Arc Physical Vapor Deposition Research Articles

Tribological behavior of TiN, AlTiN, and AlTiCrN coatings in atmospheric and vacuum environments

In this study, the tribological characteristics of TiN, AlTiN, and AlTiCrN coatings sliding against a SUS420J1 stainless steel pin were investigated in atmospheric and vacuum environments. The coatings were deposited on SUS440C substrates using the arc-physical vapor deposition technique. The friction and wear behavior of the coatings were evaluated based on the systematic analyses of the friction coefficient data as well as the physical and chemical state of the wear track. The results revealed that the friction coefficients of the SUS440C specimen and AlTiCrN coatings increased, whereas those of the TiN and AlTiN coatings decreased when the environment was changed from atmospheric to vacuum. It was confirmed that the formation of an oxide layer and adsorption of oxides on the surface were dominant factors that influenced the tribological behavior in the atmospheric environment. On the other hand, the compatibility, oxidation inhibition, and droplets of the surface mainly affected the frictional characteristics in the vacuum environment. The results of this work are expected to aid in the selection of proper coating materials for tribological systems operating in a vacuum.

Prediction of contact stress and wear analysis of nitrided and CAPVD coated AISI H11 steel under dry sliding conditions

In this study, AlTiN (monolayer) and CrN/AlTiN (bilayer) coatings are deposited on the surface of conventional heat-treated AISI H11 steel which is then nitrided by cathodic arc physical vapor deposition (CAPVD). Structural analyses of the coatings reveal that homogeneous, continuous, and defect-free coatings are obtained with a good adhesion on the diffusion layer of the substrate material. Considering the surface hardness, the CrN/AlTiN coating (1718 HV0.01) deposited on the surface of the heat-treated tool steel has a higher value than that of AlTiN coating (1658 HV0.01), and this hardness value is increased even more (1932 HV0.01) with the application of the nitriding process. With a contact model in which the ANSYS static structural module is operated, it is shown that CrN/AlTiN coating contributes to lower tensile stress distribution on the surface during indentation. Analysis has also revealed that bilayer coating, CrN/AlTiN, exhibits reduced deformation compared to monolayer coating, indicating enhanced mechanical strength under contact conditions. Additionally, nitriding is found to increase stress distribution, emphasizing its role in improving coating performance. It is determined that wear losses can be reduced by the high load carrying capacity provided by nitriding and the high surface hardness provided by CrN/AlTiN coating under dry friction test conditions performed against alumina as counterpart material at room temperature.

Investigation of the Nitriding Effect on the Adhesion and Wear Behavior of CrN-, AlTiN-, and CrN/AlTiN-Coated X45CrMoV5-3-1 Tool Steel Formed Via Cathodic Arc Physical Vapor Deposition

Monolayer (CrN, AlTiN) and bilayer (CrN/AlTiN) coatings are formed on the surface of conventional heat-treated and gas-nitrided X45CrMoV5-3-1 tool steel via Cathodic Arc Physical Vapor Deposition (CAPVD), and the adhesion characteristics and room- and high-temperature wear behavior of the coatings are compared with those of the un-nitrided ones. Scratch tests on the coatings show that the bilayer coating exhibits better adhesion behavior compared to monolayer ones, and the adhesion is further increased in all coatings due to the high load carrying capacity of the diffusion layer formed by the nitriding process. Dry friction tests performed at room temperature reveal that, among ceramic-based coatings, the coating system with a high adhesion has the lowest specific wear rate (0.06 × 10−6 mm3/N·m), and not only the surface hardness but also the nitriding process is important for reducing this rate. Studies on wear surfaces indicate that the bilayer coating structure has a tendency to remove the surface over a longer period of time. Hot wear tests performed at a temperature (450 °C) corresponding to aluminum extrusion conditions show that high friction coefficient values (>1) are reached due to aluminum transfer from the counterpart material to the surface and failure develops through droplet delamination. Adhesion and tribological tests indicate that the best performance among the systems studied belongs to the steel–CrN/AlTiN system and this performance can be further increased via the nitriding process.

