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Aluminium is a widely used metal in the world due to its abundance and easy to work with properties. One of the major users of aluminium are the auto and aero industries, since it reduces the weight of the vehicle significantly. The properties of aluminium can be customized with certain alloying components and there are plenty of combinations, among which Aluminium 4032 alloy is taken for this investigation. This Al -Si 4032 alloy is enriched in silicon content up to 13%. High presence of silicon leads to more amount of friction in machining hence the machining of this particular alloy has to be done with coated materials for enhanced results. The machining is carried out with the carbide inserts triple layer coated with Titanium Nitride (TiN), Titanium Aluminium Nitride (TiAlN) and Diamond like Carbon (DLC). These coated inserts are used to machine Al-Si alloy workpiece under various machining variables of speed, feed, depth of cut as well as in both dry and wet environments. Various parameters are premeditated from the experiments like surface roughness, tool wear, tool life and material removal rate. And the responses were recorded, optimization process is carried out with Minitab software tool to find the finest combinations for machining. The better results are found to be in wet environment machining condition.

OBJECTIVES To examine anti-adhesion and anti-biofilm effects of a diamond-like carbon coating deposited via a novel technique on the inner surface of a thin silicon tube. METHODS Diamond-like carbon coatings were deposited into the lumen of a silicon tube with inner diameters of 2 mm. The surface of the diamond-like carbon was evaluated using physicochemical methods. We used three clinical isolates including green fluorescent protein-expressing Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. We employed a continuous flow system for evaluation of both bacterial adhesion and biofilm formation. Bacterial adhesion assays consisted of counting the number of colony-forming units and visualization of adhered bacterial cells by scanning electron microscope to evaluate the diamond-like carbon-coated/uncoated samples. The biofilm structure was analyzed by confocal laser scanning microscopy on days 3, 5, 7 and 14 for green fluorescent protein-expressing Pseudomonas aeruginosa. RESULTS The smooth and carbon-rich structure of the intraluminal diamond-like carbon film remained unchanged after the experiments. The numbers of colony-forming units suggested lower adherence of green fluorescent protein-expressing Pseudomonas aeruginosa and Escherichia coli in the diamond-like carbon-coated samples compared with the uncoated samples. The scanning electron microscope images showed adhered green fluorescent protein-expressing Pseudomonas aeruginosa cells without formation of microcolonies on the diamond-like carbon-coated samples. Finally, biofilm formation on the diamond-like carbon-coated samples was lower until at least day 14 compared with the uncoated samples. CONCLUSIONS Intraluminal diamond-like carbon coating on a silicone tube has anti-adhesion and anti-biofilm effects. This technology can be applied to urinary catheters made from various materials.

The influence of corrosion upon the nanoscale topography and friction response of a hydrogenated amorphous carbon film (a-C:H) was investigated. Electrochemical atomic force microscopy was used to characterise topographical changes to the coating at two oxidative potentials. Corrosion of the coating at 1.5 V (corrosion rate 0.5 nm h−1) resulted in no changes to the nanoscale topography; whereas corrosion at 2.5 V (corrosion rate 26.4 nm h−1) caused the root mean square roughness of the a-C:H film topography to decrease, but the local fine-scale irregularity or ‘jaggedness’ of the surface to increase. X-ray photoelectron spectroscopy revealed that corrosion at both potentials oxidised the a-C:H surface to form alcohol, carbonyl and carboxyl groups. Lateral force microscopy and adhesion force measurements showed that both the friction force and surface adhesion of the coating increased upon corrosion. The outcome was attributed to the surface oxidation that had occurred at both oxidative potentials, resulting in several potential mechanisms including increased attractive intermolecular interactions and capillary forces. The highest friction coefficient was observed for the a-C:H film corroded at 2.5 V, and identified as a consequence of the jagged surface topography promoting an interlocking friction mechanism.

A reliable, high-performance coating procedure was developed using PDMS to modify a duplex MAO/DLC coating on an AZ31B Mg alloy. First, the duplex MAO/DLC coating was fabricated via a combined MAO and unbalanced magnetron sputter process. Subsequently, a PDMS solution was used to modify the MAO/DLC coating via a conventional dip-coating method. The surface characteristics, bond strength, hardness, tribological behaviour, and corrosion resistance of the coated samples were evaluated via SEM, CA, Raman spectroscopy, friction and wear behaviour, polarisation curve, and NSS tests. The PDMS modification reduced the HIT of MAO/DLC coating from 15.96 to 8.34 GPa; this is ascribed to the penetration of PDMS, which has good rheological properties to form a viscoelastic Si-based organic polymer layer on the MAO/DLC coating. However, the PDMS-modified MAO/DLC coating was denser, hydrophobic, and had higher bond strength compared with MAO- and MAO/DLC-coated samples. Moreover, the PDMS modification reduced the COF and wear rate of the duplex MAO/DLC coating. This indicates that the PDMS improved the tribological behaviour owing to the transferred Si oxide that originated from the Si-O network of the PDMS, as well as the low graphitisation of the DLC layer during sliding. Furthermore, the corrosion current density of the MAO/DLC-coated sample modified by PDMS for 10 min decreased by two order of magnitude compared with that of the MAO/DLC-coated sample but by five orders of magnitude compared with that of the bare substrate. The NSS tests proved that the PDMS layer slowed the corrosion of the Mg alloy under long-term service, enhancing the corrosion protection efficiency. The results are attributed to the high bond strength and lubricant MAO/DLC layer, and the dual role of sealing and hydrophobicity of PDMS. Therefore, PDMS modification is promising for the fabrication of protective materials for Mg alloys that require corrosion and wear resistance.

