Vacuum Arc Deposition Research Articles

ESTIMATION OF LOCAL INHOMOGENEITY OF MULTILAYER NANOSTRUCTURED ZrN/ZrO2 COATING

Multilayer nanostructured ZrN/ZrO2 coatings were applied to increase the operational resistance of various machinery parts by using vacuum-arc deposition in Bulat-type facility. To describe the structure formation, a new approach based on optical-mathematical method for processing metallographic images is proposed. The structure formation of the multilayer coating with an assessment of the degree of its inhomogeneity and diffusion processes between the layers is studied. For a reliable assessment, the changes in the horizontal and vertical directions of the images with the choice of optimal intervals were comparatively analyzed. It has been found that the most stable results are achieved using 20 and 25 dots (pixels).

Tailoring Crystalline Structure of Titanium Oxide Films for Optical Applications Using Non-Biased Filtered Cathodic Vacuum Arc Deposition at Room Temperature

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 (pO2), 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 TiOx 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.

Effects of silicon doping on low-friction and high-hardness diamond-like carbon coating via filtered cathodic vacuum arc deposition

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.

Tribological properties of multilayer tetrahedral amorphous carbon coatings deposited by filtered cathodic vacuum arc deposition

Tetrahedral amorphous carbon (ta-C) has emerged as an excellent coating material for improving the reliability of application components under high normal loads. Herein, we present the results of our investigations regarding the mechanical and tribological properties of a 2-µm-thick multilayer ta-C coating on high-speed steel substrates. Multilayers composed of alternating soft and hard layers are fabricated using filtered a cathodic vacuum arc with alternating substrate bias voltages (0 and 100 V or 0 and 150 V). The thickness ratio is discovered to be 1:3 for the sp2-rich and sp3-rich layers. The results show that the hardness and elastic modulus of the multilayer ta-C coatings increase with the sp3 content of the hard layer. The hardness reached approximately 37 GPa, whereas an improved toughness and a higher adhesion strength (> 29 N) are obtained. The friction performance (µ = 0.07) of the multilayer coating is similar to that of the single layer ta-C thick coating, but the wear rate (0.13 × 10−6 mm3/(N·m)) improved under a high load of 30 N. We further demonstrate the importance of the multilayer structure in suppressing crack propagation and increasing the resistance to plastic deformation (H3/E2) ratio.

Low-inertia method of control over nitrogen concentration in the PVD nitride coatings by non-self-sustained arc discharge with thermionic and hollow cathodes

Using the probe technique, a comparative analysis of parameters of the gas-metal plasma generated by low-pressure discharges is performed during variation of their main characteristics. It is shown that by varying the discharge current of the gas plasma source it is possible to readily change the fraction of gas ions in the gas-metal plasma generated by the arc evaporator and the gas plasma source with thermionic and hollow cathodes. In the case of nitride coatings, it is found out that the concentration of nitrogen in the coatings formed by the vacuum-arc plasma-assisted deposition increases, without any changes in the nitrogen working pressure. Using the coatings based on the Mo–N and Ti–N systems as examples, a twofold increase in the nitrogen concentration is shown as the ion current density of the gas plasma source increases by a factor of three in comparison with the modes without using this source. The method discussed in this study exhibits lower inertia compared to the traditional gas pressure variation.

Investigation of the structural, magnetic, and cooling performance of AlFe thin film and AlFeGd nanometric giant magnetocaloric thin films

