Arc Evaporation Research Articles

The effect of Bias configuration on the properties of AlCrN based thick coatings deposited by Cathodic Arc Evaporation

Die wear in forming high strength steels (HSS) operations causes increased die maintenance cost and scrap rate, being a major obstacle for automation industries to meet upcoming market requirements. Advanced PVD (Cathodic Arc) coatings of high thicknesses (> 15 μm) can be optimum solution from both an economic and technical point of view, compared to the current CVD or duplex surface treatments. Bias voltage becomes a key parameter to minimize residual stresses in the coating during its growth while ensuring optimal mechanical properties of the coating. Different configurations and their relation to coating properties have been studied. Thick coatings (up to 18 μm thickness) with optimal adhesion have been deposited at 7 μm/h under bipolar bias voltage conditions. The as deposited coatings are showing promising performance in real deep drawing production process.

Dynamic keyhole behaviors and element mixing in paraxial hybrid plasma-MIG welding with a gap

A paraxial hybrid plasma-MIG welding process is developed to join middle-thick high strength steel plates with a butting gap. The arc and metal vapor characteristics are investigated by an advanced three-dimensional spectroscope measurement system. The dynamic keyhole behaviors and element mixing are studied by a three-dimensional numerical model. The numerical and experimental results show that the Fe vapor ejected from the wire surface, other than the plasma keyhole, has a great influence on arc characteristics. The butting gap affects the keyhole stability and molten metal flow, as well as the element mixing. With a gap, the keyhole opens and closes periodically. The opposing flows at the front and rear keyhole bottom walls, and the pressure imbalance in the keyhole bottom contribute to the keyhole collapse. The gap promotes the downward flow below the MIG arc center, which helps to transport the Ni element from the top surface of the MIG pool region to the bottom. The “Pull-Push” molten metal flows in the top molten pool suppress the Ni element to flow from the MIG pool region to the plasma pool region. As a result, the Ni content is inhomogeneous in the hybrid pool, and higher in the bottom of the MIG pool region.

An integrated approach to solving the technological problem of obtaining target cathodes from transition metal silicides for vacuum ion‑plasma sources

The article discusses the technological principles of improving the manufacturing process of consumable cathodes-targets of vacuum electric arc evaporation plants from complex silicides. Which are based on: the selection of chemical composition based on the analysis of state diagrams of double and triple systems, the production of fast-cooled ingots using high-speed induction melting, subsequent grinding and grinding to a powder of the required fraction, static or dynamic pressing of the cathode blank, its sintering and soldering of the current guide. The results of laboratory studies of the process are presented and prototypes of products are obtained.

Comparative study on mechanical and tribological properties of Cr–Al–N and Cr–Al–O coatings deposited by cathodic arc evaporation

A comparative study was performed for (Cr1−xAlx)2O3 and (Cr1−xAlx)N coatings with different Al contents (x = 0, 0.5, and 0.7) concerning structural, mechanical, and tribological properties. The composition-dependent phase structure was found for Cr–Al–O coatings, where higher Al content promotes a mixed structure of cubic and minor amorphous phases. Moreover, the mixed-phase structure results in lower indentation hardness, ∼27 GPa, and residual compressive stress, ∼ −4 GPa, as compared to Cr2O3 and Cr–Al–N coatings. Besides, (Cr0.5Al0.5)2O3 and (Cr0.3Al0.7)2O3 show worse wear resistance with a wear rate higher than 1.0 × 10−5 mm3/N·m at 200 − 600 °C due to reduced hardness and lower residual stress. A higher bias potential of −150 V induces higher compressive residual stress and hardness, which is beneficial to the high-temperature wear resistance of Cr–Al–O coatings.

