Cathodic Arc Physical Vapor Deposition Research Articles

Cr-(CrN/TiAlN)m-AlSiN-AlSiO open-air stable solar selective coating for concentrated solar thermal power applications

A novel spectrally selective multilayer coating: Cr-(CrN/TiAlN)m-AlSiN-AlSiO on SS316 substrate/tube was deposited via Cathodic Arc Physical Vapor Deposition (CAPVD) technique. The coating exhibited state-of-the-art absorptivity (α = 0.95–0.96) and emissivity (ε = 0.09–0.11). In view of open-air solar thermal application requirements, the coating has been systematically analysed for its thermal, environmental (corrosion) and mechanical stability. The thermal cycling studies carried out at 500 °C in open-air conditions have shown no change in optical properties for about 150 cycles. Further, accelerated thermal aging tests have shown an extrapolated service life of 25 years at 411 °C. In the case of corrosion studies, up to 520 h of exposure to 5% NaCl medium, no considerable change in optical properties was observed. Further, the coatings were well adherent to the substrates/tubes (6 N of critical load) with a considerable hydrophobicity (104° contact angle). The observed results indicate that, Cr-(CrN/TiAlN)2–AlSiN–AlSiO coating may be a good choice for developing receiver tubes used in Concentrated Solar Power (CSP) systems with best solar selective properties and the capability to withstand harsh environments like solar flux variations, thermal shocks in the presence of open-air pollutants, dust and humidity.

Mechanical, in-vitro corrosion, and tribological characteristics of TiN coating produced by cathodic arc physical vapor deposition on Ti20Nb13Zr alloy for biomedical applications

Although Ti-based alloys have shown improved biocompatibility, the release of metal ions at long implantation times due to reduced surface hardness and wear resistance results in reduced service lifetimes of implants and cause implant loosening. To overcome these limitations and extend the lifetime of Ti-based implants, a TiN ceramic coating was deposited on the developed Ti20Nb13Zr (TNZ) alloy by using cathodic arc physical vapor deposition. The objective of this paper was to examine and assess the performance of the coating and its influence on surface hardness, in- vitro corrosion, wear rate and friction coefficient. The results exhibited that the TiN coating led to an enhancement of the surface hardness of 23.1 GPa and modulus of elasticity of 224.6 GPa. In-vitro corrosion investigations showed better corrosion protection for the coated alloy in both simulated body fluid and artificial saliva compared to the uncoated alloy. The coefficient of friction (~ 0.4) of the coated alloy was almost 30% less than that of the TNZ alloy, and the wear rate of the coated TNZ was 0.62 ± 0.07×10−5 mm3/Nm compared to 3.9 ± 0.8×10−5 mm3/Nm for the uncoated sample. The obtained results indicate that coating the TNZ alloy with TiN may be a promising option for biomedical uses.

Chromium nitride-coated copper beryllium as a cam tappet material candidate

Copper beryllium (CuBe) with good mechanical and high electrical conductivity properties is used in metalworking, electronic devices, automotive systems, and aerospace systems. Having low hardness limits its usage in tribosystems such as internal combustion engine valve train systems. In this study, heat-treated CuBe material was coated with CrN under a micron thickness by cathodic arc physical vapor deposition (arc-PVD) to improve wear resistance not only at unlubricated condition but also at the lubricated condition for tribosystem, especially a material candidate for cam tappets. Therefore, CrN-coated CuBe, CuBe, and AISI52100 steel samples were tested by a tribometer at unlubricated and lubricated sliding conditions. Surface morphological changes and tribochemical formation were investigated by optical microscope, optical profilometer, atomic force microscope, and scanning electron microscope. The results showed that CrN increased the wear resistance of the CuBe significantly, and it can be used as cam tappet material both on unlubricated and boundary lubrication regimes.

