This study investigates the structural, mechanical, and tribological performance of two functionally graded diamond-like carbon (DLC) coatings-Ti-TiC-TiNbC-a:C and Ti-TiC-TiNbC-TiNbCN-a:C-deposited on AISI M2 high-speed steel via closed-field unbalanced magnetron sputtering. The multilayer design was developed to mitigate residual stress and adhesion limitations commonly observed in conventional DLC films. Cross-sectional SEM and XRD analyses confirmed the formation of dense, nanocrystalline TiC, NbC, and Ti(C,N)/TiN phases embedded in an amorphous carbon matrix, with significant niobium enrichment verified by EDS. Mechanical testing revealed that the Ti-TiC-TiNbC-a:C coating achieved a hardness of 1250 HK0.01, while nitrogen incorporation in the Ti-TiC-TiNbC-TiNbCN-a:C structure increased hardness further to 1500 HK0.01. Both coatings maintained ultralow and stable friction coefficients (0.10-0.11), yet the nitrogen-enriched film exhibited a higher wear rate (8.0 & times; 10- 5 vs. 3.2 & times; 10- 5 mm3/N & centerdot;m). Scratch adhesion tests showed superior interfacial strength for the thinner Ti-TiC-TiNbC-a:C coating (37 N) compared to the thicker Ti-TiC-TiNbC-TiNbCN-a:C variant (28 N), suggesting that excessive layer thickness and nitrogen incorporation exacerbate residual stresses and reduce adhesion. Overall, the findings demonstrate that while Nb- and N-rich graded DLC architectures improve hardness, they compromise wear resistance and adhesion, emphasizing the importance of carefully optimizing layer composition, thickness, and stress management for practical industrial applications.

This study investigates the structural, mechanical, and tribological properties of two novel functionally graded diamond-like carbon (DLC) coatings-Ti-TiC-TiVC-a:C and Ti-TiC-TiVC-TiVCN-a:C-deposited on AISI M2 tool steel via closed-field unbalanced magnetron sputtering. The coatings, with thicknesses of 1.5 mu m and 1.7 mu m respectively, were engineered to overcome the intrinsic challenges of DLC coatings, such as high residual stress and poor adhesion. A significant enhancement in microhardness was achieved, with values reaching 1300 HK0.(0)(1) (0.1 N) for the Ti-TiC-TiVC-a:C coating and 1425 HK0.(0)(1) (0.1 N) for the Ti-TiC-TiVC-TiVCN-a:C coating, substantially exceeding the substrate hardness of 800-850 HK0.(0)(1). Scratch testing revealed excellent adhesion, with critical load (Lc) values of 24 N and 21 N, indicating only a minor trade-off for the nitrogen-enriched variant. Both coatings exhibited an exceptionally low and stable friction coefficient of 0.09. Crucially, the incorporation of a nitrogen-rich TiVCN interlayer led to a remarkable 33% improvement in wear resistance, reducing the wear rate from 1.0 x 10-5 mm3/Nm to 6.7 x 10-6 mm3/Nm. These findings demonstrate that vanadium-based graded DLC systems, particularly those utilizing carbonitride phases, offer a superior balance of high hardness, exceptional wear resistance, and excellent lubricity, making them prime candidates for advanced tribological applications.

Al 7075 is a high-strength aluminum alloy widely used in aerospace and automotive applications; however, its surface hardness and wear resistance are limited. In this study, Al 7075 was shot peened using S110 and S230 shot types at Almen intensities of 8A and 10A, followed by TiN thin film deposition by physical vapor deposition (PVD). The coatings were produced under different target currents (2-3 A), N-2 flow rates (5-7 sccm), and duty cycles (15-30 %) based on a Taguchi L-4 design. Structural, mechanical, and tribological properties were evaluated using microscopy, microhardness, scratch, and pin-on-disk tests under dry sliding conditions. The combined treatment increased surface hardness from similar to 178 Vickers microhardness (HV) to similar to 832 HV (S230 shot and 10A with titanium nitride (TiN) coating) approximate to 395 %. Shot peening (SP) increased the surface roughness from approximately 4-5 & micro;m to 9-12 & micro;m, whereas subsequent TiN coating reduced the roughness to about 3-4 & micro;m. Scratch test results revealed improved coating adhesion, with critical load values reaching up to 27 N. Among the investigated conditions, the combination of S230 shot type with 10 Almen intensity and optimized PVD parameters (R3) provided the most favorable balance between hardness, adhesion strength, and tribological performance, demonstrating the effectiveness of SP-assisted TiN coating for enhancing the surface durability of Al 7075.

