Physical Vapor Deposition Coatings Research Articles

Wear of Shaped Surfaces of PVD Coated Dies for Clinching

A clinching method that uses a simple toolset consisting of a punch and a die, is utilized for joining lightweight materials. This paper is aimed at investigating the wear of the die cavity of a clinching tool. A clinching tool with a specially shaped cavity was used for joining thin hot-dip galvanized steel sheets. Various types of physical vapour deposition (PVD) coatings such as ZrN, CrN and TiCN were deposited on the shaped surface of the die using Lateral Rotating Arc-Cathodes technology. Hot-dip galvanized steel sheets were used for testing the clinching tool. The material properties of PVD coatings that were deposited on the shaped part of the clinching die were evaluated. Finite Element Analysis was used to localize the area of the shaped part of the die and the part of surface area of the cylindrical die cavity of ϕ 5.0 mm, in which high contact pressure values were predicted. The prediction of the start of the wear cycle was verified experimentally by the clinching of 300 samples of hot-dip galvanized steel sheets. Unlike the CrN and ZrN coatings, the TiCN coating remained intact on the entire surface of the die.

Replication of micro-structured injection molds using physical vapor deposition coating and dynamic laser mold tempering

AbstractPlastics parts with micro-structured surfaces enable the development of innovative products such as optical components in sensors or light management systems for laser and LED applications. Moreover, micro-structured parts can be utilized in the medical and packaging industry for hydrophobic or antibacterial products. The production of micro-structured parts causes challenges in molding and demolding. Rough surfaces of the laser-structured mold inserts offer flow resistance during injection phase as well as increased demolding forces which cause failures of the replicated structures during ejection. Therefore, an innovative approach combines coated mold inserts by means of physical vapor deposition (PVD) and a highly dynamic laser tempering system to improve the replication of micro-structured plastics parts. Both uncoated and coated micro-structured mold inserts were used in a series of molding experiments by means of conventional and dynamic mold tempering. Based on the results, it can be shown that significant improvements of the replication of micro-structures of different sizes can be achieved by use of PVD mold coatings. This is attributed to the tribological interactions between coating and plastics melt. Furthermore, results indicate an influence of the thermal conductivity of PVD coatings to enhance replication quality.

Influence of substrate bias on microstructural evolution and mechanical properties of TiAlSiN thin films deposited by pulsed-DC magnetron sputtering

Substrate bias is one of the many factors, influencing the microstructure and, thus, properties of physical vapor deposition coatings. The aim of this study is to investigate the effect of varying substrate bias on the microstructure and mechanical properties of TiAlSiN coatings deposited on M42 tool steel substrates at 500°C by a pulsed-DC close-field unbalanced magnetron sputtering system (CFUBMS). The microstructure of the as-deposited coatings was characterized by a range of techniques, including transmission electron microscopy, glancing angle X-ray diffraction and X-ray photoelectron spectroscopy. In addition, nanoindentation measurements were conducted to evaluate the mechanical properties of these coatings. It was found that an increase in substrate bias imposed minimal effects on the composition of the as-deposited TiAlSiN coatings, but had a significant influence on both the phase composition and microstructure of the coatings. As the substrate bias voltage increased from −40 to −80V, a transition from zone-2 type structure to zone-3 type structure was observed, together with a reduction of the width of columnar grain from ~180 to ~60nm. There was also a structural transition from a mixed fcc TiN+fcc AlN phases into a single fcc TiAlN phase as the negative substrate bias was increased above 60V. Hardness and modulus were observed to increase with increasing bias voltage. Solid solution hardening and Hall-Petch effects are believed to be responsible for the hardness improvement.

The Effect of Surface Pre-Treatment and PVD Coating Post-Treatment on Texture of Surface ASP2052®/Tin

The aim of the paper is analyse changes of the surface texture during pre-treatment, PVD coating and post-treatment. Generally, the effect of the production technology is often discussed with well-known parameters such as material, geometry of tools, coating methods and conditions. Effect treatment of the substrate or tools manufacturing are mostly ignored. Pre-treatment, coating and post-treatment obviously change surface texture. Quality of surface or surface texture together with properties of the surface layer have a significant effect of lifetime and reliability of operation component in practice. Surface texture effect running accuracy components, noise and running in period, friction loss, heat transfer, fatigue strength, resistance against wear and corrosion. The experiment was performed on ASP2052® tool steels during coating by PVD (Physical Vapour Deposition). The surface of the substrate was wet and dry sandblasted. Treated surface of experimental samples were coating of TiN. After coating surface of the samples was polished by and wet sandblasted to achieve glossy finished. The results of the paper show effect various type of the treatment on surface texture before and after PVD coating. Measurement of the surface texture shows progression of the parameters surface textures.

