Influence of plasma nitriding treatment on the adhesion of DLC films deposited on AISI 4140 steel by PVD magnetron sputtering

Duplex surface treatments composed of diamond like carbon (DLC) coating followed by plasma nitriding have drawn attention for a while. In this study, AISI 4140 steel substrates were plasma nitrided at different treatment temperatures and times. Then, DLC films were deposited on both untreated and plasma nitrided samples using PVD magnetron sputtering. The effect of different plasma nitriding temperatures and times on the structural, mechanical and adhesion properties of DLC coatings was investigated by XRD, SEM, microhardness tester and scratch tester, respectively. It was found that surface hardness, intrinsic stresses, layer thickness values and phase distribution in modified layers and DLC coating were the main factors on adhesion properties of duplex coating system. The surface hardness and residual stress values of AISI 4140 steel substrates significantly increased with both DLC coating and duplex surface treatment (plasma nitriding + DLC coating). Increasing plasma nitriding temperature and time also increased the diffusion depth and the thickness of modified layers. Hard surface layers led to a significant improvement on load bearing capacity of the substrate material. However, it was also determined that the process parameters, which provided lower intrinsic stresses, improved the adhesion properties of the duplex coating system.     

Adhesion and tribological properties of TiTaBN coatings with a graded interlayer deposited by pulsed DC biased and continuous dc biased magnetron sputtering

The properties of TiBN-based coatings are significantly affected by adding alloying elements and coating parameters. Therefore, in this study, TiTaBN coatings with graded interlayer (CWGIL) were deposited on D2 steel substrates by pulsed DC biased (PDCB) and continuously DC biased (CDCB) closed field unbalanced magnetron sputtering (CFUBMS). The structural, mechanical, adhesion and tribological properties of the coatings were analysed with EDS, SEM, XRD, microhardness, scratch testing and a pin-on-disc tribo-tester (under various atmospheric conditions). TiTaBN CWGIL deposited by PDCB magnetron sputtering (MS) had a very dense microstructure, high hardness and a high critical load value. TiTaBN CWGIL deposited by PDCB MS had a lower friction coefficient, the wear rate and the penetration depth in all atmospheric conditions. In conclusion, the application of a PDCB substrate instead of a CDCB one dramatically increases the performance of CFUBMS-deposited TiTaBN coatings.     

Mechanical properties and adhesion of TiN monolayer and TiN/TiAlN nanolayer coatings

In this work, TiN monolayer and TiN/TiAlN nanolayer coatings were deposited on 100C6 (AISI 52100) steel substrate by Physical vapor deposited (PVD) magnetron sputtering system. The morphological characterization was evaluated using an atomic force microscopy. The mechanical properties were determined by nanoindentation test. The adhesion was investigated by both microindentation and scratch test. The results show that the TiN/TiAlN nanolayer coating have the more rough surface and the better mechanical properties and adhesion compared to TiN monolayer coating. The effect of microstructural and mechanical proprieties on the adhesion behavior was further discussed. It was found that the improvement in adhesion of nanolayer system is in part due to the increase in plastic deformation resistance and the enhancement of mechanical properties (hardness and elastic modulus) and to the structure with a small grain size and a high number of interfaces.     

Syntheses of nano-multilayered TiN/TiSiN and CrN/CrSiN hard coatings

Nano-structured superhard coatings represent the state-of-the-art in the rapidly increasing worldwide market for protective coatings. In this study, the combination of nano-composite and nano-multilayered structures into the same coating was attempted. Nano-multilayered coatings of TiN/TiSiN and CrN/CrSiN were deposited on tool steel substrates by closed-magnetic-field unbalanced DC magnetron sputter ion plating. The coating structures were characterized using X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Mechanical characterizations were performed including nano-hardness measurement, progressively-increasing-load scratch test, and wear test. TiN/TiSiN coatings have a nano-hardness of 40.2 GPa, whereas CrN/CrSiN coatings have a hardness of 30.9 GPa. TiN/TiSiN coatings also showed a higher critical failure force and scratch fracture toughness as well as better wear resistance and lower acoustic emission signal, indicating less total damage to the coatings.     

Investigation of the adhesion of NbN coatings deposited by pulsed dc reactive magnetron sputtering using scratch tests

Scratch tests have been used to investigate the adhesion of niobium nitride (NbN) coatings that were deposited by pulsed dc reactive magnetron sputtering at target currents of 1.5, 2.5, and 3.5 A onto M2 tool steel and silicon wafer. The coating adhesion on each material substrate was investigated using a progressive load scratch tester (PLST) and a multi-pass scratch tester (MPST). Microhardness tests and scanning electron microscopy (SEM) were also used to examine the hardness and microstructure of the NbN coatings. These results have indicated that the structural, mechanical, and adhesion properties of the NbN coatings improve with increasing target currents. While performing PLST and MPST tests, the highest adhesion and lowest friction force were obtained for the coatings deposited at a target current of 3.5 A. In addition, the triboscobic behaviors that were observed from the MPST of the coatings indicated that the target currents affect the friction behavior of the coatings.     

