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The purpose of this paper is to examine the effect of substrate temperature on friction coefficient and surface roughness of titanium nitride (TiN) coatings deposited on high‐speed steel (HSS) using commercially available cathodic arc evaporation physical vapour deposition system.

The goal of this work is to determine the usefulness of TiN coatings in order to improve the friction coefficient and surface roughness of HSS verses substrate temperature, as vastly used in cutting tool industry and many others. A Pin‐on‐Disc test was carried out to study the coefficient of friction verses sliding distance. Surface roughness of deposited coatings was studied via surface roughness tester and atomic force microscope (AFM).

Friction coefficient increased at higher temperature as compared to the coating deposited at lower substrate temperature. Surface roughness measured via both instruments showed similar trend in recorded data and, i.e. increased by increasing substrate temperature. AFM study showed that bearing ratio (per cent) decreased, whereas, fractal dimension increased with an increase in substrate temperature.

It is implied that choosing a substrate temperature above 450°C in the existing coating system could damage some machine parts.

This scenario develops an approach to optimize the coating properties verses substrate temperature for specific application, such as cutting tools for automobiles and aircrafts.

The coating deposited at lower temperature showed better friction coefficient and surface roughness than the coating deposited at higher temperature and vice versa.

The disbonding of DLC coating is a main failure mode in the high-speed cavitation condition, which shortens the service life of the bearing. This study aims to investigate influence of adhesion strength on cavitation erosion resistance of DLC coating.

Three DLC coatings with different adhesion strengths were grown on the 304 steel surfaces by using a cathodic arc plasma deposition method. Cavitation tests were performed by using a vibratory test rig to investigate the influence of adhesion strength on cavitation erosion resistance of a DLC coating. The cavitation mechanism of the substrate-coating systems was further discussed by means of surface analyses.

The results indicated that, the residual stress decreased and then increased with the increasing DLC coating thickness from 1 µm to 2.9 µm, and the lower residual stress can improve the adhesion strength of the DLC coating to the substrate. It was also concluded that, the plastic deformation as well as the fracture occurred on the DLC coating surface at the same time, owing to higher residual stress and poorer adhesion strength. However, lower residual stress and better adhesion strength could help resist the occurrence of the coating fracture.

Cavitation tests were performed by using a vibratory test rig to investigate the influence of adhesion strength on cavitation erosion resistance of the DLC coating. The plastic deformation and the fracture occurred on the DLC coating surface at the same time, owing to higher residual stress and poorer adhesion of coating. Lower residual stress and better adhesion of coating could resist the occurrence of the DLC coating fracture.

This paper aims to investigate the effects of deposition time on the structure and anti-corrosion properties of a micro-arc oxidation (MAO)/Al coating on AZ31B Mg alloy.

The study describes the fabrication of the coating via a combined process of MAO with multi-arc ion plating. The structure, composition and corrosion resistance of the coatings were evaluated using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and electrochemical methods.

The Al-layer is tightly deposited with a good mechanical interlock along the rough interface due to the Al diffusion. However, the Al layer reduces the anti-corrosion of MAO-coated Mg alloy because of structural defects such as droplets and cavities, which act as channels for corrosive media infiltration towards the substrate. Fortunately, the Al layer improves the substrate corrosion resistance owing to its passive behaviour, and the corrosion resistance can be enhanced with increasing deposition time. All results indicate that a buffer layer fabricated through the duplex process improves the interfacial compatibility between the hard coating and soft Mg alloys.

An MAO/Al duplex coating was fabricated via a combined process of MAO and physical vapour deposition. MAO/Al duplex coatings exhibit obviously passive behaviours on AZ31 Mg alloy. The structure and corrosion resistance of MAO/Al coatings were investigated.

Accurate measurements of the temperature distributions in hot section components are indispensable for the prognostic and health management of gas turbines. Thin film thermocouple (TFTC) sensors, directly fabricated on the surface of a component, add negligible mass and create little or no disturbance to airflow, and therefore, can provide accurate measurements of fast temperature fluctuations of gas turbines. The purpose of this paper is to evaluate TFTC sensors fabricated by combining pulsed laser deposition (PLD) and micromachining techniques (LM).