Silicon addition as a way to control properties of tribofilms and friction of DLC coatings

DLC-Si coatings obtained by cathodic arc evaporation on the (CrAlSi)N sublayer were investigated. The effect of Si addition to DLC on the ID/IG ratio, surface morphology, elastic modulus of surface layers, distribution of elastic modulus and microhardness (over the surface and depth of the coating), specific surface energy, coefficient of friction, wear, and thickness of nanoscale layers formed during friction was studied. The nanoscale thickness of the secondary structures has been evaluated by atomic force microscopy for the first time. It has been established that secondary structures are assembled into nanosized layers and chains, which is explained by sp2 bonds between nanosized clusters. The most hardened layer after friction is formed on the DLC + 0.8 % Si coating. The maps of the elasticity modulus and microhardness distributions are presented. The significant contact pressure is the driving force causing the transformation of the DLC phases during friction. According to the results of microtribotests in wear tracks after macrotests, the average values of the coefficient of friction from microtests correlate with the thickness of the secondary structures on the silicon content of the coatings and with the specific volumetric wear of the coating (for the DLC + 5 % Si coating have the highest values).

Investigation of corrosion and tribological characteristics of annealed CrN/CrAlN coatings deposited by CAE-PVD

In this work, the variation of tribological and corrosion performances of as-deposited and annealed CrN/CrAlN multilayer coatings on 304 stainless steel substrates deposited by the cathodic arc evaporation process was investigated. It was found that annealing resulted in the decomposition of CrN to Cr2N. Also, the surface roughness increased as the annealing temperature increased due to the coalescence of macroparticles. Thus, the wettability of annealed samples decreased as the annealing temperature increased. The hardness decreased as the annealing temperature increased due to the increase in the crystallite size. The sample annealed at 400 °C had the lowest wear rate of 3.04 × 10−5 mm3/Nm and 6.4 × 10−5 mm3/Nm in ambient air and Ringer's solution, respectively, due to the optimum ratio of CrN and Cr2N, minimum crystallite growth, and optimum adhesion strength. Based on the electrochemical impedance spectroscopy results, the highest corrosion resistance was observed in the specimen annealed at 700 °C, which can be attributed to the existence of Cr2N and larger crystallite size in this multilayer coating.

EFFECT OF ARC CURRENT ON MECHANICAL PROPERTIES OF AlCrN COATINGS DEPOSITED USING CATHODIC ARC EVAPORATION

The AlCrN coatings were formed using cathodic arc evaporation at constant nitrogen pressure and arc current ranged from 50 to 120 A. Scanning electron microscopy, energy dispersive analysis, X-ray diffractometry, nanoindentation, adhesion tests and friction tests were used to investigate the effect of arc current on surface morphology, composition, structure, and mechanical and tribological properties of coatings. It was found that all coatings present cubic AlCrN with Al/(Al+Cr) ratio independent on arc current. Increase in the arc current results in increase in lattice parameter, crystallite size as well as deposition rate and coating surface roughness. A decrease in hardness with a simultaneous increase in Young's modulus is also observed. The adhesion of the coatings shows a non-linear character with the maximum (108 N) for the coating formed at an arc current of 80 A, which may explain the best wear resistance – the lowest wear rate 1.4·10-7 mm3/Nm.

EFFECT OF NITROGEN PRESSURE ON THE STRUCTURAL AND MECHANICAL PROPERTIES OF V-Mo-N COATINGS DEPOSITED BY CATHODIC ARC EVAPORATION

The coatings of the V-Mo-N system were deposited by the cathodic arc evaporation method from the unfiltered plasma of two V and Mo cathodes. Electron microscopy, energy dispersive analysis, X-ray diffractometry, nanoindentation, and adhesion testing have been used to study the effect of nitrogen pressure during deposition on surface morphology, composition, structure, and mechanical properties of coatings. It was found that at a nitrogen pressure of 1 Pa the V29Mo21N50 coating formed with a predominantly cubic c-(V,Mo)N structure and an insignificant fraction of hexagonal h-(Mo,V)N. With an increase in the pressure of the reaction gas to 2…3 Pa, a gradual increase in the concentration of nitrogen up to 54 at.% and molybdenum up to 26 at.% is observed, which leads to a slight increase in the hexagonal phase concentration. All coatings are characterized by a fairly good surface quality, high hardness of 30…32 GPa and adhesion to the steel substrate. The c-(V,Mo)N coating has better resistance to crack propagation, correlates with a maximum H3/E2 – 0.18, and combines high hardness and ductility.

