Physical Vapor Deposition Hard Coatings Research Articles

Comparison Study of PVD Coatings: TiN/AlTiN, TiN and TiAlSiN Used in Wood Machining.

In this paper, we analyze the possibilities of the protection of tools for wood machining with PVD (Physical Vapor Deposition) hard coatings. The nanolayered TiN/AlTiN coating, nanocomposite TiAlSiN coatings, and single layer TiN coating were analyzed in order to use them for protection of tools for wood machining. Both nanostructured coatings were deposited in an industrial magnetron sputtering system on the cutting blades made of sintered carbide WC-Co, while TiN single layer coating was deposited by evaporation using thermionic arc. In the case of TiN/AlTiN nanolayer coatings the thickness of the individual TiN and AlTiN layer was in the 5–10 nm range, depending on the substrate vertical position. The microstructure and chemical composition of coatings were studied by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) method. Additionally, in the case of the TiN/AlTiN coating, which was characterized by the best durability characteristics, the transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) methods were applied. The coatings adhesion to the substrate was analyzed by scratch test method combined with optical microscopy. Nano-hardness and durability tests were performed with uncoated and coated blades using chipboard. The best results durability characteristics were observed for TiN/AlTiN nanolayered coating. Performance tests of knives protected with TiN and TiAlSiN hard coatings did not show significantly better results compared to uncoated ones.

Self‐lubricating CrAlVN coatings for turning of Ti6Al4V: oxidation and wear behavior

AbstractThe titanium alloy Ti6Al4V enables significant performance increases in various branches of industry. Nevertheless, it is difficult to machine, because of its material properties. Due to the low thermal conductivity of titanium, the heat generated while turning Ti6Al4V mainly flows into the tool leading to high temperature loads. In addition, the comparatively low Young's modulus and high yield strength contributes to high mechanical stresses during machining. Temperature active, self‐lubricating physical vapor deposition hard coatings appear to be suitable for reducing friction and tool wear during turning of Ti6Al4V compared to the most commonly used uncoated carbide tools. The ability of the coating to form lubricating oxide phases at high temperatures is crucial for this purpose. This paper investigates the oxidation and diffusion behavior of vanadium doped chromium aluminium nitride (CrAlN) coatings after heat treatment at ϑ = 600 °C, ϑ = 700 °C und ϑ = 800 °C in atmosphere as well as the resulting coating properties. The wear behavior of certain coating variants while turning of Ti6Al4V is analyzed.

Lapping and polishing of additively manufactured 316L substrates and their effects on the microstructural evolution and adhesion of PVD CrAlN coatings

Laser powder bed fusion (LPBF) enables the manufacturing of three-dimensional parts from metallic powder with a high degree of design-freedom. Due to the low hardness in order to protect tribologically stressed surfaces against severe wear, the surface of LPBF parts made of 316L stainless steel needs to be modified by coating processes such as physical vapor deposition (PVD) using hard coatings. Although 316L is among the most investigated material for LPBF, the deposition of PVD hard coatings such as ternary nitride coatings on additively manufactured 316L substrates has not been studied yet.This study aims at evaluating the effects of lapping and polishing of 316L stainless steel substrates processed by LPBF on the resulting surface integrity and its influence on the microstructural evolution and adhesion of PVD CrAlN coatings. A 316L substrate bulk material served as reference throughout the investigations. The 316L substrate CrAlN coating composites were examined with respect to the microstructural characteristics and residual stresses using nanoindentation and two-dimensional X-ray diffraction. To assess the adhesion of the CrAlN coating on the differently pre-treated 316L substrates, scratch and Rockwell C adhesion tests were conducted. The resulting scratch tracks and Rockwell C indents were metallographically examined in order to determine the failure modes. The results demonstrate that the deposited PVD CrAlN coatings differ in their texture and mechanical properties, such as hardness and residual stresses, depending on the 316L substrate surface conditions. The CrAlN coatings generally exhibit good adhesion to both the 316L LPBF substrate and 316L bulk material. However, the findings indicate improved adhesion of CrAlN coatings on lapped 316L substrates. The residual stress gradient at coating-substrate interface and imperfections at the surface of the 316L LPBF substrate are found to primarily influence the performance and failure mode of the CrAlN coating.

