils. This review describes the advantages of SLCL techniques by pointing out the synergistic effects between DLC coatings and lubricating oils. Then the main factors determining the tribological performance of SLCL systems are discussed in detail. Finally, a conclusion about the characteristics of reported SLCL systems is made, and a prospect about the potential development of SLCL technology is proposed. On the basis of the relevant literature, it could be found that the tribological properties of SLCL systems were influenced by many more factors compared with individual DLC lubrication or individual oil lubrication due to the complicated tribo-chemical reactions involving DLC and oil during friction. And under some optimized working conditions, the tribological performances of SLCL systems (friction and wear reduction) are superior to individual DLC lubrication and individual oil lubrication. However, the tribological performance of SLCL systems needs to be further improved (for example, to achieve superlubricity and ultra-low wear simultaneously) by adjusting the structures of DLC coatings, regulating the compositions of oils, and most importantly, enhancing the physicochemical and tribological synergies between DLC coatings and oils. This review provides a comprehensive understanding of the SLCL technology, which may be very helpful for the researchers and engineers in the field of industrial lubrication and tribology. [ABSTRACT FROM AUTHOR]

Hydrogenated Diamond-Like Carbon (HDLC) thin films find extensive applications in diverse fields, such as industrial settings, including biomedical coatings with bactericidal properties, as well as in mechanical, electronic, and biomolecule immobilization contexts. To enhance the surface properties of HDLC thin films, various methods are employed, including hydrogen plasma treatment, electrochemical hydrogenation, annealing, and biomolecule immobilization. The synthesis of HDLC films involves biased enhanced nucleation (BEN) under varying H2 and CH4 flow rates in the reactive gas-plasma process (RGPP). In this study, we investigated the wettability of both pristine HDLC thin films and modified HDLC thin films using the sessile drop technique, measuring contact angles with liquids of distinct physicochemical natures, such as water and glycerin. sp³ and sp² content of the HDLC and modified samples were measured by Raman spectrum. The surface energy of the samples exhibited a slight increase in correlation with the sp³ content of HDLC and modified HDLC samples. Notably, a strong correlation between hydrophilicity/hydrophobicity and the density of the sp²/sp³ ratio was observed across various HDLC surfaces, including as-prepared HDLC, electrochemically hydrogenated (ECHDLC), annealed HDLC surfaces, and surfaces modified through covalent immobilization of Bovine Serum Albumin (BSA) protein onto hydrogenated diamond-like carbon. [ABSTRACT FROM AUTHOR]

Shear deformation mechanisms of diamond-like carbon (DLC) are commonly unclear since its thickness of several micrometers limits the detailed analysis of its microstructural evolution and mechanical performance, which further influences the improvement of the friction and wear performance of DLC. This study aims to investigate this issue utilizing molecular dynamics simulation and machine learning (ML) techniques. It is indicated that the changes in the mechanical properties of DLC are mainly due to the expansion and reduction of sp3 networks, causing the stick-slip patterns in shear force. In addition, cluster analysis showed that the sp2-sp3 transitions arise in the stick stage, while the sp3-sp2 transitions occur in the slip stage. In order to analyze the mechanisms governing the bond breaking/re-formation in these transitions, the Random Forest (RF) model in ML identifies that the kinetic energies of sp3 atoms and their velocities along the loading direction have the highest influence. This is because high kinetic energies of atoms can exacerbate the instability of the bonding state and increase the probability of bond breaking/re-formation. Finally, the RF model finds that the shear force of DLC is highly correlated to its potential energy, with less correlation to its content of sp3 atoms. Since the changes in potential energy are caused by the variances in the content of sp3 atoms and localized strains, potential energy is an ideal parameter to evaluate the shear deformation of DLC. The results can enhance the understanding of the shear deformation of DLC and support the improvement of its frictional and wear performance. [ABSTRACT FROM AUTHOR]

