Influence of annealing temperature on microstructure evolution of TiAlSiN coating and its tribological behavior against Ti6Al4V alloys

TiAlSiN multicomponent coating, owing to its high hardness and excellent high temperature resistance, was widely used in the cutting field of difficult-to-cut materials such as titanium alloys. For machining titanium alloys, high temperature is easy to gather on the tool chips and deteriorate the cutting tools. Moreover, high temperature will also promote the microstructure evolution and make the wear mechanism more complex. In this paper, TiAlSiN coatings were deposited on cemented carbides and annealed at 400 °C, 600 °C and 800 °C respectively for 60 min in air, followed by reciprocating friction tests against Ti6Al4V counterparts. AFM, SEM, EDS and XPS were applied to investigate the microstructure evolution and tribological behavior of TiAlSiN coating after high temperature annealing. The results demonstrated that the oxidation resistance of TiN phase in TiAlSiN coating was worse than Si₃N₄ and AlN phases. These nitrides can be oxidized to TiO₂, SiO_x and AlO_x under 600 °C, and the depth of oxide layer was increased with the rising annealing temperature, resulting in the coarsened microstructure. The wear mechanisms of as-deposited TiAlSiN coating were oxidation wear and adhesion wear. With the rising annealing temperature, abrasive wear was gradually enhanced. For the TiAlSiN coating annealed at 800 °C, abrasive wear became the dominant wear mechanism.     

Properties of TiN–Al2O3–TiCN–TiN,TiAlN, and DLC-coated Ti(C,N)-based cermets and their wear behaviors during dry cutting of 7075 aluminum alloys

In the work, TiAlN for physical vapor deposition (PVD), multilayer TiN-Al₂O₃-TiCN-TiN for chemical vapor deposition (CVD), and diamond-like carbon (DLC) for plasma-enhanced chemical vapor deposition (PECVD) were deposited on the cermet inserts. Characteristics and wear behaviors of the three coated cermets during dry cutting of 7075 aluminum alloys were observed. The results show that TiN-Al₂O₃-TiCN-TiN coatings have highest adhesion strength and hardness. At the cutting speed of 1100 r/min, the depth of 0.2 mm, and the feed rate of 0.1 mm/r, the three coated inserts show the best wear-resistant properties. In this case, TiN/Al₂O₃/TiCN/TiN shows the worst wear-resistant properties (value of the flank wear [VBB] = 0.062 mm), while DLC coatings show the most excellent wear-resistant properties (VBB = 0.046 mm). During the cutting of aluminum alloys, which have high plasticity and low melting point, adhesive wear dominate on the flank of the inserts. The thickest coating of TiN/Al₂O₃/TiCN/TiN results in the bluntest cutting edge, which form the most serious adhesive worn zone. For the TiAlN and DLC coatings, due to a smaller cutting force, the two coatings have much better wear resistance. Further, the self-lubricating properties of DLC show excellent effect on protecting the inserts. Thus, the DLC-coated cermets have the best wear-resistant properties. Further, the TiAlN-coated cermets have the widest wear-affected zone while the DLC coating has the narrowest.     

Repair of spline shaft by laser-cladding coarse TiC reinforced Ni-based coating: Process,microstructure and properties

To repair the surface defects of spline shaft and improve wear resistance, the coarse TiC reinforced Ni-based composite coatings were fabricated on the spline shaft surface by laser cladding with six types of precursors containing Ni45, coarse TiC, and fine TiN powder. The effects of ceramic content and fine TiN addition on the formability, microstructure, and mechanical properties of the coatings were studied comprehensively. In TiC reinforced Ni-based coatings 1–3 without fine TiN addition, the porosity decreased from 20.415 % to 0.571 % with the increase of TiC concentration. The coatings mainly consist of CrB, Cr7C3, Cr23C6, coarse TiC, and γ-Ni. With the addition of fine TiN, the length of the ceramic phases in coatings 1#–3# decreased slightly, while volume fraction and porosity increased. Moreover, the ring-shaped Ti (C, N) phases were also detected at the edges of both undissolved TiC and TiN particles, which improved the bonding force between ceramics and matrix. Besides, these ceramics inhibited the generation of columnar crystals and eliminated the heat-affected zone. The performance test results show that the coating 3# with 30 wt% TiC and 6 wt% TiN exhibits the best wear resistance despite slightly decreased hardness, and its friction coefficient of 0.409 and wear rate of 42.44 × 10⁻⁶ mm³ N⁻¹·m⁻¹ are, respectively, 0.667 and 0.307 times those of the substrate. Based on the additive/subtractive hybrid manufacturing technology, the optimized coatings were ground to obtain the finishing surface, which indicates that the coarse TiC reinforced coating can be employed in repairing the damaged parts.     

