Papers by Keyword: Physical Vapour Deposition

Abstract: The manufacturing industry has a significant impact on the economy of a country. Therefore, carrying out necessary developments and modifications in manufacturing machine components is essential. Some materials, called superalloys, are challenging to machine, and they have a wide application in the turbine components of aerospace, submarines, oil, nuclear, steam, and other power generation industries. Due to the exceptional properties of these superalloys their machining becomes very difficult and time-consuming; They damage the cutting tool, and excessive use of lubricants eventually affect the material handling and cost. These problems lower down the sustainability and therefore an attempt has been made in the current research work to eliminate the use of cutting fluid by impinging solid lubricant on AlTiN coated tungsten carbide cutting tool by using pulsed direct current magnetron sputtering and cathodic arc physical vapour deposition techniques. The micro-texturing is first done on rake face of the milling insert such that graphite, which acts as a solid lubricant, can be then deposited in those micro-textures. The end milling of Nimonic 90, a superalloy, is done using the solid lubricant filled microtextured insert under compressed air environment, and the cutting forces, cutting temperature, tool wear, and surface roughness are analysed. It is found that there is a substantial decrease in the cutting forces and tool wear when compared with non-textured tool due to less friction and temperature at the machining zone. Sustainability of such solid lubricant based textured cutting tool has shown improvement when compared with non-textured cutting tool. The machinability of Nimonic 90 is increased by implementing the solid lubricant-based cutting tool, and therefore, it can be effectively utilised for the machining of superalloys soon.

Abstract: Hard nitride coatings has an important role for enhancing the wear resistance of metallic materials, thus increasing the life time of the products in industries. In this paper reviews the different methods of coating techniques, methods of PVD, mechanical properties of TiN coatings and wear resistance of titanium nitride-based coatings by physical vapor deposition (PVD) techniques. Thus the various approaches for enhancing the corrosion and wear resistance are categorized and summarized. The advantages, disadvantages and applications of Nitride based coatings are discussed.

Abstract: Nowadays, the demand for glass fibre-reinforced polymers (GFRPs) has increased in the industry owing to their low weight, high strength, corrosion resistance and low cost compared with other fibre-reinforced polymer composites. However, GFRP is anisotropic material with low interlaminar strength where the damage can occur without warning. Integrating a real-time damage detection process can mitigate this problem. Therefore, this paper presents the initial fabrication of an embedded capacitive sensor into the GFRP by using conductive electrodes inbetween its layers. To form the sensing electrodes, glass fibre yarns were coated with conductive material and braided into the fibregalss woven fabric. Two coating methods were considered to form embedded electrodes in this work which include aerosol spray coatings that were carbon based and gold-based physical vapour deposition, (PVD). It has been shown that spray coating has a weak bond and the carbon particles disperse during the molding process. In the PVD technique the nanoparticle (Au) distributed uniformly along the fibres and has a good resistance (≈100Ω). The capacitive sensor based on gold coating was exaimined using a three point bending test which demonstrate linear response toward the flexural load with a sensitivity of 25.1 fF/N.

Abstract: Background: zirconium (Zr) implants are known for having an aesthetically pleasing tooth-like colour Unlike the grey cervical collar that develops over time when titanium (Ti) implants are used in thin gingival biotypes. However, the surface qualities of Zr implants can be further improved. This present study examined using thermal vapour deposition (TVD) to coat Zr implants with germanium (Ge) to improve its physical and chemical characteristics and enhance soft and hard tissue responses. Materials and methods: Zr discs were divided into two groups; the uncoated (control) group was only grit-blasted with alumina particles while the coated (experimental) group was grit-blasted then coated with Ge via TVD. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), water contact angle test, and cross-hatch adhesion tests were then used for surface characterization Results: An XRD analysis of the Ge-coated Zr samples revealed the substrate while the FESEM results revealed a continuous coating with no cracks. The mean surface roughness and hydrophilicity of the Ge-coated Zr substrate was significantly higher than that of the uncoated Zr substrate (P≤0.01). The cross-hatch adhesion of all the samples was 0%, thereby indicating good coating adhesion. Conclusion: Therefore Coating Zr implants with Ge via TVD enhances its physical and chemical properties.

Abstract: The article considers the requirements for protective coatings operating in the conditions of injection molding of non-ferrous metal alloys, among which the most important are the provision of crack resistance and wear resistance of the forming surface. It is revealed that single-layer coatings applied by the physical vapour deposition method, regardless of its composition, are not able to fully meet the formulated requirements. It is established that multilayer coatings provide increased performance of structural elements of molds in comparison with single-layer ones.

