Vacuum Arc Deposition Research Articles

DC vacuum arc deposition system with an anode generating magnetic field for preparation of TiN films

In this study, a coiled anode that generates a magnetic field using a DC arc was designed and employed in a cathodic vacuum-arc deposition system. Its performance was evaluated by the formation of TiN films with and without a magnetic field. When the magnetic field was applied by the coiled anode, the deposition rate was approximately 1.5 times faster than that without the magnetic field. In addition, a reduction in the number of droplets with films of the same thickness was expected. Furthermore, the hardness of the film was improved by approximately 10% with the magnetic field of the coiled anode, resulting in a very hard film of 43.7 GPa. These results suggest that the coiled anode is effective in reducing the number of droplets and is promising for the formation of super-hard films, which are preferred for cutting tools.

PROTECTIVE VACUUM-ARC COATINGS ON ZIRCONIUM ALLOY FUEL CLADDING TO PREVENT CATASTROPHIC ACCIDENTS AT NUCLEAR REACTORS

The processes of vacuum arc deposition of multicomponent coatings based on Cr, Ti, Al, Fe, Y, Si, and their nitrides with a thickness of 5…9 µm for the protection of zirconium alloy fuel rods were developed. The composition, structure, and mechanical properties of the coatings were determined by electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and nanoindentation. Comparative studies of the protective properties of coatings during high-temperature oxidation of Zr1Nb tubes were carried out. It was found that metal coatings with a high chromium content have excellent protective properties during tests under simulated accident conditions. They are simultaneously resistant to high-temperature corrosion in air at 750…1100 °C and in water steam during thermal cycling up to 1020 °C. Hard nitride coatings, which significantly strengthen the surface of the zirconium alloy and provide good protection against oxidation in air, are less effective in water steam under thermal cycling. The coatings and processes of synthesis developed at NSC KIPT can be useful for improving fuel cladding made of zirconium alloys of the world's leading nuclear fuel producer Westinghouse Electric Company.

Modifying Coatings for Medical Implants Made of Titanium Alloys

This review considered various methods for depositing special modifying coatings on medical implants made of titanium alloys including techniques such as electrochemical deposition, sol–gel process, atmospheric plasma deposition, and PVD methods (magnetron sputtering and vacuum arc deposition). The rationale is provided for the use of modifying coatings to improve the performance efficiency of implants. The concept of a functional multilayer coating designed for products operating in the human body environment is proposed. The advantages and disadvantages of various methods for depositing coatings are considered based on the possibility of their use for obtaining modifying coatings for medical purposes deposited on a titanium alloy base.

Filtered cathodic vacuum arc deposition of tetrahedral amorphous carbon thin films on surgical blades and its corrosion resistance in phosphate buffer solution (PBS) at pH 7.4

Surgical blades are prone to corrosion in a body fluid environment, increasing the risk of surgical infection and inflammation. In this paper, the ta-C thin films was deposited on surgical blades by filtered cathode vacuum arc (FCVA) method. Modern analytical methods such as SEM, Raman, surface profiler and electrochemical corrosion were used for the test and analysis. The results show that the corrosion potential and corrosion current density of uncoated surgical blades are −507 mV and 2.43 μA/cm2 during surgery operation in a simulated human environment (pH 7.4 PBS solution), and the corrosion potential of the ta-C thin films surgical blades immersed in 0.25 h, 0.5 h and 1 h are −395 mV, −431 mV, −445 mV, and the corrosion current density are 1.11 μA/cm2, 1.46 μA/cm2, 1.58 μA/ cm2. The results show that the ta-C thin films surgical blades are excellent corrosion resistance during surgery operation in a simulated human environment. SEM shows that the ta-C thin films surgical blades have a smooth surface with a compact and uniform films structure, and the thicknesses of the ta-C thin films and Ti transition layer are 2.2 µm and 2.4 µm respectively. The surface profiler shows that the average roughness of the surgical blades and the ta-C thin films surgical blades are 295.979 nm and 477.417 nm. Raman shows that ta-C thin films is of high purity, without any impurity phase, and does not cause other adverse reactions during surgery operation.