Research and analysis of stress distribution in multilayers of coated tools

Abstract The paper analyses stress distribution in mono/multi-layers of coated tools. It presents an analysis performed on mono-layer, double-layer and multi-layer coatings using numerical models to detect the developed stress distribution and the most stressed zones in these mostly 1–10 micron layers. With such thin layers, experimental detection of stress distribution would be very difficult. Moreover, coating thickness is distributed differently on flat surfaces from on shaped features in coated tools. This non-uniform coating results solely from the technology applied and such uneven deposition of the coating is critical in terms of how the tools themselves function. The paper provides an analysis of stresses in thinner or accumulated layers of coating on the rounded edge, for example in cutting. This analysis was initiated by ProTech Coating Service, Ltd., which manufactures physical vapour deposition coatings for cutting and forming tools.

Development of new duplex treatments on 100Cr6steel combining Thermochemical Treatments, Laser Shock Peening and Physical Vapour Deposition

100Cr6 steel (AISI 52100) is one of the most used steel grades in the manufacturing of through hardening bearings mainly due to its properties: controlled impurities during steel making process, high hardenability and well known mechanical properties such as wear and fatigue resistance on clean environments. These characteristics play an important role on the performance of a bearing together with the bearing design, loads and environment. However, there is an increasing set of demanding applications where the above mentioned steel does not fulfil the required needs and thus, bearing manufacturers continuously work on the development of technologies to improve the bearing performance.Nowadays thermochemical treatments (TCT), such as carbonitriding are being applied to this steel in order to enhance the performance of such pieces in contaminated environment, where particles can produce defects on the raceway, increasing the onset of defects that eventually lead to premature fail. These treatments induce the formation of carbides and nitrides which are directly related to the enhancement of the wear resistance and also to increasing the amount of Retained Austenite (RA) in the surface which may have a beneficial effect as it delays the crack propagation on subsurface regions, then increasing bearing fatigue life.In this work, different TCTs have been applied to 100Cr6 steel flat samples. Using a tribometer (ball-on-disc configuration) and a grinding machine, surface and in-depth wear resistance measurements have been carried out, obtaining wear resistance profiles that have been correlated with the microstructure, microhardness profiles and RA content.The most promising TCT has been combined either with Laser Shock Peening (LSP) treatments or carbonaceous Physical Vapour Deposition (PVD) coatings with the aim of improving not only the wear resistance but also the CoF of the duplex treated sample.The results obtained on flat samples are promising; the combination of treatments produces long-lasting low CoF and a reduction of 60% in the wear rate. However, the treatments should be applied on real pieces and tested in a test bench in order to obtain more appropriate data about the lifespan of duplex treated bearings.

Evaluation of Sliding Wear Resistance of Physical Vapor Deposited Coatings by the Ball-Cratering Test Method

In this study the microstructure and wear characteristics of uncoated, TiAlN, AlCrN, and TiCN multilayer coated AISI 410 stainless steel. Tribological properties of the coatings were investigated by high carbon steel ball friction in dry sliding, sliding velocity of 0.3927 m s−1, sliding distance of 248.43 m, and under a load range of 2–4 N at room temperature. Among all the multilayer coatings tested, TiCN gave the superior wear resistance, followed by TiAlN and AlCrN. This indicates that the presence of C in TiCN coating leads to increase the wear resistance. At 2–3 N load in which oxidation was present, AlCrN coating shows the excellent wear resistance followed by TiAlN and TiCN coatings. The coating with a TiAlN proved good to acceptable wear resistance between 3 N and 4 N load. The wear rates and worn surfaces were investigated with scanning electron microscopy (SEM) (with energy dispersive spectroscopy (EDS) attachment), X-ray diffraction (XRD), and Talysurf profilometry analysis, which demonstrate that the grooved regions, pits, ploughing ridge, and cavities were found along the worn surface of the uncoated, TiAlN, and AlCrN coated surface. This result exposed that hard-coated particles were observed on the high carbon steel ball surface.