Smart PVD hard coatings with temperature sensor function

In manufacturing technology, the performance of the tools have to conform to increasingly higher standards. Aditionally, recording process data during production is becoming more and more important in the Industrie 4.0. Thin hard tool coatings deposited by physical vapor deposition (PVD) and serving as protection from wear and corrosion are state of the art in manufacturing technology since decades. Integrating additional functions into the coatings will help extend the process limits faced by the load collective in manufacturing technology. One approach here is to exploit the electrical properties of thin coatings to design sensors for temperature measurement. The overall objective of this study is therefore the design PVD sensor coatings. These coatings should facilitate an online measurement of the surface temperature and offer a thermal resistance up to a few hundred degrees centigrade that allows their application in different technical applications. The hard coatings are selected for the two multilayer sensor coatings presented, because they are state of the art as wear protection for numerous manufacturing technology tools. Their temperature sensor function is based on the thermoelectric effect, expected because of the metallic bonding parts of the single coatings. Electrically insulated by Al 2 O 3 , the one material pair consists of CrN/AlN and TiAlN layers. The other material pair consists of a CrAlN and a TiAlN layer. Both sensor coatings show a dense and fine crystalline morphology as well as interlayer without cracks or damages in the SEM crosssection, even between the oxide insulation layer and the nitride sensor layers. Phase stability and oxidation resistance up to at least T ≤ 700 °C are demonstrated for all coating materials. For both sensor coatings, the ability to measure potential differences as a function of the applied temperature is demonstrated. The sensor coating, which in addition to TiAlN consists of a second sensor layer CrN/AlN with nanolaminate architecture, shows a better response behavior and a lower scattering of the measuring values. • Combination of wear protection coatings for multilayer sensor coatings • Temperature measurement by nitridic hard coatings is possible. • Higher temperature measuring accuracy for sensor coating CrN/AlN+TiAlN • Thermal resistivity up to T ≤ 700 °C for developed nitride sensor coatings

Self-Lubricating PVD Hard Coatings through Tribological Activation

PVD (physical vapor deposition) hard coatings are widely used and common in manufacturing technologies, for the use as wear and oxidation protection of tools and components. Therefore, many specialized hard coatings systems have been developed until now. Nevertheless, there is a demand to improve the functionality of PVD hard coatings, i.e. due to a self-lubricating effect through tribological activation. According to the current state of research, solid lubricants with lattice layer structure and oxidic solid lubricants are particularly suitable for this purpose. This work gives an overview on the functional mechanisms as well as required environmental conditions and activation mechanisms of transition metal dichalcogenides (TMD) and Magnéli-phases.

Corrosion resistance of PVD hard coatings for tribological engineering applications

The present paper focuses on corrosion resistance of hard coatings deposited on tool steel via Physical Vapour Deposition (PVD) process. Three coating types were investigated – TiN, TiCN and DLC/TiAlN. An immersion corrosion test was performed on the PVD coated tool steels in accordance to ASTM G31 standard. With immersion corrosion test in aggressive media of 3.5% NaCl solution at ambient temperature of 33°C and exposure duration of up to 72 hours, the presence of the PVD coatings on the tool steel surface have improved the corrosion resistance of the tool steel surfaces. The results showed that the DLC/TiAlN coated tool steel has the highest corrosion resistance with corrosion rate of 36.58 mm/year, followed by TiCN and TiN coatings with corrosion rate of 42.10mm/year and 96.86 mm/year, respectively. The uncoated tool steel exhibits the lowest corrosion resistance of 140.61 mm/year. The present study suggests that the DLC coating deposited on SKD11 tool steel substrate has better stability than that of TiCN- and TiN-coated surfaces because the DLC can prevent the corrosion more efficiently than TiCN and TiN.