Purpose This paper aims to address the coating and compound analysis of diamond-like carbon (DLC) on steel, to understand the frictional behavior in tribological gear systems presented in paper Part I. Here, the Ti and Zr modified DLC coating architectures are analyzed regarding their chemical, mechanical and thermophysical properties. The results represent a systematic analysis of the thermal insulating effect in tribological contact of DLC coated gears. Design/methodology/approach The approach was to evaluate the effect of the substitution of Zr through Ti at the reference coating ZrCg to TiCg and the effect on thermophysical properties. Furthermore, the influence of different carbon and hydrogen contents on the coating and compound properties was analyzed. Therefore, different discrete Ti or Zr containing DLC coatings were deposited on an industrial coating machine. Thereby the understanding of the microstructure and chemical composition of the reference coatings is increased. Findings Results prove comparable mechanical properties of metal modified DLC independent of differences in chemical compositions. Moreover, the compound adhesion between TiCg/16MnCr5E was improved compared to ZrCg/16MnCr5E. The effect of hydrogen content Ψ and carbon content xc on the thermophysical properties is limited by Ψ = 18 at.% and xc = 90 at.%. Practical implications The findings of the combined papers Part I and II show a high potential for industrial application of DLC on gears. Based on the results DLC coatings and gears can be tailored to each other. Originality/value Systematic analysis of DLC coatings were conducted to evaluate the effect of titanium, carbon and hydrogen on thermophysical properties.

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.

The increasing technology of the optical elements surface strength on the example of mirrors coated with Al and Cu by applying carbon diamond-like nanostructures is developed. A method of pulsed la...

Metallic bipolar plates can significantly increase the power density of polymer electrolyte membrane fuel cells; however, they require corrosion-protection coatings with desirable physical and chemical properties. In this study, diamond-like carbon (DLC) film coatings are investigated as such coatings potentially for metallic-based bipolar plates, with the focus on the relation between the processes and properties of the coatings under different coating deposition conditions of Plasma Enhanced Chemical Vapor Depsoition (PECVD) method. Various characterization techniques are applied to study the adhesion, structure, morphology, wettability, corrosion, and electrical resistivity of the film coatings. XPS, EDAX, and SEM analyses are used to identify the ratio of sp3 (diamond-like) and sp2 (graphite-like) bonds in the coatings, surface elements, and surface morphology, respectively. Potentiodynamic polarization test is utilized to investigate the corrosion behaviors of substrates with and without DLC coatings. Further, the electrical resistivity of the DLC films is measured by the four-point probe method. The results indicate that higher deposition power along with the absence of argon gas results in more sp3 than sp2 bonds in the coating, and the electrical resistivity is increased accordingly. The coating films deposited from methane (CH4) exhibit superior adhesion to the stainless steel (SS316) substrates over those generated from acetylene (C2H2) gas. Coating films deposited on the metallic substrates change the surface wettability appreciably. Further, polarization tests show that coatings generated with a low power of 250 W and higher argon gas percentage of 30% provide better anti-corrosion protection for metallic-based bipolar plates.

Materials engineering development has led to steel and cast iron replacement by Aluminum-Silicon – Al-Si alloys in various applications due to the adequate good strength-to-weight ratio and corrosion resistance. These features of Al-Si are extremely relevant for the performance improvement of many products by applying this alloy instead of the usual materials. However, studies have shown that the machinability of these materials presents multiple negative aspects, such as adhesion and abrasion. Therefore, optime cutting parameters and tools need to be selected to combine tool life with product quality. Using hard coatings with high chemical inertia, such as Diamond-Like Carbon (DLC), has shown promising results when machining aluminum alloys. Generally, in drilling, roughness, deviations in diameter, circularity and cylindricity represent the quality of a hole. Cutting speed directly influences tool wear and hole quality. Thus, this study aimed to evaluate the quality of holes machined using high-speed steel tools in an Al-Si alloy on the influence of cutting speed and the use of DLC coating. Tools with brazed Polycrystalline Diamond (PCD) are usually chosen for machining aluminum alloys, which can absorb high cutting speeds. In this paper, the replacement of brazed PCD is studied for high-speed steel coated with a thin film that can guarantee the same performance. The tests were carried out varying the cutting speed (V) in 340, 360, and 430 m/min, comparing DLC coated with uncoated tools. Flank wear was analyzed after each machining run using Scanning Electron Microscopy (SEM). The results showed that cutting speed directly influences the roughness, diameter variation, and flank wear. DLC coating did not show hole quality improvements as it presented adhesion problems on the high-speed steel substrate.

The effect of diamond-like carbon (DLC) coating (fabricated by cathodic arc deposition) on mechanical properties, tribological behavior and corrosion performance of the Ni−Al−bronze (NAB) alloy was investigated. Nano-hardness and pin-on-plate test showed that DLC coating had a greater hardness compared with NAB alloy. Besides, the decrease in friction coefficient from 0.2 for NAB substrate to 0.13 for the DLC-coated sample was observed. Potentiodynamic polarization and EIS results showed that the corrosion current density decreased from 2.5 μA/cm2 for bare NAB alloy to 0.14 μA/cm2 for DLC-coated sample in 3.5 wt.% NaCl solution. Moreover, the charge transfer resistance at the substrate–electrolyte interface increased from 3.3 kΩ·cm2 for NAB alloy to 120.8 kΩ·cm2 for DLC-coated alloy, which indicated an increase in corrosion resistance due to the DLC coating.

In this study, silicon (Si) was doped on a tetrahedral amorphous carbon (ta-C) coating and the tribological characteristics of the resulting Si-doped diamond-like carbon (DLC; a-C:Si:H) were investigated against a SUJ2 ball. The Si fraction in the coating was varied from 0 to ~ 20 at.% by increasing the trimethylsilane gas flow rate during filtered cathodic vacuum arc deposition. The coefficient of friction (CoF) showed no obvious change when the Si fraction was less than ~ 7 at.%. However, after Si doping, it significantly decreased when the Si fraction was greater than ~ 8 at.%. The running-in period also decreased to less than 1000 cycles after Si doping. The rapid formation of Si-rich debris and transfer layer led to the fabrication of a low-friction tribofilm, which was induced by the tribochemical reaction with moisture under ambient conditions. When the Si fraction was ~ 17 at.%, the lowest CoF of less than 0.05 was obtained. Further Si doping beyond the critical point led to the destruction of the film because of reduced hardness.