Sliding electrical contacts are commonly applied in electrical connectors, such as conductive slip rings, pantographs, switches, and commutators. However, they suffer from several unavoidable problems caused by friction and wear, including high energy consumption, intermittent failures, limited life, and even failure disasters. In this study, we realized an ultralow-friction and long-distance wear-free state, defined as structural superlubricity (SSL), between sliding electrical interfaces under ambient conditions. A conductive SSL can be implemented in experiments with single-crystal graphite flakes on flattened metals, such as Au and Ni films. Furthermore, we found that depositing a 2 to 3-nm-thick diamond-like carbon (DLC) film on a nickel alloy can lead to an even lower resistivity than that of metals alone. In addition, we revealed the mechanism by which DLC films can improve the conductivity between graphite and metals through density functional-theory simulations. In addition, we prepared a prototype of the SSL slip ring and proved that it possessed ultralow friction, was wear-free, and had no intermittent failures. Consequently, our results demonstrate a unique type of electrical-contact interface for applications requiring conduction while sliding. Thus, we opened the door for SSL electromechanical coupling. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC)/poly-α-olefin (PAO) composite system attracts much attention in reducing the tribo-induced risks for mechanical mobility systems and energy saving. However, the coupled effect of applied load and PAO viscosity on the tribological behavior of the DLC/PAO system, which normally causes the transition between different lubrication states of mated surfaces, and the corresponding synergistic mechanism remain unclear. Here, we fabricated the DLC/PAO composite system, and the evolutions of microstructure, morphologies, and tribological properties induced by both PAO viscosity and applied load were investigated systematically. Results indicated that under low applied load, the system with moderate PAO viscosity exhibited the best tribological performance, while the PAO with high viscosity was suggested with increasing the applied load. Moreover, the variations of PAO viscosity and applied load seriously affected the distribution and load-bearing capacity of oil, interfacial graphitization degree, and formation of lubricating oil film, which brought complicated effects on the tribological properties of composite systems. The present results guide the selection and design of an advanced DLC/PAO lubrication system according to the working conditions. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to design a novel test device and study the wear properties and the thermal mechanisms of roller pairs in dual-freedom sliding contacts. Design/methodology/approach: On the transition process of lubrication regimes, experiments were conducted with various values of running speed and slip ratio obtained by two motorized spindles. Temperature and surviving time would be obtained of GCr15/GCr15 and DLC/GCr15 friction pairs. Micro photography was obtained with a PGI 3D stylus profiler and a confocal microscopy OLS4000-3D. An empirical mode decomposition method was used to eliminate measure errors. Findings: Results showed that, even with little initial lubricant, rolling/sliding pairs still rotated for a certain time. With the synthetic actions of the dual-freedom sliding, the loss of lubrication and the tilt, interesting helical grooves appeared. Sliding speeds had remarkable effects on survive time, temperatures and surface topographies. In addition, the equilibrium values of the temperature and the surface roughness were obtained in sufficient oil supply. Extreme wear-out conditions were obtained with starved lubrication. Diamond-like carbon coatings showed better heat resistance and better wear resistance. Originality/value: This work would be critical for the life design and the heat treatment of rolling bearings in the full flood lubrication and the starved lubrication. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0164/ [ABSTRACT FROM AUTHOR]

Diamond‐like carbon (DLC) is an amorphous material widely used in industrial applications due to its chemical, mechanical, and tribological properties and, also, for decorative purposes. However, its low adhesion to ferrous alloys reduces its effectiveness in certain applications, necessitating the use of adhesion interlayers to reduce stresses at the interfaces and enhance the density of strong bonds. In this context, the factors that promote good adhesion in this system and specify the parameters must be understood in detail. Thus, the present study aims to assess the influence of the base pressure on the deposition of an amorphous silicon carbide adhesion interlayer between DLC coating and a ferrous alloy substrate. Microstructural, physicochemical, morphological, and mechanotribological analyses were conducted to understand the adhesion behavior in terms of structural and chemical aspects. In addition to the influence of the interlayer thickness, the elemental Si/C ratios and the relative oxygen content have an impact on the maximum load supported by the coatings, as well as the different delamination mechanisms generated in adhesion tests. [ABSTRACT FROM AUTHOR]