Durability of different selective solar absorber coatings in environments with different corrosivity

The degradation and durability of different selective solar absorbers surfaces in outdoor exposure testing (OET) sites with different atmospheric corrosivity (maritime/industrial and urban atmospheres) were investigated for the optimization of accelerated aging tests to the qualification in terms of durability of selective solar absorber coatings in different environments.Two Outdoor Exposure Testing (OET) sites were constructed, the climate was characterized and the atmospheric corrosivity categories were determined by corrosion rate measurements of standard specimens (carbon steel, zinc, copper and aluminium) during 12 months, according to ISO 9223, ISO 9225 and ISO 9226:2012. Two Physical Vapour Deposition (PVD) coatings (commercially available) and three paint coatings (commercially available) were also exposed in the two OET sites with evaluation of degradation after 1, 2, 4, 6, 9 and 12 months of exposure in terms of optical properties (solar absorptance and thermal emittance), morphology and chemical evaluation (SEM/EDS and XRD). The selective solar absorber surfaces submitted to OET sites for one year were ranked according to their performance in terms of optical properties and corrosion over time.The results obtained show the relevance of outdoor exposure testing sites, namely in places with high corrosivity as in marine and/or industrial areas as a reliable way to verify the corrosion resistance of new materials and products and the evolution of optical properties degradation of absorber surfaces in the presence of high concentration of contaminants.

The Analyse of Nanocomposite Thin Coatings Using Specimens Prepared by Focused Ion Beam Milling

The microstructure of physical vapour deposition (PVD) coatings deposited by duplex technology was investigated by Dual Beam FIB/SEM system (focused ion beam / scanning electron microscope), which allows one to examine cross sections of specimens from their surface down to the substrate. Examined were PVD coatings of nanocomposite type: duplex AlXN3 (X=Cr) and duplex nACRo3, deposited by LARC and CERC technologies. Duplex coating is a modern technology, which combines plasma nitriding and PVD coating in one cycle. The FIB analysis can be widely used in the field of study of basic materials and technological applications as it is based on highly focused ion beam which enables accurate machining of the investigated specimens and flexible processing at a micro/nanometric level. Cross sections of specimens obtained by FIB-SEMs document the arrangement of individual deposited nanomultilayers within the nanocomposite coatings and their EDS analysis in specific locations.

Improving the Wear Resistance of Moulds for the Injection of Glass Fibre–Reinforced Plastics Using PVD Coatings: A Comparative Study

It is well known that injection of glass fibre–reinforced plastics (GFRP) causes abrasive wear in moulds’ cavities and runners. Physical vapour deposition (PVD) coatings are intensively used to improve the wear resistance of different tools, also being one of the most promising ways to increase the moulds’ lifespan, mainly when used with plastics strongly reinforced with glass fibres. This work compares four different thin, hard coatings obtained using the PVD magnetron sputtering process: TiAlN, TiAlSiN, CrN/TiAlCrSiN and CrN/CrCN/DLC. The first two are monolayer coatings while the last ones are nanostructured and consist of multilayer systems. In order to carry out the corresponding tribological characterization, two different approaches were selected: A laboratorial method, using micro-abrasion wear tests based on a ball-cratering configuration, and an industrial mode, analysing the wear resistance of the coated samples when inserted in a plastic injection mould. As expected, the wear phenomena are not equivalent and the results between micro-abrasion and industrial tests are not similar due to the different means used to promote the abrasion. The best wear resistance performance in the laboratorial wear tests was attained by the TiAlN monolayer coating while the best performance in the industrial wear tests was obtained by the CrN/TiAlCrSiN nanostructured multilayer coating.

Characterization and evaluation of AlCrN coated FSW tool: A preliminary study

Stemming from the success recorded in the cutting tool industries, the use of physical vapor deposition (PVD) coatings for friction stir welding (FSW) tools is a promising approach to improve their performance and useful lives and hence the economics of the process. In this study, the authors present the results of the first phase of an on-going study to test various metallurgical hard coatings for FSW tools using cathodic arc PVD coating technique for welding structural materials. Aluminum alloy 6061-T6 and alloy steel 4140 grade were chosen as workpiece and FSW tool material, respectively for this preliminary study. The tribological properties of AlCrN coating were evaluated. The tool wear and weld quality resulting from FSW were analyzed and compared for coated and uncoated tools. AlCrN coated sample exhibited improved wear resistance with weight loss of about 87% lesser compared to uncoated sample. FSW performed on 6mm thick 6061-T6 Al alloy plate showed that AlCrN coated FSW tool produced full penetration weld with no major defects. Also, no delamination of the coating was observed and no trace of the coating was detected in the weld for the FSW paramters employed. Examination of the tools after the FSW showed that the coated tool experienced less reduction in the tool pin dimension as compared to the uncoated tool.

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.

