Cathodic Arc Research Articles

Toward decoupling the effects of kinetic and potential ion energies: Ion flux dependent structural properties of thin (V,Al)N films deposited by pulsed filtered cathodic arc

Pulsed filtered cathodic arc deposition involves formation of energetic multiply charged metal ions, which help to form dense, adherent, and macroparticle-free thin films. Ions possess not only significant kinetic energy, but also potential energy primarily due to their charge, which for cathodic arc plasmas is usually greater than one. While the effects of kinetic ion energy on the growing film are well investigated, the effects of the ions’ potential energy are less known. In the present work, we make a step toward decoupling the contributions of kinetic and potential energies of ions on thin film formation. The potential energy is changed by enhancing the ion charge states via using an external magnetic field at the plasma source. The kinetic energy is adjusted by biasing the arc source (“plasma bias”), which allows us to approximately compensate the differences in kinetic energy, while the substrate and ion energy detector remain at ground. However, application of an external magnetic field also leads to an enhancement of the ion flux and hence the desired complete decoupling of the potential and kinetic energy effects will require further steps. Charge-state-resolved energy distribution functions of ions are measured at the substrate position for different arc source configurations, and thin films are deposited using exactly those configurations. Detailed characterization of the deposited thin films is performed to reveal the correlations of changes in structure with kinetic and potential energies of multiply charged ions. It is observed that the cathode composition (Al:V ratio) strongly affects the formation of the thermodynamically stable wurtzite or the metastable cubic phase. The external magnetic field applied at the arc source is found to greatly alter the plasma and, therefore, to be the primary, easily accessible “tuning knob” to enhance film crystallinity. The effect of “atomic scale heating” provided by the ions’ kinetic and potential energies on the film crystallinity is investigated, and the possibility to deposit crystalline (V,Al)N films without substrate heating is demonstrated. This study shows an approach toward distinguishing the contributions stemming from kinetic and potential energies of ions on the film growth, however, further research is needed to assess and distinguish the additional effect of ion flux intensity (current).

The tribological performance of super-hard Ta:C DLC coatings obtained by low-temperature PVD

Diamond-like carbon (DLC) coatings are widely used in industry for decorative/protective purposes or to improve tribological performance in mechanical components. In this study, three types of commercial DLC coatings have been tested and analysed to verify their potential as functional coatings to improve the wear resistance of mechanical components. DLC coatings commercially known as Dianoir, Dropless5000, and Dropless7000 were deposited on AISI 52100 steel through a proprietary cathodic arc physical vapour deposition (PVD) technique, and their properties were compared considering the differences in morphology, thickness, scratch resistance and pin-on-disc test results. The tested coatings showed excellent performance in terms of wear resistance and friction reduction, thereby showing that these coatings may be successfully applied to mechanical components in several applications.

Low-temperature hot corrosion of arc evaporated Ti1−xAlxN on Ni-Cr-Co based superalloys

Cathodic arc evaporated Ti1−xAlxN coatings were deposited on a Nimonic c-263 superalloy and tested under low temperature hot corrosion conditions. Treated with a MgSO4/Na2SO4 salt-mixture, all samples were annealed at 700 °C in a 2800 ppm(volume) SOx-rich atmosphere for 1, 5, 15 and 30 h. A significantly reduced corrosion severity was exhibited by all Ti1−xAlxN variants over the uncoated NiCrCo alloy. A synergistic fluxing mechanism was found to be the dominant factor for the coating breakdown. Depending on the relative Al-to-Ti content on the Ti1−xAlxN sublattice, differences in the coatings’ corrosion and scaling behavior were observed.

Tribological study at high temperature of the c-TiAlON oxynitride coating deposited by cathodic arc on H13 tool steel

Coatings were deposited on AISI-H13 steel by cathodic arc Physical Vapor deposition (arc-PVD). Grazing Incidence X-Ray diffraction (GI-XRD) showed that Oxygen atoms (O) replace Nitrogen atoms (N) in the cubic-Titanium Aluminum Nitride (c-TiAlN) lattice. The coating had ∼5.9 µm thickness, ∼6.3 at% O content and average roughness of Ra= 73.9 nm. High-temperature GI-XRD showed improved oxidation resistance up to 850 °C, at 900 °C the constituent oxides appeared. A columnar microstructure resulted in 21.72 GPa hardness and 418.31 GPa elastic-moduli. Adhesion tests showed critical loads > 19 N, with chipping and conformal-cracking. The pin-on-disk tests at room temperature (RT) showed coefficients of friction (COF) of 0.65 and 0.83 for the steel and the oxynitride, respectively. At 900 °C the COF decreased due to a tribolayer formation. Cyclic tribo-oxidation cause this tribolayer to wear and partially expose the substrate, showing wear mechanisms due to combined processes of the coating and the steel.

