Cathodic Arc Process Research Articles

Adhesion, structure, and mechanical properties of Cr HiPIMS and cathodic arc deposited coatings on SiC

Chromium deposited by high-power impulse magnetron sputtering (HIPIMS) versus cathodic arc (CA) processes exhibits very different mechanical properties. Combining the two can result in a single-phase with superior performance that can be tailored for use in coating SiC for advanced nuclear fuel cladding. Coating morphology, residual stress, elemental depth profiles, and mechanical testing by scratch, pull-off adhesion, and microcantilevers are shown for HiPIMS, CA, and combined coatings. CA coatings were likely to spall and had lower adhesion strength due to tensile residual stresses but had desirable material properties. By depositing an initial layer of Cr by HiPIMS followed by a layer of Cr by CA, a more adherent coating was achieved and some of the stress issues with CA morphology were resolved. Combined coatings withstood at least 80 MPa in pull-off adhesion tests and had maximum failure stress values of 5GPa in microcantilever tests. These results were better than either individual deposition method and point to a hybrid approach being a path forward for a more robust coating. • Cr coatings were deposited by HiPIMS and cathodic arc on model SiC substrates. • Properties of both individual and hybrid dual layer coatings were studied. • A hybrid coating benefitted both adhesion and mechanical properties.

Tribological and corrosion Behavior of Duplex Coated AISI 316L using plasma based ion implantation and deposItion

The implementation of a duplex process, which combines plasma nitriding with hard coatings obtained by cathodic arc, on stainless steel substrates has faced adhesion problems that affected the wear and corrosion behavior of the treated surfaces. One variation of the cathodic arc process, which could improve the adhesion, is its combination with plasma ion implantation.This work presents results of the wear and corrosion behavior of duplex TiTiN bilayer coatings obtained by cathodic arc deposition combined with ion implantation (PBII&D) on plasma nitrided AISI 316 L stainless steel. In order to compare the application of PBII&D in duplex processes against conventional cathodic arc deposition, other two types of samples were obtained; one group of samples was coated using the same experimental device with the substrate at floating potential and the other one with a commercial PVD system.The coatings were characterized by SEM, XRD, and nanoindentation. The adhesion was evaluated by the Scratch Test and Rockwell C indentation. The wear resistance was analyzed by the pin-on-disk test and the corrosion behavior was evaluated by means of anodic polarization tests in NaCl solution, as well as by the Salt Spray Fog Test.The PBII&D bilayer coatings showed better adhesion while the commercial PVD TiN coatings presented the smallest wear volume loss, but the delamination inside and around the track evidenced adhesion problems. Corrosion resistance was improved in all coatings benchmarked against nitride substrates, but PBII&D processes offered better protection.

Tetrahedral amorphous carbon prepared filter cathodic vacuum arc for hole transport layers in perovskite solar cells and quantum dots LEDs

ABSTRACT (ta-C) films coated through the filtered cathodic vacuum arc (FCVA) process as a hole transport layer (HTL) for perovskite solar cells (PSCs) and quantum dot light-emitting diodes (QDLEDs). The p-type ta-C film has several remarkable features, including ease of fabrication without the need for thermal annealing, reasonable electrical conductivity, optical transmittance, and a high work function. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy examinations show that the electrical properties (sp3/sp2 hybridized bond) and work function of the ta-C HTL are appropriate for PSCs and QDLEDs. In addition, in order to correlate the performance of the devices, the optical, surface morphological, and structural properties of the FCVA-grown ta-C films with different thicknesses (5 ~ 20 nm) deposited on the ITO anode are investigated in detail. The optimized ta-C film with a thickness of 5 nm deposited on the ITO anode had a sheet resistance of 10.33 Ω−2, a resistivity of 1.34 × 10−4 Ω cm, and an optical transmittance of 88.97%. Compared to the reference PSC with p-NiO HTL, the PSC with 5 nm thick ta-C HTL yielded a higher power conversion efficiency (PCE, 10.53%) due to its improved fill factor. Further, the performance of QDLEDs with 5 nm thick ta-C hole injection layers (HIL) showed better than the performance of QDLEDs with different ta-C thicknesses. It is concluded that ta-C films have the potential to serve as HTL and HIL in next-generation PSCs and QDLEDs.