Cyclic Loading of TiCN Coating by Vickers Indentation

Physical Vapour Deposited (PVD) coatings are used in wide range of industrial applications where requirements differ. For example, in cutting applications adhesive-abrasive wear along with high contact stresses prevail and PVD coating with thickness of ~2 μm are used. In forming applications adhesive wear usually dominates and relatively thick PVD coatings (~5 μm) are preferred. For both the applications coatings are subjected to cyclic stress and therefore it is a point of interest to learn the behaviour of PVD coatings with different thickness under cyclic loading. Cracking resistance and fatigue properties of gradient TiCN on hard metal substrate was evaluated by means of the cyclic Vickers indentation method. Hard metal was chosen as a substrate material to avoid pile-up effect and support the hard coating during indentation. The results of the single indentation Vickers test show that secondary radial and circumferential cracks appear in tested coatings already after the first indent. With increasing cycles the cracks grow up to a critical crack length after which the crack length doesn’t increase further. The tested coating thickness has no significant effect on cracking behaviour.

The influence of plasma nitriding on microstructure and properties of CrN and CrNiN coatings on Ti6Al4V by magnetron sputtering

In this paper, the CrN and CrNiN coatings were deposited on the non-nitrided and nitrided Ti6Al4V alloys with the method of closed-field unbalanced magnetron sputter ion plating (CFUBMSIP). The influence of plasma nitriding treatment on microstructure, mechanical and tribological properties of Physical Vapor Deposition (PVD) films was evacuated by means of SEM (EDS), XRD, Rockwell-C indentation testing, nanoindentation testing, and ball-on disc tribotesting. With the addition of Ni, the preferred orientation changes to CrN (200) and the grain is refined. The indentation tests indicated that the duplex treated samples exhibited the best combined properties. The nanoindentation testing results showed that the hardness of the coatings increased, the plastic deformation reduced and they had higher H3/E2 values than PVD coatings with the plasma nitriding before PVD treatment due to the increase of substrate's load bear capacity after plasma nitriding process. The friction and wear tests demonstrated that the tribological performance of the PVD coatings improved after plasma nitriding which is attributed to the enhanced the mechanical compatibility between the hard PVD coating and soft substrate and the resistance of CrN coating is better than that of CrNiN coating because of the transfer layer (constituted of TiN and Ti2N) deposited by nitriding.

Multilayer PVD Surface Engineered Coatings for Sheet Metal Forming Tools

Objectives: In this paper, the surface of sheet metal forming tool is coated by physical vapour deposition with molybdenum disulphide with the aim of preventing their premature failure. Method/Analysis: Physical Vapor Deposition (PVD) coatings have held a prominent position in this field for the last one decade. Although low friction coatings are deposited with good adhesion to the substrate there is a possibility of surface coating with poor adhesion. In the present paper molybdenum disulphide was deposited on D2 tool steel specimen by thermal evaporation. The effect of multilayer on microstructure, micro hardness, coating thickness and film adhesion were studied. Findings: It had been found that multilayer coatings has provided with improved adhesion, non columnar microstructure and harder surfaces. Improvement: The multilayer PVD MoS2 coatings provide a hard and wear resistant surface on sheet metal forming tool and improve its life.

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.

Target poisoning during CrN deposition by mixed high power impulse magnetron sputtering and unbalanced magnetron sputtering technique

Target poisoning phenomenon in reactive sputtering is well-known and has been studied in depth over the years. There is a clear agreement that this effect has a strong link on the quality, composition, properties, and pronouncedly on the deposition rate of physical vapor deposition coatings. With the introduction of ionized physical vapor deposition techniques such as the relatively novel high power impulse magnetron sputtering (HIPIMS), which have highly ionized plasmas of the depositing species (metal and gas ions), target poisoning phenomenon is highly contested and thus has been left wide open for discussion. Particularly, there have been contradicting reports on the presence of prominent hysteresis curves for reactive sputtering by HIPIMS. More work is needed to understand it, which in turn will enable reader to simplify the coating deposition utilizing HIPIMS. This work focuses on the study of chromium (Cr) targets when operated reactively in argon + nitrogen atmosphere and in different ionizing conditions, namely, (1) pure HIPIMS, (2) HIPIMS combined with unbalanced magnetron sputtering (UBM), and (3) pure UBM. Nitrogen flow rate was varied (5–300 sccm) whereas the average power on target was maintained around 8 kW. Target resistance versus N2 flow rate curves for these conditions have been plotted in order to analyze the poisoning effect. When only one UBM target was operating target poisoning effect was prominent between the flow rates of 80 and 170 sccm. However, it appeared reduced and in nearly same flow rate ranges (90 and 186 sccm) when only one HIPIMS target was operating. When four UBM targets were operated, target poisoning effect was evident, however, expectedly moved to higher flow rates (175 sccm and above) whereas appeared diminished when two UBM and two HIPIMS were running simultaneously. Further, to analyze the effect of actual target conditions (poisoning) on deposition rate and on the properties of the films deposited, commercially widely used chromium nitride (CrN) coatings were deposited in mixed HIPIMS and UBM plasma and at five different flow rates of nitrogen. Detail characterization results of these coatings have been presented in the paper which will assist the reader in deposition parameter selection.

