Papers by Keyword: Physical Vapor Deposition (PVD)

Abstract: In this work, the research team analyzes the effect of oxygen-containing additives on the microstructure and microhardness of coatings of the specimens obtained during applying pyrolytic chrome coating using metal-organic compounds (MOC) in order to obtain protective coatings. The results showed that chromium oxidation in the final phase of the coating process changed the microstructure and mechanical properties of the coating. The resulting coatings exhibit excellent adhesion, high microhardness (6-8 and up to 20-22 GPa depending on the experimental conditions) and better microplasticity, corrosion and wear resistance. In this work the effect of oxidizer on the microstructure and microhardness will be illustrated.

Abstract: Metal coating nowadays is very essential in heavy industry and many other applications, however, a coating system is designed and built to obtain pyrolytic Chrome-Oxide Cr₂O₃, so oxygen is distributed through the coating in order to enhance its properties depending on metal-organic compounds (MOC). A very large number of experiments have been performed to study the effect of oxidant comparing with inert atmosphere. A chemical vapor deposition method for preparing chromium oxide Cr₂O₃ coatings from bis-arene chromium compounds has been performed, followed by studying the effect of oxidant substances concentration on the kinetics of growth of coatings. The main finding is that coatings exhibit excellent adhesion, high microhardness, and wear resistance. The coating process is characterized by high adaptability and relatively low cost.

Abstract: In this research work, Ti/TiAlN multilayers of various designs were deposited on substrates pretreated by nitriding and etching procedures. The influence of the multilayer design on residual stress depth profiles was systematically analyzed for multilayers with different Titanium interlayer thicknesses. The depth dependency of stress was measured by a modified sin2ψ method, using various defined gracing incident angles and measuring angles that ensure constant penetration depths. The residual stresses were investigated by synchrotron X-ray diffraction (SXRD) at the HASYLAB at DESY in Hamburg, Germany. SXRD allows a phase specific stress evaluation of the ceramic and metallic layers of the multilayer systems and the adjacent substrate region. This investigation reveals an influence of the Ti layer thickness on the values and the slope of the residual stress profile in ceramic TiAlN layers.

Abstract: After researching the mould coating and the effect of different matrix hardness on the service life, it can be concluded that under the condition, the matrix materials match with its obdurability well, the higher the matrix hardness, the longer the service life after the mould’s being coated. What’s more, it is put forward that when the heat treatment technology and the coating technology are worked out, the effect of the coating temperature on the matrix hardness should be turned over so as to avoid the matrix’s being annealing again and then have a further influence on the capability after being coated.

Abstract: Titanium alloys are susceptible to sand erosion, hard zirconium nitride coatings have been deposited onto titanium alloys by Physical vapor deposition (PVD) in order to improve erosion resistance. Al and Cu were added into ZrN coatings to strength and toughing the coating. The microstructure and mechanical properties of ZrAlCuN coating were studied. Erosion tests were conducted to evaluate anti-erosion ability. Erosion rates were measured and characteristic damage features were identified on the surface of eroded specimens. The mechanisms of erosion are discussed in order to explain the promising performance of materials in erosive conditions. It was found that there is an significant increase of erosion resistance because of the increase of hardness and toughness.

Abstract: Extensive efforts are focused on the development of Direct Methanol Fuel Cells, due to the intrinsic advantages of this type of devices for mobile power supply system. One of the major drawback of the DMFC resides in the easy poisoning of the anode electrocatalyst (platinum) by COlike reaction intermediates, which implies the need of high platinum load in order to obtain reasonable performances. The development of platinum alloys is considered one of the promising routes for overcoming this problem: the second metal in fact acts as inhibitor of the Pt poisoning. In this work we have combined the use of unconventional methods to deposit the electrocatalyst nanoparticles with unconventional carbon supports. PtAu alloys have been deposited by sputter deposition process on carbon nanofibers with platelet morphology grown by plasma enhanced chemical vapour deposition on carbon paper. Cyclic voltammetry in H2SO4 was used to determine the electrochemical active surface and the electrocatalytic performance for methanol oxidation reaction. Even at lower Pt load, respect to the ones prepared with commercial catalysts supported on carbon black, the innovative electrodes showed higher performance and stability.

Abstract: The goal of this paper is to review the latest innovations in ceramic tile decorating techniques, encompassing not only the most widespread techniques, such as inkjet printing, but also other decoration techniques with a strong potential to provide tile surfaces with new finishes and enhanced aesthetics, such as physical vapour deposition and laser treatment.

Abstract: Recent interest in nanostructured titanium dioxide (TiO2) has been driven by the excellent photocatalytic and optical properties exhibited by the anatase and rutile phases. This article highlights the relationship between reaction conditions and the resultant nanostructured TiO2 and is primarily focused on wet chemical synthetic methods. We show that solvothermal syntheses of nano-TiO2 can be rationalised by making use of a diffusion-controlled model accounting for physical properties of the solvent such as the vapour-pressure, allowing the prediction and control the phase, size and type of nanostructured TiO2 product. This external control makes it possible for the systematic synthesis of TiO2 nanostructures via parameters such as the solvent chain length, the reaction temperature and time, and also by the addition of surfactants, providing the ability to design and tailor the nanostructured TiO2, which is vital for the optimal application of these nanostructures in photocatalytic or optical applications.

Abstract: Growth of ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films without initial nucleation was realized by an coaxial arc plasma gun at a substrate-temperature of 550 °C and hydrogen-atmosphere of 53.3 Pa. The pulsed arc discharge was triggered at a repetition rate of 1 Hz. The deposition rate was 80 nm/min. X-ray diffraction measurements with 12-keV X-rays from synchrotron radiation indicated extremely broad rings from diamond and none from graphite. The UNCD crystallite diameters were estimated to be approximately 1.3 nanometers by using Scherrer’s equation. The sp3/(sp2+sp3) was estimated to be approximately 57% from the X-ray photoemission spectroscopy. The coaxial arc plasma gun is a new powerful method that might enable us to realize the supersaturated condition with highly energetic ions for the growth of UNCD.

Abstract: In order to determine an effective coating film for cutting carbon steels with a coated cemented carbide tool, tool wear was experimentally investigated. Low carbon steel (AISI 5120H steel) was turned with four kinds of physical vapor deposition (PVD) coated cemented carbide tools. The coating films used were TiN coating film and three kinds of titanium-tungsten-silicon-aluminum based coating films, namely (Ti,W,Si,Al)N, (Ti,W,Si,Al)C and (Ti,W,Si,Al)(C,N) coating film. (Ti,W,Si,Al)N, (Ti,W,Si,Al)C or (Ti,W,Si,Al)(C,N) is a new type of coating film. The following results were obtained: (1) The critical load of three kinds of titanium-tungsten-silicon-aluminum based coating films was higher than that of TiN coating film. (2) The hardness of three kinds of titanium-tungsten-silicon-aluminum based coating films was higher than that of TiN coating film. (3) In cutting low carbon steel, the wear progress of three kinds of titanium-tungsten-silicon-aluminum based coating film tools was slower than that of the TiN coated tool. (4) In the three kinds of titanium-tungsten-silicon-aluminum based coating films, the wear progress of the (Ti,W,Si,Al)N coated tool was the slowest.