Papers by Keyword: Plasma

Abstract: The article examines the hardness of the coating made of PG-CP4 powder. Plasma powder deposition was performed to samples made of 40H13 steel and then the samples treated with a laser beam. A multi-factor model was established that relates the hardness of the protective coating to the radiation power W, the longitudinal feed Spr of the laser beam, and the distance L from the protective casing of the laser head to the treated surface. Depending on the laser treatment modes, coating was in a state of complete, partial reflow or its absence. Full reflow is characterized by the adhesion of the filler material to the substrate, by maximum hardness of HRC 51.2–56.6 and no defects. In the absence of reflow, gas sinks, transverse microcracks, detachments, and other defects were found in the coating material, and the hardness decreased to HB 125–212. An increase in W and a decrease in Spr lead to increases the hardness of the treated coating, which is explained by an increase in the specific heat flux supplied to the coating per unit time, and a high rate of heat removal deep into the surface layer of 40H13 steel. The thickness of the surface layer with increased hardness ranged from 0.1 to 1.5 mm. Based on the multi-factor model, laser processing modes are controlled to ensure the required values of the protective coating hardness. The research results are recommended for use in enterprises that implement laser technologies and develop modern laser systems.

Abstract: The research on phenolic compound degradation using chemical oxidation methods in a plasma reactor was performed with an Ozone-Plasma Hybrid Reactor (RHOP). This device operates by combining ozonation reactions in the liquid plasma within the reaction room. Furthermore, Ozone gas as a reagent is produced by the standard ozonator type Resun RSO-9805 made in Hong Kong and fed into this device, where the liquid phase is mixed within the injector. This way, the two-phase mixture reacts more intensively in RHOP. Also, this combination is designed to intensify hydroxyl radicals while the liquid phase is in an alkaline condition constantly exposed to plasma. The results demonstrated a continuous circulation for 2 hours at the initial concentration of 50 ppm for p-chlorophenol with a volume of 2 liters. This further obtained an 83.98% removal rate and 42.19% COD value decrease.

Abstract: This paper presents the results of the investigation of NiCrRe coating deposited by plasma spray process at the atmospheric pressure on boiler steel substrate. These coatings were characterized by means of a scanning electron microscopy, and Energy-dispersive X-ray spectroscopy. The wear resistance of plasma sprayed NiCrRe coatings has been investigated under dry sliding conditions at applied load of 10 N in air. The continuous stiffness measurement (CSM) method was used for the investigation of nanohardness using Agilent G200 Nano-indenter in order to determine the mechanical properties of the coatings. Microstructural observations pointed out that the NiCr layer with white isles of rhenium possessed porosity, oxidized, un-melted and semi-melted particles, and inclusions. According to the results the thickness of the layer is 450 µm, the indentation modulus 158 ± 24.4 GPa, hardness 3.74 ± 0.76 GPa and the coefficient of friction is 0.45.

Abstract: Gallium oxide was grown on silicon carbide substrates using a corona discharge assisted vapor phase epitaxy process and gold catalyst. It is shown that by implementing the corona discharge the morphology of the gallium oxide can be transformed. The excitation of the gas phase and the generation of excited species directly influence the growth morphology suppressing nanowire growth and supporting the transformation into heteroepitaxial growth.

Abstract: Bundles or fabrics of sized glass fibres were treated by a dielectric barrier discharge plasma in a He/CF₄ gas mixture at atmospheric pressure with and without ultrasonic irradiation. The plasma treatment introduced fluorine both inside and outside of the fibre bundle, decreasing wetting of glycerol. Ultrasonic irradiation markedly increased the fluorine content as well as the silicon, calcium, and aluminium contents, indicating simultaneous fluorination and preferential etching of organic components. It is indicated that plasma treatment in a He/CF₄ gas mixture can be used for controlling the surface properties of glass fibre bundles, and that ultrasonic irradiation can enhance functionalization and etching.

Abstract: Polyester fabric has the disadvantage of poor hydrophilicity which reduces its wearing comfort and limits its usage in clothing industry. Chitosan especially that of low molecular weight is effective in hydrophilic finishing for polyester fabric, while using plasma processing can greatly improve the effect. This is a green and environmental protection process. Two sets of orthogonal experiments and analysis are done to research the factors that influence the plasma processing effect and the chitosan finishing effect which points out the variation tendency and the best processing conditions.

Abstract: Plasma technology provides an effective way to modify the surface of polymeric materials and thus improve the physicochemical properties of this material. This study was a preliminary study in exploring the application of plasma technology in the surface modification of silk fiber. Experimental results revealed that the dyeability of silk fabric with acid dye was improved after plasma treatment.

Abstract: The practice shows availability of an electro plasma method polishing. The lack of a method, namely impossibility of its application for processing extended grooves and apertures is known. Creation of a special equipment and revealing of optimum modes have allowed to receive the given roughness on the named surfaces on products from cuprum.

Abstract: Technological difficulties of manufacture, typical to the large number of crucial elements of certain assemblies: tubes of fuel systems, details of waveguide devices, smooth gun barrels and other tubular details. Difficulties associated with the finishing of the internal surfaces of these products. Therefore, great interest is to find a finishing technology, which allow processing such products. The kind of electrolytic-plasma polishing technology - forced electrolytic-plasma polishing (FEPP) allows to receive homogenous quality of an internal surface layer along processed tubular work piece.

Abstract: Plasma technology is an effective way to modify the physicochemical properties of silk fabric. This study was a preliminary study to explore the dyeability of silk fabric with metal complex dyes after treated with plasma technology, which may improve the processability and broaden the application of silk fabric. This study investigated the optimal plasma treatment condition and evaluated treated silk fabric in terms of wettability, surface modification and dyeability. It was found that plasma treatment can enhance the wettability and dyeability of silk fabric via the formation of hydrophilic functional groups in the structure of silk fiber.