Cathodic Vacuum Arc Deposition Research Articles

Tuning the plasmonic resonance in TiN refractory metal

Plasmonic coatings can absorb electromagnetic radiation from visible to far-infrared spectrum for the better performance of solar panels and energy saving smart windows. For these applications, it is important for these coatings to be as thin as possible and grown at lower temperatures on arbitrary substrates like glass, silicon, or flexible polymers. Here, we tune and investigate the plasmonic resonance of titanium nitride thin films in lower thicknesses regime varying from ~ 20 to 60 nm. High-quality crystalline thin films of route-mean-square roughness less than ~ 0.5 nm were grown on a glass substrate at temperature of ~ 200 °C with bias voltage of − 60 V using cathodic vacuum arc deposition. A local surface-enhanced-plasmonic-resonance was observed between 400 and 500 nm, which further shows a blueshift in plasmonic frequency in thicker films due to the increase in the carrier mobility. These results were combined with finite-difference-time-domain numerical analysis to understand the role of thicknesses and stoichiometry on the broadening of electromagnetic absorption.

The Influence of Nitrogen Partial Pressure on the Microstructure and Mechanical Properties of HfNbTaTiVZr High-Entropy Nitride Coating Deposited via Direct Current Cathodic Vacuum Arc Deposition

In recent years, high-entropy alloys have attracted increasing scientific interest. Due to their promising combination of properties, such as high hardness and high temperature stability, they are attractive for use as tool coatings for machining applications, to give but one example. Previous studies often focused on layer deposition using magnetron sputtering. Comparatively little research has been carried out to date on coating deposition using direct current cathodic vacuum arc deposition (CAE), with higher achievable rates and almost completely ionized plasmas. The aim of this work is to investigate (HfNbTaTiZr)N-coatings produced by CAE. The nitrogen content was varied and the effects on the coating properties were investigated. Changing the N2/(N2 + Ar) ratio between 0.1 and 1.0 and varying the working pressure in the chamber from 2 Pa to 5 Pa resulted in variations of the nitrogen content of the coatings, ranging from 30 at% to 50 at%. Although different microstructures of the coatings were obtained, there was only a minor influence on the hardness and Young’s modulus.

Effects of Al and Si elements on oxidation behavior in 1000–1200 °C steam for PEO/CrAlSi composite coating on Zr alloy

A PEO/CrAlSi composite coating of ~10 μm thick on Zr–2 alloy was prepared by duplex plasma electrolytic oxidation (PEO) and filtered cathode vacuum arc deposition (FCVAD) techniques. The high temperature steam oxidation behavior of bare and PEO/CrAlSi–coated Zr alloys was performed in 1000–1200 °C. Their morphologies, microstructures, compositions and phase components were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X–ray diffraction (XRD) and glow discharge optical emission spectrometer (GDOES). The effects of Al and Si elements on multilayers microstructure evolution of coated Zr–2 alloy at steam atmosphere were discussed. It was found that the composite coating significantly improved the high–temperature steam oxidation resistance of Zr–2 alloy. The mass gains of the PEO/CrAlSi–coated Zr–2 alloy after 3600 s exposure in 1000 °C, 1100 °C and 1200 °C steam were 28 %, 29 % and 44 % of the bare alloy. Through the oxidations, Al diffused both inward and outward to the substrate and the surface regions, respectively. Formation of a top oxide layer (Al2O3, Cr2O3) greatly suppressed the inward oxygen diffusion. The Si enrichment in the PEO interlayer formed a Zr2Si layer, which inhibited the Cr-Zr interdiffusion at 1000 °C and 1100 °C. At 1200 °C, the Zr2Si layer was oxidized and the CrZr2 phase was formed in the Zr alloy substrate especially at the β–Zr/α–Zr(O) interface.