Impact of Nb and Al content in arc evaporation targets on Ti1−x−yAlxNbyN coating properties

Titanium-based physical vapor deposition (PVD) coatings, such as titanium nitride (TiN) and titanium niobium nitride (TiNbN), are common solutions for surface modifications in medical applications. Ex vivo studies of retrieved knee implants indicate the demand for increased scratch and abrasion resistance of PVD coatings in clinical applications. Based on the promising mechanical performance of titanium aluminum nitride (TiAlN) as a coating for tools, the aim of this study was to evaluate the impact of the chemical composition of titanium-based nitride coatings with aluminum (Al) and niobium (Nb). Nine titanium aluminum niobium nitride (Ti1−x−yAlxNbyN) coatings with 0.4 ≤ x < 0.7 and 0 ≤ y ≤ 0.18, as well as commercial TiN and TiNbN, were coated in an industrial scale arc PVD process, following a randomized, multifactorial response surface design. The deposition rate, the scratch resistance, and the hardness were measured following standardized protocols. The microstructure of the coating was analyzed by SEM and XRD. In addition, the surface roughness was determined by laser scanning microscopy. A quadratic regression was performed to determine the impact of the chemical composition on coating properties. Experimental results and regression analyses revealed the significant impact of the chemical composition of Ti1−x−yAlxNbyN on the coating microstructure, mechanics, and morphology. Scratch resistance for initial crack formation and cohesive failure could be increased decisively, compared to TiN.

Triboactive CrAlN+MoWS coatings deposited by pulsed arc PVD

Cathodic arc physical vapor deposition (arc PVD) is widely used due to its high deposition rate and degree of ionization. However, reducing droplet emission and surface roughness without compromising the deposition rate remains challenging. CrAlN+XS coatings (X = Mo, W) have shown potential for friction and wear reduction under dry-running conditions by forming solid lubricants MoS2 and WS2. Nevertheless, the evaporation of electrically low conductive materials like MoS2 or WS2 in arc PVD presents difficulties. This study investigates the use of pulsed arc PVD as a promising technology to address these challenges. CrAlN+XS coatings were developed using pulsed arc PVD, with a focus on analyzing their properties, including the incorporation of triboactive elements (S, Mo, W). Additionally, variations in coating architecture, substrate material, and process temperature were explored for CrAlN+MoS coatings. Subsequently, tribological investigations were conducted under dry-running conditions using a pin-on-disk tribometer. The results revealed that pulsed arc PVD effectively decreased droplet emission and thus surface roughness of the coatings. Moreover, the triboactive coatings exhibited significantly lower wear and friction compared to uncoated steel references. Raman spectroscopy was employed to examine the tribofilms on coated parts. This work represents the first-time deposition of CrAlN+XS coatings (X = Mo, W) using pulsed arc PVD. Notably, the CrAlN+MoS coating displayed the highest sulfur content of xS = 9 at.-%, as verified by electron probe microanalysis. The tribofilm analysis provided evidence that CrAlN+MoS coatings deposited by pulsed arc PVD can form solid lubricant MoS2 under tribological load, resulting in a reduced coefficient of friction. In conclusion, pulsed arc PVD shows promise for applications that require the evaporation of electrically low conductive target materials during coating deposition, while achieving a low surface roughness. The findings contribute valuable insights into the performance of CrAlN+XS coatings and their potential for enhancing tribological applications.

Influence of niobium and hafnium doping on the wear and corrosion resistance of coatings based on ZrN

The properties of coatings based on the ZrN system with the introduction of hafnium and zirconium (ZrN, (Zr,Nb)N and (Zr,Hf)N), deposited on a Ti6Al–4V titanium alloy substrate are compared. Coatings are deposited by controlled accelerated arc-physical vapor deposition, and the structure of the coatings is studied using a transmission electron microscope. A comparison is made of both the mechanical (hardness, wear resistance, scratch strength) and anticorrosion (in a 3 % solution of NaCl) properties. The (Zr,Hf)N coating (22 at% Hf and 78 at% Zr) has the maximum hardness (HV, 3225 ± 73) and wear resistance. This coating also exhibits higher corrosion resistance. In contrast, introducing Nb into the coating composition reduces the corrosion resistance. This combination of beneficial properties makes the (Zr,Hf)N coating useful for conditions in which the surfaces of parts must simultaneously have high wear resistance, strength, and corrosion resistance.