Fatigue and Mechanical Behavior of Ti-6Al-4V Alloy with CrN and TiN Coating Deposited by Magnetic Filtered Cathodic Vacuum Arc Process

Coatings of 3 μm CrN and TiN were prepared by a magnetic filtered cathodic vacuum arc process (MFCVA) on Ti-6Al-4V substrates, respectively. Rotating bending tests and uniaxial tests were conducted for investigating the effect of the thin and uniformly distributed hard CrN and TiN coatings on the fatigue and mechanical properties of Ti-6Al-4V substrate. During both tests, no coating spallation phenomenon was observed, which indicated that the hard coating bound well with the substrate. The fatigue test results showed that the fatigue strength of the coated sample was decreased in both the low- and high-cycling fatigue regimes compared with the uncoated Ti-6Al-4V substrate. Compared with the TiN coating, the CrN coating caused a more significant reduction on the fatigue property of the uncoated Ti-6Al-4V substrate due to its inferior plastic deformation capacity. Furthermore, the tensile test results showed that the coated sample had a relative higher ultimate strength, yield strength, and lower elongation compared with the uncoated Ti-6Al-4V substrate. This may be due to the fact that the hard coating could suppress the initiation of cracks, and so higher stress was needed for crack initiating. During the crack propagation period, the hard coating cracked at a relative higher velocity, which led to cracking of the ductile substrate and elongation reduction.

Characteristics of CrAlSiN+MoS2 coating deposited by cathodic arc and magnetron sputtering process

The subject of the research was a coating system composed of CrAlSiN film covered by molybdenum disulphide (MoS2)-based lubricant, deposited on X40CrMoV5-1 steel substrate. The CrAlSiN and MoS2 layers were deposited by cathodic ARC and magnetron sputtering technology respectively. HRTEM investigations show a quasi-amorphous structure with small crystallites of MoS2 layer. It was found that the investigated CrAlSiN layer has a compact character with fine crystallites. Basing on the XRD analysis the fcc type of the crystal structure was proposed for this layer. The atomic concentration of the MoS2 and CrAlSiN film was calculated from the XPS measurements. SEM and AES methods analyzed the chemical distribution of the elements inside the layers and at the interfaces. In sliding dry friction conditions, the investigated coating reveals good wear resistance as well as a high adhesion to the substrate material.

Using Physical Vapor Deposition to Optimize Surface Properties

Abstract Thin film cathodic arc PVD coatings offer an easy and economical way to optimize surface properties without changing bulk performance. This article describes a modified cathodic arc process called arc plasma acceleration (APA), which enables production of high density, thin film coatings containing minimal macroparticles.

Cutting performances and wear characteristics of WC inserts coated with TiAlSiN and CrTiAlSiN by filtered cathodic arc in dry face milling of cast iron

The aim of this work was to study the cutting performances and wear characteristics of Co-WC inserts coated with TiAlSiN and CrTiAlSiN by a filtered cathodic arc process in dry face milling of cast iron. Face milling experiments were conducted on turbine cast iron workpieces with TiAlSiN-coated, CrTiAlSiN-coated and uncoated inserts at various cutting speeds and numbers of inserts. The results showed that Ti-based coatings offered substantially better cutting performances for Co-WC inserts and could effectively protect the inserts over longer cutting lengths than uncoated ones. Specifically, the CrTiAlSiN coating offered the best cutting performances with the lowest workpiece surface roughness, the lowest flank wear rate and the longest maximum cutting length of 10 m, which was about 2.5 times as high as that of uncoated one owing to superior hardness relative to yielding and chemical properties. In addition, the workpiece quality in term of surface roughness was found to improve with increasing cutting speed in the range of 140–300 m/min and decreasing number of inserts ranging from 1 to 3. Microstructural analyses suggested that the CrTiAlSiN-coated inserts exhibited wear due to thermal cracking and partial delamination under high temperature ploughing abrasion while the TiAlSiN-coated ones displayed mainly ploughing abrasive flank wear behaviour, which resulted in a substantially lower flank wear rate than uncoated WC inserts that suffered from the combination of direct cutting and ploughing abrasive wear.