Development of Ti/Ti-DLC multilayers on magnesium alloys. Part 1: Microstructure and mechanical properties

To improve both the corrosion resistance and wear resistance of magnesium alloys, titanium-diamond-like carbon (Ti-DLC) monolayer and Ti/Ti-DLC multilayer films with two periods were applied to AZ31 magnesium alloys through filter cathodic vacuum arc deposition technology. The Ti-DLC monolayer film exhibited an amorphous structure doped with TiC nanocrystals. After introducing the Ti sublayer, the Ti/Ti-DLC multilayer films exhibited a layered structure, resulting in improved adhesion strength and fracture toughness and lower hardness. Compared with the (Ti/Ti-DLC)4 multilayer film with a smaller period, the (Ti/Ti-DLC)2 multilayer film with a lager period exhibited better adhesion strength, higher fracture toughness, hardness, ID/IG ratio, and lower residual stress owing to its thicker Ti sublayers.

Development of Ti/Ti-DLC multilayers on magnesium alloys — Part 2: Corrosion and wear resistance

To improve corrosion and wear resistance of magnesium alloy, the Ti-DLC monolayer and Ti/Ti-DLC multilayer films were deposited on AZ31 magnesium alloys by filter cathodic vacuum arc deposition technology. All coatings showed good corrosion and wear resistance, and low friction coefficient. The corrosion resistance of the coated samples, from high to low, was Ti/Ti-DLC)2 multi coated-, Ti-DLC mono coated-, and Ti/Ti-DLC)4 multi coated samples. That is because the good toughness and film/substrate deformation coordination of multilayer films were beneficial for improving the corrosion resistance of coating, but the thinner Ti sublayer increased the risk of corrosion liquid penetrating the coating. Under friction test under 5 N load for 30 min, the Ti-DLC monolayer film showed best wear resistance with lowest wear rate as its combination effects of high hardness and good toughness. Whereas, under higher load, the higher toughness and film/substrate deformation coordination of multilayer films played a more positive role in its wear life. Under load of 10 N, comparing to the Ti-DLC monolayer film, the (Ti/Ti-DLC)4 multi and (Ti/Ti-DLC)2 multi films improved wear life by 15 % and 36 %, respectively. The (Ti/Ti-DLC)2 multi film had the best corrosion resistance and wear life.

Performance of amorphization AlCrTiZrMo high entropy alloy barrier for copper metallization

A reliable ultra-thin diffusion barrier is required for Cu interconnection. High entropy alloy (HEA) films have received attention in the development of diffusion barrier materials due to their remarkable properties. Here, the dense and smooth 17 nm AlCrTiZrMo high entropy alloy amorphous film (HEAAF) is obtained by the cofilter cathode vacuum arc deposition. After annealing at 700 °C for 1 h, no Cu-silicide compounds are formed and the sheet resistance is 0.27 Ω/□, which indicated that AlCrTiZrMo HEAAF has excellent diffusion barrier performance. Such barrier temperature is comparable to some ceramic barriers. The excellent diffusion barrier performance of AlCrTiZrMo HEAAF is due to its good stability of amorphous structure and chemical stability at high temperature.

Cathodic Vacuum ARC Multilayer Coatings (TiZrSiY)N/NbN: Structure and Properties Depending on The Deposition Interval of Alternate Layers

Two series of multilayer coatings with different numbers of bilayers (268 and 536, respectively) were synthesised using the cathodic vacuum-arc deposition (CVAD) with the simultaneous sputtering of two different cathodes. The first cathode was made of the multicomponent TiZrSiY material, and the second one was made of technical niobium. The coatings were condensed in a nitrogen atmosphere at a constant negative bias potential applied to the substrate. The resulting coatings have a distinct periodic structure composed of individual layers of (TiZrSiY)N and NbN with the thicknesses determined by the deposition interval (10 or 20 s, respectively). The total thicknesses of the coatings determined by the number of bilayers were 11 and 9 microns, respectively. The formation of polycrystalline TiN and NbN phases with grain size comparable to the size of the layers has been identified for both series of coatings. The layers exhibit a columnar structure growth with a predominant orientation (111). The hardness of the experimental coatings depends on the thickness of the layers and reaches 39.7 GPa for the coating with the smallest layer thickness. The friction coefficient of the obtained coatings varies from 0.512 to 0.498 and also depends on the thickness of the layers. A relatively large value of the friction coefficient is due to high roughness and the presence of a droplet fraction on the surface as well as in the volume of the coatings.