Quaternary ZrCuCa-based thin films metallic glasses deposited by cathodic arc deposition

The current study’s aim is to obtain quaternary ZrCuCa based thin films using a physical vapor deposition method (PVD) - cathodic arc approach – in order to improve the surface properties of 316L stainless steel and Ti6Al4V implantable materials. The developed ZrCuCa-based layers could be potential candidates in the medical industry if they are able to combine their exceptional mechanical properties with the corrosion resistance of amorphous metallic glasses. Furthermore, addition of Mo, Mg, Si, and Sr was taken into consideration for the ZrCuCa structure and the resulted quaternary systems were analysed in detail, through electrochemical tests and bioactivity assay, which were carried out in synthetic body fluid (SBF) at human body temperature (37 °C). Surface morphology and roughness of the specimens before and after the tests were also evaluated. The results showed that regardless the substrate type, the roughness of the surface has increased for all coatings from 19 nm for 316L, and 50 nm for Ti6Al4V, to 2000 nm). The adhesion of obtained coatings was reached from 8 N to 18, the coatings on Ti6Al4V alloy was found to be from 12 N to 18 N, while on 316L steel was from 8 N to 15 N, indicating that the coatings deposited on Ti alloy have a better adhesion. The corrosion current density parameter for ZrCuCaMo and ZrCuCaMg sjowe the lowest value (316L: 21.99 µA/cm2 and 11.37 µA/cm2; Ti6Al4V: 1.62 µA/cm2 and 13.37 µA/cm2), indicating the best corrosion resistance. The mass evolution of the coatings deposited on 316L was ranged from the −0.47 mg to 1.37 mg, while for those deposited on Ti6Al4V, the values were ranged from −0.08 mg to 2.66 mg, indicating a degradation and biomineralization process, respectively. In conclusion, the electrochemical studies and bioactivity experiments demonstrated that the suggested coatings improve the substrate’s behaviour in simulated conditions, highlighting their potential as biomaterials.

Corrosion behavior of TiN and TiCN coatings synthesized by PVD on the spark plasma sintered NiTi substrate

TiN and TiCN coatings have garnered widespread attentions in the field of materials science and engineering because of their exceptional characteristics, including high melting point, excellent thermal conductivity, remarkable chemical stability, superior corrosion and wear resistance, and notable biocompatibility. These properties make them highly suitable for coating various alloys, and as a result, they have been successfully applied in numerous applications. The aim of this research study is to delve into the corrosion behavior of spark plasma sintered NiTi substrates that were coated with TiN and TiCN employing physical vapor deposition (cathodic arc technology). In order to comprehensively analyze the corrosion response, potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed. To gain deeper insights into the impact of the coating, a meticulous comparison was conducted between the corrosion resistance of the uncoated specimen and that of the coated ones. The results showcased a significant enhancement in corrosion resistance for both coated samples when compared to the uncoated NiTi substrate. However, it was found that the TiN-coated specimen showed even higher corrosion resistance than the TiCN-coated counterpart. These findings highlight the superiority of TiN coatings in terms of corrosion resistance when applied on the NiTi substrate.

Influence of Bilayer Thickness on Mechanical and Tribological Properties of (Ti-Al)N/MoN Nanostructured Hard Coatings Deposited by Cathodic Arc Ion Plating

Deposition of (Ti-Al)N/MoN multilayered coatings was carried out through a cathodic ion-plating system in an argon and then nitrogen atmosphere. Bilayer thickness (Λ) of all the samples were achieved, from 22 to 104 nm, by organizing substrate holder rotational speed (SRS). To obtain the optimum properties of the (Ti-Al)N/MoN coatings, the Ti and Al ratio was maintained at a level of 1:1. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were utilized to analyze the crystal structure and morphology of the coatings. Mechanical and tribological properties were examined by nanohardness and atomic force microscopy (AFM). The preferred orientation of the (Ti-Al)N/MoN nanoscale multilayer films was TiAlN (200) and MoN (200), which had face centered cubic (fcc) and hexagonal structures, respectively. The hardness increased with the decrease in Λ (104 nm to 26 nm), and then it increased. The highest hardness of 37 GPa was revealed at Λ = 26 nm, whereas the least wear rate of 8.09 × 10−7 mm3/N.m was attained at Λ = 22 nm. Wear rate, roughness, and coefficient of friction were decreased with decreasing bilayer period. EDS results showed that Al and Ti contents were almost the same in all samples, as per design of the experiment.