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Two series of non-hydrogenated diamond-like carbon (DLC) films and molybdenum doped diamond-like carbon (Mo-DLC) films were grown on the silicon substrate using direct current magnetron sputtering. The influence of molybdenum doping (between 6.3 and 11.9 at.% of Mo), as well as the deposited temperature (between 185 and 235 °C) on the surface morphology, elemental composition, bonding microstructure, friction force, and nanohardness of the films, were characterized by atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and a nanoindenter. It was found that the increase in the metal dopant concentration led to a higher metallicity and graphitization of the DLC films. The surface roughness and sp3/sp2 ratio were obtained as a function of the Mo concentration and formation temperature. The nanohardness of DLC films was improved by up to 75% with the addition of Mo. Meanwhile, the reduction in the deposition temperature decreased the nanohardness of the DLC films. The friction coefficient of the DLC films was slightly reduced with addition of the molybdenum. [ABSTRACT FROM AUTHOR]

In this experiment, plasma-enhanced chemical vapor deposition technology was used to deposit diamond-like carbon thin films on the surface of a 2024 aluminum alloy. The effects of deposition temperature on the microstructure, carbon, silicon, and aluminum element distribution, and film substrate adhesion of diamond-like carbon thin films were studied using field emission scanning electron microscopy, energy-dispersive spectroscopy, XRD, scratch gauge, and ultra-depth-of-field microscopy. The results showed that with the increase in deposition temperature, the thickness of DLC film decreased from 8.72 μm to 5.37 μm, and the film bonded well with the substrate. There is a clear transition layer containing silicon elements between the DLC film and the aluminum alloy substrate. The transition layer is a solid solution formed by aluminum and silicon elements, which increases the bonding strength between the film and substrate. C-Si and C-C exist in the form of covalent bonds and undergo orbital hybridization, making the DLC film more stable. When the deposition temperature exceeds the aging temperature of a 2024 aluminum alloy, it will affect the properties of the aluminum alloy substrate. Therefore, the deposition temperature should be below the aging temperature of the 2024 aluminum alloy for coating. At a deposition temperature of 100 °C, the maximum membrane substrate bonding force is 14.45 N. When a continuous sound signal appears and the friction coefficient is the same as that of the substrate, the film is completely damaged. From the super-depth map of the scratch morphology, it can be seen that, at a deposition temperature of 100 °C, a small amount of thin film detachment appears around the scratch. [ABSTRACT FROM AUTHOR]

Titanium alloys have a high cost of production and exhibit low resistance to abrasive wear. The objective of this work was to carry out diamond-like carbon (DLC) coating, with dissimilar thicknesses, on Ti-22Nb-6Zr titanium alloys produced by powder metallurgy, and to evaluate its microabrasive wear resistance. The samples were compacted, cold pressed, and sintered, producing substrates for coating. The DLC coatings were carried out by PECVD (plasma-enhanced chemical vapor deposition). Free sphere microabrasive wear tests were performed using alumina (Al2O3) abrasive suspension. The DLC-coated samples were characterized by scanning electron microscopy (SEM), Vickers microhardness, coatings adhesion tests, confocal laser microscopy, atomic force microscopy (AFM), and Raman spectroscopy. The coatings did not show peeling-off or delamination in adhesion tests. The PECVD deposition was effective, producing sp2 and sp3 mixed carbon compounds characteristic of diamond-like carbon. The coatings provided good structural quality, homogeneity in surface roughness, excellent coating-to-substrate adhesion, and good tribological performance in microabrasive wear tests. The low wear coefficients obtained in this work demonstrate the excellent potential of DLC coatings to improve the tribological behavior of biocompatible titanium alloy parts (Ti-22Nb-6Zr) produced with a low modulus of elasticity (closer to the bone) and with near net shape, given by powder metallurgy processing. [ABSTRACT FROM AUTHOR]

The double-connection structure of bionic joints of mining drill pipes has solved the problem of drill drop caused by fatigue cracks. However, with low-melting-point elastic–ductile alloy filling in the bionic joint, the thread on the joint cannot be hardened by high-temperature surface hardening treatments such as quenching and nitriding, making it prone to thread gluing or excessive wear. In this paper, the feasibility of diamond-like film deposition on the surface of a bionic drill pipe thread was studied. A tungsten transition film was used to improve the thickness of the film and the interfacial bond strength between the film and the substrate. The test results show that the total thickness of the DLC film is about 3~5 μm, the roughness is less than 2 μm, the hardness of the film reaches 24.4 GPa, the friction coefficient is 0.04, and the critical load is 56 N. SEM and EDS analyses show that the tungsten film and the bionic joint thread form a metallurgical structure. The morphology of the diamond-like carbon film is uniform and dense, and there is no obvious stratification between the substrate material. The joint with a diamond-like coating treatment has a longer service life than joints receiving conventional high-temperature nitriding treatment. [ABSTRACT FROM AUTHOR]