Electrochemical and morphological properties of zirconium conversion coating in the presence of nickel ions on galvanized steel

A hexafluorozirconic acid-based conversion coating was applied on a galvanized steel substrate and the influence of nickel ion from nickel sulfate solution (in zirconium solution and in a separate solution) on the corrosion resistance behavior and morphology of zirconium conversion coating was investigated. Electrochemical impedance spectroscopy and DC polarization were conducted in 3.5 wt% NaCl solution in order to optimize practical conditions of zirconium conversion coating and NiSO₄ solution on the galvanized steel substrate. Field emission scanning electron microscopy and X-ray photoelectron spectroscopy were employed to study the morphology and composition of the coated surfaces. Results revealed that the conversion coating obtained from solution containing zirconium and nickel ions (Zr + Ni) did not improve corrosion resistance and uniformity of the coating in comparison with Zr conversion coating in optimized condition. However, a positive effect was obtained from samples coated with separate solutions of zirconium and nickel (Zr–Ni). Improved corrosion resistance and morphology of Zr-based conversion coating were observed in Ni²⁺ concentration, pH, and immersion time of 10 g/L, 6 and 300 s, respectively. Morphology and surface composition analysis proved that two separate layers of conversion coating containing zirconium, zinc, and nickel oxide/hydroxide compounds were formed in the case samples that were treated by separate solutions. This led to better uniformity and higher thickness of the coating. Finally, adhesion strength of epoxy organic coating on galvanized steel with and without conversion coating was investigated by pull-off measurement. Zr–Ni conversion coating in optimum conditions had a positive effect on adhesion of organic coating in comparison with blank sample and samples pretreated with Zr and Zr + Ni conversion coatings through increased surface roughness and physical interlocking.     

Adhesion improvement of RF-sputtered alumina coatings as determined by the scratch test

One of the most important problems to overcome in the production of coatings, a major technology in surface modification, is the maximization of coating to substrate adhesion. In spite of its limitations, the scratch technique is most used in adhesion characterization studies. In this study, the adhesion of alumina coatings deposited by RF magnetron sputtering on AISI M2 high speed steel (HSS) was evaluated by the scratch test. An attempt to improve the adhesion of the alumina coatings was investigated by the deposition of an intermediate layer of Ti or TiN. The influence of the substrate surface roughness, the intermediate layer thickness, and the sputter etch cleaning on the coating adhesion was studied.     

Structural and tribological characterization of amorphous and crystalline titanium-nickel coatings

The interest in titanium-nickel (TiNi) alloys has increased with the discovery of the versatile properties of these alloys. In this study, the structural, mechanical and tribological properties of amorphous and crystalline TiNi coatings were investigated. The TiNi coatings were deposited with magnetron sputtering system. The crystallization process was conducted in a vacuum heat treatment furnace. The structural properties of the coatings were investigated with XRD, SEM and EDS analyses. Micro-hardness and pin-on-disc wear tests were used to obtain the mechanical and tribological properties of the coatings. AISI D2 steel, AISI 52100 steel, Aluminum 2024 alloy and copper were used as substrate materials, hence the effects of different substrates were also investigated. The highest coating hardness was obtained as 8.5?GPa and the lowest coefficient of friction value was obtained as 0.18. The tribological tests showed that the amorphous and crystalline TiNi coatings have different coefficient of friction and wear rate and using different substrate affects these properties.     

真空离子精饰镀膜技术研究

黄铜基材装饰件表面采用高能级溅射离子镀，镀不锈钢代替电镀钯－镍合金，采用等离子体型阴极弧源－磁控溅射镀技术在不锈钢镀膜表面上镀制TiN/Au透明陶瓷保护膜SiO2,TiO2，并对各膜层的硬度，耐蚀性，耐磨性及相结构进行分析。     

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.     