Giant magnetocaloric thin films are promising materials for new generation energy-efficient cooling systems. To investigate the cooling performance of AlFe and AlFeGd alloys, thin films have been deposited onto a glass substrate by thermionic vacuum arc (TVA) deposition system. TVA is a physical vapor deposition technology; it works in high vacuum and low-temperature conditions. AlFe and AlFeGd thin films are of significant importance for giant magnetocaloric materials. The surface and magnetic properties of a magnetic material are strongly dependent on the deposition process. In this paper, the structural, magnetic, and cooling performances of AlFe alloys with and without the Gd element have been investigated. When the Gd elements are added to AlFe alloys, the size of crystallite and the surface morphology of the giant nanometric magnetocaloric thin films are altered. The size of crystallite decreases to a lower value due to the Gd element added. According to the results of the elemental analysis, the elemental ratios of the AlFe and AlFeGd thin films were measured as (87:13) and (84:4:12), respectively, which are different from the ones reported previously. Magnetic cooling performance and magnetization strongly depend on these ratios. The mean values of crystallite size for the AlFe thin film and AlFeGd nanometric giant magnetocaloric thin film were measured as 50 nm and 12 nm, respectively. Following the Curie temperature of AlFeGd thin film, and the temperature difference it produces in the studied magnetic fields, 60 successive units of this material are assumed to form a magnetic refrigeration cycle. The coefficient of performance of this cycle is calculated to be 2.084—nearly two times better than the suggested cascade vapor-compression cycles in the same temperature range. This fact alongside the solid-state and environmentally friendly attributes of magnetic refrigeration cycles makes the AlFeGd thin films a strong candidate for accomplishing an efficient refrigeration system.

Multi-phase ion-plasma Cu-Ti coatings deposited on copper and copper beryllium alloy

The paper presents outcomes of vacuum-arc plasma-assisted deposition of titanium, titanium nitride and copper on copper (C11000) and the hardened copper beryllium alloy (C17200) at a temperature of 320÷k330°C. The study has revealed that multi-phase coatings form when varying discharge currents generated by arc evaporators and supply sequences of producer gas (argon) and nitrogen. An X-ray phase analysis has demonstrated these coatings to consist of copper, titanium and CuTi, CuTi2 and TiN compounds. Another important outcome to emerge from the study is that ion-plasma processing results in ageing of copper beryllium alloy and furthers the formation of CuBe particles. The microhardness of Cu-Ti coatings is as high as 400÷540 HV0.02 provided that the elements are vacuum-arc deposited at a temperature of 320÷k330°C. The microhardness of a nitrogenized Cu-TiN surface layer is measured to be 760 HV0.05. The thickness of deposited coatings is within several micrometers, so the measured hardness hardly complies with the real characteristic of coatings because the indenter breaks a thin hard layer. In addition, vacuum-arc sputtering of titanium and copper cause metal drops on the surface, as a consequence, the hardness of coatings is below referential values.

Synthesis of Diamond-like Carbon as a Dielectric Platform for Graphene Field Effect Transistors

The platform for supporting two-dimensional (2D) materials such as graphene has a critical influence on the electronic properties of the materials it supports. Here we report on the filtered cathodic vacuum arc deposition (FCVAD) of atomically flat diamond-like carbon (DLC) films with varied C sp3/sp2 content ratio by modulating the parameters of substrate bias voltage, then used as a dielectric platform for supporting graphene. By doing this, an all-carbon DLC–graphene heterostructure would be formed. Through characterizing this heterostructure and constructing graphene field effect transistors (FETs) on DLC, it was shown that graphene on DLC platforms had less doping from the substrate and improved FET carrier mobility compared with that of graphene on SiO2/Si substrate. Moreover, the graphene on different DLC platforms exhibited an increased FET mobility (up to ∼7032 and 5558 cm–2 V–1 s–1 for hole and electron, respectively) with the increase of C sp3/sp2 bond fraction in DLC which could be tuned by the negative bias voltage applied to the deposited substrates in the FCVAD synthesis of DLC here.