The tribological performance of super-hard Ta:C DLC coatings obtained by low-temperature PVD

Diamond-like carbon (DLC) coatings are widely used in industry for decorative/protective purposes or to improve tribological performance in mechanical components. In this study, three types of commercial DLC coatings have been tested and analysed to verify their potential as functional coatings to improve the wear resistance of mechanical components. DLC coatings commercially known as Dianoir, Dropless5000, and Dropless7000 were deposited on AISI 52100 steel through a proprietary cathodic arc physical vapour deposition (PVD) technique, and their properties were compared considering the differences in morphology, thickness, scratch resistance and pin-on-disc test results. The tested coatings showed excellent performance in terms of wear resistance and friction reduction, thereby showing that these coatings may be successfully applied to mechanical components in several applications.

Tribological study at high temperature of the c-TiAlON oxynitride coating deposited by cathodic arc on H13 tool steel

Coatings were deposited on AISI-H13 steel by cathodic arc Physical Vapor deposition (arc-PVD). Grazing Incidence X-Ray diffraction (GI-XRD) showed that Oxygen atoms (O) replace Nitrogen atoms (N) in the cubic-Titanium Aluminum Nitride (c-TiAlN) lattice. The coating had ∼5.9 µm thickness, ∼6.3 at% O content and average roughness of Ra= 73.9 nm. High-temperature GI-XRD showed improved oxidation resistance up to 850 °C, at 900 °C the constituent oxides appeared. A columnar microstructure resulted in 21.72 GPa hardness and 418.31 GPa elastic-moduli. Adhesion tests showed critical loads > 19 N, with chipping and conformal-cracking. The pin-on-disk tests at room temperature (RT) showed coefficients of friction (COF) of 0.65 and 0.83 for the steel and the oxynitride, respectively. At 900 °C the COF decreased due to a tribolayer formation. Cyclic tribo-oxidation cause this tribolayer to wear and partially expose the substrate, showing wear mechanisms due to combined processes of the coating and the steel.

Efficacy of TiCrN/DLC coatings for service life enhancement of stamping dies

The present study examines the applicability of wear-resistant TiCrN/DLC coatings to dies used in stamping, for extending the service life. The TiCrN/DLC coatings were deposited via the Cathodic Arc Physical Vapor Deposition (CAPVD) route on D3 tool steel. The thickness of the TiCrN layer was tailored to achieve the desired properties, such as high adhesion strength, toughness, wear resistance, and low residual stress. The tribological properties of the TiCrN coating with best properties was assessed by universal tribometer and dry sand rubber wheel tester. Further, the tribological response of the identified TiCrN coating was investigated by adding a thin layer of low friction coefficient diamond-like carbon (DLC). Finally, the emphasis was also placed on determining the real time life of stamping dies with TiCrN/DLC coating. From the surface relief data of the finished product, measured at regular intervals pertaining to both coated and uncoated dies, a two-fold increase in the productivity with enhanced flowability was observed. The enhancement in the service life of the stamping dies clearly indicates that the CAPVD TiCrN/DLC coating can be a good alternative to hard chrome coatings already in use.

Accelerated optimization of chromium coating microstructures for nuclear fuel applications through electrochemical corrosion testing

Corrosion of zirconium alloy fuel cladding in nuclear reactors is one of the main limiting factors to component lifespan. Protective coatings may be applied to reduce the corrosion rate during regular operation and can have the added benefit of mitigating follow-on risks associated with loss-of-coolant accidents. This study considers the use of electrochemical testing to rapidly evaluate the corrosion protection of chromium coatings on zirconium alloys. By correlating these electrochemical testing results with the microstructural characteristics and mechanical properties of the coating, it is possible to qualitatively predict the performance of these coatings during long-term autoclave testing and eventual in-reactor use. A series of chromium coatings were deposited using cathodic arc physical vapor deposition (CA-PVD) with varying substrate bias. Electrochemical testing showed that the coatings provided improvements in corrosion protection over the uncoated baseline zirconium alloys, with further improvements observed for substrates to which voltage bias was applied. This is attributed to the increased adatom mobility during the deposition process, allowing for the development of a dense, uniform microstructure of the chromium coating. These results were compared to autoclave exposure data over a 56-day period to show the effectiveness of electrochemical testing towards predicting significant differences in corrosion resistance under regular operating conditions. This approach provided limited qualitative insight on long-term performance in its present state, but shows promise for further development.