Controlling adhesion and thermal stability of tetrahedral amorphous carbon coatings with intermediate sp3C fraction

Tetrahedral amorphous carbon (ta-C) coatings with an intermediate sp3C fraction were deposited on single-crystal silicon wafer substrates via intermittent filtered cathode vacuum arc (FCVA) deposition. The ta-C layer thickness and sp3C fraction in the coatings were adjusted using the deposition duration and bias voltage applied to the substrate, respectively. Some of the coated specimens were annealed at 300 and 600 °C for 4 h in a 5-Pa vacuum. The morphologies and microstructures of the specimens were characterized using scanning electron microscopy and transmission electron microscopy. The hybridization of carbon atoms was analyzed using X-ray photoelectron spectroscopy and micro-Raman spectroscopy. The mechanical characteristics of the coatings, including the critical adhesion load between the coatings and substrates, residual stress in the coatings, and hardness, were characterized. For the specimens deposited by the same bias voltage, even their top ta-C layer thickness ranged from approximately 500 nm to 1500 nm, their residual compressive stress in the coatings was maintained at a low value by the intermittent deposition of FCVA, which varied slightly with the coating thickness. The adhesion strength was improved by increasing the thickness of the as-deposited coating from approximately 12 to 40 N. The residual compressive stress of the post-annealing specimens with sp3C fraction of 45–53.8 % exhibited monotonously increasing or V-shaped variation with increasing annealing temperature. Herein, the underlying mechanisms are discussed in detail.

Smooth diamond-like carbon films prepared by cathodic vacuum arc deposition with large glancing angles

Diamond-like carbon (DLC) films were prepared by cathodic vacuum arc (CVA) deposition with different glancing angles (the angle between the normal reverse direction of the arc target and the normal direction of the substrate surface) in range of 0 to 135°. The effects of the glancing angle on the morphology, carbon structure, mechanical property and tribological behavior of the DLC films were investigated. The results show that the surface quality of the DLC films is significantly improved by increasing the glancing angle. The macroparticles in the surface as well as the surface roughness of the DLC films decrease sharply as the glancing angle increases. The sp3/sp2 of the DLC films decreases at first and then increases as the glancing angle increases. The normal incidence energy of the Cn+ species becomes suitable to the formation of sp3-C when the glancing angle is 45°. The variation in the film hardness and compress stress at different glancing angles are similar in profile to the sp3 bond fractions. However, the compressive stress of the films could be reduced effectively by avoiding the bombardment of the Cn+ species with excessively high energy through increasing glancing angle. The tribological behaviors of the films could be also improved by changing the glancing angle. It is supposed that the CVA with appropriate glancing angle might be one way to prepare the DLC films with smooth surface, high hardness, low compressive stress and good tribological performance.

Effect of PEO interlayer on oxidation behavior of PEO/Cr composite coating on Zr–1 Nb alloy in 1200 °C steam

The PEO/Cr composite coating on Zr–1 Nb alloy prepared by plasma electrolytic oxidation (PEO) and filtered cathodic vacuum arc deposition (FCVAD) technologies exhibited good oxidation resistance in 1200 °C steam. The PEO interlayer was gradually dissolved by Zr substrate, and M-ZrO2 to Zr3O phase transformation occurred, but it still moderated the inward oxygen diffusion and the inter-diffusion of Cr and Zr to some extent. Moreover, the PEO interlayer suppressed the formation of ZrCr2 in Zr substrate and ZrCr2O5 secondary phases in its steam oxide layer. The PEO layer and steam oxide layer could prevent from hydrogen permeation into the Zr substrate.

High temperature oxidation of CrAl-coated Zr–1 Nb alloy in 1000 – 1300 °C steam

The CrAl coating of 13 µm thick on Zr–1 Nb alloy prepared by filtered cathodic vacuum arc deposition with Cr70Al30 target exhibited excellent steam oxidation resistance below 1200 °C, but its protective properties were obviously weakened at 1300 °C. The mass gain of CrAl-coated alloy was 7.8%, 6.5%, 16.6% and 66.0% of that of bare alloy after 3600 s oxidation at 1000 °C, 1100 °C, 1200 °C and 1300 °C, respectively. The addition of a little Al in CrAl coating was beneficial to further suppress oxygen diffusion into alloy substrate due to the hindering effect of Al2O3 against oxygen atoms.