The choice of metal dopant strongly influences the structural and tribomechanical performance of diamond-like carbon (DLC) coatings. In this study, two graded Ti-based architectures—Ti-TiC-TiZrC-a:C and Ti-TiC-TiZrC-TiZrCN-a:C—were deposited on AISI M2 tool steel by closed-field unbalanced magnetron sputtering with pulsed-dc biasing to clarify the effects of Zr and nitrogen incorporation. SEM observations revealed dense-graded morphologies with thicknesses of approximately 2 μm and 3 μm, respectively. XRD confirmed the formation of TiC and TiZrC phases in both coatings, with additional TiZrCN reflections in the nitrogen-containing system. Both coatings significantly increased hardness relative to the substrate, reaching 1280 ± 25 and 1300 ± 28 HK0.01, respectively; however, statistical analysis (p ≈ 0.27) indicated no significant difference between them. Tribological testing showed that the Ti-TiC-TiZrC-a:C coating exhibited superior balance, with lower friction (0.090), a lower wear rate ((1.21 ± 0.03) × 10−5 mm3/N·m), and a higher critical load (47 N). Nitrogen incorporation altered the phase constitution and stress state but did not enhance overall tribological performance. The results show that interlayer architecture and stress control are more decisive than compositional complexity in optimizing graded Ti-based DLC coatings.

This study investigates the effects of a duplex surface treatment, consisting of sub-β-transus heat treatment followed by W-DLC coating via closed-field unbalanced magnetron sputtering (CFUBMS), on the fatigue behavior of Ti6Al4V ELI alloy fabricated using laser powder bed fusion (L-PBF). Post-processing techniques were analyzed for their influence on fatigue performance under diverse ambient conditions (steady and cyclic). Fatigue tests were conducted using the stress-life methodology at 25 ℃ (room temperature), 50 ℃, 250 ℃, −50 ℃, and cyclic conditions ( −50/ + 50 ℃). Structural, morphological, and mechanical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Vickers hardness testing. The microstructural analysis highlighted significant strain accumulation near fracture sites and the presence of micropores, which contributed to microcrack initiation. Results demonstrated that test temperature notably influenced fatigue life, significantly reducing under cyclic conditions ( −50/ + 50 ℃) compared to room temperature. Heat treatment and W-DLC coating notably enhanced fatigue performance across all test conditions by forming a protective barrier and reducing residual stresses.

The space, aviation, and defence industries demand advanced engineering solutions that ensure high reliability, durability, and performance under extreme conditions, which has become increasingly important in recent times. In these sectors, wear and corrosion are critical factors that limit the service life of mechanical components by causing damage under operating conditions, not only impairing their expected functional properties but also potentially leading to severe consequences such as structural fatigue, breakage, and catastrophic failure. In order to improve surface qualities and reduce material consumption, repair-maintenance costs, and economic expenses, this study developed TiN-based multilayer coatings through using the CFUBMS technique to deposit various coating cycle numbers on silicon and Inconel 718 (IN718) superalloy substrates. For these purposes, the structural, mechanical, tribological, and corrosion behaviours of the coatings were characterised using SEM, EDS, XRD, microhardness measurement, pin-on-disc friction-wear evaluation, scratch adhesion test, and electrochemical corrosion analysis. The analyses revealed the following results. As the coating cycle numbers increased, the coating thicknesses ranged from 1.75 mu m to 4.85 mu m. Meanwhile, the nitrogen content in the coatings was found to reach approximately 36-39 %. The formation of AlN, TiN, and TiAlN phases during the coating process was confirmed by XRD analysis. Among the specimens, the three-cycle (C3) coating mostly exhibited superior performance with the highest hardness (HC3 = 20.5 GPa, which is 3,75 times higher than the substrate), the lowest average coefficient of friction (C3, mu mean = 0.272, which is 1.30 times lower than the substrate), the lowest wear rate (KC3 = 2.558 x10-15 m3/N & sdot;m, which is 54 times lower than the substrate), and significantly improved corrosion resistance (C3, Icorr = 94 nA, which is 12.75 times better than the substrate). However, damage progressively worsened and adhesion strength declined as the number of layers increased, which resulted in poor adhesion performance of the three-cycle coating. The highest adhesion strength was observed in the one-cycle (C1) specimen, with a critical load (Lc) of 30 N. Consequently, these findings substantiated the potential of CFUBMS technique as cost-effective and efficient methods for achieving durable surface protection and enhanced functionality of mechanical components in critical industries. Correspondingly, this study further confirmed the effectiveness of TiN-based multilayer coatings in enhancing the functional properties of Inconel 718, with the best performance corresponding to specific coating cycle numbers identified during the investigation.