Efficiency of cathodic arc-grown N-doped TiO2 films for the photocatalytic reduction of Cr(VI) under UV-Vis irradiation

The photocatalytic activity of undoped and N-doped TiO2 anatase films with different thicknesses prepared by cathodic arc deposition on glass substrates is reported. After TiO2 deposition, the doping of the films was carried out by plasma immersion ion implantation in a nitrogen environment. The composition of the films was studied by x-ray photoelectron spectroscopy, the surface morphology was analyzed by atomic force microscopy and the crystalline structure was examined by x-ray diffraction. The thickness was determined by observing the film cross section with scanning electron microscopy. The transmittance of the films in the UV-Vis range was studied as well. The photocatalytic activity of the films was evaluated through the efficiency in the reduction of Cr(VI) in the presence of ethylenediaminetetraacetic acid under UV-Vis irradiation. N-doped films presented a higher photocatalytic efficiency than undoped films: Cr(VI) reduction after 5 h irradiation augmented from 58% (pure TiO2) to 85% (N-doped TiO2) for films of 300 nm thickness, and from 69% to 85% for films with a thickness of 440 nm. On the other hand, pure TiO2 films of 790 nm thickness were more efficient (99% of Cr(VI) reduction) but the effect of doping on the photocatalytic activity was negligible.

Thermal stability of AlCrO antireflection layer for high-temperature cermet-based solar selective absorber applications

Highly stabled antireflection layers play a crucial role in enhancing the optical and thermal performance of cermet-based solar selective absorbing coatings. Few state-of-the-art antireflection layers are qualified for high-temperature (>873 K) utilizations due to the insufficient thermal stability and increased infrared emissivity. Herein, a highly stable multilayer cermet-based absorber with an AlCrO antireflection layer is developed using cathode arc ion plating. The deposited coating exhibits a solar absorptivity of 0.908 ± 0.005 and a thermal emissivity of 0.144 ± 0.004 even after annealing at 923 K for 2000 h in air, compared to the pristine coating with a spectral selectivity of 0.898 ± 0.002/0.186 ± 0.003. After undergoing the extensive annealing treatments, abundant particles with an average size of approximately 8 μm have been detected on the coating surface. However, the AlCrO layer exhibits a remarkably flawless and dense surface topography devoid of any cracks or voids. Based on the GI-XRD and TEM evaluations, the particles have been identified as Mn2O3 nanocrystals. The formation of Mn2O3 particles originates from the diffusion of Mn atoms from the stainless-steel substrate to the surface of the AlCrO layer, where they undergo oxidation. The presence of Mn2O3 can enhance the solar absorptivity by increasing transmittance in the visible light spectrum and reduce the emittance by enhancing reflection of infrared radiation. Then, the impact of Mn2O3 on spectra selectivity and thermal stability is discussed. These results indicate that the AlCrO layer exhibits remarkable durability when subjected to high-temperature annealing in an air environment, thereby significantly enhancing the thermal stability and optical performance of cermet-based solar selective absorbing coatings. These findings suggest that the AlCrO layer exhibits exceptional durability under high-temperature annealing in an air environment, thereby significantly enhancing the thermal stability and optical performance of cermet-based solar selective absorbing coatings.

Investigation of Ion Release and Antibacterial Properties of TiN-Cu-Nanocoated Nitinol Archwires

Background: The use of nitinol (NiTi) archwires in orthodontic treatment has increased significantly due to unique mechanical properties. The greatest obstacle for safe orthodontic treatment is chemically or microbiologically induced corrosion, resulting in nickel (Ni) release. The aim of this investigation was to enhance corrosion resistance and introduce antibacterial properties to NiTi archwires by coating them with copper (Cu) doper titanium nitride (TiN-Cu). Methods: NiTi archwires were coated with TiN-Cu using cathodic arc evaporation (CAE) and direct current magnetron sputtering (DC-MS). The morphology of the sample was analyzed via field emission scanning electron microscopy (FESEM) and chemical composition was assessed using energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR). Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to estimate the ion release. The biocompatibility of samples was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Antibacterial activity was tested against Streptococcus mutans and Streptococcus mitis. Results: Physicochemical characterization revealed well-designed coatings with the presence of TiN phase with incorporated Cu. TiN-Cu-nanocoated archwires showed a statistically lower Ni release (p < 0.05). Relative cell viability was the highest in 28-day eluates of TiN-Cu-nanocoated archwires (p < 0.05). The most remarkable decrease in Streptococcus mitis concentrations was observed in the case of TiN-Cu-coated archwires (p < 0.05). Conclusion: Taking into account biocompatibility and antibacterial tests, TiN-Cu-nanocoated archwires may be considered as a good candidate for further clinical investigations.