SOME ASPECTS OF ELECTROLYTIC-PLASMA PROCESSING TECHNOLOGY

A technological device (pilot model) for electrolytic-plasma processing of various surfaces has been developed. Some theoretical calculations and processing recommendations have been done. This technology contributes to significant savings in human and energy resources and achieving the required surface quality of parts, and preliminary processing, and is very usefullbefore vacuum-arc deposition of protective coatings

COMPARATIVE CHARACTERIZATION OF ARC-PVD ZrN AND PEO HYDROXYAPATITE COATINGS ON PURE Ti-6Al-4V SUBSTRATES FOR BIOMEDICAL APPLICATIONS

The nanocrystalline films of zirconium nitride have been synthesized using ion-plasma vacuum-arc deposition technique on pure Ti-6Al-4V, whereas the hydroxyapatite coatings were deposited by the method of plasmaelectrolytic oxidation in alkaline electrolytes (hydroxyapatite + 1 М potassium hydroxide). Structure evaluation by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) with microanalysis (EDS) – were performed to study phase and chemical composition, surface morphology, microstructure of coatings. The formed HA PEO coatings with spheroidal structure contain the phases of CaTiO3 calcium titanate, CaHPO4 anhydrous dicalcium phosphate, and Ca10(PO4)6(OH)2 hydroxyapatite. It was revealed that ZrN single-phase coatings of cubic modification with finecrystalline grains of 20 nm in size were formed. This experimental study found that coating Ti-6Al-4V with ZrN and HA positively influences preosteoblast cell adhesion, which results in the almost complete coverage of the surface, along with a less number of cells grown on uncoated titanium surface.

Plasma diagnosis of tetrahedral amorphous carbon films by filtered cathodic vacuum arc deposition

Filtered cathodic vacuum arc (FCVA) deposition is regarded as an important technique for the synthesis of tetrahedral amorphous carbon (ta-C) films due to its high ionization rate, high deposition rate and effective filtration of macroparticles. Probing the plasma characteristics of arc discharge contributes to understanding the deposition mechanism of ta-C films on a microscopic level. This work focuses on the plasma diagnosis of an FCVA discharge using a Langmuir dual-probe system with a discrete Fourier transform smoothing method. During the ta-C film deposition, the arc current of graphite cathodes and deposition pressure vary from 30 to 90 A and from 0.3 to 0.9 Pa, respectively. The plasma density increases with arc current but decreases with pressure. The carbon plasma density generated by the arc discharge is around the order of 1010 cm−3. The electron temperature varies in the range of 2‒3.5 eV. As the number of cathodic arc sources and the current of the focused magnetic coil increase, the plasma density increases. The ratio of the intensity of the D-Raman peak and G-Raman peak (I D/I G) of the ta-C films increases with increasing plasma density, resulting in a decrease in film hardness. It is indicated that the mechanical properties of ta-C films depend not only on the ion energy but also on the carbon plasma density.

DC vacuum arc deposition with open winding-path anode assembled with C-ring plates

Vacuum arc deposition (VAD), which utilizes the vapored high energy metal ions from an electrode, is widely used in industry. Though VAD has many advantages, the reduction of droplets on deposited films is an essential issue to solve for its industrial application. In this study, we have developed a new type of filtered arc deposition (FAD) utilizing a winding coil with copper C-ring-shaped plates in a vacuum chamber. TiN films were deposited on substrates with a normal linear FAD and the new FAD. TiN films were analyzed, and it was found that the number of droplets was significantly reduced with the new FAD.

Influence of N concentration on structure and properties of (AlCrMoTiV)Nx films by co-filter cathodic vacuum arc deposition

A novel four-arc co-filter cathodic vacuum arc deposition technique which was optimized was introduced to deposit (AlCrMoTiV)Nx high-entropy alloy nitride films that were corrosion-resistant, high hardness and adhesion. The effect of nitrogen on the microstructure, corrosion resistance and mechanical properties of films was systematically investigated. As the N2 gas flow rate continues to increase, the phase structure of the (AlCrMoTiV)Nx films transforms from a body-centred cubic structure to an amorphous structure, and then to a nanocomposite structure with nano- crystallites embedded in the amorphous matrix. The hardness of the films is proportional to the ratio of N2:Ar and reaches maximum (34.08 GPa) at a ratio of 7:4. The adhesion of deposited films was higher than 20 N owing to the bombardment of the substrate by energetic ion beams during the deposition of coatings. The enhanced hardness at higher N contents is mainly gives rise to the combined effect of formation of strong metal‑nitrogen bonding, solid solution strengthening, the formation of the nanocomposite structure and ion beam assisted bombardment strengthening. Furthermore, the excellent corrosion resistance can be obtained by the (AlCrMoTiV)Nx films.