Microstructure and tribological behavior of TiAlSiN coatings deposited by deep oscillation magnetron sputtering

Development of pulsed‐techniques aimed to generate highly ionized target species and high plasma density opens up a new way to tailor composition, structure, and properties of coatings. In this work, TiAlSiN coatings have been deposited at various negative substrate biases (V_s) using deep oscillation magnetron sputtering by sputtering a TiAlSi compound target in Ar/N₂ mixtures. The increase in V_s from ?30 to ?120 V resulted in a decrease in (111)‐preferred orientation and grain size, together with the increase in residual stress and rough morphology. The nc‐TiAlN/a‐Si₃N₄ nanocomposite structure was obtained in coatings. The highest hardness and Young's modulus reached 42.4 and 495 GPa at ?120 V, respectively. However, at ?60 V, the coatings with the highest H/E* and H³/E*² ratios of 0.095 and 0.332 exhibited excellent adhesion with above HF1 level, the lowest coefficient of friction (COF) of 0.35 and specific wear rate of 2.1 × 10^?7 mm³ N^?1 m^?1. Wear mechanism changed from the mixture of severe adhesive, oxidative and abrasive wear to mild oxidative wear to severe oxidative wear. TiAlSiN coatings with high hardness and H/E* and H³/E*² ratios exhibited the decrease in COF and wear rate due to refined grains in uniform distribution, which well promoted oxide layers formed on sliding contact surface.     

Strongly adherent Al2O3 coating on SS 316L: Optimization of plasma spray parameters and investigation of unique wear resistance behaviour under air and nitrogen environment

Plasma spray deposition of Al₂O₃ is a well-established technique for thick ceramic coatings on various substrates to shield them from corrosion and wear. Owing to its high hardness, aluminum oxide is known to protect stainless steel substrates from wear. However, the plasma process requires optimization for desired coating thickness and adhesion strength. It is also necessary to understand the sensitivity of friction and wear resistance of the deposited coating on exposed environment for evaluation of service life. The study offers comprehensive investigation on plasma process parameters for the development of strongly adherent aluminium oxide coatings on SS 316L substrate. Impact of environment like dry air and dry nitrogen on tribological properties of the coatings was also investigated. Dense adherent coatings of alumina could be deposited on SS 316L at a plasma power of 20 kW with an intermediate bond coat of NiCrAlY to enhance the adhesion properties. The effects of stand-off distance and bond coat thickness on adhesion strength were additionally examined. Further, the coatings were characterised for phase composition, microstructure, microhardness and wear resistance potential. Reciprocating wear tests of the coatings were carried out using ball on disc reciprocating tribometer at different loading conditions (5, 10 and 15 N) at constant (5 Hz) sliding frequency. Unlike the coefficient of friction (COF), wear volume was found to increase with an increase in normal load. These adherent coatings revealed promising properties for the applications where the tribological failure of SS 316L in dry air or dry nitrogen environment is to be controlled.     

Electrochemical corrosion and materials properties of reactively sputtered TiN/TiAlN multilayer coatings

TiN/TiAlN multilayers of 2 μm thickness were successfully prepared by reactive DC magnetron sputtering method. XRD pattern showed the (1 1 1) preferential orientation for both TiN and TiAlN layers. XPS characterization showed the presence of different phases like TiN, TiO₂, TiON, AlN and Al₂O₃. Cross sectional TEM indicated the columnar growth of the coatings. The average RMS roughness value of 4.8 nm was observed from AFM analysis. TiN/TiAlN coating showed lower friction coefficient and lower wear rate than single layer coatings. The results of electrochemical experiments indicated that a TiN/TiAlN multilayer coating has superior corrosion resistance in 3.5% NaCl solution.     