Deposition of nanometer-thick amorphous carbon films by filtered cathodic vacuum arc under oblique ion incidence conditions

Filtered cathodic vacuum arc (FCVA) is a promising technique for synthesizing extremely thin carbon films exhibiting highly tetrahedral (sp3) carbon atom hybridization. However, most FCVA studies are for incident ions impinging perpendicular to the substrate surface. In this study, the effects of the ion incidence angle on the thickness, structure, and surface roughness of amorphous carbon (a-C) films deposited under different substrate bias voltages were examined in the light of computational and experimental results. Dynamic simulations and film thickness measurements showed a decrease in film thickness with increasing ion incidence angle, attributed to the decrease in carbon ion fluence on the film surface. Carbon atom hybridization analysis revealed a critical ion incidence angle for a given substrate bias voltage. Simulation and experimental results demonstrated that the enhancement of sp3 hybridization resulted from carbon-carbon collision cascades on the growing film surface and densification induced by direct and recoil implantation processes controlled by the ion incidence angle and substrate bias voltage. The strong dependence of a-C film growth on the carbon ion incidence angle exemplified by the results of this study has direct implications in the oblique deposition of ultrathin a-C films with predominant tetrahedral carbon atom hybridization. The present study provides a framework for optimizing the ion incidence angle to achieve the deposition of a-C ultrathin films with high sp3 contents.

Mechanical, antibacterial and cytotoxic characteristics of nanolayered TiNb–Zr–Ta and nitrogen-doped TiNb–Zr–Ta coatings

Titanium and titanium alloy materials are often made as medical implants. Surface properties of titanium medical implants play decisive roles for antibacterial and biological response and tissue biocompatibility. In this study, cathode arc evaporation (CAE) technology was used to deposit TiNb–Zr–Ta and nitrogen-doped TiNb–Zr–Ta coatings with nanostructures on the Ti–6Al–4V dental abutment screws. The deposited coatings were then oxidized at high temperature to produce different oxides on the surface of the coatings. The mechanical properties, antibacterial properties and biocompatibilities of the coatings were analyzed. The effect of coatings on the abutment screw loosening and removal torque between the abutment screw and the pure titanium implant fixture was studied by removal torque measurement. In addition, Staphylococcus aureus (S. aureus) was used for evaluating the antibacterial properties of coatings, and mouse fibroblasts (L929) were used for ISO 10993-5 cytotoxicity analyses to determine whether it had good biocompatibility.Nanolayered structures and multiphases of polycrystalline TiNb–Zr–Ta were obtained by co-deposition of Ta, Zr and TiNb. When small content of N was introduced, the TiNb–Zr–Ta(N) showed a polycrystalline TiNb–Zr–Ta where N atoms entered the metallic lattice at interstitial sites. After oxidation, oxide phases of Ta2O5, TiO2, Nb2O5 and ZrO2 were formed on the surface of TiNb–Zr–Ta and TiNb–Zr–Ta(N). Ta2O5 was obtained on the surface of the coating prior to other oxides such as TiO2, Nb2O5 and ZrO2. The deposited TiNb–Zr–Ta and TiNb–Zr–Ta(N) coatings had high contact angle and exhibited a hydrophobic feature, while the annealed TiNb–Zr–Ta–O and TiNb–Zr–Ta(N)–O showed hydrophilicity. The deposited TiNb–Zr–Ta had similar hardness and Young's modulus values to that of the uncoated Ti–6Al–4V. When N was doped, the TiNb–Zr–Ta(N) had the highest hardness and Young's modulus. The hardness of the annealed TiNb–Zr–Ta(N) coating only decreased slightly due to the small oxide layer of ∼140 nm. Compared with the uncoated Ti–6Al–4V, TiNb–Zr–Ta serial coatings deposited on abutment screws had higher removal torques, which prevented the abutment screw of dental implant from loosening after long-term use. The biocompatibility of TiNb–Zr–Ta serial coatings was similar to that of the uncoated Ti–6Al–4V. In addition, the oxidized TiNb–Zr–Ta and TiNb–Zr–Ta(N) coatings had excellent antibacterial properties. It is speculated that the resulting Ta2O5 of both coatings may inhibit bacterial growth and improve the antibacterial effect. Based on the above advantages, the TiNb–Zr–Ta serial coatings are expected to have the potential to be applied to biomedical implants.