Effect of C Doping on Structure and Properties of TiAlCrN Coatings by Filter Cathode Vacuum Arc Deposition

Effect of C Doping on Structure and Properties of TiAlCrN Coatings by Filter Cathode Vacuum Arc Deposition

FUNCTIONAL PROTECTIVE ZrN COATINGS ON IMPLANTS FOR TRAUMA SURGERY

The nano-crystalline films of zirconium nitride have been synthesized on implants for trauma surgery made of AISI 316 L stainles steel by using vacuum-arc deposition under RF-biasing mode in “Bulat” type device. Structure examinations – X-ray diffraction analysis (XRD), X-ray fluoriscent analysis (XRF), scanning electron microscopy (SEM) with microanalysis (EDX), nanoidentation method – were performed to study phase and chemical composition, surface morphology, microstructure and nanohardness of ZrN coatings. The corrosion resistance of coatings has been tested in 0.9 % quasiphysiological NaCl solution.

Change in the Structure and Corrosion Resistance of a Nickel-Chrome Coating on Stainless Steel During Implantation of High Energy Al+ and B+ Ions

Magnetron sputtering, vacuum arc deposition, and ion implantation have been used to create a three-layer anti-corrosive coating structure on stainless steel samples. The microstructure of the coating was analyzed using scanning and transmission electron microscopy. The chemical composition and concentration profile of the coating were determined using X-ray microanalysis. The structural-phase state of the coatings was studied using X-ray diffraction and electron diffraction analysis. The roughness of the experimental samples was determined using contact profilometry. The microhardness of the substrate and coating was determined using sclerometry. The salt spray corrosion tests and analysis of polarization curve have shown a significant increase in the corrosion resistance of stainless steel after deposition of a Ni/Cr/Al+B+ protective coating.

Simulation of Magnetic-Field-Induced Ion Motion in Vacuum Arc Deposition for Inner Surfaces of Tubular Workpiece

A simulation of magnetic-field-induced ion motion in vacuum arc deposition for the inner surfaces of a tubular workpiece was performed. An auxiliary magnetic field was set to guide the motion of ions inside a pipe, with different magnetic flux densities and ion emission parameters. The results showed the trajectories, deposition ratio and depth of the ions can be controlled via a magnetic field. Within a certain range, the deposition ratio of the ions increases with magnetic flux density. When the magnetic flux density reached a certain value, both the trajectories and deposition ratio of the ions exhibited an obvious periodicity. The depth at which the ions were deposited decreased as an exponential function of the magnetic flux density and ion emission radius, respectively. With an increase in the emission angle, the deposition depth decreased linearly. A numerical model was proposed to express the distribution of the deposition depth. In addition, the deposition ratio and depth are improved with a magnetic field in an environment with a certain density of neutral gas.

Improvement of the performance properties of cutting tools using the multilayer composite wear-resistant coatings based on nitrides of Cr, Mo, Zr, Nb, and Al

The article deals with the properties of the Cr,Mo-(Cr,Mo)N-(Cr,Mo,Al)N, Zr,Nb-(Zr,Nb)N-(Zr,Nb,Al)N, and Zr,Nb-(Zr,Nb)N-(Cr,Mo,Zr,Nb,Al)N multilayer composite wear-resistant coatings. The coatings were deposited using technology of Filtered Cathodic Vacuum Arc Deposition (FCVAD). The investigation of the coating structures, conducted using the transmission electron microscopy (TEM), showed the presence of the nanolayer structure with the nanolayer thicknesses within a range of 0.5–20 nm and the period λ within a range of 92–136 nm. The microhardness of the Zr,Nb-(Zr,Nb)N-(Cr,Mo,Zr,Nb,Al)N coating turned out to be significantly higher than the microhardness of the other studied coatings, and that may be associated with the formation of a multicomponent fcc phase of (Cr,Mo,Zr,Nb,Al)N. According to the results of the cutting tests during the turning of American Iron and Steel Institute (AISI) 420 steel, the tool with the Zr,Nb-(Zr,Nb)N-(Cr,Mo,Zr,Nb,Al)N coating demonstrated the tool life which 2.5 times exceeds the tool life of the tool with the (Ti,Al)N commercial coating of similar thickness and by 50 and 30% exceeds the tool life of tools with two other studied coatings. The investigation of the fracture processes in coatings during the turning revealed a significant difference in the mechanisms of cracking and wear.