Structure and Properties of CrN/TiN Multi-Layer Coatings Obtained by Vacuum-Arc Plasma-Assisted Deposition Method

The paper presents the study results of CrN/TiN multi-layer coatings, as well as single-layer TiN and CrN coatings on Cr12MoV cold work die steel deposited by the vacuum-arc plasma-assisted method. Three CrN/TiN coatings of 8-, 16-, and 32-layers were deposited, in which the thickness of each layer was 500 nm, 250 nm and 125 nm, respectively. All of the coatings reveal a face-centered cubic structure with highly oriented (111) growth. The hardness of the CrN/TiN multi-layer coatings was about 27 GPa. Changing the architecture of CrN/TiN multi-layer coatings by reducing the thickness of the CrN and TiN layers from 500 nm to 125 nm promotes a smooth decrease in both the wear parameter and the coefficient of friction. By using an X-ray phase analysis with synchrotron radiation, it was found that 32-layer CrN/TiN coating retained thermal stability during heating in air to a temperature of 1120–1125 °C, and in a vacuum at least to a temperature of 1200 °C.

Effect of the thickness on electrical resistance of thin diamond-like carbon coatings on silicon substrate

The relationship between sp2/sp3-hybridizations ratio of atomic bonds in diamond-like carbon ( DLC --- Diamond-Like Carbon) and its electrical resistivity for coatings with a thickness in the range 22-70 nm prepared by vacuum arc deposition on silicon substrate of the KDB-8 brand has been established. It is established, that an increase in the coating thickness from 22 to 70 nm is accompanied by a decrease in the specific transverse electrical resistance of samples from 17 to 2 GΩ·m. This effect is explained by an increase in the proportion of carbon atoms with sp2-hybridization of electronic orbitals from 86 to 91%, which leads to the appearance of an additional number of π-bonds. A mathematical model, describing the spatial distribution of current when measuring transverse I-V characteristic, has been developed. The results obtained will be useful in creating resistive layers on the electrodes of gas-discharge detectors of charged particle to limit the amount of current in the event of rare spark discharges inside them caused by the registration of random highly ionizing particles. Keywords: ( DLC), electrical properties of thin films, hybridization of electronic orbitals, Raman scattering, I-V characteristic.

Влияние толщины на удельное электросопротивление тонких покрытий из алмазоподобного углерода на кремнии

The relationship between sp^2/sp^3 hybridizations ratio of atomic bonds in diamond-like carbon (DLC) and its electrical resistivity for coatings with a thickness in the range 22-70 nm prepared by vacuum arc deposition on silicon substrate of the SHB-8 brand has been established. It is established, that an increase in the coating thickness from 22 to 70 nm is accompanied by a decrease in the specific transverse electrical resistance of samples from 17 to 2 GOhm·m. This effect is explained by an increase in the proportion of carbon atoms with sp^2 hybridization of electronic orbitals from 86 to 91%, which leads to the appearance of an additional number of π-bonds. A mathematical model, describing the spatial distribution of current when measuring transverse I-V characteristic, has been developed. The results obtained will be useful in creating resistive layers on the electrodes of gas-discharge detectors of charged particle to limit the amount of current in the event of rare spark discharges inside them caused by the registration of random highly ionizing particles.

Исследование фазовых превращений в двухслойном жаростойком покрытии Ti–Al–C+Y–Al–O на жаропрочном никелевом сплаве

Currently, an active increase in requirements for fuel efficiency and specific gravity of aircraft turbojet engines is observed. Existing coatings based on zirconium dioxide intended for protecting engine parts are largely outdated and have exhausted their development potential, so new ceramic systems for the production of protective coatings based on them are an area of research. The authors carried out a study of a heat-resistant two-layer coating based on the Y–Al–O system (outer layer) and the Ti2AlC MAX phase of the Ti–Al–C system (sublayer) produced using vacuum-arc deposition on the Inconel 738 heat-resistant nickel alloy and molybdenum by alternate deposition of layers based on Ti–Al–C and a Y–Al–O layer. Using synchrotron radiation, phase transformations in the coating were examined when samples were heated to 1400 °C in a vacuum and to 1100 °C in the atmosphere to study the process of oxidation and coating formation in the presence of oxygen. Using scanning electron microscopy, the authors studied the microstructure and chemical composition of the coating. The study identified that heating the coating in a vacuum and in the atmosphere causes various phase transformations in it, but in both cases, the formation of a mixture of oxides of the Y–Al–O group and destabilization of the Ti–Al–C-based sublayer are observed. After heating the coating in the atmosphere without preliminary heat treatment, the coating was destroyed upon cooling, which was not observed when the coating was heated in a vacuum.