Understanding the deformation and cracking behavior of Cr-based coatings deposited by hybrid direct current and high power pulse magnetron sputtering: From nitrides to oxynitrides

The increasing demand for corrosion and wear reduction in modern tribological systems places high requirements on hard coatings deposited by physical vapor deposition (PVD) technology in numerous technical applications e.g., plastic processing, die casting or machining. One possible approach to withstanding the excessive wear is coating of tools with PVD hard coatings of the system Cr-Al-O-N. Each of the constituent elements can provide the coating with particular characteristics in point of its performance under different loading conditions. Therefore, the ongoing improvement in modern surface engineering requires comprehensive insights into the elastic-plastic deformation and cracking behavior of such coatings. For this purpose, several modifications and extensions of established experiments are required to overcome the limitations involved in characterization of thin hard coatings e.g., as a result of the μm ranges. In the presented work, three coatings CrN, (Cr,Al)N and (Cr,Al)ON deposited on quenched and tempered AISI 420 steel substrate were investigated. All coating systems were deposited through a hybrid technology, consisting of direct current and high power pulse magnetron sputtering (dcMS/HPPMS). The deformation and cracking behavior of the coatings and coating/substrate compounds were studied through application of static loadings by nanoindentation and Rockwell tests as well as dynamic loading conditions using nanoscratch tests. Complementary quantitative investigations were performed by means of depth profiling using confocal laser scanning microscopy (CLSM). Qualitative analyses of Rockwell imprints and nanoscratch tracks were conducted through scanning electron microscopy (SEM). Based on the results, precise analyses of nanoindentation force-displacement curves can improve the understanding about the possible crack formation in the coatings. Compared to (the binary) CrN, the ternary coating system (Cr,Al)N exhibits more promising characteristics in point of elastic-plastic deformation behavior and crack resistance. The crack resistance decreases through incorporation of oxygen into the ternary nitride and deposition of quaternary oxynitrides (Cr,Al)ON. Such character of oxynitrides can be overseen taking into consideration only the static loadings and therefore, applying of the both static and dynamic loading conditions are required to gain precise knowledge on the deformation and cracking behavior of thin hard coatings.

Dünne PVD‐Hartstoffschichten zur Online‐Temperaturmessung

SummaryThin PVD hard coatings for the online temperature measurementIn the processing industry, process control and the improvement of manufacturing processes become increasingly important. Therefore the acquisition of important process data during production becomes the focus of attention. Physical Vapor Deposition (PVD) allows the deposition of only a few micrometers thin coatings, which follow the shape of the coated surface. They have functionalities and can also increase the wear and corrosion resistance of the coated production tool or components. The aim of this article was the development of thin PVD coatings which can measure temperatures ranging from room temperature up to several hundred centigrades. Therefore, two different coating systems are presented and analyzed with regard to their suitability for temperature measurement. The overall aim is intended to measure the temperature in the interface between the tool surface and the processed workpiece in cutting process or between the tool surface and the melt by primary forming. The sensor coating provides the possibility of an online temperature measurement and the forwarding of this process data. The operating principle is based on the thermoelectric effect, which is also known as the Seebeck effect.

Microstructural effect on the tribo-corrosion behaviors of magnetron sputtered CrSiN coatings

Minimization of corrosion loss or corrosion-related loss is highly desirable for enhancing the tribo-corrosion resistance of physical vapor deposition (PVD) hard coatings. Various tribo-corrosion tests against Al2O3 counterparts combined with microscopic examinations, were used to study the tribo-corrosion behaviors of three typical kinds of magnetron sputtered CrSiN coatings. The dense and columnar coating exhibited superior tribo-corrosion resistance, with a lowest specific tribo-corrosion rate of 6 × 10−16 m3/N m and a lowest friction coefficient of ~0.14, where the dominant mechanism was considered as a layer-by-layer mechanical removal and the chemical corrosion was inappreciable. The porous and columnar coating failed for its poor intrinsic corrosion resistance. For the almost column-free coating, brittle fracture leaded to an increase of the corrosion component in the material wear, despite that the coating had the best intrinsic corrosion resistance. The comparison studies demonstrated that the dominant factors of the tribo-corrosion resistance are more complicated than purely mechanical wear or purely chemical corrosion; high compactness, effectively crack-controlled wear, and the dynamic equilibrium of depassivation-repassivation surfaces on the worn are indispensable for the highly tribo-corrosion resistant PVD hard coatings.