The Role of Period Modulation on the Structure, Composition and Mechanical Properties of Nanocomposite Multilayer TiAlSiN/AlSiN Coatings

This paper presents the results of the investigation of a multilayer TiAlSiN/AlSiN coating. A novel coating architecture with a period consisting of nanocomposite sublayers of TiAlSiN and AlSiN was developed. We discovered that the combination of a harder sublayer with a more elastic one allows for obtaining a suitable combination of superhardness and enhanced toughness. The coating was deposited by cathodic arc technology. The EDS, XRD, and XRS analyses revealed that the nanocomposite structure is composed of TiAlSiN and AlSiN nanocrystallites, with sizes of 12–13 nm and 4–5 nm, respectively. The nanograin phase is incorporated in an amorphous Si3N4 matrix. The achieved structure causes the presence of four factors contributing to the hardness increase: nanocomposition, solid solution, refinement hardening, and the formation of many interfaces. An instrumented indentation test was used to investigate the mechanical properties. The developed coating possesses a superhardness of 49.5 GPa and a low elastic modulus of 430 GPa, resulting in an improved elastic strain resistance of 0.11, a plastic deformation resistance of 0.58 GPa, and an elastic recovery of 68%. These results imply that the developed coating combines high stability with mechanical degradation under external influence and provides an improved ability to absorb energy at deformation before fracture, and high elastic recovery. The investigation of the effect of the period modulation on the structure, composition, and mechanical properties of the nanocomposite multilayer TiAlSiN/AlSiN coating showed that the superhardness was due to the nanocomposite and solid solution hardening rather than the increased number of interfaces. The demonstrated combination of superhardness with high elasticity and improved toughness determines the developed nanocomposite TiAlSiN/AlSiN coating as very suitable for industrial applications such as high speed and dry machining.

Substrate bias effects on cathodic arc deposited Cr coatings

We investigate the effects of substrate bias on cathodic arc deposition of Cr coatings without external substrate heating at four different substrate bias levels, floating, −30, −50, and −70 V. After 10 min of deposition, the substrate temperature reaches 180, 210, 230, and 260 °C for floating potential, −30, −50, and −70 V, respectively. Time-of-flight energy elastic recoil detection analysis shows that all grown coatings are of high purity, with no coating containing more than 0.2 at.% of C and/or O. Increasing the substrate bias also reduces the number of macroparticles, steers the texture from preferred [110]- to [100]-orientation and induces a residual compressive stress of ∼450 MPa in the coatings. The hardness of the coatings remains at a constant 7.5 GPa irrespective of the substrate bias. The four-point probe resistivity of the grown coatings is 15–17 μΩcm regardless of substrate bias, close to the 12.9 μΩcm of bulk Cr.

The influence of corrosive medium on the selected tribological properties of ZrSi-based nitride and oxynitride deposited on 316L stainless steel

Targeting to restore the function of load-bearing joints which are subjected to high levels of friction and wear during the normal activity, the aim of the current study was to assess the extent of the role played by the corrosive environment on the underlaying tribological mechanism. In this study we deposited by reactive cathodic arc evaporation technique ∼ 1 μm thick, stoichiometric ZrSi-based nitrides and oxynitrides coatings, either as monolayer or double-layer structure on 316L steel substrates. Tribological tests were conducted in dry and two commonly used corrosive environments: Ringer and 0.9 % NaCl solutions. We demonstrate that the ZrSiN and ZrSi(N,O) coatings improved the wear performance of 316L stainless steel in biological environments, reaching even ∼ 94 % improvement as compared with the bare substrate for the ZrSi(N,O) coating.

Heat Transfer in the Solid Cathode of a Hollow Cathode Plasma Torch

After recalling the working principle of hollow cathode plasma torches, we evaluate the heat flux profile on the cathodic arc root. This evaluation takes into account the physics of the cathode sheath. Particular attention is devoted to electron emission from the cold copper cathode. This heat flux profile is then used as a moving boundary condition to obtain the temperature field in the solid cathode with a heat conduction study, with the aim of discussing the problem of its erosion.