In this research, two intermediate layers were deposited on 316L stainless steel to improve the adhesion of diamond-like carbon (DLC) films, one composed of TixAl and produced using the RF sputtering technique with three thicknesses, 100 nm, 200 nm, and 300 nm; the other, interlayer composed of amorphous hydrogenated silicon (a-Si:H). The DLC films were deposited using the pulsed-DC PECVD method with an active screen to achieve the AISI 316L/TixAl//DLC and AISI 316L/TiₓAl/a-Si/DLC configurations. The binding energy between the substrate/TixAl and TixAl/a-Si:H was investigated via X-ray photoelectron spectroscopy with high-resolution spectra. The chemical composition and microstructure of the titanium–aluminum interlayers were investigated using energy-dispersive X-ray spectroscopy and X-ray diffraction, and the microstructure of the DLC coatings was studied using Raman spectroscopy. The coatings' adherence was measured using scratch and indentation tests, and the hardness of the DLC coatings was determined with the nanoindentation test. The X-ray diffractograms did not allow the determination of any crystalline structure in the TixAl interlayers. The XPS results showed that between the AISI 316L substrate and the TixAl intermediate layer, Ti-O-Fe and FeAl2O4 were formed. On the other hand, at the TixAl/a-Si:H interface, TiSi2 and Al2SiO5 compounds were identified. The DLC coatings grew as hydrogenated amorphous carbon with a hydrogen content of around 30 at.% and a hardness of 24 GPa. The deposition methods used and the TixAl/a-Si:H interlayers allowed the obtainment of adherent DLC coatings on AISI 316L stainless steel substrates. High critical load values of about 30 N were obtained. The novelty of this work is underscored by the absence of previous studies that thoroughly examine the bonds present in interlayers used as gradients to enhance the adhesion of DLC. [ABSTRACT FROM AUTHOR]

In recent years, the exponential growth of the machining industry and its needs has driven the development of new manufacturing technologies, more advanced cutting tool types, and new types of coatings to extend tool lifespan. New coating solutions have been studied and implemented for machining tools, which provide a low friction coefficient and lubrication, thus increasing tool lifespan. Following this line of reasoning, it is relevant to develop scientific work aimed at studying the behavior of cutting tools coated with thin films that promote low friction and high lubrication, as is the case with DLC (diamond-like carbon) coatings. These coatings promote good resistance to oxidation and allow high machining speeds, properties also exhibited by TiAlN (titanium aluminum nitride) coatings. In fact, there is a gap in the literature studying the performance of cemented carbide tools provided with multilayered coatings in milling operations of Cu–Be alloys, commonly used in inserts of plastic injection molds. This study's objective was to investigate the effect of a multilayer coating (TiAlN/DLC) on end-milling tools to analyze their cutting performance when milling a Cu–Be alloy known commercially as AMPCOLOY®83. The quality of the machined surface was evaluated, and the wear of the cutting tool was studied. A comparative analysis of milling parameters with respect to their effect on the condition of the surface after machining and the resulting wear on the tools, using coated and uncoated tools and different machining parameters, allowed us to verify a better quality of the machined surface and wear quantified in approximately half when used coated tools. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC) films achieved superlubricity rapidly, making them a promising material for the development of mechanics and manufacturing. However, the fundamental mechanisms governing friction evolution at the interfaces remain elusive. This study utilized atomic force microscopy to investigate the friction behavior of nanoscale interfaces formed by DLC films under macroscopic friction experiments. The evolution of sp2-hybridized carbon structures on different load transfer film interfaces was observed. Finally, combining Raman spectroscopy demonstrated that the formation of rich sp2-hybridized carbon structure transfer films is a primary factor in reducing the nanoscale friction of DLC films. This research fills the gap in the structural evolution of DLC films at friction interfaces and reveals the nanoscale mechanism behind the macroscale friction phenomenon of DLC films. [ABSTRACT FROM AUTHOR]

