Arc Physical Vapor Deposition Research Articles

The role of droplets on the cavitation erosion damage of TiN coatings produced with cathodic arc physical vapor deposition

In this study, the role of droplet-related defects on the initiation and propagation of cavitation erosion damage of TiN coatings produced by Cathodic Arc Physical Vapor Deposition (CA-PVD) was investigated. Ultrasonic-aided cavitation erosion tests were conducted in distilled water, using a specially designed specimen holder. By using this holder, following of the defect-related damages on the same region of the sample became possible by scanning electron microscopy (SEM) during a total test duration of 12h. Focused ion beam (FIB) investigations were also carried out on cross-sections of some selected defects to understand the damage mechanisms. Results of the study revealed the important role of droplet-related defects on the cavitation erosion damage. Deep cavities formed by detaching of conical droplets were determined as the most detrimental type of defects. At these sites, large impact craters were formed with sizes extending to 100μm with a substrate-reached area at their center after 3.5h of cavitation erosion test. However, the damage created by buried droplets was very limited when compared to the cavities. Their role on the initiation and propagation of the cavitation damage depends on their shape and position in the coating. Conical droplets embedded in the coating resulted in the capping of a coating layer above them. These damages were not deepened or extended during the test duration. On the other hand, wide droplets with a flat top that sat on the substrate did not result in the formation of neither capping of the coating nor impact craters after 12h of testing.

Effect of substrate roughness on adhesion and tribological properties of nc-TiAlN/a-Si3N4 nanocomposite coatings deposited by cathodic arc PVD process

TiN and Ti–Al–Si–N nanocomposite coatings of the type nc-TiAlN/a-Si3N4 have been prepared by cathodic arc physical vapour deposition process using cylindrical cathodes on high speed steel substrates with different surface roughness values, where the roughness is induced by emery paper method and diamond hand polishing. Fracture toughness studies by indentation method have shown that TiN is tougher than Ti–Al–Si–N nanocomposite coatings. Scratch and pin on disc wear tests have been conducted on the specimens to study the adhesion and tribological behaviour of these coatings respectiely. The wear mode between two mating surfaces is complex, and the wear behaviour can be understood better by studying the progression of surface changes and wear debris. The adhesion pattern of harder nanocomposite coating on smooth substrate surfaces is different from that of tougher TiN coating. Wear volume of these coatings decreases with substrate roughness, but it is found more for nanocomposite than for TiN.

Phase composition, structure, and mechanical properties of arc PVD Mo–Si–Al and Mo–Si–Al–N coatings

Using an arc physical vapor deposition process, we have produced nanostructured Mo–Si–Al coatings with a uniform distribution of equiaxed grains 8–12 nm in size and Mo–Si–Al–N coatings with a multilayer structure and a modulation period from 22 to 25 nm. The former coatings consist of MoSi2 and Mo and the latter consist of Mo2N and amorphous Si3N4 and AlN. The hardness of the Mo–Si–Al–N and Mo–Si–Al coatings is 41 and 18 GPa, respectively; they are similar in resistance to elastic deformation; and the Mo–Si–Al–N coating has a considerably higher resistance to plastic deformation. The coatings have roughly identical coefficients of friction (~0.67–0.69 at 20°C and ~0.52–0.56 at 550°C), but the wear resistance of the Mo–Si–Al–N coating is higher by three and two orders of magnitude at 20 and 550°C, respectively. The coatings of the two systems exhibit good adhesion to the substrate and cohesive fracture. Partial wear of the Mo–Si–Al and Mo–Si–Al–N coatings in the course of scratch testing occurs at indentation loads of 80 and 63 N, respectively.

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.

Thick CrN/NbN Multilayer Coating Deposited by Cathodic Arc Technique

The production of tribological nanoscale multilayer CrN/NbN coatings up to 6 µm thick by Sputtering/HIPIMS has been reported in literature. However, high demanding applications, such as internal combustion engine parts, need thicker coatings (>30 µm). The production of such parts by sputtering would be economically restrictive due to low deposition rates. In this work, nanoscale multilayer CrN/NbN coatings were produced in a high-deposition rate, industrial-size, Cathodic Arc Physical Vapor Deposition (ARC-PVD) chamber, containing three cathodes in alternate positions (Cr/Nb/Cr). Four 30 µm thick NbN/CrN multilayer coatings with different periodicities (20, 10, 7.5 and 4 nm) were produced. The coatings were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The multilayer coating system was composed of alternate cubic rock-salt CrN and NbN layers, coherently strained due to lattice mismatch. The film grew with columnar morphology through the entire stratified structure. The periodicities adopted were maintained throughout the entire coating. The 20 nm periodicity coating showed separate NbN and CrN peaks in the XRD patterns, while for the lower periodicity (≤10nm) coatings, just one intermediate lattice (d-spacing) was detected. An almost linear increase of hardness with decreasing bilayer period indicates that interfacial effects can dominate the hardening mechanisms.

