Search Results (16)

Silicon-doped tetrahedral amorphous carbon (ta-C:Si) coatings are promising materials for achieving ultralow friction in water-lubricated environments, attributed to the formation of Si(OH)_x-based tribofilms. However, the deposition process via filtered cathodic vacuum arc (FCVA) often introduces large particles into the film, increasing surface roughness and causing accelerated wear during the initial sliding phase, despite the high hardness of the coating. In this study, ball-on-disk tribological tests were performed to investigate the wear behavior of ta-C:Si coatings under water lubrication. Friction coefficients, wear volume, and surface roughness were analyzed over various sliding durations. The Archard wear equation and the plasticity index were used to analyze wear and contact behavior. The friction coefficient decreased from 0.14 to 0.04 within the initial 100 m section, and the surface roughness of ta-C:Si decreased sharply from 0.35 μm to 0.01 μm based on the Rpk parameter during 10 h. Following this period, the plasticity index decreased from an initial value of 1.1 to below 0.6, transitioning to a fully elastic contact stage, marking the onset of steady-state wear after 10 h. These results indicate that the reduction in surface roughness plays a crucial role in stabilizing wear behavior and provide insights into optimizing the long-term performance of ta-C:Si coatings in aqueous environments. Full article

Copper-doped hydrogenated amorphous carbon (Cu-doped a-C:H) films were synthesized using copper as the cathode and C₂H₂ as the precursor. The result shows that the negative bias voltage can affect the composition and microstructure of nanocomposite films. With bias voltage increasing, Cu content first increases in the range of 50~300 V and then declines with higher voltage, while the deposition rate decreases continuously. The stress and sp³ content present a similar trend with the bias voltage, increasing during the range from 50 V to 200 V and then decreasing with higher voltage. Full article

Filtered cathodic vacuum arc (FCVA) deposition technology was applied to prepare tetrahedral amorphous carbon (taC) thin films with different substrate pulse biases. Their structure, adhesion strength, and corrosion behavior in 5 × 10⁻² M hydrochloric (HCl), sodium chloride (NaCl), calcium chloride (CaCl₂), lead (II) chloride (PbCl₂), and mercury (II) chloride (HgCl₂) solutions were studied with respect to the substrate pulse bias. Increasing the substrate pulse bias from 0 to 1000 V increased the graphitization of the taC thin films and thereby resulted in a 9.9% increase in their adhesion strength from 406 mN to 446 mN. The taC thin films exhibited the lowest (8.48 × 10⁴ Ω to 11.55 × 10⁴ Ω) and highest (146.89 × 10⁴ Ω to 387.44 × 10⁴ Ω) corrosion resistance in the PbCl₂ and HgCl₂ solutions, respectively, while they had higher corrosion in the HCl (62.07 × 10⁴ Ω to 131.73 × 10⁴ Ω) solution than in both the NaCl (143 × 10⁴ Ω to 231.31 × 10⁴ Ω) and CaCl₂ (102.13 × 10⁴ Ω to 351.92 × 10⁴ Ω) solutions. Nevertheless, the taC thin films with higher substrate pulse biases had lower corrosion resistance in all the solutions used in this study. The substrate pulse bias emerged as a significant parameter in the FCVA deposition process, playing a crucial role in influencing the structure, adhesion strength, and corrosion resistance of taC thin films. Full article

In order to address the weaknesses of poor corrosion resistance of hydraulic cylinder piston rods, we have developed a surface protection strategy for titanium aluminum nitride coatings by filter cathode vacuum arc (FCVA) technology. The optimization and regulatory mechanism of N₂ flow rate on the microstructure, mechanical, and electrochemical oxidation behaviors have been emphasized. The results indicated that all coatings revealed a nanocrystalline amorphous composite structure dominated by an fcc TiAlN phase. However, the solid solution content, growth orientation, and grain size could be controlled by the nitrogen flow rate, thereby achieving optimized hardness, adhesion strength, corrosion, and oxidation resistance. Specifically, with the increase in the N₂ flow rate, the solid solution content continued to rise, while the crystal orientation transformed from the (111) to the (200) plane, and the grain size initially increased and then decreased. As a result, mechanical properties, including hardness, toughness, resistance to plastic deformation, and adhesion strength, displayed a trend of initially increasing and then decreasing. The corrosion failure of coatings was linked to surface defects controlled by the N₂ flow rate, rather than the composition and phase structure. The coating displayed superior corrosion resistance at low N₂ flow rates due to fewer macroscopic particles and pore defects. This study provides valuable insights into the corrosion behavior of an aluminum titanium nitrogen coating, providing crucial guidance for coating design in harsh environments. Full article

