Abstract
In this work, Ti6Al4V alloy was surface modified by a scanning electron beam. During the modification procedure, the current of the electron beam was 25 mA, the frequency of scanning of the ...e-beam was 200 Hz, the accelerating voltage was 60 kV, the velocity movement of the sample was 5 mm/s and 10 mm/s. The samples were modified using a continuous electron beam, where the geometry of the beam deflection was in the form of a Lissajous curve. The phase composition of the obtained samples was investigated by X-ray diffraction. The microstructure was studied by optical microscopy. The microhardness was also investigated. The results showed that the treatment process causes the formation of a single-phase structure of α’ martensite, where the velocity of the specimen during the modification procedure does not affect the phase composition of the modified surfaces. The hardness values at the sample treated with 5 mm/s speed motion are lower than that treated at speed of sample movement of 10 mm/s.
We report electron-beam surface alloying of Al substrates with Hf. The Al substrates were covered by a Hf coating with a thickness of 2 μm; the samples were alloyed by means of a scanning electron ...beam with circular geometry of the beam deflection. The phase composition of the obtained specimens was studied by X-ray diffraction (XRD); their microstructure and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The results showed that the phase composition did not depend on the speed of sample motion. However, their microstructure was significantly finer and more homogeneous in the case of the lower speed of motion V1 = 0.5 cm/s in comparison with the higher speed V2 = 1 cm/s.
Abstract In the present work, the effect of the deposition time on the structure and electrical impedance of reactive DC magnetron sputtered TiN coatings was studied. The structure of the coatings ...and the substrates was studied using X-ray diffraction (XRD). The electrical impedance and high frequency stability of the specimens was experimentally measured and the results were indicative of whether the application of the coatings as protective layers between the electrical contact pads of electrical contact systems is feasible.
Black powders were prepared from chimney soot by means of treatment with different solvents and drying. The powders were used to prepare inks, which were deposited on copper foils. The as prepared ...electrodes were assembled as supercapacitor structures with KOH as electrolyte. The charge-discharge characteristics were measured to evaluate the electrical capacitance and to compare the technology for soot treatment. The soot was studied as a source before and after treatment using IR spectroscopy, XRD and SEM EDX.
Abstract This work presents a preliminary experiment used to determine the possibility of developing a thermal model used to predict the thermal gradients formed during the process of wire and arc ...additive manufacturing (WAAM). For this purpose, an Al99.7 specimen was built using gas metal arc welding (GMAW) in the cold arc pulse mode. The temperature of both the substrate and each consecutive layer was measured using thermocouples and infrared thermometers and the experimental data was used for the calibration of the developed thermal model. The obtained results can be used for the further development of the thermal model.
The mechanical properties and surface topography of TiN/TiO2 coatings deposited by reactive magnetron sputtering on electron beam surface treated Ti5Al4V substrates were studied. The phase ...composition and crystallographic orientation were studied by X-ray diffraction. The hardness was investigated by nanoindentation test. The surface topography was evaluated using atomic force microscopy.
The results show that polycrystalline TiN and anatase - TiO2 phases are present in all cases. The electron beam treatment (EBT) leads to a more symmetrical distribution of the heights in comparison with the untreated substrates, as well as to increase in the surface roughness. The hardness of the Ti5Al4V substrates before and after the electron beam treatment process increases which is due to the transformation α+β to α′ martensitic microstructure occurring due to the fast cooling rate after the melting process. EBT leads to increase the surface roughness from 8 nm to 25 nm for the deposition of TiN/TiO2 coatings on Ti5Al4V. The treatment of Ti5Al4V substrates leads to decrease in the hardness of the coatings - from 7 GPa to 6 GPa. The scratch tests of the coated samples confirm the decrease of the friction coefficient as compared with the uncoated substrates.
•The mechanical properties and the topography of TiN/TiO2 coatings on Ti5Al4V substrates, deposited by reactive magnetron sputtering has been studied.•Polycrystalline TiN and anatase - TiO2 phases are present in all cases.•The electron beam treatment leads to an increase in the surface roughness.•The hardness of the Ti5Al4V substrates before and after the electron beam treatment process increase.•EBT of Ti5Al4V substrates leads to decrease in the hardness of the coatings - from 7 GPa to 6 GPa.
Abstract
In this work, CuO coatings were deposited on 304 L stainless steel substrates by reactive magnetron sputtering. During the process, the substrate temperature was varied in the range from 100 ...°C to 400 °C. The crystallographic structure of the samples thus prepared was characterized by X-ray diffraction, and the results are discussed with respect to the technological conditions applied. It was found that the phase composition of the deposited CuO coatings is in the form of a monoclinic crystal structure. Also, the growth of the coatings was accompanied by a change in the orientation of the crystallites from (022) to (110) and a decrease in the concentration of imperfections.
Abstract
In this study, we demonstrate a combined treatment technique of R18 high-speed tool steel comprising deposition of a WN coating followed by electron-beam surface treatment (EBT). In order to ...understand the influence of the deposited WN coating on the resultant structure and properties, an uncoated specimen was directly electron-beam treated under the same EBT technological conditions. The structure of the specimens was studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The microhardness was also investigated. The phase composition consisted of a double phase structure of Fe and M
6
C carbides in both cases. The microstructure was significantly finer in the case of an EBT of the steel with WN coating, leading to a much higher microhardness in comparison with the case without WN.
Titanium-based vacuum coatings, such as TiN and TiO2, are being widely used for functionalization of the surfaces and for forming protective surface layers for a number of applications. In this ...study, TiN/TiO2 coatings were deposited by two physical vacuum deposition (PVD) methods: cathodic-arc (for TiN) and glow-discharge (for TiO2) deposition. We studied the bilayer film composition, structure and properties by means of X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and scratch test analysis. The XRD spectrum indicated the presence of both anatase and rutile TiO2 phases, together with TiN reflections. The Ti 2p, O 1s and N 1s core level of XPS spectra in the depth of the oxide up to the oxide-nitride interface indicated intimate heterojunction between the layers. This results in a lower coefficient of friction and improved adhesion strength of the TiN/TiO2 film compared with pristine TiN coating.
Abstract
In the present study, TiN and VN surface coatings are applied on copper substrates, and their influence on the electrical contact resistance (ECR) of the primary material is studied. The ...coatings are deposited using reactive magnetron sputtering in an Ar/N
2
environment. The formed TiN and VN thin films have a thickness of 600 nm and 350 nm, respectively. The preferred crystallographic orientation of both coatings is in the (311) plane. This corresponds to a high crystallite size, high plastic deformations, and high mobility of any structural defects. The I(200)/I(111) ratios of the coatings indicate that the deposited TiN coating is perfectly stoichiometric, and the VN one is hyper stoichiometric, resulting in its’ slightly higher electrical contact resistance. The electrical contact resistance of both coatings is significantly lower compared to that of the pure copper substrate due to their excellent corrosion resistance.
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