First principles studies on the impact of point defects on the phase stability of (AlxCr1−x)2O3 solid solutions

Density Functional Theory applying the generalised gradient approximation is used to study the phase stability of (AlxCr1−x)2O3 solid solutions in the context of physical vapour deposition (PVD). Our results show that the energy of formation for the hexagonal α phase is lower than for the metastable cubic γ and B1-like phases–independent of the Al content x. Even though this suggests higher stability of the α phase, its synthesis by physical vapour deposition is difficult for temperatures below 800 °C. Aluminium oxide and Al-rich oxides typically exhibit a multi-phased, cubic-dominated structure. Using a model system of (Al0.69Cr0.31)2O3 which experimentally yields larger fractions of the desired hexagonal α phase, we show that point defects strongly influence the energetic relationships. Since defects and in particular point defects, are unavoidably present in PVD coatings, they are important factors and can strongly influence the stability regions. We explicitly show that defects with low formation energies (e.g. metal Frenkel pairs) are strongly preferred in the cubic phases, hence a reasonable factor contributing to the observed thermodynamically anomalous phase composition.

An Integrated Tribological and Vibration Signal Behaviour of TiN and AlCrN based PVD Coatings for Roller Bearings

Objective: The goal of current work is to check the suitability of Titanium Nitride (TiN) and Aluminium Chromium Nitride (AlCrN) coatings for the outer race of roller bearings. Methods: Physical Vapour Deposition (PVD) method of coating is employed since it provides less coating thickness. Tribological behaviour is studied for wear rate and co-efficient of friction using PIN-ON-DISC machine. Statistical method of Vibration analysis is performed by extracting values such as kurtosis, skewness, crest factor and RMS from time domain signals captured. Findings: It is revealed in the results that wear rate for TiN coated bearing is 0.03mm3 /min which is less than that of AlCrN coated bearing and uncoated bearing. Findings of the vibration study showed that kurtosis value is 7.6 for worn out AlCrN coated bearing compared to 4.4 for worn out TiN coated bearing. This clearly shows that TiN offers better wear resistance which supports the results of wear analysis. It is observed in SEM images of morphological studies that more wear tracks and ploughing marks occurred in uncoated and AlCrN coated bearing surfaces compared to TiN coated bearing. Application/Improvements: Current work provides a good integrated approach for tribological and vibration signal behavior of TiN and AlCrN based PVD coatings thus improving correlation between the two methods and it can be prolonged for prognosis. Keywords: Kurtosis, Physical Vapor Deposition, Tribology, Time Domain Signal, Wear Rate

Multilayer nitride coating performance optimized by an artificial neural network approach

One of the most important problems occurred in many industries is due to friction and wear process. Over the years, minimizing friction and controlling wear is one of the difficult tasks for the researchers. Both properties can be minimized by the application of adequate coating technology. Many coating deposition technologies have been employed to limit friction and wear but only few succeeded, those are directly affected by the nature of the material under investigation and process parameters. A suitable coating strategy varying from single layer to multilayer should be applied to the materials whose superficial properties such as low friction, improved wear resistance, and adhesion are the prime interest. Multilayer coatings possess high hardness, ductility and fracture strength compared to single layer coatings. The advantageous properties of these multilayers can be preciously tailored according to specific application. For this purpose Physical Vapour Deposition (PVD) coatings have been developed considerably due to increasing industrial demands. In the present research, friction and wear study of multilayer PVD-nitride coating deposited on tool steel by unbalanced reactive magnetron sputtering technique have been discussed. Later on an Artificial Neural Network approach was used to predict the tribological properties of multilayer nitride films. Bias voltage, total gas flow rate, lap, time, velocity and load were considered as controllable factors. The regression and performance curve analysis is used to assess the optimized outcome of deposited film properties such as friction and wear. The analyzed results shows that experimented and predicted values are in a good agreement.