Laser-structured high performance PVD coatings

Structured plastic components, which are used for flow-optimization, self-cleaning surfaces and optical applications, are usually produced by injection molding using structured tools. A suitable technique for structuring these tools on macro and nanometer scales is laser ablation, which offers a high level of accuracy and flexibility. The influence of laser treatments for the fabrication of nanostructures on the surface properties of steel has been extensively investigated. In contrast, there are only few studies dealing with the cause-effect mechanisms between a corresponding laser treatment and PVD (physical vapor deposition) hard coatings.This work deals with the influence of a laser nanostructuring on the properties of different CrAl-based PVD hard coatings. For this purpose, three coatings, one nitride (Cr,Al)N and one oxynitride (Cr,Al)ON, as well as one CrN/AlN nanolaminate were deposited on steel AISI 420 (X42Cr13, 1.2083) using a PVD process. The coatings were structured by means of an ultra-short pulsed (USP) laser with a varying laser pulse energy (Ep) ranging from Ep1=0.005mJ over Ep2=0.011mJ to Ep3=0.018mJ. On the one hand, an increasing laser pulse energy leads to significantly greater structural depths. This was quantified by confocal laser scanning microscopy (CLSM). On the other hand, it has been found that, in excess of a certain laser pulse energy, the universal hardness of the coatings decreases. By means of microstructural investigations, such as X-ray diffraction (XRD) and transmission electron microscopy (TEM), this effect was investigated and characterized. It was found that thermal effects induced during laser structuring lead to an increasing ratio of amorphous to crystalline domains of the PVD coating, causing the reduction in hardness. Finally, suitable combinations of PVD hard coatings and laser structuring parameters are recommended.

Industrial evaluation of duplex PVD hard coatings for HPDC

During high pressure die casting (HPDC), molten metal is injected into the tool cavity where it reaches high velocities that cause substantial wear of the tool components. In order to mitigate this problem, different surface treatments are sometimes employed for high production tools. The most common treatments are nitriding and physical vapor deposition (PVD) of hard coatings. Within this study, effectiveness of two duplex PVD hard coatings, CrN and TiAlN, was tested on core pins, which are the most endangered elements of high pressure die casting tools. Core pins were tested in four industrial production runs of an automotive component. In every run, the tool was mounted with one pin that was PVD-coated, and one that was gas-nitrided. Nitrided core pins were used as a base standard since the nitriding is the most commonly used surface treatment. TiAlN-coated pins were able to complete a full production run of 22,000 shots without significant damage. CrN coating showed somewhat higher soldering tendency and erosion rates. Considering that the untreated core pins were able to withstand only 5500 shots, it can be concluded that duplex PVD coatings can significantly improve tool lifetime. Additionally, results indicate that often disregarded variances in casting temperature or in cleanliness of ingots used in production can significantly influence wear performance of HPDC tools. Analysis of the production costs has shown that the application of duplex TiAlN coating on the core pins can lead to significant savings for tested automotive components.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Improvement of Wear Performance of Nano-Multilayer PVD Coatings under Dry Hard End Milling Conditions Based on Their Architectural Development

The TiAlCrSiYN-based family of PVD (physical vapor deposition) hard coatings was specially designed for extreme conditions involving the dry ultra-performance machining of hardened tool steels. However, there is a strong potential for further advances in the wear performance of the coatings through improvements in their architecture. A few different coating architectures (monolayer, multilayer, bi-multilayer, bi-multilayer with increased number of alternating nano-layers) were studied in relation to cutting-tool life. Comprehensive characterization of the structure and properties of the coatings has been performed using XRD, SEM, TEM, micro-mechanical studies and tool-life evaluation. The wear performance was then related to the ability of the coating layer to exhibit minimal surface damage under operation, which is directly associated with the various micro-mechanical characteristics (such as hardness, elastic modulus and related characteristics; nano-impact; scratch test-based characteristics). The results presented exhibited that a substantial increase in tool life as well as improvement of the mechanical properties could be achieved through the architectural development of the coatings.