Effect of TiN/Ti coating combined with laser shock peening pre-treatment on the fatigue strength of Ti-6Al-4V titanium alloy

The multilayer gradient TiN/Ti coating was deposited by using filtered cathodic vacuum arc (FCVA) deposition method. The laser shock peening (LSP) process was carried out before deposition. The surface morphology, mechanical properties were measured by atomic force microscope (AFM), nanoindentation and scratch tester. The fatigue strength was investigated on a vibration test platform and the fracture morphologies were observed by scanning electron microscope (SEM). The results showed that the compound process has little negative influence on the roughness. A hardened layer with high hardness and compressive residual stress was formed by the LSP pre-treatment. This layer can also suppress plastic deformation, making the adhesion strength between the coating and substrate increased from 54.9 N to 79.1 N. The TiN/Ti coating and the compound process improve the fatigue strength of TC4 alloy by 58.1% and 98.8%, respectively. The coating can restrain crack initiation on the surface and slow its propagation. The crack initiation location of the compound process sample moved into the deeper site and the improved adhesion strength further reduces the crack propagation rate. Thus, the compound process of TiN/Ti coating combined with laser shock peening pre-treatment greatly improves the fatigue strength of TC4 alloy.

Synthesis of smooth low friction graphitic nanoparticle film by vacuum arc deposition

Formation of smooth low friction carbon onion nanoparticle film was carried out using vacuum arc deposition. Carbon onions were synthesized by the arc discharge of carbon rod as a cathode and deposited directly onto the substrate in a vacuum. The process of carbon onion synthesis and nanoparticle film growth was investigated using transmission electron microscopy (TEM), atomic force microscopy (AFM), and quadrupole mass spectrometer (QMS). It was observed that isolated carbon onions were successfully synthesized by pulsed arc discharge of the carbon rod as a cathode under relatively low pressure of 10−7 Pa. The synthesized isolated carbon onions around the cathode were in flight in vacuum and deposited onto the substrate. A smooth carbon onion nanoparticle film with surface roughness (Ra) of 0.37 nm was gradually formed on a graphite substrate by 100 pulse shots of the arc discharge. A smooth nanoparticle film was achieved due to the mixture of the deposition of carbon onions and amorphous carbon in this process, where amorphous carbons were filled between carbon onions interparticle. AFM friction measurements in the vacuum revealed that the synthesized nanoparticle film possessed lower friction coefficient than graphite, which was attributed to the low adhesive force and smooth surface roughness of the carbon onion nanoparticle film.

Micro-mechanical investigation of (Al50Ti50)N coatings enhanced by ZrN layers in the nanolaminate architecture

A series of nanolaminate (Al50Ti50)N/ZrN coatings with different modulation period (λ) and bias voltage were synthesized by vacuum arc deposition (VA-PVD). The composition, evolution of the microstructure, and mechanical properties were studied during the transition from the basic monolayer (Al50Ti50)N coating to the nanolaminate architecture with a stepwise decrease in the modulation period. XRD and HR-TEM results showed that the binary layer in (Al50Ti50)N/ZrN nanolaminates composed of fcc-(Ti, Al)N phase with the (1 1 1) preferred orientation of crystallite. The isostructurality of fcc-(Ti, Al)N and B1-ZrN lattices contributed local epitaxial grain growth in multilayer nanolaminate. ZrN layers, as the second component of the bilayer, had a highly textured structure with a predominant texture axis (1 1 1). The maximum values of nanohardness of 26.5 GPa and elastic modulus of 287.3 GPa were obtained for the sample with the lowest modulation period of about 15 nm. According to the results of chemical analysis by XPS, we established the oxidized state of all elements of the metal component of the surface layer, such as ZrO, TiON, ZrNO, and the presence of TiN, TiNx, ZrN nitride compounds.