Effects of B/C ratio on the structural and mechanical properties of TiBCN coating deposited by PACVD

TiBCN coating is known as a hard, self-lubricant and wear resistant coating which can be applied on industrial tools to increase their working life time under severe wear conditions. In this paper, TiBCN coatings with different B/C ratios were applied on H13 steel using plasma-assisted chemical vapor deposition from BBr₃, TiCl₄, CH₄, N₂ and H₂ reactants at 500 °C. The results signified that the introduction of B and C elements to TiN changed its preferred crystalline orientation from (200) to (111) and decreased crystal size from 12 to 9 nm as a result of the formation of amorphous phases which constrain grain growth. The addition of B and C altered the coating's nucleation and growth mechanisms and generated a strong surface etching agent of HBr which significantly changed surface morphology and roughness. Increasing flow ratio of CH₄ to BBr₃ from 0.125 to 0.25 influenced the coating's mechanical properties and increased coating's hardness from 18.1 to 23.2 GPa and Young's modulus from 296 to 334.7 GPa. Rising coating's C content remarkably improved its nano-wear resistance and the coating with the highest C content exhibited a wear volume of 1*10⁻¹⁹ m³ which was about 63% lower than that of TiN coating.     

Mechanical,biocorrosion, and antibacterial properties of nanocrystalline TiN coating for orthopedic applications

The current study analyzes the surface, mechanical, biocorrosion, and antibacterial performances of a nanocrystalline TiN ceramic coating synthesized using cathodic arc-physical vapor deposition (PVD) on biomedical Ti6Al4V substrates. The surface hardness and modulus of elasticity were assessed using the microindentation method. The adhesion, friction coefficient, and antibacterial properties of the coating were evaluated. The in vitro corrosion of the prepared coated Ti alloy substrate was analyzed in simulated body fluid (SBF) via cyclic potentiodynamic polarization (CPP), dynamic electrochemical impedance spectroscopy (DEIS), and scanning vibrating electrochemical technique (SVET). The results demonstrated that a nanocrystalline TiN coating with a crystallite size of 10.33 nm and a thickness of 5 μm was formed with good adhesion on the alloy surface. The coating had an enhanced surface hardness of 38.63 GPa and a modulus elasticity of 358 GPa, and exhibited enhanced resistance to plastic deformation compared with the substrate – features that can enhance the service life of an implant. The antibacterial experiments indicated an upgraded antibacterial performance of the TiN coating compared to the bare alloy. The in vitro corrosion-resistance analyses confirmed the enhanced surface protective performance of TiN ceramic coatings against biocorrosion in SBF. The results showed higher impedance values in DEIS, a higher passive region in the CPP analysis, and a lower anodic current density in the SVET analysis compared with the bare substrate.     

Thermostability,oxidation, and high-temperature tribological properties of nano-multilayered AlCrSiN/VN coatings

In this study, monolithic AlCrSiN, VN, and nano-multilayered AlCrSiN/VN coatings were deposited using a hybrid deposition system combining arc ion plating and pulsed direct current magnetron sputtering. The microstructure, thermostability, mechanical, oxidation and tribological properties of the coatings were comparably investigated. The multilayered AlCrSiN/VN coating exhibited a face-centered cubic (fcc) structure with (200) preferred orientation and showed the highest hardness (30.7 ± 0.5 GPa) among these three coatings due to the multilayer interface enhancement mechanism and higher compressive stress. The AlCrSiN sublayers effectively prevented the V element from rapid outward diffusion to the surface of AlCrSiN/VN coating at elevated temperatures, which improved the oxidation resistance of the coating. Decomposition of V (Cr)–N bonds occurred at annealing temperatures from 800 °C to 1000 °C and V₂N phase appeared at 1100 °C. The AlCrSiN/VN coating showed excellent tribological performance at high temperatures by combining the merits of VN layers for low friction coefficient and AlCrSiN layers for superior oxidation resistance. Compared to VN and AlCrSiN coatings, AlCrSiN/VN coating showed the lowest wear rate of 2.6×10^-15 m³/N·m at 600 °C and lowest friction coefficient of 0.26 at 800 °C with a relativity low wear rate of 39.4×10^-15 m³/N·m.     

Wear behavior of graded Cr-CrN-Cr(1−x)Al(x)N coatings synthesized by closed-field unbalanced magnetron sputtering for advanced machining operations