Abstract: It is known from theory that coatings on the forming surface increase the service life of injection molding molds. In practice, the most widespread method of nitriding, which has a number of undeniable advantages, while there are other promising coatings. Therefore, the article considered coatings applied by the physical vapour deposition method in comparison with nitriding. The comparison was carried out on the basis of pressure and temperature indicators on the walls of the forming surface of the working inserts of the molds.

Abstract: In the present work TiAlN coatings were deposited by plasma spray process as titanium aluminium based nitride (Ti, Al)N coatings possess excellent tribological behaviour with respect to metal cutting and polymer forming contacts. Three coatings of TiAlN were deposited on AISI-304 grade boiler steel substrate out of which two were thin nanocoatings deposited at different temperatures of 500°C and 200°C and one conventional coating was deposited by plasma spraying. The as sprayed coatings were characterized with relative to coating thickness, microhardness, porosity and microstructure. The optical microscopy (OM), the XRD analysis and field mission scanning electron microscope (FESEM with EDAX attachment) techniques have been used to identify various phases formed after coating deposited on the surface of the substrate. Subsequently the sliding wear behaviour of uncoated, PVD sprayed nanostructured thin TiAlN coatings deposited at 500°C and 200°C and plasma sprayed conventional coated AISI-304 grade boiler steel were investigated according to ASTM standard G99-03 using pin on disk wear test rig. Cumulative wear volume loss and coefficient of friction, μ were calculated for the coated as well as uncoated specimens for 0.5, 1 and 2 m/sec sliding velocities at a constant normal load of 10 N. The worn out samples were analysed with SEM/EDAX. Wear rates in terms of volumetric loss (mm3/g) for uncoated and coated alloys were compared. The nanostructured TiAlN coatings deposited at 500°C and 200°C has shown minimum wear rate as compared to conventional TiAlN coating and uncoated AISI-304 grade boiler steel. Nanostructured TiAlN coatings were found to be successful in retaining surface contact with the substrate after the wear tests.

Abstract: In the manuscript conventional and nanostructured nitrided coatings developed to increase hardness and to improve the wear, erosion and corrosion resistance of structural materials. Three coatings of TiAlN were deposited on AISI-304, out of which two were thin nanocoatings at different temperatures of 500°C and 200°C are developed by Oerlikon Balzer’s rapid coating system machine under a reactive nitrogen atmosphere. One conventional coating TiAl was deposited by Plasma spraying method which was post nitrided. Then the coated samples were characterized with relative to coating thickness, microhardness, porosity and structure. The XRD and SEM/EDAX techniques have been used to identify various phases formed after coating on the surface of steel.The microhardness of conventional TiAlN coating was found to be of the order of 900-950 Hv. The grain size for nanostructured TiAlN coatings deposited at 500°C and 200°C are 15nm and 14nm respectively as calculated by Sherrer’s formula from XRD plot.

Abstract: Manufacturing industries are presently using many tool materials, such as high speed steel, carbide tool and diamond tools etc. The most widely and commonly used tool in the engineering industries is high speed steel (HSS). The HSS tools are the cheapest and reliable for medium and small scale industries. In this work, the HSS single point cutting tool is taken as substrate material and coated with two different combinations of TiAlN composite coating using Physical vapour deposition (PVD) technique. Also, Tool life was calculated and compared with uncoated HSS tool. The hardness and surface roughness value for both the tools have been taken under same condition. The loss of weight in the tool after machining has been weighed using standard equipments. The differences have been closely observed with sufficient trials and find out the loss in weight in both the tools. The weight loss percentage was calculated after proper machining trials. The tool life of the Titanium Aluminium Nitride (Ti 70%, Al 25%) coated tool has been increased by 3.74 times than that of uncoated tool. The surface finish for TiAlN (Ti 70%, Al 25%) coating is better than the uncoated tool. The PVD coated tools having better performance comparing with uncoated HSS tool.

Abstract: Nanocomposite thin films composed of a TiO₂ matrix doped with noble metals nanoparticles (MNPS), Au and Ag, were deposited on Si (100) and glass substrates by dc magnetron sputtering. The samples were annealed in a protective atmosphere at temperatures ranging from 200 to 700 °C. The main goal of this work is to characterize and compare the Surface Plasmon Resonance (SPR) behaviour in both systems. The studies have been focused on the growth of the nanoclusters and on their role on the optical properties of the films. Size, shape and distribution of the nanoclusters embedded on the titanium oxide dielectric matrix are reported as key factors on the SPR behaviour in both systems (Au:TiO₂ and Ag:TiO₂). The MNPs grew due to diffusion mechanisms, which were led by the annealing treatments, even at the highest annealing temperatures. Evidences of the correlation between the nanocomposite film structural changes and the evolution of the optical properties due to the SPR activity are reported. The SPR phenomenon manifests itself as a wide band on the visible range on the absorption spectra, and it is confirmed by an important change on the surface colour tones of the samples.