Mechanical, biocorrosion, and antibacterial properties of nanocrystalline TiN coating for orthopedic applications

The current study analyzes the surface, mechanical, biocorrosion, and antibacterial performances of a nanocrystalline TiN ceramic coating synthesized using cathodic arc-physical vapor deposition (PVD) on biomedical Ti6Al4V substrates. The surface hardness and modulus of elasticity were assessed using the microindentation method. The adhesion, friction coefficient, and antibacterial properties of the coating were evaluated. The in vitro corrosion of the prepared coated Ti alloy substrate was analyzed in simulated body fluid (SBF) via cyclic potentiodynamic polarization (CPP), dynamic electrochemical impedance spectroscopy (DEIS), and scanning vibrating electrochemical technique (SVET). The results demonstrated that a nanocrystalline TiN coating with a crystallite size of 10.33 nm and a thickness of 5 μm was formed with good adhesion on the alloy surface. The coating had an enhanced surface hardness of 38.63 GPa and a modulus elasticity of 358 GPa, and exhibited enhanced resistance to plastic deformation compared with the substrate – features that can enhance the service life of an implant. The antibacterial experiments indicated an upgraded antibacterial performance of the TiN coating compared to the bare alloy. The in vitro corrosion-resistance analyses confirmed the enhanced surface protective performance of TiN ceramic coatings against biocorrosion in SBF. The results showed higher impedance values in DEIS, a higher passive region in the CPP analysis, and a lower anodic current density in the SVET analysis compared with the bare substrate.

Effect of number of layers on erosion, corrosion, and wear resistance of multilayer Cr–N/Cr–Al–N coatings on AISI 630 stainless steel

AbstractIn the present study, multilayered Cr–N/Cr–Al–N coatings were prepared by cathodic arc physical vapor deposition (PVD) with different numbers of layers and the same total thickness on AISI 630 steel in an attempt to improve the wear and erosion–corrosion resistance. Structural analysis of the coatings was performed by field scanning electron microscopy, X‐ray diffraction (XRD), and energy‐dispersive spectroscopy. Depth profiles and roughness parameters of worn surfaces were calculated after erosion and wear tests. XRD indicated that nitride compounds were formed in multilayer coatings by PVD. The Cr–N/Cr–Al–N coating exhibited superior corrosion resistance compared with AISI 630 substrate. The erosion–corrosion results revealed that the smoothest wear track with the minimum erosion rate and wear depth was obtained for five‐ and seven‐layered coatings. The failure mechanism of the bare substrate was influenced by plastic deformation via cutting and plowing, while the failure mechanism for coated samples was chipping and delamination. According to the wear results, the multilayer coatings showed a lower friction coefficient and better surface morphology that demonstrated their high ability for wear protection.

Effect of ion bombardment and micro-blasting on the wear resistance properties of hard TiN coatings

Ion bombardment (IB) is conventionally used as a pre-coating treatment process to increase surface energy of tools to improve the adhesion of coatings produced using cathodic arc Physical Vapour Deposition (CA-PVD) technique. Micro-blasting (MB) as a post-treatment process is used to improve the surface finish of the coated tools. Both these processes impact surface finish, adhesion and wear resistance of the coated tools. This article presents a systematic study to understand the effects of these two processes on the surface finish, adhesion and wear resistance properties of TiN coated HSS substrate. IB process was carried out using Ti ions for different time periods which results in the formation of Ti layer on HSS M2 grade substrate. This was followed by TiN coating deposited at −150 V bias voltage and 1.3 Pa of nitrogen gas. Coating properties evaluated were: coating micro-structure, surface morphology, surface roughness, macroparticle (droplet) density, adhesion and wear rate. TiN coating with FCC structure was confirmed using XRD measurements. With the decrease in IB time from 25 min to 5 min, the surface roughness reduces from 0.31 µm to 0.15 µm respectively. Adhesion and Calo wear tests also showed improvement in adhesion and wear resistance with the reduction in IB time. The TiN coated sample without IB process was also prepared, which exhibited lowest surface roughness and droplet density, but the coating adhesion and wear resistance properties were optimum for 5 min IB treated HSS. The Ti layer deposited during the IB process helps in improving the coating adhesion. However, as the result shows, higher Ti inter-layer thickness results in poor adhesion and higher roughness. Thus, to get better wear resistance and adhesion, ion bombardment is necessary but has to be kept as low as possible. In addition, Post-coating MB process was carried out at different pressures and time on TiN coated sample to identify the optimum pressure and time which improves wear resistance of the coating.