Short pulse-enhanced vacuum arc evaporation

The paper studies a new method in vacuum-arc deposition technology that can be called short pulse-enhanced vacuum arc evaporation (s-PEVAE). This deposition technique combines sub-microsecond high-current pulsed and direct current operation of the arc-discharge source with the pulse frequency of several kilohertz. The high pulse voltage provides a high growth rate and amplitude of discharge current pulses, i.e., over 109 А/s and 1 kА, respectively. During the s-PEVAE process, the arc discharge power can achieve several hundreds of kilowatts. According to optical and probe measurements performed during the titanium evaporation in argon gas, ionization provided by s-PEVAE is higher than that provided by direct current vacuum arc evaporation (DCVAE). In s-PEVAE, the increase in the average discharge power is accompanied by the growth in the average density of the substrate ion current. At the same time, the deposition rate of the titanium coating decreases. All this leads to a significant change in the ratio between the ions bombarding the substrate and metal atoms forming the coating. Along with the substrate bias voltage, this ratio exerts a strong effect on the structure and properties of the deposited coating and can be controlled by the pulse parameters such as amplitude, time, and frequency.

The effect of substrate surface integrity on the surface properties of TiCrN coating applied via the CAE‐PVD method

AbstractThis study aims to investigate how the predeposition machining processes such as magnetic grinding, turning machining, and wire electrical discharge machining can influence the surface properties including electrochemical and tribological behavior of TiCrN nanostructured coating applied on Mo40 steel substrate. A physical vapor deposition technique using cathodic arc evaporation was used to apply the coating. The crystallographic phases and the microstructure of the coating were studied by X‐ray diffraction and scanning electron microscope, respectively. Rockwell‐C, electrochemical impedance spectroscopy and potentiodynamic polarization, and pin‐on‐disk wear tests were employed to evaluate the adhesion strength, corrosion behavior, and tribological property of specimens, respectively. The electrochemical results after 24 h of exposure to 3.5 wt% NaCl solution showed that TiCrN coating pretreated with a turning process with polarization resistance of about 3525.32 Ω.cm2 had the best corrosion resistance among all specimens. This was because of the improvement of the smoothness, surface quality, and adhesion after the turning process. On the other, the friction coefficient of the grounded sample is less than that of other ones. This is probably due to its higher adhesion strength and higher surface smoothness.

Tailoring the Hybrid Magnetron Sputtering Process (HiPIMS and dcMS) to Manufacture Ceramic Multilayers: Powering Conditions, Target Materials, and Base Layers.

The mechanical and wear behavior of CrN/CrAlN multilayers were improved by tailoring the experimental conditions of a hybrid magnetron sputtering process based on a high-power impulse (HiPIMS) and two direct current magnetron sputtering (dcMS) power supplies. To this end, the influence of the base layer and of the combination of Cr and CrAl targets, which were switched to the dcMS and HiPIMS power supplies in different configurations, were investigated with respect to the growth of ceramic CrN/CrAlN multilayers onto commercial gas-nitrided diesel piston rings. The microstructure, grain morphology, and mechanical properties were evaluated by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and instrumented nanoindentation. Bench wear tests simulating the operation of a combustion engine were conducted against a gray cast iron cylinder liner under reciprocating conditions using 0W20 oil as a lubricating agent enriched with Al2O3 particles. The results revealed a significant increase in hardness, resistance to plastic strain, and wear resistance when two CrAl targets were switched to a HiPIMS and a dcMS power supply, and a Cr target was powered by another dcMS power supply. The compressive coating stresses were slightly reduced due to the soft Cr base layer that enabled stress relief within the multilayer. The proposed concept of hybrid magnetron sputtering outperformed the commercial PVD coatings of CrN for diesel piston rings manufactured by cathodic arc evaporation.