Влияние режимов нанесения покрытий на основе системы MAX-фазы Ti-Al-C методом вакуумно-дугового осаждения на структуру и фазовый состав

The paper presents the results of studies of the phase and chemical composition and structure of coatings based on the MAC phase system Ti2AlC, obtained under different technological regimes, by means of X-ray diffractometer and synchrotron radiation source imaging. The coating based on the MAX phase of the Ti-Al-C system was deposited on samples made of molyb-denum andintermetallic γ-TiAl alloy Ti-43.5Al-4Nb-1Mo-0.1B by vacuum-arc deposition from two single-component cathodes made of titanium and aluminum in acetylene reaction gas. The results of the phase composition study showed that the formationof Ti2AlC and TiAl2phases depends on the composition of the gas mixture and the values of the arc evaporator current. Synchro-tron radiation was used to study phase transformations in the coating when the sample was heated to 1400 °C in vacuum. Heat resistance tests of the coatings were carried out, which showed gradual destruction of the protective coating after 500 hours of exposure at a temperature of 850 °C

Infrared sensitive mixed phase of V7O16 and V2O5 thin-films.

We report an infrared (IR) sensitive mixed phase of V7O16 and V2O5 thin films, grown by cathodic vacuum arc-deposition on glass substrates at relatively low temperatures. We have found that the mixed phase of V7O16 and V2O5 can be stabilized by post-annealing of amorphous VxOy between 300-400 °C, which gets fully converted into V2O5 after annealing at higher temperatures ∼450 °C. The local conversion from VxOy to V2O5 has also been demonstrated by applying different laser powers in Raman spectroscopy measurements. The optical transmission of these films increases as the content of V2O5 increases but the electrical conductivity and the optical bandgap decrease. These results are explained by the role of defects (oxygen vacancies) through the photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements. The IR sensitivity of the mixed phase is explained by the plasmonic absorption by the V7O16 degenerate semiconductor.

Corrosion behavior of graphene coated Ti-6Al-4 V alloy by anodic plasma coating method

In this study, graphene layers were deposited onto Ti-6Al-4 V plates by Thermionic Vacuum Arc (TVA) deposition technology to improve the corrosion resistance of biomedical material. For this purpose, the distance from the sample (4 and 7 cm) and duration of coating (5 and 15 mins) parameters were tested. The corrosion performance of the sample was carried out using electrochemical tests in 0.9 wt% NaCl medium. Furthermore, the applied coatings were characterized by using FESEM, AFM, EDS, and FTIR devices. The microstructural findings revealed that the graphene coating was found dispersed in the grain and grain boundaries and was applied successfully to the surface of Ti-6Al-4 V for all applied TVA parameters. In general, the corrosion potential of the coated sample was more anodic when compared to the uncoated sample. The passivation area of the sample TP21 was more prominent, and the corrosion current was lower than in other samples. Furthermore, the polarization resistance was higher, and the corrosion rate was 8 times lower compared to the uncoated sample. Graphene coatings are promising anticorrosion coating materials for Ti-6Al-4 V.

Effect of temperature on the tribocorrosion and high-temperature tribological behaviour of strong amorphization AlCrNiTiV high entropy alloy film in a multifactor environment

Here, we fabricated an AlCrNiTiV high entropy alloy amorphous film (HEAAF) by co-filter cathode vacuum arc deposition (Co-FCVAD). The systematic experiments demonstrate that excellent mechanical properties and a stable dense microstructure are important contributing factors in a friction-corrosion coupling environment, in which the AlCrNiTiV HEAAF oxidized at 600 °C exhibits optimal tribocorrosion resistance with a minimum Δ open circuit potential (ΔOCP), friction coefficient (COF) and wear rate of 0.015, 0.01 and 2.36 × 10−6 mm−3 N−1•m−1, respectively. Through study of the oxidation behaviour, it is found that the diffusion barrier formed in situ by the Al2O3, NiCr2O4 and Cr2O3 composite inner oxide layer after oxidation at 800 °C can effectively impede the outward diffusion of metal ions and inward diffusion of O ions, but the film shows a deterioration in hardness and a loose microstructure, which are the main failure factors under a friction-corrosion coupling environment. Additionally, the AlCrNiTiV HEAAF shows excellent high-temperature tribological performance under a friction-temperature (600 °C) coupling environment with the lowest COF (0.22) and wear rate values (1.1 × 10−5 mm3 N−1•m−1). However, a brittle oxide film composed of rutile TiO2 on the worn track is found to be responsible for the weak high-temperature tribological performance under a friction-temperature (800 °C) coupling environment.