Structural and Mechanical Properties of DLC/TiN Coatings on Carbide for Wood-Cutting Applications

In this work, the diamond-like carbon and titanium nitride (DLC/TiN) multilayer coatings were prepared on a cemented tungsten carbide substrate (WC—3 wt.% Co) using the cathodic vacuum arc physical vapor deposition (Arc-PVD) method and pulsed Arc-PVD method with a graphite cathode for the deposition of TiN and carbon layers, respectively. The structural and mechanical properties of the prepared coatings were studied, and different techniques, such as scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and microindentation techniques investigated their microstructure, composition, and phases. The prepared coatings had a multilayer structure with distinct phases of DLC, TiN, and carbide substrate. The potentiodynamic polarization method (PDP) was performed for the DLC/TiN multilayer coatings in 3% NaCl solution to evaluate the corrosion resistance of the prepared coatings. It has been shown that the DLC layer provided the coating with a polarization resistance of 564.46 kΩ. Moreover, it has been demonstrated that the DLC/TiN coatings had a high hardness of 38.7–40.4 GPa, which can help to extend the wood-cutting tools’ life.

An Investigation Into the Synergistic Effect of CAPVD Cr/CrN Nanolayered Coating Deposition and Hard-Anodizing Methods on Fretting Fatigue Life of 7075-T6 Aluminum Alloy

The influence of duplex surface treatment including a Cr/CrN nanolayered coating deposited by cathodic arc physical vapor deposition (CAPVD) and an alumina layer coated by hard-anodizing method on the fretting fatigue strength of Al7075-T6 alloy is studied in this investigation. Although fretting fatigue life of both single Cr/CrN coated alloy and Cr/CrN coating deposition onto hard-anodized alloy was increased in high cycle fatigue (HCF) regime, employing an alumina layer as a pretreatment for the Cr/CrN deposition enhanced the life improvement in the HCF regime. In low cycle fatigue (LCF) regime, despite a decrease in fretting fatigue life of both Al7075-T6-coated alloys, using the alumina layer beneath the Cr/CrN coating resulted in mitigation of fretting fatigue life deterioration. Interestingly, a single-hard-anodized specimen represented a completely different variation trend of fretting fatigue life in HCF and LCF regimes. Unlike the as-received and single-hard-anodized specimens, Cr/CrN-coated specimens did not bear the maximum axial stress, 260 MPa. Partial slip regime was mostly seen at the contacting area.

Alternative approach for the growth of a TiB2/TiC multilayer on M2 steel using the duplex method: Cathodic arc physical vapor deposition and cathodic reduction and thermal diffusion boriding

An alternative approach for producing a hard TiB2/TiC multilayer on M2 high-speed steel was introduced by combining cathodic arc physical vapor deposition (CA-PVD) and cathodic reduction and thermal diffusion-based boriding (CRTD-Bor). In this regard, the CRTD-Bor process was applied on CA-PVD Ti-deposited M2 steel and the effects of boriding parameters (i.e., temperatures and durations) on multilayer growth were examined. During boriding, Ti coating on the substrate was converted into Ti-borides on the top surface and a TiC layer was simultaneously formed at the interface of the Ti deposit and the steel matrix. The growth of boride and carbide phases was found to obey the parabolic law. The pre-exponential factors (K0) and the activation energy (Q) values were calculated as 7.50 × 10−9 m2/s and 146.10 kJ/mol for TiB2 growth and 1.81 × 10−7 m2/s and 187.31 kJ/mol for TiC formations, respectively. Additionally, empirical equations for estimating the thicknesses of TiB2 and TiC layers were derived. The penetration depth-dependent hardness measurements revealed the TiB2 layer hardness as 41 ± 5 Gpa, which decreased gradually toward the TiB region (24 ± 2 GPa) and fell to 13 ± 1 GPa in the Ti-rich area. The hardness then increased to 20 ± 1 GPa with the contribution of the TiC layer adjacent to the substrate. This multilayer coating exhibited −5.5 to −4.5 GPa compressive stress and good adhesions (HF1) to the substrates. Also, the results of tribological tests indicated a sevenfold increase in wear resistance under dry sliding conditions.