Hard and wear-resistant niobium, molybdenum carbide layered coatings on WC-Co tools produced by ion bombardment and cathodic vacuum arc deposition

Phase and element composition, microhardness, adhesive strength, wear resistance and microstructure of the coatings and underlying layers formed on WC-Co hard alloy using Nb and Mo vacuum-arc sources were studied. It is shown that the influence of ion beams with energy of 1 keV created by Nb and Mo vacuum-arc sources for at least 1–2 min allows the formation of carbide coatings based on embedded metals and alloy elements with (Nb,W)C0.7, Mo2C and Co6W6C2 phases. The synthesis of carbide layers occurred by ion exposure by Nb or Mo at a surface temperature of the hard alloy of at least 1300 °C, controlled by an optical thermograph. Reducing of Nb and Mo ion exposure time down to 30 s does not allow heating of samples surface to temperatures above 700 °C, as a result, the formation of carbide layers on the alloy surface does not occur. The plasma deposition of NbC or MoC coatings on sublayers created by preliminary Nb or Mo ion treatment accompanied by heating of the sample surface up to 1300°С forms carbide layered system with hardness of 60 GPa, adhesive strength of 120–140 N and 2–3-fold lower volume wear compared to NbC and MoC plasma coatings deposited on a hard alloy without preliminary treatment.

STRUCTURE AND PROPERTIES OF COATINGS BASED ON FeCrAl AND Cr18Ni10T

The process of vacuum-arc deposition of protective coatings from multicomponent FeCrAl cathodes and 18Cr10NiT stainless steel onto fragments of Zr1Nb alloy claddings has been developed. The influence of the reaction atmosphere (vacuum, nitrogen, oxygen) during the deposition of coatings on their structure, mechanical and corrosion properties is investigated. Coatings deposited in vacuum from the Cr18Ni10T cathode have the best set of mechanical properties and corrosion resistance; whereas coatings based on FeCrAl require composition optimization. It has been established that coatings deposited from FeCrAl and stainless steel cathodes with a thickness of 20 μm significantly increase oxidation resistance and prevent the destruction of fuel cladding under exposure to air at 1150 °C for 1 h.

Two-dimensional BN-doped ZnO thin-film deposition by a thermionic vacuum arc system

Graphene is an interesting two-dimensional dopant for the electronic, electrochemical, and optoelectronic devices due to its high electron mobility, high electrical, and thermal conductivity, and high optical transparency. Another graphene-like material is boron nitride (BN). h-BN shares similar lattice structure with graphene and many physical properties except large bandgap. In this study, optical, morphological, and structural properties of the two-dimensional BN-doped ZnO thin films have been investigated with various techniques such as UV–Vis spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. Two-dimensional BN-doped ZnO thin films were produced onto glass, indium tin oxide-coated glass, and fluorine tin oxide-coated glass using by a Thermionic Vacuum Arc (TVA) deposition technique. The results show that the substrate effect causes the different growth mechanisms for the two-dimensional BN-doped ZnO thin films. It is found that bandgap of ZnO changed drastically and bandgaps of the deposited thin films were found to be 3.96 eV, 3.97 eV, 4.05 eV for two-dimensional BN-doped ZnO thin films deposited onto glass, ITO-coated glass, and FTO-coated glass substrates, respectively. According to the Raman spectra, BN crystal orientations are in hexagonal form in ZnO crystal.

Effect of defects on wear behavior in ta-C coating prepared by filtered cathodic vacuum arc deposition

This study examined the tribological behavior of a ta-C coating fabricated at a substrate bias of −100 V via filtered cathodic vacuum arc (FCVA) deposition. Defects in the ta-C coating were categorized as droplets, pores, and spikes, considering the morphological, structural, and mechanical properties of the ta-C surface. A friction test was conducted at 170 °C in ambient air using a ball-on-disk tribometer. The friction coefficient was 0.08 during the steady state and the wear rate was 4.3 × 10−6 mm3/Nm. To explain the friction and wear behavior, the morphological and structural properties of the defects in the designated area were compared among different sliding cycles.