Dry wear behavior of identical tetrahedral amorphous carbon nanofilms on sintered composites and metal substrate with varying load bearing capacities

Diamond-Like Carbon (DLC) coating is an effective surface treatment method for improving the tribological properties of machine elements and tool materials. Among them, the tetrahedral amorphous carbon (ta-C) coating has recently received much attention due to its high hardness and good heat resistance. When characterizing friction and wear patterns related to the lifetime and cost, the thickness of the ta-C coating and the type of substrates play an important role. In this paper, ta-C coatings of two thicknesses are deposited on 304 stainless steel (SS) and cemented carbide (WC–Co), which have significant differences in mechanical properties, through filtered cathodic vacuum arc (FCVA) equipment. After ta-C coating on substrates, the tribological properties of each sample are investigated. As a result, compared to bare materials, ta-C-coated materials have a reduced coefficient of friction and improved wear resistance. However, as the base material is softer, tearing occurs in a thin coating so that a thicker ta-C coating might improves the tribological properties. Since thicker ta-C coatings do not always improve tribological properties, the efficiency can be increased by customizing the ta-C coating thickness according to the substrate layer material.

Effect of Nitrogen Pressure and Substrate Bias Voltage on Structure and Mechanical Properties of Vacuum Arc Deposited VN Coatings

The binary vanadium–nitrogen (V–N) coatings were formed using cathodic arc evaporation. Two sets of coatings were produced using: (a) nitrogen pressure (pN2) from 0.001 Pa to 3 Pa at a constant substrate bias voltage (UB) of − 100 V and (b) a substrate bias voltage from − 50 to − 300 V at a constant nitrogen pressure of 1.5 Pa. The influence of the above parameters on the coating properties, in particular on the insufficiently investigated and described adhesion of the coatings to the substrate, was demonstrated. The phase transformation V → V + V2N → V + c-VN → h-VN → h-VN + c-VN and c-VN → h-VN occurs for coatings formed with increasing nitrogen pressure and substrate bias voltage, respectively. With the increase in pN2 and UB, an increase in coating hardness and adhesion to the substrate is observed, as well as an improvement in wear resistance.

Efficacy of TiCrN/DLC coatings for service life enhancement of stamping dies

The present study examines the applicability of wear-resistant TiCrN/DLC coatings to dies used in stamping, for extending the service life. The TiCrN/DLC coatings were deposited via the Cathodic Arc Physical Vapor Deposition (CAPVD) route on D3 tool steel. The thickness of the TiCrN layer was tailored to achieve the desired properties, such as high adhesion strength, toughness, wear resistance, and low residual stress. The tribological properties of the TiCrN coating with best properties was assessed by universal tribometer and dry sand rubber wheel tester. Further, the tribological response of the identified TiCrN coating was investigated by adding a thin layer of low friction coefficient diamond-like carbon (DLC). Finally, the emphasis was also placed on determining the real time life of stamping dies with TiCrN/DLC coating. From the surface relief data of the finished product, measured at regular intervals pertaining to both coated and uncoated dies, a two-fold increase in the productivity with enhanced flowability was observed. The enhancement in the service life of the stamping dies clearly indicates that the CAPVD TiCrN/DLC coating can be a good alternative to hard chrome coatings already in use.

The effect of substrate bias voltage on the mechanical and electrochemical corrosion properties of multilayered CrN/CrAlN coatings produced by cathodic arc evaporation

AbstractThe multilayered CrN/CrAlN film was deposited on the SS420 substrate by cathodic arc evaporation technique. The effect of substrate bias voltage was investigated on the microstructure, surface morphology, and mechanical and electrochemical corrosion properties of the deposited film. The deposited CrN/CrAlN coatings were characterized by X‐ray diffraction and field emission scanning electron microscope techniques. Mechanical properties, corrosion resistance, and surface morphology of the coated samples were studied by nano‐indentation, polarization test, electrochemical impedance spectroscopy, and atomic force microscopy, respectively. Adhesive and dense nanostructure CrN and CrAlN phases were successfully deposited on the substrate. The refinement of the coating crystallite was observed from 31.2 to 24.3 nm by increasing the substrate bias voltage, this improved the mechanical properties of the coating. The number of macroparticles, pinholes and porosities, and the surface roughness of coatings significantly decreased by increasing the substrate bias voltage. The CrN/CrAlN coating reduced the corrosion current density in contrast to the SS420 substrate. Better corrosion resistance was obtained for the coating deposited at 150 V of bias voltage due to lower defects in the film structure.