Papers by Keyword: Nanocomposite Coating

Abstract: TiN coatings with a thickness of 2 μm were deposited using the magnetron sputtering has developed rapidly over the last decade in such a way that it has become an established process of choice for the deposition of a wide range in various applications for different domains as it gives excellent performance in many aspects. In view of this, we have deposited the TiN coatings by magnetron sputtering using Ti target at different nitrogen content to study the influence of the nitrogen content on the mechanical properties and tribological behaviors of the TiN coatings were systematically investigated using nanoindentation and a pin-on-disk tribometer. Nanoindentation results shows that the hardness and Young's modulus of the TiN coatings increase with increasing N content in the coatings.Wear test results indicate that the wear rate and friction coefficient of the XC100 steel substrate were significantly reduced by deposition of the TiN coatings, and the tribological behaviors of the TiN coatings are strongly dependent on the nitrogen content in the coatings.

Abstract: Landing gear is an aircraft component often subjected to wear, fracture, mechanical failure and erosion, principally caused by impact with sand and other small particles. Erosion wear can cause deformation and material removal with consequent efficiency reduction. Coatings can protect stressed structural part and impede the erosion of the metallic components. This work focus on the investigation of the erosion resistance of two ceramic multilayer coatings, AlSiTiN and AlSiCrN, deposited by Physical Vapour Deposition (PVD) on a high speed steel (H11) usually used for landing gear application. Erosion test were carried out with an erosion machine using alumina particles. Powder was directed to the specimens (coatings and substrate) at nominal impingement angles of 90° and 20° with different impact speed (50, 75, 100 and 125 m/s at 90° and 100, 125, 150 and 175 m/s at 20°), at a nozzle-specimen distance of 10 mm. All the tests were performed for two minutes. Hardness and Young's modulus were obtained by nanoindentation, and adhesion between coating and substrate was evaluated by scratch test. Volume lost was measured with Taylor Hobson profiler while cracking behaviour and microstructure modifications were examined with a scanning electron microscope (SEM). AlSiCrN coating significantly enhanced the erosion resistance of H11 substrate, showing higher resistance also with respect to AlSiTiN coating. Indeed, the coating was not completely removed from the surface neither at 90° nor at 20°. The erosion wear rapidly increased by increasing the impact speed in the case of substrate and AlSiTiN, while such parameter was not significantly influent in the case of AlSiCrN. The results suggest that adhesion should play an important role to explain the highest erosion resistance of AlSiCrN coating. Erosion mechanism was principally driven by the intrinsic brittleness of both ceramic coatings.

Abstract: In order to improve the high temperature oxidation resistance of exhaust pipes, the nanocomposite coatings are carried out on the surface of exhaust pipe by electrodeposition technology, and the microstructure and oxidation behavior of the nanocomposite coatings are investigated experimentally. This paper mainly focuses on the experimental work to determine the structural characteristics and oxidation resistance of nanocomposite coatings in presence of Al₂O₃ and cerium oxide CeO₂. The results show that the amount of the Al₂O₃-CeO₂ has significant influence on the structural properties of nanocomposite coatings. The surface of coating becomes more compact and smooth with the increase of the amount of the Al₂O₃ and CeO₂. Furthermore, the anti-oxidation performance of the nanocomposite coatings formed with Al₂O₃ and CeO₂ were both better than those of the composite coatings formed without Al₂O₃ and CeO₂.

Abstract: The Inconel 718 superalloy is one of the most-used nickel based superalloys in the aerospace industry due to its superior mechanical properties, for instance, high thermal and chemical resistance, and high strength at elevated temperatures. However, the work hardening tendency, low thermal conductivity and high hardness of this superalloy cause early tool wear, leading to the material to be called as a hard-to-cut material. Therefore, deposition of a wear resistant hard coating on carbide cutting tools has a critical importance for longer tool life in milling operations of the Inconel 718 superalloy. In this study, carbide cutting tools were coated with multilayer nanocomposite TiAlSiN/TiSiN/TiAlN coating using the magnetron sputtering technique, and wear behavior of the coated tool was investigated during face milling of the Inconel 718 superalloy under dry conditions. Abrasive and adhesive wear mechanisms were founded as main failure mechanisms. The nanocomposite TiAlSiN/TiSiN/TiAlN coated carbide cutting tool gave better wear resistance, and thus it provided 1.7 times longer tool life and a smoother surface (R_a<0.18 μm) on the Inconel 718 material than the uncoated one.