Electrochemical Behaviour of TiCN and TiAlN Gradient Coatings Prepared by Lateral Rotating Cathode Arc PVD Technology

TiCN and TiAlN gradient coatings were deposited on the AISI 316L stainless steel substrates by lateral rotating cathode arc (LARC) physical vapour deposition (PVD) technology. Corrosion and tribocorrosion behaviour was studied in 3.5 wt. % NaCl solution. The thickness of coatings was about 3 μm. For both coatings the corrosion potential shifted to more positive values as compared to the uncoated substrate. The corrosion current density decreased for TiCN and TiAlN coatings indicating up to 40 folds higher polarization resistance. The coefficient of friction value of TiCN coating is three times lower and durability is six times higher than that of TiAlN coating under the same tribocorrosion conditions.

Comparison of Properties of Ti/TiN/TiCN/TiAlN Film Deposited by Cathodic Arc Physical Vapor and Plasma-assisted Chemical Vapor Deposition on Custom 450 Steel Substrates

This study investigated the effects of deposition techniques on the microstructural and tribological properties of Ti/TiN/TiCN/TiAlN multilayer coatings onto a Custom 450 steel substrate. The coatings were produced using cathodic arc physical vapor deposition (CAPVD) and plasma-assisted chemical vapor deposition (PACVD). The microstructural of the coatings was evaluated using (SEM), and phase formation was analyzed by (XRD). The mechanical properties of the coatings were examined by nano-indentation testing machine. Erosion behavior was studied using an erosion tester and the electrochemical behavior of the deposited films in 3.5% (wt) NaCl solution was investigated using potentiodynamic polarization. XRD analysis indicated that TiN, TiCN, and TiAlN featured different chemical compositions in each coating. Nano-indentation showed that the hardness of the CAPVD coating was 23.35 GPa and of the PACVD coating was 12.92 GPa. The coefficient of friction was 0.22 for the CAPVD and 0.17 for the PACVD coatings. Erosion testing was conducted using two abrasive powders at impact angles of 30° and 90°. The results showed that erosion rate at an impingement angle of 90° was greater than at 30° and the CAPVD coating showed better performance. The potentiodynamic polarization curves showed that the CAPVD coating provided better corrosion resistance than the PACVD coating.

Experimental investigations on hot forming of AA6082 using advanced plasma nitrocarburised and CAPVD WC: C coated tools

The use of lubricant for hot stamping process of sheet material can reduce the tendency of adhesion between work-piece and tool significantly and the friction coefficient. However, the post-process of cleaning the formed part and lubricating the tools before each stamping operation can compromise the manufacturing efficiency. It is especially challenging for hot stamping because reducing lubricant could lead to severe adhesion between tool and blank during stamping. Hence, it is desirable to develop an advanced tooling technique suitable for hot stamping processes of aluminium alloys. In this paper, an innovative tooling technology enabling hot and cold forming of aluminium with little lubricant has been developed using plasma thermochemical treatment and Cathodic Arc Physical Vapour Deposition (CAPVD) technologies. The forming performance was validated on a top-hat part stamping test to benchmark the performance of the developed tools at different forming temperature, blank-holding force (BHF) and lubrication state. The results show that WC: C coating prepared by CAPVD adequately reduced the aluminium sticking on the tool surfaces, to the extent that it achieved an 80% lubricant reduction in the hot forming stamping of a top-hat part with a drawing depth of 70mm. The morphology of die showed that aluminium adhesion at the corner area of the die where the contact pressure doubled was still noticeable, while no severe adhesion was observed on the top flat surfaces. A further investigation of tribology on hot and cold stage tribometers was deployed to quantify the friction coefficient and wear resistance of tooling materials which were found correlated to the material’s universal hardness and time-dependent adhesion rate of aluminium.