Modification of Cr/CrN composite structure by Fe addition and its effect on decorative performance and corrosion resistance

A CrN ceramic coating is a promising substitution for electroplated Cr (Ⅵ) hard coatings; however, it has not yet replaced a decorative Cr (Ⅵ) layer owing to its low reflectivity of visible light and relatively poor corrosion resistance. A Cr/CrN composite structure can address these shortcomings. Our recent work demonstrated that an addition of Fe can facilitate the densification of hot-pressed Cr sputtering targets and enhance the mechanical properties of Cr/CrN composite coatings. In this work, we focus on reporting optical properties and corrosion resistance of the Fe-modified Cr/CrN layers for decorative applications, and clarifying the effect of Fe on these performances. The results show that Fe can increase the amount of metallic phase in the Cr/CrN composite structure and helps enhance its reflectance in the visible region. The composite coating deposited by Cr₉₀Fe₁₀ (at.%) target/alloy exhibits a greater reflectivity of visible light and a better corrosion resistance than those of a single-phase CrN coating. This is attributed to its fine microstructure, which is beneficial for a dense and smooth surface. The color of the coating can be controlled by both the partial pressure ratio of N₂ during deposition and the Fe content in the Cr-Fe sputtering target. The present results show that the addition of Fe can lead to the reduction in the processing cost of Cr targets, enhance the mechanical properties of the composite coatings, and broaden the deposition window. Such cost-effective Fe-modified Cr/CrN composite coatings are expected to be used in various decorative applications.     

Effect of MoS2 content on friction and wear properties of Mo and S co-doped CrN coatings at 25–600 °C

With increasingly harsh working environments for mechanical systems and the rapid development of various high-tech industries, requirements for the stable operation of mechanical systems are increasing in a wide temperature range. Mo and S co-doped CrN coatings with different MoS₂ contents were prepared via unbalanced magnetron sputtering to provide better friction properties to the coatings at high temperatures. Scanning electron microscopy and nanoindentation were adopted to analyze the microstructure and mechanical performance. The mechanical performance of the coatings was enhanced by increasing the MoS₂ content, however, excessive MoS₂ reduced the mechanical properties of the coatings. Besides, the adhesion of the coatings first increased and then decreased rapidly with the increase of the MoS₂ content. In addition, the residual stress of the coating first decreased and then increased upon increasing the MoS₂ content. The high-temperature tribological behavior of the coatings was measured from room temperature (25 °C) to 600 °C. The CrN/MoS₂-0.6A coating was found to exhibit low friction and wear coefficient at room temperature and relatively good comprehensive properties at high temperature. This study provides a feasible design for engineering applications and lays the foundations for the preparation of coatings with superior high-temperature friction properties.     

磁控溅射氮化铬和氮化钛薄膜的性能

采用磁控溅射在4Cr5MoSiV热作模具钢表面分别沉积了CrN和TiN薄膜.通过扫描电镜(SEM)和电子能谱(EDS)分析了试样的微观结构和相结构,研究了CrN和TiN薄膜的抗氧化性能,并用压痕法测定了薄膜的力学性能.结果表明,CrN薄膜的高温抗氧化性能和结合强度高于TiN薄膜,但TiN薄膜的韧性比CrN薄膜好.     

Atomic force microscopy analysis of cathodic arc ion-plated CrN and CrC coatings

Coatings of CrN and CrC were deposited on a YT14 cemented carbide cutting tool using cathodic arc ion plating (CAIP). The surface and interface morphologies of the as-obtained CrN and CrC coatings were analyzed using a field emission scanning electron microscope. The heights, particle diameters and power spectral densities of CrN and CrC coatings were analyzed using atomic force microscopy and the correlated parameters of roughness were obtained. The results show that the roughness of the CrN and CrC coatings is 81.7 × 10^?3 and 70.2 × 10^?3 nm, respectively, and CAIP has little effect on the CrN and CrC coating roughness. The height of the peak values of CrN and CrC coatings is 0.498 and 0.502 nm, respectively, and the reduction friction of the CrN coating was slightly better than that of the CrC coating. The average particle diameter of the CrN and CrC coatings is 6.575 × 10² and 7.678 × 10² nm, respectively, and the particles are uniformly distributed with no large-scale fluctuations. The power between the cursors of the CrN and CrC coatings is 1.44 × 10^?2 and 9 × 10^?3 nm², respectively, with the power spectral density of the CrN coating being the dominant frequency.     

Comparison of electrochemical behavior of CrN single-layer coating and Cr/CrN nanolayered coating produced by cathodic arc evaporation physical vapor deposition

The aim of the present work is to study the CrN single-layer coating and the Cr/CrN nanolayered coating by cathodic arc evaporation physical vapor deposition (CAE-PVD) on AISI 304 stainless steel and to assess the electrochemical behavior of the coatings. Field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were utilized to study the morphology and microstructure of the coatings. The mechanical behavior of the coatings was studied by the nanoindentation technique. The electrochemical behavior of the formed coatings in 3.5 wt.% NaCl solution was investigated via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests. Based on the microscopic images, it was realized that both CrN and Cr/CrN coatings were formed having a dense structure on the substrate. The results of EIS measurements showed gradual changes in the polarization resistance of the Cr/CrN nanolayered coating during the immersion time. However, significant changes in the polarization resistance of the CrN single-layer coating were seen by increasing immersion time comparing with the Cr/CrN coating. The higher polarization resistance of the Cr/CrN coating can be attributed to the effects of the interface between the layers in comparison to the CrN coating.     