Graded Cr-CrN-Cr_(1?x)Al_(x)N coatings were synthesized onto M42 HSS substrates used in advanced machining operations by closed-field unbalanced magnetron sputtering (CFUBMS). The tribological behavior of these graded coatings was explored in detail by advanced electron microscopy, confocal laser scanning microscopy, nanoindentation and dry sliding wear tests. The presence and magnitude of residual stresses in these coatings were determined by the XRD – sin²ψ method, which revealed increasing compressive stresses with increasing Al content. The coating surface morphology, mechanical properties were determined prior to dry sliding wear by atomic force microscopy (AFM) and nanoindentation methods, which yielded decreasing surface roughness (R_a) as well as enhancement of hardness and modulus along with increase in H/E and H³/E² ratios with increasing Al content. Tribological investigation was performed with a pin-on-disc arrangement by keeping the sliding velocity (0.2?ms^?1) and normal axial load (10?N) constant and varying the sliding distance. Specific wear rates of the order ~ 10^–17 m³ N^?1 m^?1 were encountered for all coatings with the wear rates increasing as the Al content increased implying a decrease of wear resistance of the coatings. Abrasive wear has been found to be the dominant wear mechanism during dry sliding wear. Increasing modulus mismatch between coating and substrate can be mainly attributed to a decrease in wear resistance of the coatings.     

Complex study of protective Cr3C2–NiAl coatings deposited by vacuum electro-spark alloying,pulsed cathodic arc evaporation,magnetron sputtering,and hybrid technology

Coatings were obtained by vacuum electro-spark alloying (VESA), pulsed cathodic arc evaporation (PCAE), magnetron sputtering (MS) techniques and VESA-PCAE-MS hybrid technology using Cr₃C₂–NiAl electrodes. The structure of the coatings was analyzed using scanning and transmission electron microscopy, X-ray diffraction and energy-dispersive spectroscopy. Mechanical properties were determined by nanoindentation, while tribological properties were assessed using pin-on-disk tribometer. Corrosion resistance was estimated by voltammetry in 1 N H₂SO₄ and 3.5%NaCl solutions. Oxidation resistance tests were performed at 800°С in air. The VESA coating had the highest thickness, low friction coefficient and high wear resistance. PCAE coating demonstrated the highest hardness (24 GPa) and elastic recovery (59%), oxidation resistance and superior corrosion resistance both in 1 N H₂SO₄ (i_corr = 70 μА/cm²) and 3.5%NaCl (i_corr = 0.74 μА/cm²) solutions. The MS coating had average mechanical properties and low corrosion current density (71 μА/cm²) in 1 N H₂SO₄. Deposition of coatings using VESA-PCAE-MS hybrid technology led to an increase in corrosion and oxidation resistance at least by 1.5 times in comparison with the VESA coating.     

Friction behavior of TiN–MoS2/PTFE composite coatings in dry sliding against SiC

To improve the dry friction behavior of traditional hard coatings, MoS₂/PTFE lubricating coatings were prepared on the PVD TiN-coated cemented carbide using spray method. The influences of MoS₂/PTFE lubricating coatings on the primary characteristics of TiN coatings were investigated. Reciprocating sliding tests were carried out with the TiN–MoS₂/PTFE coated specimen (T-M-P) under dry sliding conditions, and the tribological behaviors were compared to those of the TiN-coated one (T-N). The test results indicated that the adhesion force of coatings with substrate for T-M-P specimen increased, the surface micro-hardness, roughness and friction coefficient significantly decreased. Meanwhile, the surface adhesions and abrasion grooves of T-M-P specimen were reduced, and the main wear forms of T-M-P were abrasion wear and coating delamination. The MoS₂/PTFE lubricating coatings can be considered effective to improve the friction properties of traditional hard coatings.     

Scratch and wear resistance of hydrophobic CeO2-x coatings synthesized by reactive magnetron sputtering

CeO_2-x coatings were deposited under variable oxygen flow ratios (%f_O2) onto Si substrates by reactive magnetron sputtering. Nanoindentation testing revealed an increase in the hardness, elastic modulus, H/E and H³/E² ratio with increasing oxygen flow ratio, which in turn increased the adhesion and tribological performance of the coatings. Scratch testing yielded the highest critical load (L_C2 = 28.8 N) and CPR_S = 103 for the coating deposited with the highest oxygen flow ratio (57 %f_O2). Cracking events during scratch testing were initiated by tensile forces behind the scratch stylus, which led to the formation of semi-circular ring cracks. As the normal load increased, transverse cracks emerged extending outwards from the scratch track towards the edge causing the exposure of substrate. Beyond L_C2, severe spallation of the CeO_2-x coatings led to coating failure. Furthermore, the specific wear rates of the CeO_2-x coatings were determined to be within the ~10⁻¹⁵ m³/Nm range influenced by three-body abrasive wear. In-depth analyses from scratch and wear data indicates that these coatings possess good adhesion and durability.     