Evaluation of Residual Stresses in PVD Coatings by Means of the Curvature Method of Plate

Physical Vapor Deposition (PVD) coatings are primarily designed for metal cutting tools operating in extreme machining and blanking conditions. Residual stresses arising during coating deposition exert an important effect on the service life of the coating through influencing mechanical and tribological properties and adhesion. To determine macroscopic residual stresses, the conventional curvature method was used. As an application, residual stresses in four aluminum based PVD hard coatings, i.e. AlTiN, AlTiSiN, AlCrN, and AlCrSiN, were investigated in the presence of the Ti adhesion layer. Nickel steel plates and steel plates were used as the substrate. Residual stresses were compressive and high (3.0-7.5 GPa) in all coatings. Compressive stresses in coatings are desirable in cohesive tool damage as they strengthen the coating. The values of residual stresses were not significantly dependent on the angle of plate placement (parallel (0°), inclined (45°) and perpendicular (90°)) in relation to the PVD cathode in the deposition chamber. The magnitude of residual stresses is influenced by intrinsic strain at layer growth rather than by thermal stress.

Tribological behavior of superduplex stainless steel against PVD hard coatings on cemented carbide

Superduplex stainless steels (SDSS) are used to manufacture components in the oil and gas extraction industries. Machining of SDSS is difficult due to both built-up edge (BUE) formation on cutting tool surface at relatively low cutting speeds and rapid tool wear at higher cutting speeds caused by high strength and work hardening. Appropriate coating systems on cemented carbide tools (WC-Co) are crucial for adequate process performance, as well as SDSS/coated WC-Co tribological pair characterization. In this work, three types of coatings with chemical composition (at %) Al50Cr50N, Al60Cr40N, and Al50Cr50N/Ti95Si5N were deposited, by physical vapor deposition (PVD), on cemented carbide substrate. After, characterization was performed through X-ray diffraction (XRD), SEM, nanoindentation, tribological tests, and surface roughness. The results showed that SDSS prevailing wear mechanism was adhesion for all coatings investigated. Wear rate and friction coefficient are associated to coating chemical composition; Al50Cr50N/Ti95Si5N coating system presented the lowest interaction with SDSS, resulting in the lower friction coefficient and, consequently, reduced specific wear rate.

On the plastic deformation of chromium-based nitride hard coatings deposited by hybrid dcMS/HPPMS: A fundamental study using nanoscratch test

Tribological behavior and elastic-plastic deformation of hard coatings deposited by physical vapor deposition (PVD) under normal and lateral loads can be investigated using innovative nanoscratch tests. However, a comprehensive study of thin PVD coatings requires a precise insight into mechanisms of the observed plastic deformation. Nanoscratch analyses on nanostructured PVD hard coatings and investigations of the mechanisms of resulted plastic deformation are the subjects of current research. In the presented work, two coatings CrN and (Cr,Al)N deposited on quenched and tempered AISI 420 steel substrate were investigated. The coatings were synthesized using a hybrid technology, consisting of direct current and high power pulse magnetron sputtering dcMS/HPPMS. Nanoscratch tests were performed with constant normal loads applying Berkovich and conical indenters. Despite significant hardness, these coatings deformed plastically under applied forces. Plastic deformation of the coatings was investigated by means of confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were applied to explore the mechanism of plastic deformation of the investigated coatings. Based on the results of CLSM and SEM, (Cr,Al)N exhibited a higher resistance against plastic deformation compared to CrN. The TEM investigations furthermore revealed that neither micro-crack formation nor dislocation motion inside the individual grains led to the observed plastic deformation. The dominating mechanism of the plastic deformation of investigated coatings is explained by sliding of grain boundaries (GBS) as the main reason.

PVD硬質薄膜の塑性加工への応用の現状

PVD硬質薄膜の塑性加工への応用の現状

Effect of Annealing Temperature on the Water Contact Angle of PVD Hard Coatings.