Fracture behaviour of nc-TiAlN/a-Si3N4 nanocomposite coatings under cyclic nano impact testing

ABSTRACTTiN, nanocomposite nc-TiAlN/a-Si3N4 (NC) and multi-layered TiN/NC coatings were deposited on commercially used tungsten carbide-cobalt (WC-Co) based tool material substrates by cathodic arc physical vapour deposition (CA-PVD) technique. The coatings were subjected to cyclic nanoimpact testing with impact loads of 1 and 5 mN. Properties such as fracture probability, (h1–hs)/(hf–h1) index and crack morphologies were analysed based on which, the performance order of the coatings was evaluated. It was observed that the multi-layer coating performed better followed by monolithic titanium nitride and nanocomposite coating (TiN/NC > TiN > NC). The order of the coatings so obtained was further compared with their relative performance during real-time machining studies. It was observed during machining that the order was changed to TiN/NC > NC > TiN. The better performance in TiN/NC coating was due to arresting of cracks formed in NC layer by TiN layer.

Scratch and indentation adhesion characteristics of multilayered PVD coatings before and after the heat treatment deposited by duplex process

In this research, the adhesion of multilayered nitride coatings produced by cathodic arc physical vapour deposition to hot work tool steel (AISI H13) substrate was evaluated and the effect of heat treatment on mechanical properties of these coatings was studied. Plasma nitriding was carried out as part of a duplex process, prior to physical vapour deposition of TiN-TiAlN or TiN-TiAlN-CrAlN, to improve adhesion of nitride coatings of thicknesses 5 μm and 7 μm, respectively, to the hardened steel substrate. The adhesion strength of the coatings was evaluated by scratch and indentation tests. Experimental results indicated that TiN-TiAlN coatings after annealing treatment possessed the optimum properties, as compared to other coatings. Rockwell indentation tests revealed severe delamination in TiN-TiAlN-CrAlN, whereas TiN-TiAlN coatings experienced microcracks at higher critical loads.

Triple sandwich design of multilayered (CrN/ZrN)/(Cr/Zr) hard coating with nanoscale architecture: microstructure and composition

A novel multilayered (CrN/ZrN)/(Cr/Zr) coating of a ‘triple sandwich’ design was fabricated by the cathodic arc physical vapour deposition technique. The thickness of (CrN/ZrN)/(Cr/Zr) coating was 56 microns, and the thicknesses of constituent (CrN/ZrN) and (Cr/Zr) films were 1070 and 115 nm, respectively. Preferential crystallographic orientation for nitride layers was (200). This evidenced the formation of coherent interfaces between CrN and ZrN layers through the epitaxial stabilization of one material in the structure of another lattice. It was found that the diffraction peaks of CrN and ZrN shifted slightly to lower diffraction angle, which pointed to the presence of intrinsic stress in the experimental sample. The average grain size values for ZrN and CrN were 12.5 and 9.5 nm, respectively. The TEM results showed the formation of the face-centered cubic (fcc) phase in nitride layers. The substrate-coating region had a polycrystalline structure. The sample demonstrated relatively high micro- and nanohardness of 28.5 and 34 GPa, respectively.

Neutronic and mechanical evaluation of rare earth doped and undoped nitride-based coatings for accident tolerant fuels

As a part of the effort to develop accident-tolerant fuel (ATF) that would delay potential deleterious consequences of loss-of-coolant-accidents (LOCA), TiN and TiAlN coating application on nuclear fuel claddings were shown as a promising path to enhance corrosion resistance of nuclear fuel cladding. Recently, ytterbium doping was shown to contribute to improving TiAlN coating corrosion performance. However, overall cladding coating performance evaluation requires investigation of neutronic penalties and mechanical properties in addition to corrosion resistance. The current study is composed of two parts. First, the neutronic impact of adding monolithic TiN, monolithic TiAlN and 8-layer TiAlN/TiN coatings (with and without Yb dopants) to the exterior of conventional zirconium-alloy cladding was investigated. Second, an experimental investigation was performed through the deposition of select coating design architecture using cathodic arc physical vapor deposition process onto ZIRLO®1 sheets followed by mechanical testing to examine the adhesion and hardness of the coatings. Characterizations were performed using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA), Raman spectroscopy and X-ray diffraction (XRD). It is concluded that to minimize the neutronic penalties, a limitation on the concentration of Yb-dopant is necessary. Mechanical testing showed that hardness decreased with increasing Yb content. The adhesion of the TiAlN coatings was not affected by doping but was affected by the cathode composition.