The environmental susceptibility of Ti-alloy adversely affects its mechanical properties, operational capability, and friction encountered through surface interaction has been recognized, resulting in wear, corrosion, and fatigue of the material. Therefore, this study focused on the synthesis and characterization of hybrid environmentally friendly silicon carbide-graphene oxide coating on Ti-alloy using liquid additive manufacturing (LAM) approach. The work encompassed the investigation of surface topography, microstructure, phase constituents, and microhardness of the LAM-processed hybrid coated Ti-alloy, employing optical microscopy, scanning electron microscopy, X-ray diffraction, and microhardness testing. Following the Taguchi design of experiments, nine samples were prepared with variations in factors such as current (70, 80 and 90 A), voltage (15, 20 and 35 V), silicon carbide-graphene oxide (70–30, 75–25 and 80–20 wt

The main issue with machines operating together is energy waste and component deterioration due to friction and wear. To overcome this, the parts may be coated with a thin film to make them smoother and less prone to wearing out. Technology offers a lot of possibilities for employing cubic boron nitride thin films (c-BN). The major disadvantage of the hard c-BN film is its low adhesion. In order to find the most adhesive and hard film, c-BN films were coated using high power impulse magnetron sputtering (HiPIMS)-closed field unbalanced magnetron sputtering (CFUBMS) with different B4C target voltage values. The structural and chemical properties were investigated using SEM and XPS and FT-IR, respectively. Moreover, FT-IR was used to calculate the internal compressive stress and c-BN concentration. Microhardness and a scratch tester were used to determine the mechanical characteristics. The pin-on-disc tribometer was used to conduct tribological testing. The results showed that films coated with HiPIMS technique had better adhesion than other techniques. This process decreased the compressive internal stress in the film, which led to increased mechanical and tribological properties.

The increasing expectations and requirements for engineering materials are steadily compelling researchers to evolve and innovate further. Adding transition metals to coating architectures is becoming increasingly attractive as it improves structural and mechanical properties. In this work, CrYN thin films incorporating transition metals Nb, Ta, and V were deposited on a 316L stainless steel substrate using Closed Field Unbalanced Magnetron Sputtering (CFUBMS) with a DC and Pulsed-DC power supply. The microstructural properties of the thin films were analyzed using scanning electron microscopy (SEM), while X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) provided a comprehensive understanding of the coating structure by providing information on crystallographic and surface chemical properties. Mechanical properties were evaluated using nano-indentation testing, which provided accurate measurements of hardness and elasticity, while scratch testing assessed critical load values. In addition, four-point bending tests were performed at room temperature to characterize the CrYN:Nb/Ta/V transition metal nitrides (TMNs), providing a more comprehensive analysis of the mechanical behavior (bending strength and elastic modulus) and adhesion properties of the coating. The mechanisms of coating damage (crack formation and density, spalling, flaking, and separated coating particles) were analyzed as a result of four-point bending tests. The Taguchi approach was employed to investigate how deposition parameters-such as target current, duty cycle, and pulse frequency affect elastic modulus and bending strength. Superior structural (homogeneous and dense film) and mechanical properties (CrYN:Nb/Ta/V high hardness values of 21.4, 18.2, 16.1 GPa, and bending strengths of 707, 711, and 709 MPa, respectively) were obtained. The positive correlation between hardness and bending strength points to an enhancement in the overall durability of the thin film.

This study focuses on enhancing the wear and corrosion resistance of AISI 4130 alloy steel, a chromium-molybdenum alloy steel, through the application of a functional thin films. Targeting various industrial uses, notably in the aerospace and automotive industries, the research aims to improve the durability and performance of AISI 4130 alloy steel. As the functional thin film, niobium-doped hydrogenated amorphous carbon (Nb-doped a-C:H) thin films were deposited using a closed-field unbalanced magnetron sputtering technique under various parameters, which were systematically optimized following the Taguchi L-9 orthogonal array method. The microstructural properties of the thin films were analyzed using a scanning electron microscope providing a comprehensive understanding of the thin films structure. The structure of the Nb-doped a-C:H thin films was examined using Raman and X-ray photoelectron spectroscopy. To evaluate the mechanical properties, microhardness tests and scratch tests were employed, providing accurate measurements of the thin film hardness and adhesion properties, which are critical for assessing performance and durability. The tribological characteristics of the Nb-doped a-C:H thin films were evaluated using a pin-on-disc tribometer, examining their wear resistance and frictional behavior under ambient air. These comprehensive analyses reveal the Nb-doped a-C:H thin films potential for applications requiring optimized surface properties, combining enhanced superior tribological and corrosion performance.