Tailoring the scratch adhesion strength and wear performance of TiNiN nanocomposite coatings by optimising substrate bias voltage during cathodic arc evaporation

The tribological properties of TiN-based coatings can be substantially influenced by the choice of substrate bias employed during physical vapor deposition. However, the effects of applied substrate bias voltages during cathodic arc evaporation on to the scratch adhesion strength and wear resistance of TiNiN coatings have not been previously studied. In this present work, a series of TiNiN coatings were fabricated onto tool steel (M2) substrates using the cathodic arc evaporation method by applying a range of bias voltages to the substrate. The aim of this study is to investigate the scratch response and wear performance of these coatings along with an investigation of the deformation mechanisms in operation during scratch and wear tests. The best scratch adhesion strength (i.e., greater LC1, LC2 and CPRs values) was noted for the coating prepared at a bias voltage of −100 V, which was ascribed to the synergistic responses arising from superior mechanical properties, the influence of a high compressive residual stress and a fine, equiaxed nanocomposite structure, that acted to promote effective resistance against cohesive and adhesive failure. Further, the failure mechanisms under progressive loading conditions were also investigated through observation of the complex crack patterns generated, compressive residual stress values and the coatings' hierarchical design. An approximately 85 % enhancement in wear resistance for these TiNiN coatings was achieved as the bias voltage was increased from 0 V to −100 V. This −100 V coating exhibited the highest values of H/Er (>0.1) and We (>60 %), as well as the highest Ni concentration (~ 4 at.%).

Influence of ion irradiation-induced defects on phase formation and thermal stability of Ti0.27Al0.21N0.52 coatings

The influence of changes induced by ion irradiation on structure and thermal stability of metastable cubic (Ti,Al)N coatings deposited by cathodic arc evaporation is systematically investigated by correlating experiments and theory. Decreasing the nitrogen deposition pressure from 5.0 to 0.5 Pa results in an ion flux-enhancement by a factor of three and an increase of the average ion energy from 15 to 30 eV, causing the stress-free lattice parameter to expand from 4.170 to 4.206 Å, while the chemical composition of Ti0.27Al0.21N0.52 remains unchanged. The 0.9% lattice parameter increase is a consequence of formation of Frenkel pairs induced by ion bombardment, as revealed by density functional theory (DFT) simulations. The influence of the presence of Frenkel pairs on the thermal stability of metastable Ti0.27Al0.21N0.52 is investigated by scanning transmission electron microscopy, differential scanning calorimetry, atom probe tomography and in-situ synchrotron X-ray powder diffraction. It is demonstrated that the ion flux and ion energy induced formation of Frenkel pairs increases the thermal stability as the Al diffusion enabled crystallization of the wurtzite solid solution is retarded. This can be rationalized by DFT predictions since the presence of Frenkel pairs increases the activation energy for Al diffusion by up to 142%. Hence, the thermal stability enhancement is caused by a hitherto unreported mechanism - the Frenkel pair impeded Al mobility and thereby retarded formation of wurtzite solid solution.

Effect of Silicon on the Surface Modification of Al-Cr Powder Cathodes Subjected to Vacuum Arc Treatment

Al-Cr and Al-Cr-Si composite cathodes were obtained by the hot compaction of aluminum, chromium, and silicon powder mixtures. The phase transformations in the surface layer of the Al-Cr-Si composite cathodes subjected to the arc heating were considered. The elemental and phase compositions of the modified cathodes’ surfaces were studied using X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The effect of the silicon addition on the structural evolution in the cathode surface during arc evaporation is shown. It was found that an arc impact on the cathode surface resulted in the melting and consequent crystallization of the multiphase mixture of intermetallic compounds and eutectic in the cathode surface layer. Cathode surface layers were found to be depleted of aluminum and silicon due to the ejection of these elements in drop form from the Al-Si liquid layer on the cathode surface. This can result in the change in the elements ratio in the deposited coating as compared with that in the cathode and thus influence the coated tools’ durability.