Delafossite CuFeO2 (CFO) has attracted much attention as a candidate p-type photocathode for photoelectrochemical (PEC) solar hydrogen production. In this paper first, a detailed electrochemical study was carried out in order to determine the best potential range for the potentiostatic deposition of nanostructured CFO on FTO glass. The structural and morphological properties of prepared samples were characterized by XRD and FESEM. Optical and photoelectrochemical investigations show that the sample prepared at − 0.7 V exhibits the best optical properties, charge separation, and charge transfer among prepared samples. We also provided direct evidence of surface states as charge trapping centers cause carrier recombination and limit photovoltage and charge transfer at SCLJ (semiconductor/liquid junction). Deposition of plasmonic Au nanoparticles (NPs) embedded in the diamond-like carbon (DLC) scaffold on the surface of CuFeO2 not only improved optical properties but also passivated these surface states and enhanced the PEC performance, consequently.

Poor osseointegration ability and the release of worn debris after implantation are the main issues impeding the clinic application of polyether ether ketone (PEEK) as orthopedics. To address these problems, we expect that the initial deposition of diamond-like carbon (DLC) coating on PEEK substrate and the subsequent introduction of amino groups onto sample surface using plasma immersion ion implantation (PIII) have the potential to simultaneously improve the mechanical performance and osseointegration. On one hand, the surface hardness is raised from 0.38 ​GPa to 2.99 ​GPa and the elastic modulus reaches 35 ​GPa after DLC deposition, while no failure is observed in the scratch tests even the loading force is up to 100 ​N. On the other hand, the introduced amino groups facilitate the adhesion, proliferation, and osteogenic differentiation of the osteoblasts in vitro, and further enhanced the peri-implant bone regeneration in vivo. With the merits of low cost, clean approach, and ease of operation, the approach described here holds great potential for biomedical applications.

Co-Cr-Mo alloy is a key material of total joint replacements. Ions releases (corrosion) in addition to Wear are a common failure mechanism in metal-on-metal (MOM). One of many new methods to coating DLCs is Plasma assisted chemical vapor deposition (PACVD) technique. Using PACVD to coat Co-Cr-Mo alloy is a new technique needs many research to allow for using in biomedical applications. DLCs provides smooth morphology surface. That morphology is reducing of surface roughness improvement tribological behavior. Using a best condition of coating parameters are Acetylene gas flow rate 40 sccm and voltage is 1600 v with Voltage between electrodes is 250 v for (PACVD) results coating film with 83% diamond like carbon (sp3) with thickness is 100 μm. Observations of surface indicate by suing both SEM and AFM indicate no crack and smooth surface with surface roughness is 0.679 µm in DLCs. Raman tested to determine the amount diamond like carbon (sp3) is 83%.that meaning the minimum of hydrogen content. Hardness tested to indicate increasing up to three times. The hardness of coating samples is 11.77 Hv, while in substate was about 3.923 Hv. Corrosion test by using simulated body fluid solution. DLCs improved the corrosion resistance of Co-Cr-Mo alloy with semi-body fluid solution. The samples have spontaneously passive in semi-body fluid solution at current density is 32.6 × 10−6 A/cm2 at potential is −416.5 mV for uncoated sample. While for DLCs current density is 3.92 × 10−6 A/cm2 with the potential of −35.5 mV. From comparing the maximum current for both samples shows the density for uncoated more than the DLCs, it is 207 and 11.1 mA/cm2 respectively. This reduction of the current densities explains improvement of corrosion resistance due to the surface modification by DLCs. Also, the reduced of electron conductivity of DLCs in comparison to uncoated sample indicate low electrical conductivity of the DLCs. That reduces the electron transport and the exchange of electrical charges at the samples surface, which is necessary for the electrochemical corrosion. In addition, reduces the Ni ion release of alloy.

In the last few years, Graphene oxide material and biomolecules studies have increased. The various synthesis methods of graphene oxide are constantly pursued to improve and provide safer and more effective alternatives. Though the preparation of graphene oxide from Graphite powder or Graphite flake through Hummers method is one of the oldest techniques but still now it is one of the most suitable methods. Here, Graphene Oxide has been prepared from a tunable material Hydrogenated diamond like carbon (HDLC) which is an atomically smooth surface that can be deposited on high-surface area Silicon (100) wafer plate. The HDLC film was heated at a fixed temperature of 900°C for 30 min in high vacuum ~1 × 10−6 torr and oxygenated at room temperature. A synthetic sequence is described involving Oxidation of annealed HDLC (A-HDLC). Raman measurements confirm the G and D peak by Oxidation of A-HDLC and FTIR confirms functional groups. Atomic force microscopy (AFM) images describe the surface of A-HDLC, Oxidized Graphene and BSA immobilized GO. This GO onto Silicon substrate offers many technical advantages than as oxidized graphene Synthesis from other Chemical methods.

Nitrogen-doped diamond-like carbon films were deposited on tool steel substrate througha plasma electrolytic technique. These coatings were fabricated using the hydrocarbons containing nitrogen vap...

The wear-resistant coatings formed by the vacuum ion-plasma codeposition of titanium and carbon have been studied in this work. Single-layer and multilayer coatings with the systematically repeated [(Ti1 – xCx/a-C] pair are deposited onto P8M5 and 18KhN10T steel substrates. The highest erosion resistance is inherent in the multilayer [Ti0.2C0.8/a-C]40 coating with a layer thickness of 25 nm. The erosion wear rate of this coating is 1.6–1.8 times lower than the wear rate of the single-layer а-С and Ti0.2C0.8 coatings. The wear of [Ti0.2C0.8/a-C]40 occurs layer by layer without crumbling of individual square sections of the coating, thus increasing its service life. The interphase boundaries in the Ti0.2C0.8 composite layer, as well as the Ti1 ‒ xCx → а-С interface boundaries, serve as a barrier for the propagation of microcracks, decreasing the probability of macrocracking, which destroys the continuity of a coating.