Metallurgical, erosion, and sensitization performance of TiAlN monolayer and TiAlN/TiN multilayer ceramic coatings on AISI 304 boiler steel

In the present work, TiAlN monolayer and TiAlN/TiN multilayer ceramic coatings were deposited on AISI 304 austenitic stainless steel by plasma arc physical vapor deposition (PAPVD) process. The metallurgical, erosion, and sensitization performance of these coatings were compared with uncoated 304 boiler steel. Metallurgical studies depicted formation of Al and Ti nitrides on monolayer and multilayer coated steel surfaces, which resulted into higher nitriding at the surface and dense coating formation on boiler steel substrate. Multilayer film exhibited comparatively lesser porosity, lower surface roughness, and higher hardness than monolayer coated and uncoated steel. The erosion performance was evaluated at 30° and 90° besides 2 g/min and 3 g/min flow rates of Al2O3 erodent material for coated and uncoated steel substrate. Multilayer coated 304 steel possessed lower erosion wear rate as evaluated through lesser weight loss before and after erosive wear, smaller crater formation, and minimal adherence of erodent material along with lesser Fe content on eroded surface relative to monolayer coated and uncoated steel. Multilayer coated steel thermally aged at 750° for 24 h had least degree of sensitization (DOS) compared to monolayer coated and uncoated aged boiler steel. Although monolayer coated steel performed better than uncoated one in erosion and sensitization performance but multilayer coating performance was best among all coated and uncoated steel used for present study. Thus, it was established that TiAlN/TiN multilayer coating on AISI 304 boiler steel has improved its metallurgical, erosion, and sensitization performance.

Contribution of galvanic coupling with TiN, TiAlN, and CrN to the corrosion of steel in neutral and acidic chloride solutions

AbstractThe inherent defective morphology of the physical vapor deposition (PVD) hard coatings limits their corrosion protective ability. We examined the impact of nitride‐based PVD coatings, including TiN, TiAlN, and CrN deposited on inert substrates by cathodic arc PVD method (CA‐PVD), on the galvanic corrosion of carbon steel. Their contribution was evaluated by zero‐resistance ammeter (ZRA) and electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl at pH 2 and 6, with and without aeration. The results indicated the prominent role of the coating type and the coupling environment on the generated galvanic currents. Immersion tests for the TiN‐, TiAlN‐, and CrN‐coated steel cross‐sections visually verified these results. The galvanic current contribution was distinct in environments where oxygen reduction is the dominant cathodic reaction. However, the layers' contribution to galvanic corrosion was minimal in deaerated acidic solutions, which is attributed to the high bonding strength of adsorbed intermediates to the coating surfaces.

Influence of substrate bias on machining performance of TiAlN-coated drill bits

ABSTRACT The present study investigates the influence of substrate bias on edge-rounding of TiAlN-coated drill bits arising out of coating deposition and the resulting cutting performance while machining Inconel 718. Tungsten carbide (WC) drill bits were deposited with TiAlN coating through a cathodic arc physical vapor deposition (CAPVD) system. Five different substrate bias voltages varying from −20 V to −60 V were employed for the deposition. The hardness, adhesion strength, and residual stress were significantly influenced by substrate bias. The sharp edges of coated drill bits exhibited significant edge-rounding at relatively higher levels of substrate bias. The reason for such edge-rounding is the re-sputtering and residual stress-induced micro-chipping of the previously formed coating layer during the deposition. The edge-rounding of drill bits was in the order of: 20 V <30 V <40 V <50 V <60 V. The drill bits deposited at −50 V substrate bias exhibited the best tool life owing to optimum edge radius (resulting in better edge stability) and coating properties. The present study helps identify an optimum level of substrate bias, which results in a favorable edge radius and the best tool life of the coated drill bits.