Modelling and experimental investigations of composition-dependent heat and mass transfer during Cu–Ni alloy nanoparticle synthesis in a transferred arc helium plasma

In the synthesis of alloy nanoparticles (NPs) via arc evaporation and fast quenching, the composition of the synthesized NPs differs significantly from that of the precursor. The properties of the NPs formed following evaporation of a copper–nickel anode by a helium arc are investigated using a nucleation model coupled to the thermal and flow fields derived from a magneto-hydrodynamic simulation of the arc, and experimentally. Results are obtained for three different Cu:Ni precursor compositions, 10:90, 50:50 and 90:10 at%. The synthesized particles are spherical with different size distributions and have a higher concentration of Cu than the precursor in all three cases, in contrast to previous observations, but in accordance with the predictions of the model. Emission spectroscopic measurements of copper and nickel lines indicate that the concentration of atomic copper in the plasma region near the anode is much higher than that of the nickel, in accordance with the predictions of the model. The higher vapour pressure of copper compared to nickel, and its higher activity in the alloy precursor (anode), immersed in a self-consistent thermal and flow field maintained by the transferred arc are found to play a critical role. The thermodynamic, radiative and transport properties of the helium plasma contaminated with evaporated precursor are important in determining the thermal and flow fields.

Evolution of the fracture properties of arc evaporated Ti1-xAlxN coatings with increasing Al content

Although the positive effect of an increasing Al content in Ti1-xAlxN hard coatings within the cubic regime is thoroughly investigated, there is a lack of systematic studies on the fracture properties. Thus within the present work, seven Ti1-xAlxN coatings with increasing Al content from x = 0 up to x = 0.78 were deposited by cathodic arc evaporation. Using scanning electron microscopy and X-ray diffraction, a grain refinement with increasing Al content up to x = 0.65 could be observed, while the coating with the highest Al content of x = 0.78 showed again a coarser grain size. The presence of a single phase face-centered cubic (fcc)-structure up to an Al content of x = 0.49 was confirmed by X-ray diffraction. Ti0.44Al0.56N and Ti0.35Al0.65N exhibited a dual phase fcc- and wurtzitic (w)-structure, where for the latter the w-structure is dominating. A single phase w-structure was observed for the Ti0.22Al0.78N coating. Nano-indentation experiments revealed an increasing hardness with increasing Al content up to x = 0.56 and thus, as long as the fcc-phase is dominating, due to decreasing grain size and increasing compressive stress. For the coatings with dominating and pure w-structure a drop in hardness was observed. Similar to the hardness, the micromechanical bending tests also revealed improving fracture properties with increasing Al content up to x = 0.56 and deteriorating fracture properties when the w-structure becomes dominant.

The Impact of Bias and Nitrogen Pressure on TiNbN Coatings in Arc-PVD Processes—A Multifactorial Study

Titanium-based nitride physical vapour deposition (PVD) coatings, such as titanium nitride (TiN), are state-of-the-art solutions for surface modifications of CoCrMo-based implants for patients who are hypersensitive to metallic ions such as cobalt, chromium and nickel. Variations of the process parameters during the cathodic arc evaporation are known to exhibit an impact on the surface properties of coatings. The aim of this study was to characterise the effect of the substrate bias and the nitrogen pressure on the surface properties of TiNbN coatings deposited on CoCrMo alloys in a limited parameter set. Eighteen parameter sets were coated with TiNbN. The substrate bias (−100 to −200 V) and the nitrogen pressure (0.3–3.0 Pa) were selected following a randomised, multifactorial response surface test design. The coating thickness, roughness, hardness and scratch resistance were measured following standardised procedures. The structure of the coating was analysed by SEM and XRD. The substrate bias and the pressure exhibited a significant impact on the coating thickness and the surface roughness. The grain growth was predominantly impacted by the bias. The parameter variation did not show any significant impact on the XRD, hardness or scratch test results.