Multilayered Si-doped DLC film with thicknesses of 5.5, 10.1, 21.8 and 28.3 μm was deposited on stainless steel, aluminum alloy and copper alloy substrates by plasma-enhanced chemical vapor deposition. The mechanical and tribological properties of multilayered Si-doped DLC films deposited on three different substrates were evaluated in this study. The hardness of the multilayered Si-doped DLC film of different substrates is related to the substrate material and internal stress. In a scratch test, the adhesion of the multilayered Si-doped DLC film increased with the film thickness. The multilayered Si-doped DLC film with a thickness of 28.3 μm on stainless steel substrate has the highest adhesion of 31 N. The adhesion of the multilayered Si-doped DLC film with different thicknesses on the copper alloy is relatively poor. The ball-on-disk friction test results show that the multilayered Si-doped DLC film with thicknesses of 5.5 and 10.1 μm is prone to shear deformation and exhibit high friction coefficient. The uneven stress distribution and surface deformation of the multilayered Si-doped film deposited on the aluminum alloy and the copper alloy cause the fluctuation and rise of the friction coefficient. The wear resistance of multilayered Si-doped DLC films on different substrates is related to stress shielding and adhesion strength.

Thin-film lithium-ion microbatteries with a high energy density and long lifespan are exceedingly desired for developing self-powered integrated micro-nano devices and systems. However, exploring high-performance thin-film anodes still remains a challenge. Herein, a double-layer-structure diamond-like carbon-ZnS (DLC-ZnS) thin-film anode fabricated by radio frequency magnetron sputtering exhibits high specific capacity and good cycling stability up to 1000 cycles, superior to the pure ZnS thin-film anode. To understand the mechanism, the bimodal amplitude modulated-frequency modulated atomic force microscopy was used to explore the mechanical properties of the thin films, and the DLC layer shows significantly higher Young's modulus than the ZnS thin film. The DLC interface with a high Young's modulus can effectively buffer the mechanical stress originating from the huge volume changes of the ZnS layer during lithiation/delithiation processes; therefore, the DLC interface maintains the higher mechanical integrity of the DLC-ZnS thin film and improves the utilization of ZnS. In addition, the electrochemical kinetics of the DLC-ZnS and ZnS thin films were also investigated by electrochemical methods. Electrochemical impedance spectroscopy tests indicate the obstacle of the DLC interface to Li+ ion diffusion in the initial charge/discharge processes; however, the DLC-ZnS thin film exhibits lower total resistance than the ZnS thin film afterward. In particular, galvanostatic intermittent titration technique tests were performed to find out the differences between the two thin films during the galvanostatical charge/discharge processes. The results demonstrate the obviously enhanced conversion reaction reversibility and decreased alloy reaction polarization of the DLC-ZnS thin film; therefore, it delivers higher reversible capacity.

This study examines the effects of different pulse powers and gas fluxes on the mechanical and tribological properties and high-speed drilling performance of diamond-like carbon coatings deposited on tungsten carbide substrates by high-power impulse magnetron sputtering. It is shown that an appropriate pulse power is essential in improving the mechanical and tribological properties of the coatings. Specifically, coatings deposited with a pulse power of 5 kW possess a high hardness and good tribological properties, as evidenced by a high hardness-to-elastic modulus ratio. The optimal deposition parameters are determined to be a pulse power of 5 kW and an argon flux of 80 sccm. The resulting coating (designated as C80/5) has the highest hardness (24.95 GPa) of the various coatings and wear rates 11.1, 7.3 and 6.2 times better than those of the bare WC substrate under loads of 6 N, 10 N and 14 N, respectively. Moreover, the coating has low coefficient of friction values of 0.086, 0.098 and 0.062 under loads of 6 N, 10 N and 14 N, respectively. The micro-drilling tests show that the drill coated with C80/5 has a lifetime three times longer than that of an uncoated micro-drill.

We have conducted a comparative study on the deposition of diamond thin film on uncoated Al2O3, diamond-like carbon (DLC, grown by pulsed laser deposition) film-coated Al2O3, and Q-carbon (fabricat...

Coating crack and interfacial delamination are recognized as two critical factors inducing spallation of thick diamond-like carbon (DLC) coatings. The effect of the two factors is found to dramatically accelerate the failure of thick DLC coatings. However, there are few reports on the effect of interfacial delamination on coating crack. In this work, in order to investigate the evolution of the coating crack and interfacial delamination, as well as the effect of interfacial delamination on coating crack, a finite element model that combines the bilinear cohesive zone model and the extended finite element method (XFEM) is established. It is found that the occurrence of interfacial delamination triggers a second expansion of coating crack. Factors influencing the degree of interfacial delamination on coating crack can be modulated by coating thickness and coating elastic modulus. As the coating thickness increases, the length of interfacial delamination increases, and thus the propagation of coating crack is accelerated. In contrast, the increase of coating elastic modulus could reduce the length of interfacial delamination, which consequently weakens its influence on the propagation of coating crack.

Based on genetic algorithm (GA) and fuzzy neural network, a new method for the study of sputtering process is proposed in this paper. Diamond-like carbon (DLC) coatings were deposited on SKD11 steel by magnetron sputtering. An orthogonal array design is implemented and the effects of control factors on surface properties of the coatings were systematically analyzed. The coating properties were investigated by scanning electron microscopy and Raman spectroscopy, and wear volume surface performance of the Zr-doped DLC coatings was evaluated by a wear tests pin-on-disk tribometer. The Raman analyses showed that, at lower ID/IG ratio, a lower wear volume of the Zr-doped DLC coatings can be obtained. Scratch tests as well as Rockwell indentation tests revealed that the graded Zr-doped DLC structures efficiently provide better adhesive strength of DLC coatings. The results show that the wear behaviors of the DLC coatings can be improved by Zr-doping, which the Zr-doped DLC coatings exhibited promising tribological properties. Also, the predictive ability of the GA-ANFIS computations for the tribological behaviors of the Zr-DLC coatings within the experimental domains proved to be reliably obtained, where the forecasted values and experimental results are close.