Wear protection potential of TiN coatings for 304 stainless steels used in rotating parts during olive oil extraction

Abstract The aim of this study is to determine the damage mechanisms affecting 304L Stainless Steel (SS) parts used in olive oil production, and to evaluate the performance of TiN coatings in improving their resistance to these effects. Tribological behavior of 304L SS parts was investigated through pin on disc tests against olive seed counter bodies, both in uncoated state and after TiN coating via cathodic arc physical vapor deposition. Further assessment of tribological behavior was carried out through the means of an in house centrifugal testing setup, designed to simulate the environment encountered during the de­seeding step of oil production, and cavitation erosion tests with an ultrasonic probe. The results of pin on disc tests showed considerable wear damage of uncoated SS while TiN coated samples exhibit excellent wear resistance, with no visible damage to the coatings. Further results obtained from centrifugal tests indicated a damage mechanism related to impact from olive seed particles. Plastic deformation of the SS substrate surface was observed via SEM, both for uncoated and TiN coated samples, leading to fracturing of the TiN coatings and their subsequent removal in the latter. This observation is supported by the results of cavitation erosion tests, in which similar damage can be observed on TiN coated SS samples. The same test carried out on TiN coated high speed steel samples which have a higher substrate hardness than SS showed better resistance to fracture of the coating.

Effect of Magnesium and Osteoblast Cell Presence on Hydroxyapatite Formation on (Ti,Mg)N Thin Film Coatings

TiN and (Ti,Mg)N thin film coatings were deposited on Ti substrates by an arc-physical vapor deposition technique. The effect of cell presence on hydroxyapatite (HA) formation was investigated using surfaces with four different Mg contents (0, 8.1, 11.31, and 28.49 at.%). Accelerated corrosion above 10 at.% Mg had a negative effect on the performance in terms of both cell proliferation and mineralization. In the absence of cells, Mg-free TiN coatings and low-Mg (8.1 at.%)-doped (Ti,Mg)N surfaces led to an early HA deposition (after 7 days and 14 days, respectively) in cell culture medium (DMEM), but the crystallinity was low. More crystalline HA structures were obtained in the presence of the cells. HA deposits with an ideal Ca/P ratio were obtained at least a week earlier, at day 14, in TiN and low-Mg (8.1 at.%)-doped (Ti,Mg)N compared with that of high-Mg-containing surfaces (>10 at.%). A thicker mineralized matrix was formed on low-Mg (8.1 at.%)-doped (Ti,Mg)N relative to that of the TiN sample. Low-Mg doping (<10 at.%) into TiN coatings resulted in better cell proliferation and thicker mineralized matrix formation, so it could be a promising alternative for hard tissue applications.

Studies on cathodic arc PVD grown TiCrN based erosion resistant thin films

Titanium chromium nitride (TiCrN) coatings with varying Cr content in two configurations, mono- and multilayer, were deposited on high speed steel substrates using a cylindrical cathodic arc physical vapor deposition technique. The physical, mechanical, and erosion behavior of the coatings were investigated. Among the monolayer coatings, the thicker Ti0.48Cr0.52N coatings yielded the best erosion resistance property. But with the increase in thickness, a considerable increase in residual stress is observed. Toward minimizing the stress accumulation, the effect of multilayering with periodic in situ heat treatment (after each 1 μm film growth) was studied by growing films in Ti0.52Cr0.48N/Ti0.40Cr0.60N bilayer configuration. A new approach based on % area of erosion damage for measuring relative wear rate of thin films has been proposed and implemented. The multilayer coatings exhibited superior erosion performance compared to the well-known erosion resistant TiN coatings that are in use for compressor blades from past few decades. Further, the erosion failure mechanisms in TiCrN coatings were also studied and found to be clearly different for mono- and multilayer configurations. The results reveal that the thicker multilayer TiCrN coatings (20 μm) exhibit promising choice for erosion resistance applications.

Effect of Coating Surface Finishing on Fatigue Behavior of C450 Steel CAPVD Coated with (Ti,Cr)N

The present study evaluated the effect of the surface quality of a custom 450 stainless steel substrate coated with a (Ti,Cr)N nanolayer by cathodic arc physical vapor deposition on fatigue performance in air and in a 3.5% NaCl solution. Scanning electron microscopy was used to locate crack origin sites and characterize the coating. X-ray diffraction was used to analyze the phase formation and measurement of residual stress in the coating. The results showed that the determined in plane residual stress is compressive, with amount of \(- 2.8 \pm 0.4\) GPa. Chemical mechanical polishing was used to decrease the coating surface roughness (Ra from 0.35 to 0.07 µm). This significantly decreased the area having a high stress concentration and delayed the appearance of micro-cracks in the coating during fatigue testing. The results showed that when the material is tested under axial loading at a maximum alternating stress of 555 to 930 MPa, the fatigue strength of coated specimens with polished surfaces increased 10.6% in air and 26.7% in NaCl solution over the coated specimens with normal surfaces. Post-treatment of the coating increased the fatigue strength 3.5% in air and 10.1% in NaCl solution over the uncoated specimens and the weakness of CAPVD coating was eliminated in the field of fatigue.