Improving the mechanical, tribological, and electrochemical behavior of AISI 304 stainless steel by applying CrN single layer and Cr/CrN multilayer coatings

The purpose of this study was to assess the mechanical and tribological behavior of chromium nitride (CrN) single layer and multilayer nanostructured coatings of chromium/chromium nitride (Cr/CrN) applied on AISI 304 stainless steel to be used in a marine application. CrN and Cr/CrN coatings were performed using cathode arc evaporation a division of physical vapor deposition (CAE-PVD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM) were utilized for phase identification of coatings and surface morphology, respectively. Nano-indentation method was used to investigate the mechanical behavior of coatings. The tribological behavior of the coatings was studied by the ball-on-disk method. The results indicate that the mechanical behavior of the Cr/CrN multilayer nanostructured coatings is better in comparison to the CrN single-layer coatings. The hardness values of CrN and Cr/CrN coatings were 21.5 and 23.3 GPa, respectively. The higher hardness of the nanolayered coating might be owing to blocking the movement of dislocations and microcracks by its layered structure. Furthermore, the tribological behavior of AISI 304 stainless steel was highly amended by applying the coatings. The coefficient of friction for CrN and Cr/CrN coatings in a dry condition decreased from 0.61 to 0.49 and 0.46, respectively. Also, the CoF value reduced from 0.57 to 0.38 and 0.37 in 3.5 wt% NaCl electrolyte. The lower friction coefficient of the Cr/CrN multilayer nanostructured coating is perhaps due to its higher hardness and lower roughness.

High-Efficiency of PVD Coating Process by Applying an Additional Rotation

This article analyzes PVD coatings (physical vapor deposition—the coating material is vaporized and deposited by sputtering or arc evaporation, and PVD coatings are applied at lower substrate temperatures and thus can be applied to a wider range of substrates) applied to samples which are located in a fixture. This fixture enables additional rotation of the sample via the coating process. The fixture allows an increase of coated tools in one batch, and therefore an increase of the current capacity of the coating machine. The introductory section of the article describes the process of product design, including its modifications. The experimental section is focused on the functionality checking of the proposed design. The coating process was carried out on a machine named INNOVA. To guarantee the correct coating application during the process, it is necessary to research the coating thickness and the chemical composition of the samples and compare these results with the results of samples which were coated without using a designed fixture. Round bars with a diameter of 10 mm were chosen as test samples. On these samples, a FUTURA monolayer was applied on a TiAlN base. Chemical composition and coating thickness were evaluated using a scanning electron microscope (SEM). Using a fixture with a fourth rotation, the same chemical composition and coating thickness were achieved as those samples which were coated in a process without the use of a fourth rotation. Therefore, it was possible to confirm a capacity increase of the coating machine.

Effect of the alloying elements in TiN sublayer on the structure and mechanical properties of carbon coatings

Amorphous carbon (a-C) coatings have numerous practical applications as antifriction or hard coatings. However, they are incredibly fragile and not compatible with many substrates. Therefore it is necessary to manage and improve the mechanical properties of a-C coatings, which depend on the properties and composition of the intermediate sublayer deposited between the substrate and coating. In this study, we proposed to control the structural and phase composition and, therefore, properties and practical applicability of a-C coatings deposited by pulsed cathodic arc by altering the chemical composition of the titanium nitride (TiN) sublayer deposited by direct current arc evaporation. We studied the effect of highly reactive and chemically neutral alloying elements on the coating structure and properties using aluminum and copper as typical examples. The results of Raman and X-ray photoelectron spectroscopies, atomic force microscopy, and mechanical testings suggested that highly reactive alloying elements led to an increase of the hardness and elastic modulus of the bilayered coating while alloying with copper resulted in a reduced friction coefficient. We also demonstrated that the introduction of aluminum in TiN sublayers increased the strength of the bilayer coatings and the crack resistance of the upper a-C layer. As a result, we achieved a significant level of control of the mechanical properties of the a-C coatings, which could be of interest in mechanical engineering or metallurgy for targeted control of the surface properties of products through the application of these coatings with expected and controllable mechanical properties.