The tribo-component materials in automotive injector nozzle systems face challenges related to durability and longevity, leading to increased maintenance costs and negative environmental impacts. Diamond-like carbon (DLC) coatings can provide a promising solution to these issues. Therefore, this work aims to investigate the coating characteristics of niobium-doped diamond-like carbon (Nb-DLC) on H13 tool steel and evaluate the tribological performance in biodiesel environment. Design Expert software was utilized to optimize the coating process parameters. Employing the Taguchi design of experiments, four samples (r1, r2, r3, and r4) were prepared with coating parameters of 3A target current, 2 μs duty time, and 50 V bias voltage. The primary methodologies involved characterizing the Nb-DLC coatings on H13 tool steel synthesized using the Closed Field Unbalanced Magnetron Sputtering (CFUBMS) technique. Tribological tests were conducted using a High-Frequency Reciprocating Rig (HFRR) wear tester according to ASTM D6079 standards under biodiesel conditions to evaluate wear and friction performance. The Nb-DLC coating thickness ranged from 3.2 to 7.0 μm in this investigation. Experimental results demonstrated that the higher hardness and lowest wear rate were achieved in sample r4. This study reveals that the novel Nb-DLC coating significantly enhances surface properties and improves tribological performance, making it a potential sustainable material for automotive engine injector nozzle components in biodiesel environment.

The aerospace, automotive, and defense industries extensively use AISI 4130 alloy steel, a significant material type for most engineering applications in the industry, due to its crucial characteristics, such as high strength, durability, machinability, and corrosion resistance. In this study, enhancing the surface mechanical and tribological properties of the material with tungsten (W)-doped diamond-like carbon (DLC) coatings emerges as a prominent approach to improving performance. Amorphous hydrogenated diamond-like carbon (a-C:H) coating has outstanding mechanical and tribological properties. In this study, W-doped a-C:H-DLC coatings have been deposited on AISI 4130 using closed-field unbalanced magnetron sputtering. A L9 orthogonal array of the Taguchi method was utilized to optimize the variable coating parameters applied in the magnetron sputtering process. The microstructure and thickness of the W-doped a-C:H-DLC coatings were examined using scanning electron microscopy. Raman spectroscopy was used to characterize the structure of these DLC coatings. The hardness values of the coatings were determined using the Knoop microhardness test. The scratch test method was used to examine the adhesion properties of the coatings by determining their critical load values at which coating delamination occurred. The tribological behavior of uncoated AISI 4130 substrate and coating was determined with a pin-on-disc tribometer against an Al2O3 ball under dry sliding conditions. Delamination and gradual failures occurring in the wear test of the uncoated specimen increased the friction coefficient. On the contrary, the coating exhibits such superior tribological properties that the friction coefficient decreased due to the prevention of delamination and gradual failures to a certain extent. It was observed that the scratch-adhesion properties of the coated specimens significantly contributed to the improvement of tribological performance. These thin films are particularly valued for their ability to provide high wear resistance and low coefficients of friction, properties that are critical to industries that deal with harsh conditions, such as automotive and aerospace.

TiNi/Ti2AlN multilayer films are deposited on AISI M2 steel and Inconel 718 substrates using the magnetron sputtering technique. After heat treatment at 750 degrees C, TiNi and Ti2AlN MAX phase crystal structures are obtained in these films. The effects of different layer numbers on the structural, mechanical, tribological, adhesion, and fatigue properties of TiNi/Ti2AlN multilayer films are investigated. All films' thickness is measured to be approximate to 2 mu m. The 20 layers film deposited on Inconel 718 exhibited the best mechanical properties, with a hardness of 30.6 GPa and an elastic modulus of 407 GPa. A significant improvement in the tribological performance of the films is observed with an increasing number of layers. The lowest wear rate, calculated as 1.96 x 10(-5) (mm(3) (Nm)(-1)), is observed for the 20 layers film deposited on Inconel 718 at room temperature. At high temperatures, the friction coefficients of the 16 and 20 layers films deposited on Inconel 718 decreased to 0.25. In terms of adhesion properties, the 10 layers films deposited on AISI M2 steel demonstrated the best performance with a critical load value of 45 N. The results of the multipass scratch test clearly showed that the 20 layers film deposited on Inconel 718 exhibited the best fatigue behavior among all films.