Effect of MoS2/PTFE coatings on performance of Si3N4/TiC ceramics in dry sliding against WC/Co

To enhance the tribological performance of Si₃N₄/TiC ceramics, MoS₂/PTFE composite coatings were deposited on the ceramic substrate through spraying method. The micrographs and basic properties of the MoS₂/PTFE coated samples were investigated. Dry sliding friction experiments against WC/Co ball were performed with the coated ceramics and traditional ones. These results showed that the composite coatings could significantly reduce the friction coefficient of ceramics, and protect the substrate from adhesion wear. The primary tribological mechanisms of the coated ceramics were abrasive wear, coating spalling and delamination, and the tribological property was transited from slight wear to serious wear with the increase of load because of the lower surface hardness and shear strength. The possible mechanisms for the effects of MoS₂/PTFE composite coatings on the friction performance of ceramics were discussed.     

Substrate effect on wear resistant transition metal nitride hard coatings: Microstructure and tribo-mechanical properties

Four types of different hard transition metal nitrides (TMN:ZrN, CrN, WN and TiN) coatings were deposited on Si (100) and 316LN stainless steel substrates using DC magnetron sputtering. A comprehensive study of microstructure and substrate dependent tribo-mechanical properties of TMN coatings was carried out. Higher hardness (H) and elastic modulus (E) were obtained for WN (H=40 GPa and E=440 GPa) and TiN (H=30 GPa and E=399 GPa) coatings. This is related to the formation of (100) and (111) preferred orientations in WN and TiN coatings, respectively. However, the less hardness and elastic modulus were obtained for ZrN and CrN coatings where (200) orientation is preferred. Remarkably, low friction coefficient (0.06–0.57) and higher wear resistance in the coatings deposited on steel substrates are directly associated with the higher resistance to plastic deformation (H³/E²) and the presence of intrinsic compressive stress. Three body wear modes enhanced the friction coefficient (0.15–0.62) and the wear rate in the coatings deposited on Si substrates. This is primarily associated with low fracture toughness of brittle single crystalline Si (100) substrates. Steel-on-steel contact was dominated in ZrN/steel sliding system. This occurs due to the severe adhesive wear mode of steel ball, whereas, the abrasive wear modes were attained for the CrN, WN and TiN coatings sliding against steel balls.     

Effect of laser power on microstructure and tribological performance of WC−10Co4Cr coating

In order to enhance wear resistance of cold work molds, WC−10Co4Cr coating was fabricated on Cr12MoV steel by laser cladding. The morphologies, chemical compositions, and phases of obtained coatings were analyzed using a scanning electron microscopy (SEM), energy disperse spectroscopy, and X−ray diffraction, respectively. The effect of laser power on the tribological performance was analyzed using a ball−on−plate friction machine, and the wear mechanism was also discussed. The results show that the WC−10Co4Cr coating is composed of WC and Co₆W₆C phases, and the average hardness of coating cross−sections fabricated at the laser power of 1200, 1500, and 1800 W was 1296, 1375, and 1262 HV_0.5, respectively, in which that fabricated at the laser power of 1500 W is the highest among the three kinds of coatings. The average coefficients of friction of coatings fabricated at the laser power of 1200, 1500, and 1800 W are 0.61, 0.52, and 0.59, respectively; and the corresponding wear rates are 64.38, 35.38, and 123.92 μm³•N⁻¹•mm⁻¹, respectively, showing that the coating fabricated at the laser power of 1500 W has best friction reduction and wear resistance. The wear mechanism of WC−10Co4Cr coating is fatigue wear and abrasive wear, which is contributed to the increase of hard WC mass fraction.     

Preparation of Al2O3 coating on TiN coating by polymer-assisted deposition to improve oxidation resistance in coking inhibition applications

In order to inhibit the metal catalytic coking and improve oxidation resistance of single TiN coating, the TiN/Al₂O₃ double layer coatings were designed as a chemically inert coating for methylcyclohexane supercritical pyrolysis. Internal TiN coatings were prepared by atmospheric pressure chemical vapor deposition using TiCl₄–H₂–N₂ system. The external Al₂O₃ coatings with different thicknesses were prepared on the TiN surface by polymer-assisted deposition, and the coating with the most suitable thickness was further annealed at different temperatures of 600, 700, 800 and 900 °C. The morphology, elemental and phase composition of TiN/Al₂O₃ coatings were characterized by SEM, EDX and XRD respectively. The chemical state information of the coating elements was based on Ti 2p, Al 2p core level X-ray photoelectron spectroscopy (XPS) spectra. The results indicated that the external Al₂O₃ coating will partially peel off at 900 °C annealing temperature. The thermogravimetric analysis results indicated that all TiN/Al₂O₃ coatings show better oxidation resistance than single-layer TiN coating. The anti-coking test with methylcyclohexane supercritical pyrolysis showed that the TiN/Al₂O₃ coatings can effectively cover the metal catalytic sites and eliminate metal catalytic coking. However, the acid sites of external Al₂O₃ coating slightly promoted coking, so the anti-coking ratios of TiN/Al₂O₃ coatings were smaller than that of TiN. Thus, the addition of external Al₂O₃ coating can greatly improve the oxidation resistance of TiN coatings with little loss of coking resistance.     