Indigenous design and development of the cathodic arc system for the growth of nanocarbon thin Films

Carbon based thin films in its various forms is becoming very attractive for a wide range of applications ranging from simple protective coatings to biocompatible coatings and even conformal coatings. Cathodic arc is emerging as a viable technology for a wide range of applications especially low temperature coating. Presented in this paper is some of the initial results of low temperature nanocarbon thin films and nanocluster carbon (NC) grown using cathodic arc process. The films were deposited on aluminium foil and glass substrates. The process and growth parameters were varied to establish the material properties and presented in this paper are the surface morphological, compositional and electrical properties of the nanocarbons thin films and possible correlation to the process parameters. The surface morphology and composition were studied using SEM (SU-1500 HITACHI), Raman Spectroscopy & AFM, NSOM (ALPHA 100RAS), and the electrical and electronic properties were measured using Kiethly Semiconductor device analyzer.

Wear behaviours of filtered cathodic arc deposited TiN, TiAlSiN and TiCrAlSiN coatings on AISI 316 stainless steel fishing net-weaving machine components under dry soft-sliding against nylon fibres

The aim of this work was to study the wear behaviours and mechanisms of Ti-based coatings deposited by a filtered cathodic arc process on fishing net-weaving machine components, namely hooks, under dry soft-sliding against nylon fibres. A set of dry soft-sliding experiments were conducted on AISI 316 stainless steel hooks with filtered cathodic arc-deposited TiN, TiAlSiN and TiCrAlSiN films along with uncoated and hard-chrome plated ones. The results showed that Ti-based coatings offered substantially better wear resistance improvement for stainless steel hooks than hard-chrome plating in an accelerated dry soft-sliding condition of a net-weaving machine. Among the three Ti-based coatings, TiAlSiN coating displayed the best dry soft-sliding wear resistant characteristics with the lowest wear rate and the longest maximum sliding distance of 189km, which was about 5 times as high as that of uncoated one due to superior hardness and chemical properties. Microstructural analyses suggested that the wear mechanisms of hard tool surface such as TiAlSiN mainly involved repetitive two-step adhesive wear processes including a corrugated transfer film onto the hard surface and the subsequent detachment of transfer film along with the outermost layer of hard material. Moreover, the hard-chrome plated hook exhibited a rather high wear rate despite its low surface roughness due to rapid material detachment by the adhesive fracture wear mechanisms.

Modeling intrinsic residual stresses built-up during growth of nanostructured multilayer NbN/CrN coatings

Composition modulated NbN/CrN nanostructured multilayer coatings were deposited onto martensitic stainless steel. The coatings were obtained by cathodic arc process, in an industrial-size physical vapor deposition (CAPVD) chamber. The coatings reached 15μm thick, consisting of multilayers of different periodicities (4nm≤Λ≤20nm), which were achieved by varying the rotating speed of the samples in a 2-fold rotation table. The obtained coatings were characterized by High Resolution Transmission Electron Microscopy (HRTEM) and Selected Area Diffraction (SAD) in order to assess the crystal structure, epitaxy and degree of coherency of the NbN/CrN interface. The results showed that the coatings were formed by alternate individual layers of NbN and CrN separated by highly coherent interfaces, and revealed cross-contamination between the layers. Compositional variation measured across the multilayers, by Electron Energy Loss Spectroscopy (EELS) showed that the lower the coating periodicity (Ʌ), the greater is the cross-contamination in the NbN and CrN individual layers. A Finite Element Analysis (FEA) model was developed for assessing the intrinsic residual stresses due to differences of lattice parameters of the NbN and CrN structures, based on chemical composition gradients obtained from EELS measurements. The results show the build-up of stress gradients from the center of individual layers towards the interface, differently from other results published in literature. The smaller the periodicity the higher are the stress gradients developed near the NbN/CrN interfaces. The results are discussed based on the possible interaction of dislocations with stress fields developed near the NbN/CrN interfaces. The proposed model is consistent with former experimental results, which indicates that the smaller the periodicity, the greater is the coating hardness when periodicities range from 4nm to 20nm.