Enhanced Experimental Testing of New Erosion-Resistant Compressor Blade Coatings

Performance differences between bare 17-4PH steel V103 profile (NACA 6505 with rounded leading edge (LE) and trailing edge (TE)) gas turbine engine axial compressor blades, and those coated with either a chromium-aluminum-titanium nitride (CrAlTiN) or a titanium-aluminum nitride (TixAl1−xN) erosion-resistant coating were tested. A coating thickness of 16 μm was used, based on experimental results in the literature. Coatings were applied using arc physical vapor deposition at the National Research Council of Canada (NRC). All blades were tested under identical operating conditions in the Royal Military College of Canada (RMC) turbomachinery erosion rig. Based on a realism factor (RF) defined by the authors, this experimental rig was determined to provide the best known approximation to actual compressor blade erosion in aircraft gas turbine engine axial compressors. An average brown-out erosive media concentration of 4.9 g/m3 of air was used during testing. An overall defined Leithead–Allan–Zhao (LAZ) score metric, based on mass and blade dimension changes, compared the erosion-resistant performance of the bare and coated blades. Blade surface roughness data were also obtained. Based on the LAZ Score, CrAlTiN-coated blades performed at least 79% better than bare blades, and TixAl1−xN-coated blades performed at least 93% better than bare blades. The TixAl1−xN-coated blades performed at least 33% better than the CrAlTiN-coated blades. Extrapolation of results predicted that a V-22 Osprey tiltrotor military aircraft, for example, could fly up to 79 more missions with TixAl1−xN-coated compressor blades in brown-out sand concentrations than with uncoated blades.

Nano-Scale Structure Investigation of Vapour Deposited AlCrSiN Coating Using Transmission Electron Microscope Techniques

Abstract The investigations concerned the structural analysis of the AlCrSiN coating deposited by arc Physical Vapour Deposition method on the X40CrMoV5-1 hot work tool steel substrate. The deposition process was carried out on a device equipped with a technique of lateral, rotating cathodes. The nano/microstructure, phase identification and chemical state of the coating were analysed by high-resolution transmission electron microscopy. It was found that the investigated coatings have nanostructured nature consisting of fine crystallites. The fractographic tests were made using the scanning electron microscope and allow to state, that the coating was deposited uniformly and tightly adhere to the substrate material. In the work is presented the nature of a transition zone between the produced AlCrSiN coating and substrate material.

INFLUENCE OF NITROGEN FLOW RATE IN REDUCING TIN MICRODROPLETS ON BIOMEDICAL TI-13ZR-13NB ALLOY

Cathodic arc physical vapor deposition (CAPVD) is one of the promising techniques that have a potential to coat titanium nitride (TiN) on biomedical implants due to its good adhesion and high evaporation rate. However, this method emits microdroplets which have the possible detrimental effect on the coating performance. Past studies indicated that micro droplets can be controlled through proper deposition parameters. In the present work, an attempt was made to study the effect of nitrogen gas flow rates (100 to 300 sccm) on TiN coating of the Ti-13Zr-13Nb biomedical alloy. Scanning electron microscopy (SEM) was used to evaluate surface morphology and coating thickness while crystal phase of the coated substrates was determined using X-Ray Diffraction (XRD). Image analysis software was employed to quantify microdroplets counts. Results show that higher nitrogen gas flow rate able to decrease a significant amount of microdroplets and concurrently increase the thickness of TiN coating. A mixed crystal planes of (111) and (220) are obtained on the coated substrates at this setting which exhibits denser structure with higher adhesion strength as compared to substrates coated at the lower N2 gas flow rate.

STUDY ON MICRO DROPLET REDUCTION ON TIN COATED BIOMEDICAL TI-13ZR-13NB ALLOY

Cathodic arc physical vapor deposition (CAPVD) is one of the physical Vapor deposition (PVD) techniques used to coat titanium nitride (TiN) on biomedical implants due to its good adhesion and high evaporation rate. However, this technique emits micro droplets which have can detrimental effect on the coating performance. Previous studies reported that micro droplets can be controlled through proper deposition parameters. In this paper, the PVD coating was performed on the Ti-13Zr-13Nb biomedical alloy with different substrate temperatures. Scanning electron microscopy (SEM) was used to characterized the surface morphology and coating thickness while X-Ray Diffraction (XRD was employed to evaluate the crystal phase of the coated substrates. Image analysis software was used to quantify micro droplets counts. The results show that higher substrate temperature able to decrease a significant amount of micro droplets and concurrently increase the thickness of TiN coating. A mixed crystal planes of (111) and (200) are obtained on the coated substrates at this setting which exhibits denser structure as compared to substrates coated at lower substrate temperature.