The “dry” PLD/LM fabrication approach allows for excellent control of the chemical composition and physical characteristics of the constituent layers and their interfaces, thus achieving good adhesion of the layers to the substrate.

The results of thermal cyclic durability testing of the fabricated TFTC sensors demonstrated that the proposed PLD-based approach can be used to fabricate sensors that are fully functional at temperatures up to 750°C. Analyses of the sensor performance during durability testing revealed: the existence of a threshold temperature below which accurate temperature measurements were achieved; an abrupt drop in the sensor output occurring when the sensor temperature exceeded the threshold value, with a fast recovery of the sensor output once the temperature was reduced below the threshold level; and sensor “training” capable of increasing the threshold value of the TFTC through its exposure to above-the-threshold temperatures.

The work is the first time to demonstrate that simple PLD and LM processes can be used to fabricate TFTC that are fully functional at temperatures up to 750°C.

This study aims to investigate the high-temperature wear behavior of the TiN- and AlTiN/TiSiN-coated WC materials.

The coating process was carried out using the physical vapor deposition (PVD) method. Wear tests were performed by a ball-on-disc wear device with a high-temperature wear module. In microstructural investigation of the materials, it was benefited from traditional characterization methods such as, SEM, EDX analysis and microhardness measurement.

The best wear performance was obtained with AlTiN/TiSiN-coated WC materials at all loads and temperatures, followed by TiN-coated and uncoated WC samples. An important wear was not observed on the samples tested at room temperature tests. It was found that the temperature increase is an effective parameter on the decrease of the wear resistance of the samples. In addition, it was seen that the increasing load and temperature change the wear mechanism on the uncoated WC sample. The wear mechanisms observed at high temperatures were delamination and oxidation for the WC, fatigue for AlTiN/TiSiN-coated WC and micro-scratch and micro-spalling for TiN-coated WC.

The results of the experimental studies demonstrated that hard coatings improving wear resistance of WC.

In this study the microstructure and wear characteristics of Multilayer AlCrN coated AISI 410 stainless steel with the physical vapor deposition technique.

The friction and wear performance of the ML-AlCrN-coated AISI410 steel and uncoated AISI410 steel sliding against with high carbon steel were investigated by the ball cratering test at room temperature. The tribological characteristic of coated AISI410 steel was determined by applying constant sliding velocity of 0.3927 ms⁻¹ and total sliding distance of 353.43 m over various normal loads of 2, 3 and 4 N.

The AlCrN-coated AISI410 steel showed excellent wear performance up to 4 N load. The uncoated AISI410 steel showed good to acceptable wear resistance up to 2 N load. The wear tracks and worn surface were examined by scanning electron microscopy with energy-dispersive X-ray spectroscopy (EDS) attachment for explaining the differences in wear mechanism.

The ability of coating to delay substrate oxidation, with an excellent wear resistance, was identified under different parameters on worn areas.

The purpose of this paper is to evaluate the use of nickel and nickel oxide thin films as anticorrosive protection for low‐carbon steel when expose to sour media. The purpose of this paper is also the study of a superior oxide nickel thin film over the nickel thin film.

Nickel thin films are applied on steel AISI 1018 (UNS G 10180) by magnetron sputtering and electrolytic techniques. The films are tested after deposition on low‐carbon steel. A massive nickel electrode also is evaluated as a reference. In order to evaluate the protective properties of films in sour media, electrochemical techniques are employed, but also scanning electron microscopy in order to identify the difference in porosity and surface of the films coated by both techniques.

Micrographs of thin films deposited by magnetron sputtering reveal a homogeneous surface whereas the electrolytic films show many micro‐crevices and expose the substrate even on the oxide films. These results indicate that localize corrosion on the film surface diminishes the corrosion resistance, even if the film itself has a superior corrosion resistance.