Structural optimisation and synthesis of multilayers and nanocomposite AlCrTiSiN coatings for excellent machinability

In the present work, based on AlCrN coatings, AlTiSiN and AlCrTiSiN multilayer and nanocomposite coatings were designed and deposited on high-speed steel (HSS) specimens and cutters by cathodic vacuum arc process. The microstructures of these coatings were investigated by grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscope (HRTEM), in association with mechanical property characterisation, and also with a cutting test used to check the service life of coated tools. The results showed that the AlTiSiN coating was composed of nanocrystalline TiN and hcp-AlN. The AlCrTiSiN multilayers and nanocomposite coating contained (111), (200), and (220) planes of TiN and CrN with a face-centred cubic structure (fcc) and nanocrystalline fcc-(Cr,Al)N phases. The AlCrTiSiN coating had a stronger diffraction (200) peak compared with the AlTiSiN coating. Those coatings were superlattice with nanocomposite structures containing nanocrystalline and amorphous phases. The modulation period (7nm) of the AlCrTiSiN coating was much smaller than the 12nm of AlTiSiN. A special Cr2N particulate phase existed in the AlCrTiSiN coating. The service life of an AlCrTiSiN coated tool increased by approximately 50% when compared with that with an AlCrN coating because of its excellent mechanical properties (41.14GPa hardness, 1.07GPa toughness, 60N LC2 adhesion strength, 0.2 average friction coefficient, and 36.5nm (Ra) roughness).

Ultrathin Carbon with Interspersed Graphene/Fullerene-like Nanostructures: A Durable Protective Overcoat for High Density Magnetic Storage.

One of the key issues for future hard disk drive technology is to design and develop ultrathin (<2 nm) overcoats with excellent wear- and corrosion protection and high thermal stability. Forming carbon overcoats (COCs) having interspersed nanostructures by the filtered cathodic vacuum arc (FCVA) process can be an effective approach to achieve the desired target. In this work, by employing a novel bi-level surface modification approach using FCVA, the formation of a high sp3 bonded ultrathin (~1.7 nm) amorphous carbon overcoat with interspersed graphene/fullerene-like nanostructures, grown on magnetic hard disk media, is reported. The in-depth spectroscopic and microscopic analyses by high resolution transmission electron microscopy, scanning tunneling microscopy, time-of-flight secondary ion mass spectrometry, and Raman spectroscopy support the observed findings. Despite a reduction of ~37 % in COC thickness, the FCVA-processed thinner COC (~1.7 nm) shows promising functional performance in terms of lower coefficient of friction (~0.25), higher wear resistance, lower surface energy, excellent hydrophobicity and similar/better oxidation corrosion resistance than current commercial COCs of thickness ~2.7 nm. The surface and tribological properties of FCVA-deposited COC was further improved after deposition of lubricant layer.

Excellent wear life of silicon nitride/tetrahedral amorphous carbon bilayer overcoat on functional tape heads

Developing ultrathin and highly wear-resistant overcoats for magnetic tape heads is one of the current research areas of interest, because of its potential to delay pole tip recession and increase the operational lifetime of high areal density tape drives. Using optimized process conditions and an appropriate overcoat design, we report on the development of a ∼20 nm thick silicon nitride/tetrahedral amorphous carbon (Si/SiNx/ta-C) bilayer overcoat, where the ta-C film was deposited by a filtered cathodic vacuum arc process. The bilayer overcoat deposited on a functional tape head survived 40–50 × 106 m of testing with commercial tape media under standard industrial testing conditions. The excellent wear resistance of the overcoat was attributed to the generation of high (∼72%) sp3 carbon content and the formation of strong interfacial bonds, such as Si-C, C=N, nitrile, and (Al, Ti)N at the interfaces, as confirmed by various spectroscopic techniques. This study demonstrates the pivotal role of high sp3 carbon bonding combined with enhanced interfacial bonding in developing an ultrathin yet durable protective overcoat for magnetic tape heads.