The generation of a field emission (FE) cathode electron source has attracted wide attention for its miniaturization, high-frequency operability, and low energy consumption. However, the FE performance of cold cathodes is limited by poor current stabilities of carbon nanotube (CNT) emitters. Coating CNTs with sp3-bonded carbon coatings is considered as a successful approach to stabilize the FE currents. High-quality ultrathin diamond-like carbon (DLC) films, which serve as sp3 carbon coatings, are deposited uniformly on CNTs by filtered cathodic vacuum arc evaporation in this research. The thicknesses of DLC coatings and the field enhancement factors of pristine CNTs affect to a large extent the FE properties. An optimum coating thickness of DLC layers corresponding to the lowest threshold field exists due to space-charge-induced band bending, at which the depletion region of the DLC layer in equilibrium is maximized. The optimum coating thickness increases with the geometric field enhancement factor of p...

Currently a high amount of lubricants is used in aluminum forming processes to ensure a long tool lifetime and a high product quality. These technological and economical goals are traded for a negative environmental impact caused by the usage of lubricants. One approach to reduce the environmental impact is the utilization of dry forming of aluminum. Therefore, alternative methods for a tribological optimization need to be implemented like the deposition of tool coatings. Diamond like carbon (DLC) coatings are well known for their exceptional tribological properties. However, state of the art DLC coatings fail due to rapid formation of aluminum adhesions. In this paper, the nanoscopic roughness of DLC coatings will be presented as a critical property for preventing the formation of aluminum adhesions and enabling dry forming of aluminum. For this purpose, an amorphous hydrogenated carbon (a-C:H) coating will be deposited, subsequently polished and characterized to validate the impact of the material selection and surface treatment on the coating roughness. For an evaluation of the tribological properties, polished and unpolished a-C:H coatings will be tested in application oriented strip drawing and industry-oriented deep drawing tests. These tests demonstrate the capability of smooth a-C:H tool coatings to enable dry forming of aluminum with a reduced environmental impact.

In the present research work, the exhaust valve was coated with the hydrogenated diamond like carbon (H-DLC) material with different thicknesses such as 2,3,4,5, and 6 µm over the whole surface using magnetron sputtering technique. The main emphasis was on optimizing the best coating thickness and studying the effect of diesel engine performance characteristics at varying load conditions. The study showed that brake thermal efficiency (BTE) and NOx emissions were increased and the specific fuel consumption (BSFC), CO and HC emissions were decreased for thermal coated exhaust valve compared with the base engine. The peak cylinder pressure for 4 µm thickness coating increased upto 8.30% in the TBC engine, specifically at high power output; however, the exhaust gas temperatures were generally lower, signifying noble gas expansion in the power stroke that in turn increased the peak cylinder pressure and enhanced the BTE which increased by 1.6%. From the result it could be inferred that the engine with DLC coated valve enhanced the engine performance up to an optimum coating thickness beyond which the performance of the engine declined. The coated and uncoated surfaces were characterized by EDS and their microstructures were analyzed by SEM.

Chemical vapor deposition (CVD) of a diamond film on a non-diamond substrate begins with the insertion of diamond seeds or the formation of diamond nuclei on the substrate. For the deposition of a smooth, large-area and pin-hole free diamond film that adheres well to the substrate, diamond seeds or nuclei need to be of high density, uniformly distributed and adhere well to the substrate. Diamond seeding is not a diamond nucleation process. Bias enhanced nucleation (BEN) is the most effective means of heterogeneous nucleation of diamond for CVD diamond. It is based on a negative biasing voltage between the substrate and the diamond CVD plasma to accelerate positive ions from the plasma to bombard the substrate. Both direct diamond seeding and BEN have technical barriers in practical applications. New diamond nucleation techniques are desired. This paper reports novel heterogenous diamond nucleation along edge line of graphene on tungsten leading to the deposition of continuous diamond films. Based on experimental observation, a diamond nucleation mechanism assisted by sp3 C-W bonds at graphene edge is proposed. It is wished that scientists will become interested in revealing the precise diamond nucleation mechanism. With that, further optimization of this invention may lead to a new, complementary diamond nucleation process for practical deposition of diamond films.

Active screen plasma nitriding (ASPN) has recently emerged as an alternative nitriding technology with the potential to eliminate problems such as edge effect, arcing, and hollow cathode effects, associated with conventional direct current plasma nitriding technology. Amorphous hydrogenated carbon (a-C:H) is a thin film characterized by high hardness, a low friction coefficient, and superior wear resistance. However, the high residual stress of the a-C:H leads to poor adhesion between the a-C:H film and substrate. This study's objective was to investigate the properties of samples obtained by a duplex treatment (i.e., ASPN and a-C:H coating) of SUS304 austenitic stainless steel. The ASPN treatment was performed in 25% N2 + 75% H2 atmosphere for 5 h at 673 K under 600 Pa. An a-C:H film was coated using RF plasma-enhanced chemical vapor deposition in the presence of methane for 90 min. The results indicated that an a-C:H film with an S-phase interlayer formed after the duplex treatment of ASPN and a-C:H coating. Moreover, this treatment improved the adhesion and wear properties of the resulting sample.