This study focused on developing a high-temperature tribological coating for AISI 316L stainless steel. CrYN coatings doped with transition metals such as niobium, tantalum, and vanadium (Me-CrYN) were deposited using a closed-field unbalanced magnetron sputtering (CFUBMS) system. In a previous study, the Taguchi L9 orthogonal array design was employed to optimize the deposition parameters based on tribological performance under dry sliding conditions at room temperature. Among the nine experimental runs, the three coatings exhibiting the lowest friction coefficients and highest wear resistance were selected for high-temperature tribological testing. In the present work, these three optimized Me-CrYN coatings were systematically evaluated for their tribological and adhesion properties at elevated temperatures. High-temperature tribological performance was assessed using a pin-on-disc tribometer in ambient air at 450 degrees C, 550 degrees C, and 650 degrees C, with particular attention given to their frictional behavior. Additionally, adhesion strength was evaluated at room temperature via scratch testing, both on the as-deposited coatings and those subjected to high-temperature tribological testing at 450 degrees C, 550 degrees C, and 650 degrees C. The results demonstrate that the Me-CrYN coatings maintain tribomechanical stability at elevated temperatures, with hardness values ranging from 8.8 to 15.3 GPa. Nb-doped coatings exhibited a reduction in friction from similar to 0.55 at room temperature to similar to 0.30 at 650 degrees C (approximate to 45 % decrease), while Ta-doped coatings maintained stable values around 0.40 across all temperatures (<5 % variation). In contrast, V-doped coatings showed an initial rise from similar to 0.13 at room temperature to similar to 0.30 at 450 degrees C (approximate to 115 % increase), but then decreased to similar to 0.10 at 550 degrees C (approximate to 25 % below RT) and similar to 0.12 at 650 degrees C (approximate to 10 % below RT). Adhesion strength was preserved after thermal exposure, supporting their potential for high-temperature applications.

Despite their extensive use in the automotive and aerospace industries, Mg and Mg alloys, which are light metals, exhibit low fatigue and tensile strength. In this study, transition metal-nitride (TMN) multilayer coatings (Ti+TiN+Ti+TiVN) were coated twice on AZ91 Mg alloy using a Confined Field Unbalanced Magnetron Sputtering (CFUBMS) system to increase fatigue and tensile strength. The structural properties of the films were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometry (EDS) methods, and the mechanical properties were analyzed by rotating bending fatigue and tensile testing machines. Ti+TiN+Ti+TiVN multilayer nitride surface coatings on AZ91 Mg alloys showed a dense and columnar microstructure and according to XRD results (111) was the preferred orientation with the dominant peak. The fatigue limit value of the AZ91 base material was fixed at 60.46 MPa, while it increased to 68.48 MPa after being coated with multilayer nitride. Along with the multilayer nitride coating, the tensile strength increased from 169.98 MPa to 175.43 MPa. As a result, the multilayer hard nitride coating with low surface roughness, which fills the defects, notches, and voids on the surface of the AZ91 base material, increased the fatigue and tensile strength in parallel. Based on the outcomes of the research, the literature has been enriched with an innovative approach through the enhancement of fatigue and tensile strengths by applying a CFUBMS coating to lightweight metals and alloys, such as AZ91, especially in the transportation industry where lightness and dynamic load resistance are essential.

Titanium diboride, TiB2, is well known as a ceramic material with a hexagonal structure which presents various attractive properties, such as high hardness and excellent corrosion, thermal oxidation, and wear resistance. However, one drawback of TiB2 coatings is their poor adhesion to substrate materials due to high compressive residual stress after deposition. The present study aimed to assess whether a PVD-TiB2 coating with both high hardness and sufficiently good adhesion to the substrate and good wear properties can be developed by a closedfield unbalanced magnetron sputtering system using pulsed-dc biasing. The TiB2 coating deposited on AISI M2 steel substrates was characterized in terms of the structural, mechanical and tribological property. From the experimental results, it can be concluded that a closed-field unbalanced magnetron sputtering system using pulsed-dc biasing can be used to produce a TiB2 coating with sufficiently good adhesion (82 N), and high hardness (2300 HK0.01), and low friction (0.34) under given deposition conditions. The deposition conditions, particularly substrate biasing and rotation, which inhibited the formation of (001) orientation, played a role the coating's lack of superhardness.