High-quality diamond-like carbon (DLC) films are renowned for their exceptional hardness, low friction coefficient, and superior chemical stability. These properties make DLC films exceptionally suitable for protective coatings in optical, mechanical, aerospace, and military applications. Thick DLC films with outstanding mechanical properties were deposited on DC53 die steel using a mixed energy carbon plasma generated by a filtered cathodic vacuum arc (FCVA) device. The structural, mechanical, tribological, and optical properties of the films were tested by Raman, surface morphology instrument, Vickers Indenter, tribometer, and UV-VIS spectrophotometry. The results indicated that 14 µm tetrahedral amorphous carbon (ta-C) films with a good combination with DC53 die steel substrate were obtained. The hardness was 9415 HV, which is close to that of diamond films. The fracture toughness was 4 MPa·m^1/2. The friction coefficient was 0.0898, and the optical band gap was 3.12 eV. Full article

(AlCrMoNiTi)N high-entropy alloy nitride (HEAN) films were synthesized at various bias voltages using the co-filter cathodic vacuum arc (co-FCVA) deposition technique. This study systematically investigates the effect of bias voltage on the microstructure and performance of HEAN films. The results indicate that an increase in bias voltage enhances the energy of ions while concomitantly reducing the deposition rate. All synthesized (AlCrMoNiTi)N HEAN films demonstrated the composite structure composed of FCC phase and metallic Ni. The hardness of the (AlCrMoNiTi)N HEAN film synthesized at a bias voltage of −100 V attained a maximum value of 38.7 GPa. This high hardness is primarily attributed to the synergistic effects stemming from the formation of strong metal-nitrogen (Me-N) bonding formed between the target elements and the N element, the densification of the film structure, and the ion beam-assisted bombardment strengthening of the co-FCVA deposition technique. In addition, the corrosion current density of the film prepared at this bias voltage was measured at 4.9 × 10⁻⁷ A·cm⁻², significantly lower than that of 304 stainless steel, indicating excellent corrosion resistance. Full article

This study explores the utilization of cathodic vacuum arc (CVA) technology to address the limitations of magnetron sputtering technology in preparing amorphous carbon (a-C) coatings, such as having a low ionization rate, low deposition rate, and insufficiently dense structure. Specifically, a-C coatings were prepared by the cathodic vacuum arc (CVA)and the filtered cathodic vacuum arc (FCVA) technology,, one with embedded carbon particles and one without, both having closely related carbon structures. Research is currently underway on bipolar plate coatings for fuel cells. The corrosion behavior of the prepared a-C coatings was examined through Tafel polarization analysis under simulated fuel cell operating conditions as well as potentiostatic analysis at 0.6 V under normal conditions and 1.6 V under start–stop conditions for 7200 s. The coatings before and after corrosion are characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, and infrared spectroscopy. The results reveal that the incorporation of conductive graphite-like particles in the coatings reduces their contact resistance. However, the gaps between these particles and the coatings act as pathways for corrosive solution, exacerbating the corrosion of the coatings. After corrosion at 0.6 V, both sets of coatings with sp²-hybridized carbon structures are contaminated by elements such as hydrogen and oxygen, leading to an increase in their contact resistance. Under high potential conditions (1.6 V), large corrosion pits and defects appear at the locations of graphite-like carbon particles. Furthermore, both sets of samples exhibit more severe oxygen contamination and a transformation of broken carbon bonds from sp³- to sp²-hybridized forms, irrespective of whether embedded graphite particles are present. Full article