This study reports a route to spatial control of neuronal adhesion onto Diamond-Like Carbon (DLC) by surface functionalisation by poly (oligo-ethyleneglycol methacrylate) (pOEGMA) and consequent laser ablation to produce cell adhesive tracks. DLC can be deposited as a tough and low friction coating on implantable devices and surgical instruments and has favourable properties for use as a biomaterial. The pOEGMA surface coating renders the DLC surface antifouling and the laser ablation creates graphitised tracks on the surface. The surfaces were coated with laminin, which adhered preferentially to the ablation tracks. The patterned surfaces were investigated for neuronal cell growth with NG108-15 cells for short term culture and rat neural stem cells for longer term culture. The cells initially adhered highly selectively to the ablation tracks while longer term cell culture revealed a more uniform cell coverage of the surface.

This study reports the fabrication of carbon using ions of carbon generated by high temperature, high density and extremely non-equilibrium argon plasma produced in modified dense plasma focus device. Carbon is deposited using two bursts of focussed plasma on n-type silicon substrates kept at a temperature of 20 (room temperature) and 130°C. The formation of nano-diamond-like carbon (nano-DLC) is observed at substrate temperature of 130°C. The samples deposited at different substrate temperatures are found to have amorphous in nature as observed from X-ray diffraction studies. These amorphous samples of carbon and nano-DLC possess nanostructures of average size ~27 and ~10 nm for 20 and 130°C substrate temperature, respectively, as obtained from atomic force microscopy and scanning electron microscopy studies. The possibility of formation of nano-DLC was analysed using Raman measurements. Peaks related to D and G band of graphitic carbon are observed in Raman spectra of both the samples. However, the samples grown at substrate temperature of 130°C show peaks related to nano-grain of diamond in Raman spectra, indicating high sp3 content, thereby confirming the formation of nano-DLC. The hardness measurement reveals the maximum value of hardness ~45.5 GPa for nano-DLC sample, which reconfirms that sample is of nano-DLC nature. The nano-DLC are found to have band gap of ~2.45 eV, which makes the nano-DLC a potential candidate for applications in protective optical window coating.

Diamond-like carbon (DLC) coatings are recognized for a broad range of industrial applications due to their superior mechanical properties such as high hardness, low friction, and promising wear resistance. DLC coatings are commonly produced with physical vapour deposition (PVD) and plasma-enhanced chemical vapour deposition (PECVD) methods. New DLC markets are emerging in electronics, biomedical, additive manufacturing and textiles sectors with industrial transformations. The conventional PVD and PECVD methods may have limited usage for depositing emerging DLC products due to their elevated thermal and high vacuum environment, lack of localized deposition function, and production throughput restrictions. This review begins by briefly describing DLC coatings background, the volume of research outcomes and the global revenue in the past decade and projections for the future. DLC structural designs made with conventional deposition methods and corresponding operational parameters are then discussed in detail and enhancement in conventional methods to improve DLC coating quality and to resolve unaddressed problems are summarized. The emerging DLC applications and potential of non-conventional methods to produce DLC coatings are critically analysed with specific attention to scientific, technological and economical aspects. Representative investigations suggest that DLC coatings can be produced with hardness values up to ~20 GPa using dielectric-barrier-discharge deposition, hydrophobicity up to ~167° with electrospray assisted plasma jet coating, high deposition rates up to ~6 μm/min with microwave resonator deposition, and critical load of ~30 N with a friction coefficient of ~0.1 when deposited with the plasma gun technique. The review concludes by recommending systematic investigations to optimize geometric and operational parameters of non-conventional DLC deposition methods which can produce high-quality DLC coatings at low temperatures and atmospheric pressures with scalability to meet emerging market demands.

In this work, unidirectional valves made of bare polydimethylsiloxane (PDMS) and PDMS provided with a micrometric diamond-like carbon (DLC) coating were fabricated and characterized, in terms of surface properties and opening pressure. The valve performance was also tested over 1250 repeated cycles of opening/closure in water, finding a slight decrease in the opening pressure after such cycles (10%) for the PDMS valves, while almost no variation for the PDMS + DLC ones. The valves were then immersed in urine for 126 days, evaluating the formation of encrustations and the trend of the opening pressure over time. Results showed that PDMS valves were featured by a thin layer of encrustations after 126 days, but the overall encrustation level was much smaller than the one shown by PDMS in static conditions. Furthermore, the opening pressure was almost not affected by such a thin layer of crystals. DLC-coated valves showed even less encrustations at the same time-point, with no significant loss of performance over time, although they were featured by a higher variability. These results suggest that most encrustations can be removed by the mechanical action of the valve during daily openings/closures. Such a self-cleaning behavior with respect to a static condition opens exciting scenarios for the long-term functionality of mobile devices operating in the urinary environment.

In diamond/silicon heterointerfaces fabricated by surface activated bonding at room temperature, an amorphous layer with carbon and silicon is formed in the bonding process, via atomic intermixing across the interfaces. The layer is crystallized by 1000°C annealing, forming a SiC compound.

Fluorinated diamond-like carbon (F-DLC) coating is biologically safe, provides superior antibacterial properties, and shows promise in preventing postoperative peri-implant infections. However, potential negative effects of this coating on in vivo bone formation and resorption have not been studied. The authors investigated the effects of F-DLC coatings on bone union in beagle dogs. Seventy-two solid columns of titanium alloy were prepared with equally spaced slits. Half of these columns were coated with F-DLC (Group F), and the others were left uncoated as controls (Group C). Columns were implanted in the femurs of beagle dogs, and in vivo bone formation and resorption were assessed 4, 8, and 12 weeks after implantation. In comparison to Group C, Group F showed significantly greater bone volume and trabecular thickness at Week 8 (p &lt, 0.05) and Week 12 (p &lt, 0.005) and significantly lower bone resorption activity, measured by the ratio of osteoclasts to bone surface and of eroded surface to bone surface, at Week 12 (p &lt, 0.05). The F-DLC coating encouraged bone formation in vivo more effectively than uncoated titanium alloy, suggesting that F-DLC will prove to be a useful coating material for antibacterial intraosseous implants.