Metallurgical and mechanical characterization of TiCN/TiAlN and TiAlN/TiCN bilayer nitride coatings

In the present work, attempt has been made to analyse the metallurgical and mechanical characterization of Titanium Carbonitride (TiCN) and Titanium Aluminium Nitride (TiAlN) duplex coatings. TiCN/TiAlN and TiAlN/TiCN bilayer combinations were deposited on cemented carbide cutting insert substrates by means of the cathodic arc physical vapour deposition (CAPVD) process. The metallography analysis revealed a highly densed uniform structure and a fewer voids for the TiAlN/TiCN bilayer coating when compared to TiCN/TiAlN combination. Nano-indentation analysis was performed for the assessment of the surface hardness of the coatings followed by the measurement of adhesive strength through use of a scratch tester. The TiAlN/TiCN bilayer coating revealed a higher hardness and greater adhesion strength than the TiCN/TiAlN bilayer coating. Roughness parameters of the coated films were obtained using atomic force microscopy (AFM). TiAlN/TiCN bilayer coating showed a smooth surface, when compared to TiCN/TiAlN bilayer coating.

Surface characterisation of TiCxN1 − x coatings processed by cathodic arc physical vapour deposition: XPS and XRD analysis

The properties of titanium carbonitride (TiCN) can be controlled by maintaining the C―N ratio within the coating to a certain level. An experimental study was carried out to vary the composition and properties of TiCN using cathodic arc physical vapour deposition (CAPVD). The substrate used was tungsten carbide (WC‐6Co), which was prepared in‐house through a powder metallurgy process. In order to form the TiCxN1 − x coatings, titanium (Ti) was used as the cathode, while methane (CH4) and nitrogen (N2) gases were used as sources for C and N, respectively. X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD) were used to investigate the composition, chemical state, and bonding structure of the deposited coatings. The results show that the composition, intensity of elements, lattice parameter, and d‐value of TiCxN1 − x coatings were successfully varied by controlling the CH4 fraction (CH4/N2 ratio). With the increase in CH4 fraction, the intensity of C and N within the TiCxN1 − x coatings increased and decreased, respectively. Consequently, the C―Ti and C―N bonds were increased and N―Ti bonds were decreased.

Corrosion study of TiN, TiAlN and CrN multilayer coatings deposit on martensitic stainless steel by arc cathodic physical vapour deposition

In this study, several multilayers nitride coatings were deposited on 17-4 PH stainless steel by employing a cathodic arc physical vapour deposition process to improve the resistance of this stainless steel in corrosive solution environment. Morphology and structure of the coatings were investigated by scanning electron microscopy and x-ray diffraction. Nano instrument equipped method was used to obtain the hardness of the coatings. To evaluate the corrosion resistance, the potentiodynamic polarization and electrochemical impedance spectroscopy tests, in 3.5% NaCl solution, were carried out. The potentiodynamic tests revealed the Ecorr shifted to more positive potential in all nitride coated that deposited on the substrate. Specimens with CrN/CrAlN multilayer coating revealed superior corrosion resistance compared with substrate and TiN/TiAlN multilayer coating. The electrochemical impedance spectroscopy measurements represent a single time constant lead to corrosion of the coatings without degradation of the substrate. The results also showed that aluminum content of the coating improved the protective role of the layer because of its ability to form the passive film.