Tetrahedral amorphous carbon (taC) is a hydrogen-free carbon with extensive properties such as hardness, optical transparency, and chemical inertness. taC coatings have attracted much attention in recent times, as have coatings doped with a noble metal. A known antimicrobial metal agent, silver (Ag), has been used as a dopant in taC, with different Ag concentrations on the Ti64 coupons using a hybrid filtered cathodic vacuum arc (FCVA) and magnetron sputtering system. The physiochemical properties of the coated surface were investigated using spectroscopic and electron microscopy techniques. A doping effect of Ag-taC on biofilm formation was investigated and found to have a significant effect on the bacterial-biofilm-forming bacteria Staphylococcus aureus and Pseudomonas aeruginosa depending on the concentration of Ag. Further, the effect of coated and uncoated Ag-taC films on a pathogenic bacterium was examined using SEM. The result revealed that the Ag-taC coatings inhibited the biofilm formation of S. aureus. Therefore, this study demonstrated the possible use of Ag-taC coatings against biofilm-related complications on medical devices and infections from pathogenic bacteria. Full article

Al₂O₃ and MgO composite (Al₂O₃/MgO) films were rapidly deposited at low temperatures using filtered cathode vacuum arc (FCVA) technology, aiming to achieve good barrier properties for flexible organic light emitting diodes (OLED) thin-film encapsulation (TFE). As the thickness of the MgO layer decreases, the degree of crystallinity decreases gradually. The 3:2 Al₂O₃:MgO layer alternation type has the best water vapor shielding performance, and the water vapor transmittance (WVTR) is 3.26 × 10⁻⁴ g·m⁻²·day⁻¹ at 85 °C and 85% R.H, which is about 1/3 of that of a single layer of Al₂O₃ film. Under the action of ion deposition, too many layers will cause internal defects in the film, resulting in decreased shielding ability. The surface roughness of the composite film is very low, which is about 0.3–0.5 nm depending on its structure. In addition, the visible light transmittance of the composite film is lower than that of a single film and increases with the increase in the number of layers. Full article

To improve the anti-tribocorrosion property, and decrease the metal dissolution and wear of stainless-steel components caused by the synergistic action of corrosion and friction in marine environments, Ti-DLC coatings were obtained on steel substrate using a filtered cathodic vacuum arc (FCVA) system by adjusting bias voltage. The structure, mechanical properties, corrosion, and tribocorrosion behavior were investigated. Increasing the bias voltage from −50 V to −300 V, Ti content decreased from 23.9 to 22.5 at.%, and grain size decreased first, and then increased. Obvious TiC grains embedded in the amorphous carbon matrix were observed in the coating from the TEM result. Hardness increased from 30.23 GPa to 34.24 GPa with an increase in bias voltage from −50 to −200 V. The results of tribocorrosion testing showed that the Ti-DLC coatings at −200 V presented the best anti-tribocorrosion performance with the smallest friction coefficient of 0.052, wear rate of 2.48 × 10⁻⁷ mm³/N∙m, and high open-circuit potential, which is mainly due to the dense structure, high value of H/E* and H³/E*², and great corrosion resistance. Obtained results suggest that the Ti-DLC coating with nanocomposite structure is a potential protective material for marine equipment. Full article

Titanium oxide films were deposited at room temperature and with no applied bias using a filtered cathodic vacuum arc (FCVA) system in a reactive oxygen environment. The dependence of film growth on two process parameters, the working pressure (Pw) and the O₂ partial pressure (p_O2), is described in detail. The composition, morphological features, crystalline structure, and optical properties of the deposited films were systematically studied by Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), Raman Spectroscopy, UV-vis spectroscopy, and spectroscopic ellipsometry. This systematic investigation allowed the identification of three different groups or growth regimes according to the stoichiometry and the phase structure of the titanium oxide films. RBS analysis revealed that a wide range of TiO_x stoichiometries (0.6 < × < 2.2) were obtained, including oxygen-deficient, stoichiometric TiO₂ and oxygen-rich films. TiO, Ti₂O₃, rutile-type TiO₂, and amorphous TiO₂ phase structures could be achieved, as confirmed both by Raman and XRD. Therefore, the results showed a highly versatile approach, in which different titanium oxide stoichiometries and crystalline phases especially suited for diverse optical applications can be obtained by changing only two process parameters, in a process at room temperature and without applied bias. Of particular interest are crystalline rutile films with high density to be used in ultra-high reflectance metal-dielectric multilayered mirrors, and reduced-TiO₂ rutile samples with absorption in the visible range as a very promising photocatalyst material. Full article