Pulsed Vacuum Arc Deposition of Nitrogen-Doped Diamond-like Coatings for Long-Term Hydrophilicity of Electrospun Poly(ε-caprolactone) Scaffolds.

The surface hydrophobicity of poly(ε-caprolactone) electrospun scaffolds prevents their interactions with cells and tissue integration. Although plasma treatment of scaffolds enhances their hydrophilicity, this effect is temporary, and the hydrophobicity of the scaffolds is restored in about 30 days. In this communication, we report a method for hydrophilization of poly(ε-caprolactone) electrospun scaffolds for more than 6 months. To that end, diamond-like coating was deposited on the surface of the scaffolds in a nitrogen atmosphere using pulsed vacuum arc deposition with sputtering of graphite target. This approach allows for a single-side hydrophilization of the scaffold (water contact angle of 22 ± 3° vs. 126 ± 2° for pristine PCL scaffold) and preserves its structure. With increased nitrogen pressure in the chamber, sp3-hybridized carbon content decreased twice (sp2/sp3 ratio decreased from 1.06 to 0.52), which demonstrates the possibility of tailoring the content of carbon in sp2 and sp3 hybridization state. Nitrogen content in the deposited coatings was found at 16.1 ± 0.9 at.%. In vitro tests with fibroblast cell culture did not reveal any cytotoxic compounds in sample extracts.

Robust ferromagnetism of (Co, Er) co-implanted ZnO-based diluted magnetic semiconductor

The present study reports room temperature ferromagnetism observed in Co implanted, Er implanted and (Co, Er) co-implanted ZnO films deposited by filtered cathode vacuum arc (FCVA) on sapphire substrates. The microstructures, surface morphologies, electrical and magnetic properties of pure and implanted ZnO films were investigated. X-ray diffraction results confirm that the implantation of Co and Er ions cause the substitution of Zn ions without the formation of secondary phases. The results of X-ray photoelectron spectroscopy indicate that the Er ions and Co ions are in trivalent and divalent states, respectively. After ions implantation, the electrical properties of the films are improved and the carrier concentration of Er implanted ZnO film is higher than that of Co implanted ZnO film. Substantial intrinsic ferromagnetism has been observed for all the implanted ZnO films. The saturation magnetization for the Er implanted ZnO film is higher than that of the Co implanted ZnO film and the magnetization is further enhanced by (Co, Er) co-implanting. The carrier mediated exchange mechanism can well describe the origin of ferromagnetism in the doped ZnO films. Our results can provide a reference for preparing high-quality diluted magnetic semiconductors (DMSs) by RE elements and TM elements co-doping in ZnO films. The saturation magnetization for the Er implanted ZnO film is higher than that of the Co implanted ZnO film and the magnetization is further enhanced by (Co, Er) co-implanting. • A filtered cathode vacuum arc (FCVA) deposition system was used to grow ZnO films on sapphire substrates. • The saturation magnetization for the Er implanted ZnO film is higher than that of Co implanted ZnO. • The magnetization is enhanced by Co-Er co-doping compared with Co doped and Er doped film. • The magnetization shows carrier concentration-dependent behavior.

Optical and surface properties of Gd-doped ZnO thin films deposited by thermionic vacuum arc deposition technology

In this paper, Zinc oxide (ZnO) was doped with Gadolinium (Gd) and it was deposited onto the glass and silicon substrates by thermionic vacuum arc (TVA) method to examine its morphological, compositional, and optical properties. The results show that the substrates strongly affect the morphological structures of the thin films. According to the obtained information, the surface roughness was found to be 38 nm and 6 nm for silicon and glass respectively. The images showed that the surface onto the glass had more symmetry and more regular grains. The optical properties of the nano composite on the glass substrate were analyzed with an optical interferometer and UV–Vis spectrophotometer. Absorbance, transparency, and refractive index of the thin film were obtained. It also had a relatively high refractive index. Furthermore, it was found that the band gap of ZnO decreased. The band gap of the deposited thin film was found 3.3 eV.