The study on the properties of TiCxN1−x coatings processed by cathodic arc physical vapour deposition

ABSTRACTTitanium carbonitride (TiCN) is a popular hard coating for carbide cutting tools in various applications. The properties of TiCN are within its composition and can be controlled by maintaining the C–N ratio within the coating to a certain level. This paper studied the influence of carbon content and coating composition within TiCxN1−x coatings with regard to their mechanical properties. The substrate used was tungsten carbide (WC-6Co), which was prepared in-house through a powder metallurgy process, while the TiCxN1−x coatings were deposited in-house using cathodic arc physical vapour deposition (CAPVD). TiCxN1−x coatings improved the mechanical properties of carbide inserts. An increase in carbon content within TiCxN1−x coatings improved surface lubricity, reduced coefficient of friction, improved surface microhardness and increased Young's modulus, but reduced thermal conductivity of carbide inserts. The colour of TiCxN1−x coatings also changed with carbon content.

The wear performance of carbide tools coated with TiAlSiN, AlCrN and TiAlN ceramic films in intelligent machining process

Nitride-based coatings are applied by cathodic arc physical vapor deposition (CAPVD) to improve the tribological properties of cutting tools. The present study examines the tool life of carbide tools coated with TiAlSiN, AlCrN and TiAlN films in intelligent machining process. Coating process was applied on both prismatic carbide test specimens and solid carbide end mills. Coating characterization was carried out on the test specimens. The structural, mechanical and tribological properties of different nitride-based coatings were investigated by means of field emission scanning electron microscope (FEG-SEM), X-ray diffractometer (XRD), scratch tester, reciprocating tribometer, calotester, microhardness device and optical profilometer. Impax steel was machined in CNC vertical machining center with uncoated and coated carbide end mills in order to determine the actual operating performance of the coatings. The g codes and toolpaths were created in the SolidCAM iMachining software. The cutting speed, feeds and overlap values are selected automatically and variably depending on geometry, tool and workpiece materials. The flank wear widths of tools were determined by SEM. In addition, the surface roughness values of the impax steel were measured from the finish surfaces. According to the scratch test results, the best adhesion results were obtained for TiAlN coating and the Lc1 critical load value was determined as about 30 N. The reciprocating sliding test results showed that the highest wear rate was obtained for the TiAlSiN coated specimen and the lowest wear rate was obtained for the uncoated specimen. Flank wear was observed on the tools after the milling process and the highest wear resistance was obtained TiAlN coated end mill. The lowest surface roughness value was obtained from the surface of impax steel workpiece which was milled with carbide end mill coated with TiAlN ceramic film.

Tribological Behavior of TiAlN, AlTiN, and AlCrN Coatings at Boundary Lubricating Condition

In this study, ~ 3.5 µm thick multilayer titanium alumina nitride (TiAlN), alumina titanium nitride (AlTiN), and alumina chromium nitride (AlCrN) coatings were deposited on the H13 steel surface by cathodic arc physical vapor deposition (CAPVD) method. The tribological performance of the coatings was evaluated by a tribometer at boundary lubrication condition. Then, coating surfaces were observed by optical microscope, optical profilometer, and atomic force microscope to evaluate the morphological changes, wear volumes, and tribofilm thickness. Also, scanning electron microscopy (energy dispersive X-ray) and X-ray photoelectron spectrometry analyses were applied to coating surfaces for the tribochemical evolution of the tribofilm. Results showed that AlCrN coating performed the best tribological behavior at boundary lubricated condition, when compared to TiAlN and AlTiN coatings and it can be used as a wear resistant cam tappet coating in internal combustion engines.

Multilayered ZrN/CrN coatings with enhanced thermal and mechanical properties

Multilayered ZrN/CrN coatings were produced by the cathodic arc physical vapor deposition (CA-PVD). Morphology, element distribution, structural and thermal properties were investigated. Microhardness and nanoindentation tests were conducted to study the mechanical properties of the coatings. The experimental results of scanning electron microscopy (SEM) revealed the cellular microrelief of the surface and well-defined multilayered architecture of the coatings. Energy dispersive spectroscopy (EDS) provided the chemical characterization of the coatings and revealed the formation of stoichiometric composition in coatings. X-ray diffraction (XRD) studies showed that (200) and (111) plane reflections of ZrN and Cr2N phases, correspondingly, were with maximum intensity. Transmission electron microscopy (TEM) analysis revealed that the films comprise of nanometric equiaxed grains with average sizes from 12.8 to 15.1 nm for ZrN layers and from 14.5 to 28.1 nm for CrN layers. The high-temperature heat treatment caused exothermic and endothermic reactions, which were mainly attributed to the improvements or disordering of the coatings' structure, consequently. The highest values of microhardness (4966HV0.025) and nanohardness (24.58 GPa) were obtained for the sample with a bilayer thickness of 732 nm, the average crystallite size of 13.3 nm and nitrogen content of 49 at%. Experimental results indicated that deposited composites can be effectively used in the production of industrial tools, implements for cutting etc.