60 years of DLC coatings: Historical highlights and technical review of cathodic arc processes to synthesize various DLC types, and their evolution for industrial applications

Diamond-like carbon (DLC) films deposited by cathodic vacuum arc evaporation (CVAE) have attracted worldwide interest from research groups and industry since the beginning of the 1990s. Hydrogen-free amorphous carbon (a-C) coatings were first deposited by CVAE about two decades after the first description of hydrogenated a-C coatings (a-C:H) deposited by glow-discharge techniques. This paper highlights the development and broad potential of hard a-C coatings deposited by direct (DCVAE) and filtered (FCVAE) cathodic arc evaporation, including pulsed arc.DLC films offer a wide range of exceptional physical (optical, electrical), chemical (interaction with media), mechanical (hardness, elastic modulus), biomedical and tribological properties. Monolithic tetrahedrally-bonded hydrogen-free coatings (ta-C) provide the highest hardness, while various softer a-C coatings are also useful in some applications. Many film properties such as electrical conductivity and surface energy can be modified by alloying with elements such as H, N, Si, B, F, P and metals. Recent research and industrial solutions for generating DLC coatings by CVAE of carbon-based cathodes are described, and hybrid methods using metal cathodes and gas-phase sources are discussed. Coatings containing additional elements and having complex architectures are also discussed, and selected properties for various coating types are presented.The number of industrial applications of ta-C and a-C coatings continues to increase, mainly for tribological coatings to reduce wear and friction. Various applications of coatings deposited by CVAE are described, including data hard disks, engine parts, razor blades, valve seals, decorative coatings, cutting and forming tools, biomedical products and others.

Effect of electron irradiation on morphological, compositional and electrical properties of nanocluster carbon thin films grown using room temperature based cathodic arc process for large area microelectronics

The influence of 8MeV electron beam bombardment on room temperature grown nanocluster carbon using cathodic arc process has been studied here. Atomic force microscopy (AFM) study shows that surface roughness varies with varying electron doses. High doses of electrons could causes thermal induce graphitization and morphological changes in the films. Raman spectroscopy analysis reveals that G-peak vary from 1555cm−1 to 1570cm−1 and D-peak varying from 1361cm−1 to 1365cm−1 indicating the disorderness and presence of both graphitic and diamond-like phases. Room temperature conductivity changes by two to three orders in magnitude. The conductivity in the films could be due to conduction of charge carriers through neighboring islands of conductive chains. Defect states calculated using the differential technique varies from 8×1017cm−3eV−1 to 1.5×1019cm−3eV−1. Irradiation of nanocluster carbon thin films could be helpful to tune the electrical properties and defect densities of the nanocluster carbon films for various large area, flexible electronic and nano electronic applications.

The influence of nitrogen pressure and substrate temperature on the structure and mechanical properties of CrAlBN thin films

Thin films of CrAlBN were deposited on SKD 11 tool steel and Si wafer substrates using Cr and Al0.95B0.05 alloy cathodes in a nitrogen gas flow in a cathodic arc process. The influence of nitrogen pressure (PN) and substrate temperature (TS) on the microstructure and mechanical properties of the films was investigated. The CrAlBN films had a nano-multilayered structure in which the nano-crystalline CrN layer alternated with the AlBN layer at the PN below 6.67Pa. With a further increase of PN, no multilayered structure of the film was observed. The hardness of the films decreased with increasing PN. The films deposited at various TS also had a nano-multilayered structure, but the AlBN layers had an amorphous state at the TS of 250°C. The hardness of the films increased with the increase of the TS from 250 to 350°C. Further increase in the TS decreased the hardness. The maximum hardness of 53GPa was obtained at the TS of 350°C. A good correlation between the residual stress and the hardness of the films was observed. We also presented the simulation of CrN/AlBN/CrN systems with different structure of AlBN layer. The simulation revealed that the Young's modulus, yield stress and flow stress increased with the increase of the fraction of hexagonal crystal AlBN.