(AlCrMoTiNi)1-XNX high entropy ceramic with high hardness and toughness prepared by co-filtered cathodic vacuum arc deposition

High entropy ceramic (HEC) coatings have become candidates for new protective coating due to their high strength. However, the hardness - toughness balance of the ceramic coatings is still a difficult problem to solve. The strong nitride forming elements Al, Ti, Cr, Mo, and the non-nitride forming element Ni were selected as the components of the (AlCrMoTiNi)1-XNX HEC coatings to regulate the hardness and toughness. When x = 0 and 0.29, the composite structure of amorphous and metallic Ni phase is observed in these coatings. When x = 0.37, 0.40, and 0.45, the phase structure changes to the composite structure of nanoscale face-centered cubic (FCC) phase, metallic Ni, and amorphous phase. When x = 0.45, the maximum hardness of the HEC coating is 31.25 GPa, and it also has high toughness with a KIC value of 3.25 MPa m1/2. The HEC coating with high hardness and toughness also presents excellent wear resistance and corrosion resistance. Therefore, the (AlCrMoTiNi)0.55N0.45 HEC coating has potential as a protective coating applied in various areas.

Effect of Thermal Shock on Properties of a Strongly Amorphous AlCrTiZrMo High-Entropy Alloy Film.

AlCrTiZrMo high-entropy alloy (HEA) films with strong amorphization were obtained by co-filter cathode vacuum arc deposition, and the effect of thermal shock on the films was investigated in order to explore the protection mechanism of HEA films against mechanical components in extreme service environments. The results show that after annealing at 800 °C for 1 h, the formation of a dense ZrTiO4 composite oxide layer on the surface actively prevents the oxidation from continuing, so that the AlCrTiZrMo HEA film exhibits excellent oxidation resistance at 800 °C in air. In the friction-corrosion coupling environment, the AlCrTiZrMo HEA film annealed at 800 °C for 1 h shows the best tribocorrosion resistance due to the stable dense microstructure and excellent mechanical properties, and its ΔOCP, COF and wear rate possess the smallest values of 0.055, 0.04 and 1.34 × 10-6 mm-3·N-1·m-1.

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.

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.

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.

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.

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.

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.

Crystalline flower-like nickel cobaltite nanosheets coated with amorphous titanium nitride layer as binder-free electrodes for supercapacitor application

Fabrication of high-performance supercapacitors involves a three-step strategy - selection of suitable electrode material, optimized morphology, and efficient synthesis approach. For the first time, an integrated synthesis approach using the facile hydrothermal technique (for growing NiCo2O4 nanosheets) followed by vacuum cathodic arc deposition (for depositing thin TiN layers) is used to improve the electrochemical stability of pristine nickel cobaltite (NiCo2O4). The hierarchical flower-like NiCo2O4@TiN nanosheets grown on nickel foam as binder-free electrode shows a high specific capacity of 402.57 Cg−1 at 1 Ag−1, excellent rate capability of 82.8% when current density increases from 1 Ag−1 to 20 Ag−1, and cycling stability of 90% over 2000 charge-discharge cycles. The remarkable electrochemical performance of NiCo2O4@TiN-220/Ni signifies its ample potential for the fabrication of a supercapacitor device. A coin-cell symmetric supercapacitor (CR2032) is assembled using the NiCo2O4@TiN-220/Ni electrodes, which exhibits remarkable electrochemical performance, including a specific capacitance of 178 Fg−1, an energy density of 46.4 Wh kg−1 at a power density of 1363 W kg−1, and a capacitance retention of 129.4% after running 3500 cycles. The enhanced performance can be attributed to the porous morphology with core/shell flower-like nanosheet structure of NiCo2O4@TiN grown on nickel foam. The study also emphasizes a good tuning of crystalline metal oxide (NiCo2O4) with amorphous metal nitride (TiN) as high performing electrode for supercapacitor application.