Various PVD (physical vapor deposition) hard coatings including nitrides and metal-doped diamond-like carbons (Me-DLC) were applied in plastic injection and die-casting molds to improve wear resistance and reduce sticking. In this study, nitrides hcp-AlN (hexagonal close-packed AlN), Cr2N, (CrAl)2N) and Me-DLC (Si-DLC and Cr-DLC) coatings were prepared using a closed field unbalanced magnetron reactive sputtering system. The coatings were annealed in air for 2 h at various temperatures, after which the anti-sticking properties were assessed using water contact angle (WCA) measurements. The as-deposited hcp-AlN, Cr2N and (CrAl)2N coatings exhibit hydrophobic behavior and exhibit respective WCAs of 119°, 106° and 101°. The as-deposited Si-DLC and Cr-DLC coatings exhibit hydrophilic behavior and exhibit respective WCAs of 74° and 88°. The annealed Cr2N and (CrAl)2N coatings exhibit hydrophobic behavior with higher WCAs, while the annealed hcp-AlN, Si-DLC and Cr-DLC coatings are hydrophilic. The increased WCA of the annealed Cr2N and (CrAl)2N coatings is related to their crystal structure and increased roughness. The decreased WCA of the annealed hcp-AlN, Si-DLC and Cr-DLC coatings is related to their crystal structures and has little correlation with roughness.

Investigation of the performance of carbide cutting tools with hard coatings in hard milling based on the response surface methodology

Machining of hard materials has become a great challenge for several decades. One of the problems in this machining process is early tool wear, and this affects the machinability of hard materials. In order to increase machinability, cutting tools are widely coated with nanostructured physical vapor deposition hard coatings. The main characteristics of such advanced hard coatings are high microhardness and toughness as well as good adhesion to the substrate. In this paper, the influence of hard coatings (nanolayer AlTiN/TiN, multilayer nanocomposite TiAlSiN/TiSiN/TiAlN, and commercially available TiN/TiAlN) and cutting parameters (cutting speed, feed rate, and depth of cut) on cutting forces and surface roughness were investigated during face milling of AISI O2 cold work tool steel (∼61 HRC). The experiments were conducted based on 313 factorial design by response surface methodology, and response surface equations of cutting forces and surface roughness were obtained. In addition, the cutting forces obtained with the coated and uncoated tools were compared. The results showed that the interaction of coating type and depth of cut affects surface roughness. The hard coating type has no significant effect on cutting forces, while the cutting force F z is approximately two times higher in the case of uncoated tool.

Runner-Up Magnetron Sputtered CrNx Coatings as Alternative to Electroplated Hard Chromium

The coating of engineering components with electroplated hard chromium is a widely used practice. These coatings are reasonably hard (~1000 HV) and are deposited in thicknesses of ~20 μm, having a fine microcracked structure. Physical vapour deposition (PVD) is an alternative technique, replacing the limited performance and environmentally unfriendly electroplating process (hexavalent chromium). CrNx is the most promising PVD coating to replace electroplated hard chromium. In contrast to other PVD hard coatings, it can be deposited in thicknesses up to 50 μm and at deposition temperatures below 250°C. The unbalanced magnetron sputtering technique allows reasonably high growth rates, typically several micrometers per hour. In contrast to cathodic arc evaporation, unbalanced magnetron sputtered coatings are smooth, without the arc typical droplets. The deposition equipment used in the present study allowed a wide range of deposition parameters leading to insights in the growth of bcc Cr–N, hcp Cr2N, and fcc CrN coatings. The following modifications were observed: a fine grained solid solution bcc Cr–N (1800 HV at 18 at.-%N) with a Young's modulus similar to that of steel; an under stoichiometric hcp Cr2N phase (2200 HV at 24 at.-%N); a soft single phase stoichiometric hcp Cr2N phase (1600 HV at 33 at.-%N); the established {110} textured fcc CrN phase (1800–2000 HV) and finally, a new hard fcc CrN phase (2700–3100 HV) obtained with high bias voltages ( >- 200 V) and nitrogen flow rates in excess of the argon flow. The latter coating promises excellent properties with respect to wear, friction and corrosion.