Abstract: The transparent coatings on the basis of Al- Si- N system with high Al content and the opaque Al-Si-N with a low Al content were prepared by impulse magnetron sputtering method. Structural-phase state of the two types of coatings was examined by X-ray analysis. The microhardness was measured by nanoindentation method. The microhardness, the elastic modulus and the coefficient of elastic recovery were determined. Also the optical transmission was measured for all types of samples.

Abstract: Nanocomposite coatings on the basis of Si-Al-N with different ratios of Al and Si concentrations were prepared using the reactive magnetron sputtering method. Internal stresses and structural-phase state of the two types of coatings was examined by X-ray analysis. The microhardness was measured by nanoindentation method. The microhardness, the elastic modulus and the coefficient of elastic recovery were determined. The optical transmission was measured for all types of samples.

Abstract: Article is dedicated to development of the scientific and technological principles allowing by means of innovative beam and plasma technologies to receive a new class of heterogeneous nanocomposite coatings having the increased cyclic crack resistance and hardness on the conductive and dielectric complex-shaped products. On the basis of the received results the source of metal atoms and beams of high-energy molecules with a rectangular target was developed and new installation for coating deposition is made.

Abstract: Ni-ZrO₂-CeO₂ nanocomposite coating was prepared by pulse electrodeposition. The effect of addition of ZrO₂ and CeO₂ nanoparticles, average current density, duty cycle and pulse current on microhardness of Ni-ZrO₂-CeO₂ nanocomposites were studied. The results show that microhardness of nanocomposite is increased at first and then decreased with the increasing additive amounts of two kinds of nanoparticles. With increasing reverse the average current density, the microhardness of the composite coating increases. Also, the microhardness of nanocomposite fall with the increasing of pulse frequency. With the positive duty ratio increasing, the microhardness of the composite coating increase at first and then decreased, but with the increasing of the reverse duty ratio, the microhardness of nanocomposite coating is gradually decreased.

Abstract: To the best of our knowledge, this work presents the first successful effort to fabricate and study nanostructured Ni-based composite coatings using the electrophoretic deposition method with nanostructured SiO₂ particles. In this work, Ni/SiO₂ nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) [ and their hardness, wear and corrosion resistances [ were examined. After studying the morphology of the coatings and finding the optimum conditions for uniform coating, in order to improve the mechanical properties as well as resistance to corrosion, sintering was performed. The Ni/SiO₂ nanocomposite coatings show excellent hardness (~376 HV), reduced Youngs modulus (~180 GPa), contact stiffness (~110 μN/Nm) as well as the wear and corrosion resistances which are considered in the different SiO₂ concentrations and particle sizes. In addition, by controlling the size of the SiO₂ particles, in optimum coating voltage and proper time duration, hardness and wear resistance of nanocomposite coatings were controlled.

Abstract: The aim of this study was to evaluate the interaction of bioactive and biodegradable poly (lactide-co-glycolide)/bioactive glass (PBG) nanocomposite coating with bone and human adipose-derived stem cells (hASC) in vivo and in vitro, respectively. Sol-gel derived 58S bioactive glass (BG) nanoparticles and 50/50wt% poly (lactic acid)/poly (glycolic acid) (PLGA) were used to prepare the coating. The nanocomposite coating was characterized by SEM, XRD, and AFM. Mechanical stability of the prepared nanocomposite coating was studied during intramed­ullary implantation of coated Kirschner wires (k-wires) into rabbit tibiae. Titanium mini-screws coated with PBG nanocompoite coating was implanted intramedullary in rabbit tibia. Bone tissue interaction with the prapared nanocomposite coating was evaluated 30 and 60 days after surgery. The effect of PBG nanocomposite coating on the attachment and viability of human adipose-derived stem cells (hASCs) was investigated. Results showed that PBG nanocomposite coating remained stable on the K-wires with a minimum of 96% of the original coating mass. Tissue around the coated implants showed no adverse reactions to the coating. Woven and trabecular bone formation were observed around the coated samples with a minimum inflammatory reaction. The hASCs showed excellent attachment and viability on the PBG nanocomposite coating. It was concluded that PBG nanocomposite coating provides an ideal surface for bone formation and stem cells attachment and it could be used as a candidate for coating the dental and orthopedic implants.