In this study, we describe reducing the moisture vapor transmission through a commercial polymer bag material using a silicon-incorporated diamond-like carbon (Si-DLC) coating that was deposited using plasma-enhanced chemical vapor deposition. The structure of the Si-DLC coating was analyzed using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, selective area electron diffraction, and electron energy loss spectroscopy. Moisture vapor transmission rate (MVTR) testing was used to understand the moisture transmission barrier properties of Si-DLC-coated polymer bag material, the MVTR values decreased from 10.10 g/m2 24 h for the as-received polymer bag material to 6.31 g/m2 24 h for the Si-DLC-coated polymer bag material. Water stability tests were conducted to understand the resistance of the Si-DLC coatings toward moisture, the results confirmed the stability of Si-DLC coatings in contact with water up to 100 °C for 4 h. A peel-off adhesion test using scotch tape indicated that the good adhesion of the Si-DLC film to the substrate was preserved in contact with water up to 100 °C for 4 h.

Diamond-like carbon (DLC) is an amorphous form of carbon that contains aspects of both the diamond and graphite structures. It is composed of carbon and hydrogen, and owing to its texture, high mechanical hardness, chemical inertness, and optical transparency, DLC is widely used as a protective coating in the form of a thin film, which is applied to the surfaces of many materials. Recently, it has attracted attention as a biomedical material because of its high biocompatibility and stability [1,2]. DLC is particularly suitable to be embedded in the body owing to its low friction properties and selective cell surface attachment properties [3]. The material is currently being developed for the treatment of bone fractures [4]. However, unlike fibroblasts, the attachment of osteoblasts has not been extensively examined and no morphological data is available on how osteoblastic cells form contacts with the surface of biocompatible DLC-coated materials. Herein, such data were collected by coating DLC on the surface of silicon plates. The attachment of mouse cells to the DLC-coated plates was examined by colorimetric cell proliferation assay, and morphological observations were made using a field emission scanning electron microscope. Also, the flat cross section of the cell and plate was obtained by the ion milling method.

Diamond-like carbon (DLC) coatings are becoming well established across many industrial sectors including aerospace, automotive, oil and gas, and cold-forming tools. While DLC coatings exhibit good mechanical properties and a low coefficient of friction, the coating–substrate systems may suffer from insufficient wear resistance. This paper describes the effect of mechanical and thermochemical tool steel substrate pre-treatment on DLC coating durability. We have investigated two tool steel substrates, Sverker 21 (AISI D2) and an advanced powder metallurgy alloyed steel Vanadis 8. Initially, the substrates were heat treated in a vacuum furnace and gas quenched resulting in hardness of 59 ± 1 and 64 ± 1 Hardness Rockwell C (HRC) respectively. Subsequently, the samples were subjected to mechanical turning and burnishing with 130 N and 160 N forces, using diamond composite tools with a ceramic bonding phase. Afterwards, a plasma-assisted vacuum nitriding process in a physical vapour deposition (PVD) coating chamber, as a pre-treatment for subsequent DLC coating deposition, was carried out. Coated samples were subjected to a series of ball-on-disc wear tests against Al2O3 and Si3N4 counterparts. X-ray diffraction, instrumented indentation and scanning electron microscopy were employed to examine the mechanical and chemical properties of the wear scars. Selected variable factors, including the type of steel, the burnishing force and the type of counterbody material, were analysed in order to correlate them with the durability of DLC coating deposited on a pre-treated steel substrate. The effect of sequential processes used as pre-treatment on DLC coating durability was demonstrated. The wear resistance was over 180 (Sverker 21 substrate) and 10 (Vanadis 8 substrate) times greater against the Al2O3 counterbody for samples subjected to the following treatment: turning + burnishing with 160 N force + vacuum nitriding + DLC coating, comparing with the sample after grinding. The results are discussed in light of improving the cold-forming tools' tribological performance.

Molecular dynamics simulation of ultrathin carbon disulfide film confined between atomically flat stiff diamond plates is exposed. While calculating the radial distribution functions, we specify three site-site distribution functions that are possible to measure experimentally: gCC,gCS and gSS. Films with one and two molecular layers are detailed and TIP4P model is applied for carbon disulfide molecules. The radial distribution function is also calculated as a function of the load on the substrate. Internal energy is calculated, for one-layer film with a zero load, such a dependency is irregular with considerable fluctuations. For a higher value of load, periodic spikes are observed. Similar spikes are inherent in experiments when the film is in a solid-like state and they are characteristic to the stick-slip friction. In general, the pattern of the studied model is in agreement with the experiments with simple fluids from spherical molecules.

Due to their outstanding properties, carbon-based structures have received much attention from the scientific community. Their applications are diverse and include use in coatings on self-lubricating systems for anti-wear situations, thin films deposited on prosthetic elements, catalysis structures, or water remediation devices. From these applications, the ones that require the most careful testing and improvement are biomedical applications. The biocompatibility and antibacterial issues of medical devices remain a concern, as several prostheses still fail after several years of implantation and biofilm formation remains a real risk to the success of a device. Sputtered deposition prevents the introduction of hazardous chemical elements during the preparation of coatings, and this technique is environmentally friendly. In addition, the mechanical properties of C-based coatings are remarkable. In this paper, the latest advances in sputtering methods and biocompatibility and antibacterial action for diamond-based carbon (DLC)-based coatings are reviewed and the greater outlook is then discussed., This research is sponsored by national funds through FCT—Fundação para a Ciência e a Tecnologia, under the projects UIDB/00285/2020, UID/EMS/00285/2019 and UIDB/04650/2020, ATRITO-0 (co-financed via FEDER (PT2020) POCI-01-545 0145-FEDER-030446) and On-SURF (cofinanced via FEDER (PT2020) POCI-01-0247-FEDER-024521). Also, this work is supported by European Regional Development Fund (ERDF), through the Centro 2020 Regional Operational Programme under project CENTRO-01-0145-FEDER-000012-HealthyAging2020, and through the COMPETE 2020—Operational Programme for Competitiveness and Internationalization and Portuguese national funds via FCT-Fundação para a Ciência e a Tecnologia, under projects POCI-01-0145-FEDER-007440 and UID/NEU/04539/2019.