In this study, the anti-impact performance of the TiN coatings prepared under various substrate temperatures (35, 200, 400, and 600 °C) were evaluated using a cyclic impact tester under 10⁴ cycles. Moreover, the microstructure and anti-impact performance-related mechanical properties (adhesion strength and nano-hardness) were investigated to reveal the underlying mechanism of how the substrate temperature affects the anti-impact performance of the coatings. The results showed that the substrate temperature has a great influence on the internal stress, nano-hardness, and adhesion strength as well as the anti-impact performance of TiN coatings, and the coatings prepared under 400 °C exhibit the best impact resistance. The small internal stress, strong adhesion strength as well as high hardness and H³/E² value for the 400 °C prepared coatings are the main contributes. Full article

Machine-tool life is one limiting factor affecting productivity. The requirement for wear-resistant materials for cutting tools to increase their longevity is therefore critical. Titanium diboride (TiB₂) coated cutting tools have been successfully employed for machining of AlSi alloys widely used in the automotive industry. This paper presents a methodological approach to improving the self-lubricating properties within the cutting zone of a tungsten carbide milling insert precoated with TiB₂, thereby increasing the operational life of the tool. A unique hybrid Physical Vapor Deposition (PVD) system was used in this study, allowing diamond-like carbon (DLC) to be deposited by filtered cathodic vacuum arc (FCVA) while PVD magnetron sputtering was employed to deposit WS₂. A series of ~100-nm monolayer DLC coatings were prepared at a negative bias voltage ranging between −50 and −200 V, along with multilayered DLC-WS₂ coatings (total thickness ~500 nm) with varying number of layers (two to 24 in total). The wear rate of the coated milling inserts was investigated by measuring the flank wear during face milling of an Al-10Si. It was ascertained that employing monolayer DLC coating reduced the coated tool wear rate by ~85% compared to a TiB₂ benchmark. Combining DLC with WS₂ as a multilayered coating further improved tool life. The best tribological properties were found for a two-layer DLC-WS₂ coating which decreased wear rate by ~75% compared to TiB₂, with a measured coefficient of friction of 0.05. Full article

Multilayers of Ti doped diamond-like carbon (Ti-DLC) coatings were deposited on aluminum alloys by filtered cathodic vacuum arc (FCVA) technology using C₂H₂ as a reactive gas. The effect of different Ti transition layer thicknesses on the structure, mechanical and adhesion properties of the coatings, was investigated by scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation and a scratch tester. The results showed that the Ti transition layer could improve interfacial transition between the coating and the substrate, which was beneficial in obtaining excellent adhesion of the coatings. The Ti transition layer thickness had no significant influence on the composition and structure of the coatings, whereas it affected the distortion of the sp²-C bond angle and length. Nanoindentation and scratch test results indicated that the mechanical and adhesion properties of the Ti-DLC coatings depended on the Ti transition layer thickness. The Ti transition layer proved favorable in decreasing the residual compressive stress of the coating. As the Ti transition layer thickness increased, the hardness value of the coating gradually decreased. However, its elastic modulus and adhesion exhibited an initial decrease followed by an increasing fluctuation. Among them, the Ti-DLC coating with a Ti transition layer thickness of 1.1 μm exhibited superior mechanical properties. Full article

Combinatorial deposition, comprising filtered cathodic vacuum arc (FCVA) and physical vapor deposition (PVD) magnetron sputtering is employed to deposit molybdenum disulphide (MoS₂) and titanium (Ti) thin films onto TiB₂-coated tool inserts specifically designed for the dry machining of aluminium alloys. Titanium is deposited by FCVA while MoS₂ is magnetron sputtered. The deposition set up allows several compositions of Ti-MoS₂ to be deposited simultaneously, with Ti content ranging between 5 and 96 at. %, and their machining performances to be evaluated. Milling took place using a CNC Vertical Machining Center at a 877 mm/min feed rate. The effect of different coating compositional ratios on the degree of aluminium sticking when a milling insert is used to face mill an Al alloy (SAE 6061) was investigated using a combination of energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. XPS studies suggest that the greater degree of Al sticking on the rake face of the inserts is due to the formation of greater amounts of non-protective Ti-O phases. EDX mapping of the milling inserts after machining reveal that a Ti:MoS₂ ratio of around 0.39 prevents Al from sticking to the tool edges. Since we prevent Al from sticking to the tool surface, the resultant machined surface finish is improved thus validating the machining performance of TiB₂-coated tools using optimum compositions of Ti:MoS₂ thin film coatings. Full article