These kinds of nickel thin films deposit by magnetron sputtering and their oxides are an excellent anticorrosion alternative even for mild carbon steel exposed on sour media.

The sputtered nickel deposit is consistently more protective against corrosion than an electrolytic deposit of the same thickness. The nickel oxide benefits the steel by displacement of the corrosion potential towards more positive values. The electrochemical performance of solid nickel oxide is superior compared to the nickel metallic film on the steel substrate.

The purpose of this study is to investigate the effects of zinc dialkyl dithiophophates (ZDDP) and ash-less triphenyl phosphorothionate (TPPT) on hydrogen-free diamond-like carbon (DLC) coatings. For many years, ZDDP have traditionally been used in engine oils as antiwear (AW) and extreme pressure (EP) additives. However, additives containing sulfated ash, phosphorus and sulfur (SAPS) have a detrimental effect on the exhaust after-treatment device found on modern vehicles. Besides the automotive industry, DLC is also used in hydraulic applications where zinc-free and ash-less hydraulic fluids have gradually gained popularity in recent years.

The tribological tests were performed using a disk-on-cylinder tribometer, where the stationary hydrogen-free DLC-coated steel disk formed a line contact with an uncoated rotating steel shaft under lubricated conditions.

It was found that TPPT and ZDDP separately at a concentration of 1.0 wt% increased the amount of friction of the base oil by approximately four times. TPPT appeared more effective than ZDDP in minimizing wear on the DLC-coated surface. Also, primary ZDDP seemed to have a more detrimental effect on the DLC-coated surface compared to a mixture of primary and secondary ZDDP. With regard to surface roughness of the hydrogen-free DLC-coated surface, the values corresponding to a lubricant containing TPPT were lower than those obtained for a lubricant with ZDDP and a lubricant without any additive.

This is the first report on the effects of ZDDP and ash-less TPPT on the tribology of hydrogen-free DLC coatings.

The purpose of this paper is to improve the corrosion resistance of stainless-steel bipolar plate by magnetron sputtering.

TiC/amorphous carbon composite film was deposited by magnetron sputter at four different temperature of 25°C, 200°C, 300°C and 400°C. The morphology, composition and structure of the film were characterized by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. And its corrosion behavior was analyzed through electrochemical impedance spectroscopy, potentiodynamic and potentiostatic polarization tests.

A compact TiC/amorphous carbon film was prepared by magnetron sputtering on 316L stainless steel, and the particles of the film were refined with the increase in sputtering temperature. High temperature promoted the formation of TiC and C–C sp² hybrid carbon, but excessively high temperature caused the oxidation of Ti and a significant decrease in sp² hybrid carbon. The corrosion resistance of the film increased with the temperature, and the corrosion current density polarization at 0.86 V and 1.8 V for TiC/a–C film prepared at 400 °C is only 1.2% and 43.2% of stainless steel, respectively.

The corrosion resistance of amorphous carbon films was improved by the doping of Ti carbide, and the appropriate sputtering temperature was obtained.

The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN coating HSS materials in detail.

In this study, high-speed steel (HSS) parts were processed by the way of machining and were coated with AlTiN on physical vapour deposition (PVD) workbench at approximately 650°C for 4 h. Tensile strength, fatigue strength and hardness tests for AlTiN coated HSS samples were performed. Samples were also analyzed by energy dispersive X-ray analysis (EDS), X-ray diffraction (XRD) and scanning electron microscope (SEM). The results were compared with uncoated HSS components.

It was found that an amorphous aluminium-oxide layer emerges on surface of parts by AlTiN coating. This layer prevents further oxide formations. The coating thickness of AlTiN-coated sample is between 1,530 and 1,558 μm. Compared to uncoated HSS, AlTiN coated HSS gives higher performance.

It would be interesting to search different coatings for cutting tools. It could be the good idea for future work concentrated wear properties on tool materials using different coatings.

This paper provides information on mechanical and metallurgical behaviour of AlTiN coated HSS materials and offers practical help for the researchers and scientists working in the coating area.