The effect of Ti and Si on the mechanical and electrochemical behaviors of the AlCrN coating deposited by CAPVD on 304SS

This study aimed to investigate the effect of adding titanium (Ti) and silicon (Si) elements on the mechanical and electrochemical properties of the AlCrN-based coating. For this purpose, a cathodic arc physical vapor deposition machine was used. Scanning electron microscopy, X-ray diffraction, and nanoindentation tests were utilized for morphological, microstructural, and mechanical characterization of the coatings. The hardness value and plastic deformation index of CrAlN-based coating increase with the presence of Si element. The mechanical properties improvement is attributed to the reduction of crystallite size as well as to the tendency of the coating structure to become amorphous. The specimens were subjected to 3.5 wt% NaCl solution to electrochemical impedance corrosion and potentiodynamic polarization tests. The results showed that by increasing the coatings’ titanium content, the coatings’ corrosion resistance improved. Moreover, by adding 3% and 5% of Si elements to the coatings’ composition, the corrosion resistance of the AlCrTiSiN coatings was enhanced by 35% and 78%, respectively. Improving the corrosion resistance of the AlCrN-based coatings by adding the Si element is attributed to the change in the microstructure and reduction in the porosity of the coatings.

Structural, mechanical, and tribological properties of CrCN coatings obtained by cathodic arc physical vapour deposition technology at different CH4/N2 gas ratio

Chromium carbonitride coatings were deposited by cathodic arc physical vapor deposition technology at a temperature of 300 °C, as were used the reactive gasses CH4 and N2. The structural analysis of the CrN coating showed a polycrystalline structure with mixed CrN and Cr2N phases. All studied coatings, including the CrC exhibits fcc structure. The phases were confirmed by X-ray photoelectron spectroscopy measurements where a surface oxidation was also detected. The increase of the CH4 gas flow during the deposition process leads to a parabolic trend with the highest hardness of 33.5 GPa for the coating deposited at CH4 / N2 = 0.53. At the same time the lowest coefficient of friction for both counterparts Al2O3 and ZrO2 (0.28 and 0.26, respectively) were measured at CH4 / N2 = 1.86. The tribological tests reveal that the wear of the coatings increases with an increasing CH4 flow rate, whereas the coefficient of friction decreases. This observed contradiction is explained by a phenomenon described as the effect of Rebinder.

Effect of duplex treatment on the long-term stability of the abutment-implant interface by plasma nitriding and TiN coating

The purpose of this study was to evaluate the mechanical properties of abutments subjected to duplex treatment with arc plasma nitriding and physical vapor deposition (PVD) TiN coatings. The surface properties of abutments were analyzed. Then, the screw preload and microgap at the abutment-implant interface were measured. Screw loosening, abutment settlement, and abutment pullout force were tested before and after loading. The fatigue life of implant systems was compared. Finally, abutment surface wear and fatigue fracture surfaces were observed and analyzed. The results showed that duplex-treated abutment increased screw preload, interface contact area, loosening torque, and pullout force. Furthermore, the duplex-treated abutment exhibited good wear resistance and prolonged the fatigue life of implant systems. After cyclic loading, the screw torque loss rate decreased by 15.63 % and the abutment pullout force increased by 3 times. Therefore, duplex-treated abutments could effectively improve the long-term stability of the abutment-implant interface, which may be a suitable method for dental application.

Photocatalytic Evaluation of TiOx Films Produced by Cathodic Arc-PVD with Silver Addition by UVC Photo-Reduction Method

A titanium (Ti) commercial cathode material and high purity Ar and O2 were used in the cathodic arc physical vapor deposition (arc-PVD) process. The TiOx coating was deposited on the three sets of Raschig rings using decreasing ratios of Ar/O2:440/60, 400/100 and 300/100. The cross sections of the TiOx PVD coating were analyzed using field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). A homogeneous layer of Ti with small O content was observed, and the data suggest that a thin TiOx oxide film was deposited. For this reason, a thermal treatment was applied to the coating to oxidize it and form the rutile phase of TiO2 in the coating, which was demonstrated by grazing incidence XRD. In addition, the TiOx coatings absorb radiation, which was observed by diffuse reflectance band gap energy measurement. Silver (Ag) was added by the photo-reduction method, using UVC light to activate the TiO2 coating, and the band gap energy was analyzed by diffuse reflectance. The photocatalytic activities of the films were evaluated by degradation of the model dye rhodamine B and in the removal of fecal coliforms using two matrices, water from a secondary treatment effluent, and synthetic water.