Reciprocating micro-scale sliding tests and micro-scale repetitive impact tests were performed with diamond probes on un-doped, Si-doped and W-doped diamond-like carbon (DLC) coatings on hardened steel with a nanomechanical test instrument. Analytical modelling showed that differences in coating behaviour during sliding contact could be interpreted by differences in the stress distribution that develops. The softer W-doped DLC exhibited the lowest wear resistance in reciprocating sliding. The deformation in the wear track under the test conditions (R = 25 µm, P ≤ 500 mN, total sliding distance = 1 m) was largely controlled by plastic deformation and hence hardness, since micro-scale fatigue wear was only a small contributor. The relationship between friction and wear was more complex, due to the changing influence of surface topography, asperity ploughing and wear with increasing reciprocating sliding cycles. The Si-doped DLC showed the lowest resistance to repetitive impact. The hardest and highest H3/E2 coating, un-doped DLC, was also susceptible to fracture throughout the load range. Although the W-doped DLC was the softest coating studied and had low wear resistance in reciprocating sliding, it was significantly more damage tolerant to repetitive impacting than the other coatings despite its low hardness and low wear resistance in reciprocating tests.

In this study, diamond-like carbon (DLC) coating made from spherical powder SP and Irregular powder IP manufactured for plasma of cold sprayed by gas atomization is presented. Sliding assessment is carried out at different loads on each DLC coating. All DLC coating surfaces are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Furthermore, coatings show low porosity and extreme hardness. Irregular powder IP coatings have proved to be less hardness than SP coatings. In case of IP coatings, abrasive plowing with used particles is resulted in an increased wear, while the available porosity in SP of the used particles is formed in some points of reduced sliding of wear. Coatings of IP cause an increasing of coefficient of friction (CoF). The load limitations are associated with tribooxidation in IP coatings, while mixed particles together with tribooxidation result in lower CoF with SP coatings. The range of CoF for all test parameters is 0.24–0.32. Transmission electron microscopy (TEM) shows characteristics body-filled pores composed of a deformed material with an ultrafine microstructure and micron-sized particles. The characterization confirms that 30% of pore-filled coatings are ultra-deformed fabric with microstructure and particles, while the worn surfaces have a rough microstructure. The effects confirm that SP hardness and porosity help attract particles and reduce abrasiveness.

Made available in DSpace on 2021-06-25T10:32:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Cutting precision is extremely affected by a phenomenon known as built up edge (BUE) that occurs on tungsten carbide tools during low cutting speed of aluminum alloy. BUE is responsible for early tool breakage due to excessive material build up from the machined part on the cutting face, leading to problems of shape irregularity and tool-tip breakage. Thus, diamond-like carbon (DLC) was deposited and tested to verify cutting precision in aluminum alloy by using tungsten carbide tools. The characterizations of the film were morphology analysis through scanning electron microscopy (SEM), structural atomic analyze of chemical bond from Raman backscatter spectroscopy, the distribution of carbon atoms on the film surface by X-ray photoelectron spectroscopy (XPS), and the evaluation of Young's modulus and hardness using the Oliver-Pharr method. To analyze the cutting precision, drilling tests were performed on coated/uncoated drills at two cutting speeds (340 and 430 m/min). As an evaluation parameter in the aluminum alloy, the hole diameter deviation was measured after pre determined numbers of drilling operations. Statistical comparisons between the diameter deviation as a function of the number of drilling test indicated better cutting accuracy for the DLC-coated tool. The factors identified in this work, such as the reduction of the friction coefficient, and the hardness and Young's modulus of the DLC helped in the performance of the tool, mainly in the lower cutting speed. Material Science and Engineering Laboratory São Paulo State University IBTEC-UNESP, Al. Tecomarias s/n Fiat Chrysler Group, Av. Contorno, 3455 Department of Physics Federal University of Minas Gerais, Av. Presidente Antônio Carlos 6627 Laboratory of Technological Plasmas Institute of Science and Technology São Paulo State University, Av. Três de Março 511 Department of Mechanical Engineering Pontifical Catholic University of Minas Gerais, Av. Dom JoséGaspar 500 Material Science and Engineering Laboratory São Paulo State University IBTEC-UNESP, Al. Tecomarias s/n Laboratory of Technological Plasmas Institute of Science and Technology São Paulo State University, Av. Três de Março 511 FAPESP: 2015/20438-6

—The study investigates the antifriction properties of both a diamond-like coating (DLC) and titanium aluminum nitride (AlTiN) used as an intermediate layer to improve adhesion. Tribological tests of coatings were carried out without lubricant, in an inactive lubricant environment, and in lubricant environments with surfactant and chemically active additives. The studied DLC increases surface wear resistance and significantly lowers the friction coefficient; at the same time, the lubricant environment has no significant effect on the antifriction properties of the DLC.

Dye-sensitized solar cells (DSSC) based on diamond-like carbon (DLC) anti-reflection coating (ARC) thin films are investigated. The DLC film was proposed to improve the cell performance of DSSC devices. In this work, the DLC films were fabricated by using the FVA (filtered vacuum arc) method, the structural, optical, and physical properties of the fabricated DLC films with various film thicknesses were experimentally investigated. All DLC films showed smoother and more uniform surfaces with increasing film thickness. Furthermore, the values of rms surface roughness, friction coefficient, the refractive index, and the absorption coefficient increased with increasing film thickness, the hardness and the elastic modulus of the DLC films were improved. These results are associated with the increased sp3 contents in the amorphous carbon film due to the effects of the energetic ion bombardment during film deposition.