Effect of high-voltage pulse bias on the stress and morphology of CA-PVD TiN coatings

ABSTRACTWe investigated the role of high-voltage pulse bias (HVPB) on the structure, morphology and residual stress of TiN coatings produced with cathodic arc physical vapour deposition and compared them with the ones produced with DC bias. Annealing heat treatment was also performed for surveying stress-relieving behaviour within the coatings. The preferred orientation of the coatings changed from (111) to (220) by the application of HVPB. Coatings produced with DC bias exhibited Zone T structure, while the growth morphologies of the coatings produced with HVPB were very similar to the structures in the beginning of Zone II. The presence of Ar in the deposition environment increased the residual stress of all coatings. Intra-grain stresses of the coatings produced with DC bias were almost totally annihilated by annealing. However, for coatings produced with HVPB, stress relief magnitudes were very low, indicating that intra-grain defects could not be totally annihilated.

Chemical and mechanical stability of air annealed cathodic arc evaporated CrAlON coatings

This study reports the synthesis and characterization of ternary Cr-Al-O and quaternary Cr-Al-O-N coatings deposited by cathodic arc physical vapour deposition, for various nitrogen and oxygen mass flow ratios during the growth process. The composition, microstructure, indentation hardness and modulus of the films have been characterized by scanning electron microscopy, electron probe micro-analysis, X-ray diffraction, and nanoindentation techniques. The evolution of the microstructure and mechanical properties of the coatings after ambient air annealing from 800 °C up to 1100 °C have been investigated. As the oxygen to nitrogen mass flow increases, the as-deposited coatings exhibit lower hardness, higher roughness, lower crystallinity and a more marked columnar structure. At oxygen to nitrogen mass flow ratios bigger than 10/90, the coatings exhibit a stoichiometry of the type (CrAl)2+εO3−ε. Only the coatings with an oxygen to nitrogen mass flow ratio smaller than 10/90 retained nitrogen in their compositions. In all cases, the coatings developed a cubic fcc lattice structure.After annealing at 1100 °C the resulting microstructure showed a clear dependency upon the initial composition of the films. The evolution of the microstructure during the high temperature tests, as well as the analysis of the nanoindentation hardness, composition and thickness also provided valuable information about the combined effects of the thermal stability and the oxidation of the deposited coatings.

The corrosion protection ability of TiAlN coatings produced with CA-PVD under superimposed pulse bias

In this study we have investigated the contribution of superimposing high voltage pulse on DC bias on the corrosion protection ability of TiAlN coatings deposited with cathodic arc physical vapor deposition (CA-PVD). Superimposing high voltage on DC bias resulted in the decrease of the number of attached macroparticles (MP) and also densified the columnar structure. These differences significantly improved the corrosion protection ability of the coatings that were determined by electrochemical impedance spectroscopy (EIS) in 0.1 N HCl solutions. An approximately 6 fold increase in the polarization resistance for the samples deposited by using −1000 V superimposed pulse voltage on 40 V DC bias when compared to the ones deposited only by DC bias. For further elaborating these results, the distribution, size and morphology of the corrosion sites were determined with ferroxyl test, scanning electron microscopy (SEM) and 3D optical profilometry. Results of the ferroxyl tests indicated a dramatic decrease of corrosion sites by superimposing −1000 V on DC bias. Closer investigation of these sites showed that corrosion of the substrate is first initiated at the bottom of the defects extending through the coating and then expanded below the coating. The depths and diameters of the corroding sites, revealed by removing their caps with ultrasonication were substantially lower for the samples produced with superimposed bias. Results of the study indicated the necessity of combining electrochemical corrosion test results with the morphology and distribution of corrosion sites for a proper understanding of the corrosion protection ability of hard coatings.