Influence of Ti–Si cathode grain size on the cathodic arc process and resulting Ti–Si–N coatings

The influence of the Ti–Si cathode grain size on cathodic arc processes and resulting Ti–Si–N coating synthesis has been studied. 63mm Ti–Si cathodes containing 20–25at.% Si with four dedicated grain size of ~8μm, ~20μm, ~110μm, and ~600μm were fabricated via spark plasma sintering or hot isostatic pressing. They were evaporated in 2Pa nitrogen atmosphere in an industrial-scale arc deposition system and the Ti–Si–N coatings were grown at 50A, 70A, and 90A arc currents. The composition and microstructure of the virgin and worn cathode surfaces as well as the resulting coatings were characterized using optical and electron microscopy, X-ray diffraction, elastic recoil detection analysis, X-ray photoelectron spectroscopy, and nanoindentation. The results show that the existence of multiple phases with different work function values directly influences the cathode spot ignition behavior and also the arc movement and appearance. Specifically, there is a preferential erosion of the Ti5Si3-phase grains. By increasing the grain size of the virgin cathode, the preferential erosion is enhanced, such that the cathode surface morphology roughens substantially after 600Ah arc discharging. The deposition rate of the Ti–Si–N coating is increased with decreasing grain size of the evaporated Ti–Si cathodes. The droplet number density and the droplet shape of the coatings are influenced by the arc movement, which is also shown to depend on the cathode grain size.

Superconducting Nb Thin Films on Cu for Applications in SRF Accelerators

This article describes Nb thin films deposited on Cu using coaxial energetic deposition (CED). CED is a nonequilibrium cathodic arc process that drives medium energy (50-150 eV) ions into a few atomic layers beneath the surface to promote the growth of dense, ordered films via subplantation physics. Nb films deposited on crystalline substrates by CED have shown bulk-Nb like (>; 300-500) RRR values. Here we describe Nb films of 1-10 μm deposited on coupons and complex structures made of Cu at substrate temperatures of 400 °C or less. The coated samples were sectioned and the substrate material etched away so the superconducting transition temperature (Tc), as well as residual resistivity ratio (RRR) at 10 K of the Nb films could be measured. RRR values of >;100 have been achieved on fine-grain Cu with little surface preparation. The vortex penetration magnetic field was measured by DC SQUID and these results are presented along with comparisons between bulk Nb and thin film Nb on crystalline substrates. The CED approach has applications in superconducting bellows interconnects as well as in SRF cavities.

Structural, surface, and thermomechanical properties of intrinsic and argon implanted tetrahedral amorphous carbon

The structural, surface, and thermomechanical properties of intrinsic and argon incorporated tetrahedral amorphous carbon films deposited using the filtered cathodic vacuum arc process are reported. Argon atoms were simultaneously incorporated during the deposition of the films using an argon ion gun in the energy range of 0–180 eV. Contact angle measurements revealed that all of the deposited films are hydrophobic, regardless of the substrate bias voltage that was applied during the depositions. Thermal desorption spectroscopy measurements revealed that high argon bombarding energy favors films that are structurally more compact and thermally more stable. An investigation unbinding the mechanism of argon effusion and intrinsic stress relief is presented.

Raman spectroscopy and conductivity variation of nanocluster carbon thin films grown using a room temperature based cathodic arc process

Nanocluster Carbon (NC) thin films grown at room temperature, using a cathodic arc process, under varying deposition conditions, exhibit interesting electrical and opto-electronic properties. These films are mixed phase material containing both sp2 (graphite-like) and sp3 (diamond-like) bonding. A Raman G-peak has been observed between 1585 and 1595 cm−1, which indicates graphite-like bonding. A Raman D-peak has been observed between 1355 and 1365 cm−1, which indicates disorderliness in the carbon structure of the films. The Raman spectra of the films were deconvoluted using Breit–Wigner–Fano line shapes. The Raman parameters, including intensity ratios, peak positions, Full-Width Half Maxima (FWHM) and coupling coefficients obtained from both line shapes, were described and compared with varying Helium partial pressures. The dependence on temperature of the conductivity, showing two regions of electronic transport, is explained based on a thermal-assisted tunneling process. The electrical conductivity varies from 1×10−4 S/cm to 1.66×10−5 S/cm with respect to varying deposition parameters, such as arc current, DC bias and throw distance.