Dependence of mechanical and tribological performance on the microstructure of (CrAlTiNbV)Nx high-entropy nitride coatings in aviation lubricant

The (CrAlTiNbV)N_x coatings are fabricated by controlling the substrate bias via magnetron sputtering method. Under low substrate bias, the coating tends to form a loose columnar crystal structure with (200) preferred orientation. However, when the substrate bias increases, the coating transforms into a dense nanocrystalline structure, and the (111) orientation is enhanced. As the substrate bias increases, the residual stress and hardness of the coating gradually increase, while the adhesion strength decreases slightly. Friction tests show that the coating possesses the lowest average friction coefficient (about 0.06) and wear rate (8.7 × 10^-9 mm³/N·m) in 4050# aviation lubricant, which is achieved under the substrate bias of -96 V and -126 V, respectively.     

Effect of BEO in the electrodeposition process of Ni/diamond composite coatings for preparation of ultra-thin dicing blades: Experiments and theoretical calculations

Ni/diamond dicing blades is the main tool for scribe of silicon wafer at present. In order to decrease the width of dicing slot on the wafer, it is necessary to reduce the thickness of blades, and to increase the hardness, toughness and wear resistance of the Ni/diamond composite coatings in the process of electrodeposition. In this paper, 1,4-bis(2-hydroxyethoxy)-2-butyne (BEO) was used as an organic additive in the composite baths containing nickel amino-sulfonate, nickel chloride, boric acid, sodium dodecyl sulfate (SDS) and diamond particles in sizes of 3–5?µm, in order to improve the properties of Ni/diamond coatings and produce ultra-thin Ni/diamond dicing blades. The textures of Ni/diamond composite coatings were mainly Ni (200) and Diamond (111) since the addition of BEO in the baths inhibited the growth of Ni (111) and Ni (220). Quantum chemical calculations and molecular dynamics (MD) simulations showed that BEO could adsorb at the nickel surface strongly and inhibit the electrodeposition of nickel atoms. With the increase in concentration of BEO in the baths, the cathodic polarization potentials shifted to more negative direction and the thicknesses of the coatings decreased. Adding the appropriate amount of BEO (0.1–0.2?g/L) in the baths, the roughness of the coating decreased the number of individual diamond particles in the coating increased, and the hardness and the wear resistance of the coating was improved. When the thickness of Ni/diamond composite coating on aluminum alloy wheeled substrate was 15?µm, the width of its dicing slot was 22?µm. However, the addition of BEO in the bath cannot change the adhesive wear mechanism of the coating.     

Effect of substrate temperature on the mechanical and tribological properties of W/WC produced by DC magnetron sputtering

W/WC bilayers were grown using the DC magnetron sputtering technique and varying substrate temperature. The mechanical and tribological behaviors were characterized using the nanoindentation and pin-on-disk techniques. The hardness and Young's modulus tended to increase, while the coefficient of friction tended to be stable with increasing substrate temperature. Moreover, better mechanical and tribological performances were observed for all of the coated systems compared with the uncoated steel. Furthermore, the inclusion of a W interlayer did not significantly influence the hardness; nevertheless, this interlayer dramatically improved the coating tribological behavior, thus producing less coating damage and decreasing the wear rate.     

Adhesion of SiO2 thin films to plasma-treated SUS304 stainless steel substrates

The adhesion strength of the coated SiO₂ thin film to SUS304 stainless steel substrates with various surface treatment conditions is studied in this research. The surface of the SUS304 stainless steel substrate is first treated with 1000-W plasma and then a SiO₂ thin film is deposited onto the surface via radio-frequency magnetron sputtering. Scanning electron microscopy is employed to observe the surface and cross section of the coating and X-ray diffraction is used to analyze the crystallographic structure. Moreover, a nanoscratch test instrument was employed to examine the indentation, scratches, coating hardness, modulus of elasticity, coefficient of friction, and critical adhesion of the SiO₂ film and to obtain surface profiles. A comparison of the coating adhesion of the substrate surfaces with and without plasma treatment indicates that critical adhesion increases significantly after Ar/N₂/O₂ plasma treatment.