During petroleum drilling, the reciprocating motion in the seal device leads to piston and sleeve wear, which may cause leakage of the sealing medium. Selecting appropriate materials for the piston and sleeve, along with surface modifications, can effectively prolong the seal service life of the seal. The friction and wear properties of piston and sleeve pairs of different materials in a metal sealing device were simulated by the laboratory "pin-on-block" reciprocating friction test. Pins made of 45# steel, 35CrMo, and 20Cr13 were used to simulate piston bulges, while 35CrMo samples were used to simulate sleeves. Additionally, the influence of DLC (diamond-like carbon) coating and QPQ (Quench–Polish–Quench) nitriding on the wear resistance of the materials was studied. Based on this, the friction and wear properties, along with the wear mechanism of different material pairs, were analyzed. The results show that the friction coefficient curves of the three piston base materials and the 35CrMo sleeve are similar, and the friction coefficient of 45# steel is lower than that of 35CrMo and 20Cr13 at the initial stage. The DLC surface coating exhibited the best anti-wear performance, with the lowest friction coefficient, minimal wear, and the most stable friction coefficient. Surface QPQ nitriding treatment can also improve the wear resistance of the base material. However, due to the oxide formed during nitriding being prone to flaking, the friction coefficient fluctuates significantly at the initial stage of testing, and its anti-wear performance was inferior to that of the DLC coating. This study on material pairing and surface modification provides theoretical support for material selection and surface modification design of pistons and sleeves in oil drilling sealing devices. [ABSTRACT FROM AUTHOR]

Developing a robust zinc (Zn) anode, free from Zn dendrites and unwanted side reactions, relies on designing a durable and efficient interfacial protection layer. In this study, gradient coating technology is employed to construct a hierarchically structured composite of Sn with diamond‐like carbon (DLC/Sn‐DLC) as an artificial protective layer. The DLC framework endows DLC/Sn‐DLC layer with high stability and adaptability, achieving long‐term stability of the anode–electrolyte interface. The gradual‐composite Sn, with its Sn─O─C interface chemical bonds, facilitates rapid charge transfer and offers ample zincophilic sites at the base, promoting uniform Zn2+ reduction reaction and deposition. Additionally, the DLC/Sn‐DLC composite exhibits a "lotus effect" and favorable hydrophobic properties, preventing water‐reduced side reactions. Leveraging this structural design and the synergistic cooperation of DLC and Sn, the DLC/Sn‐DLC@Zn electrode demonstrates remarkable Zn plating/stripping reversibility, eliminating Zn dendrites and side reactions. Notably, under a high current density of 10 mA cm−2, the DLC/Sn‐DLC@Zn anode‐based symmetrical cell exhibits stable operation for over 1550 h, with a low nucleation overpotential of 101 mV. The DLC/Sn‐DLC@Zn||Mn3O4‐CNTs full battery delivers a high capacity of 109.8 mAh cm−2 after 5800 cycles at 2 A g−1, and the pouch cell shows potential for energy storage applications. [ABSTRACT FROM AUTHOR]

In this study, for the first time, the optimization of applied pressure for achieving the one of the best tribological properties of diamond-like carbon (DLC) coating on graphite surface using plasma-enhanced chemical vapor deposition (PECVD) method was investigated. Raman spectroscopy and microscopy methods were used to characterize the applied coating. Additionally, the mechanical properties of the coating were investigated through nanoindentation testing. The wear resistance of coating has been tested as functional test. The results indicated that with increasing gas pressure, the sp3 hybridization percentage decreases, while the ID/IG ratio increases. The average roughness values for the uncoated sample and the coated samples at working pressures of 25, 30, and 35 mTorr were obtained as 1.6, 5.1, 3, and 2.4 nm, respectively. The results of hardness and wear tests showed that these properties were optimized by reducing the applied gas pressure. The highest hardness was 11.59 GPa, and the best sample in terms of the mechanical properties of the coating was the sample applied at a gas pressure of 25 mTorr. Results show that the optimal sample in tribological performance is the one applied at a working pressure of 25 mTorr. Because this sample demonstrates the lowest coefficient of friction, and wear depth. [ABSTRACT FROM AUTHOR]