Multilayer (TiN, TiAlN) ceramic coatings for nuclear fuel cladding

In an attempt to develop an accident-tolerant fuel (ATF) that can delay the deleterious consequences of loss-of-coolant-accidents (LOCA), multilayer coatings were deposited onto ZIRLO® coupon substrates by cathodic arc physical vapor deposition (CA-PVD). Coatings were composed of alternating TiN (top) and Ti1-xAlxN (2-layer, 4-layer, 8-layer and 16-layer) layers. The minimum TiN top coating thickness and coating architecture were optimized for good corrosion and oxidation resistance. Corrosion tests were performed in static pure water at 360 °C and 18.7 MPa for up to 90 days. The optimized coatings showed no spallation/delamination and had a maximum of 6 mg/dm2 weight gain, which is 6 times smaller than that of a control sample of uncoated ZIRLO® which showed a weight gain of 40.2 mg/dm2. The optimized architecture features a ∼1 μm TiN top layer to prevent boehmite phase formation during corrosion and a TiN/TiAlN 8-layer architecture which provides the best corrosion performance.

Improvement of structure and quality of nanoscale multilayered composite coatings, deposited by filtered cathodic vacuum arc deposition method

This article studies the specific features of cathode vacuum arc deposition of coatings used in the production of cutting tools. The detailed analysis of the major drawbacks of arc-Physical Vapour Deposition (PVD) methods has contributed to the development of the processes of filtered cathodic vacuum arc deposition to form nanoscale multilayered composite coatings of increased efficiency. This is achieved through the formation of nanostructure, increase in strength of adhesion of coating to substrate up to 20%, and reduction of such dangerous coating surface defects as macro- and microdroplets up to 80%. This article presents the results of the studies of various properties of developed nanoscale multilayered composite coating. The certification tests of carbide tool equipped with cutting inserts with developed nanoscale multilayered composite coating compositions in longitudinal turning (continuous cutting) and end symmetric milling, and intermittent cutting of steel C45 and hard-to-cut nickel alloy of NiCr20TiAl showed advantages of tool with nanoscale multilayered composite coating as compared to the tool without coating. The lifetime of the carbide inserts with developed NMCC based on the system of Ti–TiN–(NbZrTiCr)N (filtered cathodic vacuum arc deposition) was increased up to 5–6 times in comparison with the control tools without coatings and up to 1.5–2.0 times in comparison with nanoscale multilayered composite coating based on the system of Ti–TiN–(NbZrTiCr)N (standard arc-PVD technology).

High temperature stable solar selective coatings by cathodic arc PVD for heat collecting elements

A functionally multilayered Cr/CrTiAlN-G/TiAlN/AlSiN/AlSiO coating configuration, suitable for enhancing solar selectivity of stainless steel substrates used in concentrated solar power (CSP) systems, has been formulated using cathodic arc physical vapor deposition (CAPVD) technique. The sequence of functional layers was decided based on their refractive index values and their relative thickness was optimized to achieve maximum solar selectivity. The optimized coating exhibits encouraging values of solar absorptivity (α) – 0.95 and thermal emissivity (ε) – 0.09 to 0.14 up to 600°C. Further, the solar selectivity factor (α/ε) for the coating is found to be comparable with the best selective coatings currently available for elevated temperature operation. The coatings were also studied for their long term stability and found to be stable up to 500°C, although considerable change in optical properties was observed on increasing the temperature to 600°C. The noted properties make the present coating a promising candidate as a high temperature solar selective coating on stainless steel substrates.

Characterization Using XPS and XRD of Ti(C,N) Coating Properties for Cutting Tool Applications

The properties of titanium carbonitride (TiCN) are a result of its composition, which can be adjusted by controlling the material’s C-N ratio to a precise level. An experimental study was conducted to vary the composition and properties of TiCN. The substrate used for cathodic arc physical vapour deposition (CAPVD) was tungsten carbide (WC-6Co), which was prepared in-house by a powder metallurgy process. Pure titanium (Ti) was used as a cathode and source of Ti. Methane (CH4) and nitrogen (N2) gases were used as sources of C and N to form the Ti(C,N) coating applied in the CAPVD process. Tests showed that the composition and properties of Ti(C,N) were successfully varied by controlling the CH4-N2 ratio. The surface microhardness of coated carbide samples improved and the coefficient of friction declined as the carbon content incorporated within the Ti(C,N) coating increased.