The honeycomb pattern possesses a distinctive hexagonal structure capable of seamless repetition on a flat surface, leaving no gaps. Moreover, all arm thicknesses and angles are equal to one another. This remarkable configuration is deemed biomimetic, with numerous examples found in nature. Notably, it exhibits remarkably low density and exceptional mechanical strength. MAX phase films have gathered significant attention due to their exceptional capacity to amalgamate the essential properties of both metals and ceramics. Additionally, they possess the unique ability to effectively mend surface cracks that may arise as a result of friction-wear, restoring the material to a certain degree of integrity. In this study, Ti 2 AlN MAX phase thin films were deposited on M2 steel substrates by a closed field unbalanced magnetron sputtering system (CFUBMS). 750 °C heat treatment was applied to obtain the produced films in crystalline form. In addition, plasma etching parameters suitable for the phase structure of the deposited film were determined. With the inductive coupling plasma etching (ICP) process, the honeycomb pattern was given to the Ti 2 AlN MAX phase films with a continuous and smooth geometry at a depth of 2 μm. This study gives ideas for the development of multi-coating systems in which patterns of different geometries are included in a single layer.

Ti 2 AlN MAX phase films produced at different N 2 flow rates and different annealing temperatures were deposited on 52100 steel substrates using the closed-field unbalanced magnetron sputtering technique. N 2 flow rates were changed to 2, 3.5, and 5 sccm. Due to the increasing N 2 flow rate, film thickness decreased from 2 to 1.3 µm. Then the produced films were subjected to annealing at temperatures of 700, 750, and 800°C. After the film produced at a flow rate of 2 sccm was annealed at 750°C, the presence of the Ti 2 AlN MAX phase was determined. The binding energies of Ti 2p, Al 2p, and N 1s determined in the XPS analysis confirmed the existence of the Ti 2 AlN film. The friction coefficient measured for Ti 2 AlN MAX phase films was calculated as 0.53, the hardness value as 22.8 GPa, the elastic modulus as 291.4 GPa, and the wear rate as 2.96 × 10 −4 mm 3 /(N·m).

One of the most promising approaches to enhancing the tribological properties of engineering coatings is to add transition elements to the structure. In this study, Nb-doped CrYN and V-doped CrYN thin films were deposited by pulsed DC reactive sputtering in a closed-field unbalanced magnetron sputtering (CFUBMS) system. The deposition parameters examined were target current (1, 1.5 and 2 A), deposition pressure (0.15, 0.25 and 0.35 Pa), pulse frequency (100, 200 and 350 kHz) and duty cycle (85 %, 70 % and 50 %). A Taguchi L9 orthogonal design was used to define the deposition process parameters for each doped film. The Nb and V-doped CrYN thin films were characterized in terms of their microstructure, thickness, composition, hardness and tribological properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), nanohardness and pin-on-disc testing, respectively. The bond strength between the substrate and the films (adhesion) was analyzed by scratch testing. For the Nb-doped thin films, a maximum hardness value of 21.4 GPa and the lowest friction coefficient of 0.36 were obtained. On the other hand, in the V-doped thin films, the maximum hardness value was 16.1 GPa, while the lowest friction coefficient obtained was 0.11. In addition, Nb-doped and V-doped CrYN thin films exhibited extraordinary adhesion properties. The effect of the selected deposition parameters (target current, pulse frequency, and duty cycle) in relation to the film thickness, hardness, and coefficient of friction properties of the Nb and V-doped CrYN thin films were investigated using the Taguchi approach and optimum operating conditions were identified and confirmed.

Magnesium-lithium alloy is used in different areas of industry and is known as a super light metallic engineering material. However, the use of these alloys is limited due to their surface properties under extreme loads and aggressive environments. Surface treatments can be applied to these alloys to increase their usage areas and improve their weak surface properties. In this study, the micro-arc oxidation method was applied to improve the surface properties of LA91 alloy. The corrosion and adhesion behaviour of the coated samples were investigated. The lowest corrosion current density in the coatings was obtained under Experiment 3. Experiment 3 has the highest Lc2 value due to the coating thickness and the denser and smaller diameter pores of the functional intermediate layer.