Sand erosion and crack propagation mechanism of Cr/CrN/Cr/CrAlN multilayer coating

Herein, we have deposited Cr/CrN/Cr/CrAlN multilayer coatings with various modulation ratios on TC11 alloy substrate using cathodic arc system. The influence of various modulation ratios on microstructure and Al₂O₃ sand erosion behavior of coatings is systematically studied. Results reveal that the coatings are about 200 nm per cycle and total thickness is 8 μm. Five groups of coatings exhibit high hardness (>3000 HV_0.025). The coating with modulation ratio of 12 adhesion can reaches 55 N. The residual stress increases with the decrease of the modulation ratio, but the increase is generally low (less than ?2 GPa). In addition, according to sand erosion test, it is found that sand erosion resistance of multilayer coating is significantly around 5 times higher than TC11 alloy matrix. The erosion morphology shows that a large number of irregular cracks and layered spalling appear on the surface of the coating, indicating that the cracks are constantly initiated under the continuous impact of the sand and gravel，and finally gather together and then spalling. Moreover, dynamic response and stress field of the coating under the impact of single sand (Al₂O₃) are studied by numerical simulations. It is determined that coating cracking is caused by high tensile stress under CrAlN layer. In addition, according to crack propagation morphology and influence of different interfaces between multilayered structures on crack tips, propagation/termination mechanism of cracks is analyzed in detail. Cracks are easy to initiate in hard CrAlN layer and consume a lot of energy after propagating into soft Cr layer, thereby ending at next soft and hard interfaces. These results provide experimental and theoretical support for the study of high tenacity and anti-erosion coating.     

DLC–ceramic multilayers for automotive applications

The present work explores the deposition of hard, wear resistant multilayer coatings, by magnetron sputtering onto Aluminium (Al) alloy substrates that are used in the automotive industry. Multilayer coatings have been manufactured to increase surface hardness and wear resistance for a commercial powder metallurgy Al alloys (Al 2618). The multilayer coating consisted of 25 bi-layers of Titanium Diboride (TiB₂) and diamond-like carbon (DLC). These DLC/TiB₂ coatings were fabricated, maintaining a constant composition wavelength (sum of two layers [λ] = 200 nm) for an array of ceramic fractions ranging from 75% to 95% by volume. The effect of the DLC content on the structure and performance (hardness and adhesion) of the films was investigated. The bi-layer thickness influences the failure patterns resulting from the scratch testing. This study has found hardness values of 27.8 GPa, with a critical load of 20 N and a friction coefficient of 0.47. As a result of these findings the multilayer with 10% of DLC was found to be a better compromise between high hardness (23.8 GPa) and high adhesion (critical load higher than 20 N) and with no signs of cracking during friction testing, proving to be a solution to be employed in components located in the upper valve train area of high performance vehicles.     

Enhancement of the Ti-6Al-4V alloy corrosion resistance by applying CrN/CrAlN multilayer coating via Arc-PVD method

In this study, the Ti-6Al-4V substrate was coated by CrN-CrN/TiN-TiN and CrN/CrAlN multilayer coatings using the cathodic arc physical vapor deposition (Arc-PVD) method. The results of potentiodynamic polarization (PDP) have shown the lowest and highest corrosion current density belong to the double-layer (0.16 µA/Cm²) and TiN (0.51 µA/Cm²) samples, indicating the higher corrosion resistance of the double-layer coating. The field emission electron microscope (FESEM), X-ray diffraction pattern (XRD), open circuit potential (OCP), PDP, and electrochemical impedance spectroscopy (EIS) analysis were employed in order to characterize the coatings and evaluate their corrosion behavior. Finally, applying the double-layer coating resulted in the significant improvement of the protective behavior of the Ti-6Al-4V alloy, as compared to the sample coated with TiN in corrosive environments.