Papers by Keyword: Plasma Treatment

Abstract: This study presents the results of thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy to investigate the effects of air plasma treatment on polyamide 12 (PA12) powder for 1 and 2 h. Plasma treatment raised the degradation starting temperature from 376 °C for untreated PA12 powder to 389 °C for 2 h of treated powder. The crystallization temperature revealed by DSC increased from 133.31 to 141.7°C, whereas the melting point remained essentially unaltered at approximately 185°C. The fusion enthalpy decreased from 90.64 to 73.5 J/g, and the crystallinity also decreased from 41.9% to 34%. SEM results show a steady improvement toward homogeneity, accompanied by a diminishing amount and size of surface defects as the treatment proceeds. Such findings promote plasma treatment as an alternative route without any additives in raising the PA12 crystallization level and changing surface morphology together with improving its thermal stability, thus finding broad future application prospects in modified polymer engineering processing.

Abstract: Among the numerous metal oxide semiconductors, zinc oxide (ZnO) is one of the most widely used materials in various fields due to its non-toxic nature, tunable electric and optical properties, and good thermal and chemical stability. This research aims to study the tuning of optical, electrical, and surface properties of ZnO film treated with dielectric barrier discharge (DBD) plasma produced at atmospheric pressure. The result revealed a significant decrease in its optical band gap, but there was an increase in conductivity. The results of contact angle measurement clearly showed the change of surface nature from hydrophobic to hydrophilic for DBD-treated ZnO film.

Abstract: This work aims to analyse the effect of plasma and alkaline pre-treatment to improve the adsorption of GNPs onto 100% cotton knits. For this purpose, in one approach, 2% GNPs were dispersed in an aqueous/ethyl-based solution, in another approach the same concentration of said nanoparticles were dispersed in different % of PEG (10%, 30% and 50%, w/ v). The functionalised samples with and without plasma pre-treatment were characterized by Field Emission Scanning Electron Microscopy (FESEM), Contact Angle, Ground State Diffuse Reflectance (GSDR), and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR). Electrical and washability properties until 10th wash cycles were also evaluated. The dopped samples obtained semiconductor values, and the ones that received the plasma treatment became hydrophilic, which contributed to excellent absorption bands. However, it is necessary to carry out more in-depth studies that contribute not only to better adsorption, as well as an adequate anchoring of nanoparticles in textile substrates.

Abstract: In this article we investigated properties of elementary carbon fibers after their activation and subsequent deposition of thin layers of metal coatings on their surface. For deposition we used copper, titanium and stainless steel. We investigated influence of various technologies of preliminary processing of the fiber surface on the value of the adhesion strength of the metal coating to the carbon tape and on the mechanical properties of elementary fibers. We established that the strength of carbon plastics at interlayer shear increases by 10-30% when using carbon tapes and fabrics with a metal coating.

Abstract: A new surface texturing technique, based on liquid plasma discharging in an aqueous electrolyte, is proposed to modify the surface morphology of grey cast iron. During the process, a grey cast iron sample serves as a cathode where the reduction of hydrogen from the aqueous electrolyte occurs and consequently plasma discharging is generated on the sample surface under applied high voltages (up to 480V). The formed hydrogen bubbles are exploded during the electrical discharging, leaving an irregular array of craters on the sample surface due to the high temperature and shockwaves of the plasma micro-arc discharging. After polishing the crater-like textured surface, surface roughness and oil retention are measured by a profilometer. Reciprocating tribotests are utilized to determine the coefficients of friction. The surface morphology of the polished and tested surface is studied by SEM. The same tests are also conducted for the cast iron with a cross-hatched surface. These two set of results are compared to determine the effects of the texturing and polishing on friction. The results show that the polishing of textured surface can decrease the roughness and coefficients of friction significantly at starved lubricating conditions. This method has potential to be applied on the cylinder bore surface of a cast iron liner for the internal combustion engine (ICE). By honing the textured bore surface, the friction between piston and cylinder bore is expected to decrease and the ICE efficiency to increase for environmental benefits.

Abstract: The paper investigates the effect of plasma treatment of basalt fiber on its wettability, which is determined by the ability to absorb water. As the treatment time increases the wettability becomes higher, up to 10 minutes. The wettability-treatment power dependence passes through a maximum. The highest value is observed at a treatment power of 0.6 kW both on the day of treatment and after a 5-day rest period. A further growth in power not only does not increase this value, but in fact decreases it. The retreatment after a 5-day curing period yields lower results, but remains sufficiently high. The highest wettability is observed at a treatment power of 0.6 kW, gas flow rate of 0.04 g/s, chamber pressure of 20 Pa, air/argon mixture (1:1) as plasma support gas. The strength of concrete specimens BST V40 P2 was tested with two treatment modes: in mode 1 the treatment time was 10 minutes, the treatment power was 1.5 kW; and in mode 2 the treatment time was 5 minutes, the treatment power was 0.6 kW, with the addition of plasma treated basalt fiber (0.5 and 3 mass percent). Concrete has the highest strength when basalt fiber (3 mass percent) is subjected to plasma treatment in mode 2. In addition, the strength increases by 18 mass percent in comparison with the reference.

Abstract: X-ray photoelectron spectroscopy (XPS) and Spectroscopic Ellipsometry (SE) were used to analyse the effect of oxygen plasma treatment on properties of aluminum oxide thin films. The aluminum oxide films were fabricated using a reactive sputtering system. The as-deposited films were treated with oxygen plasma powered by an RF generator. During the plasma treatment, the pressures were set at 1 x 10^-1 to 1x 10^-2 mbar, while the RF supplied powers at 100 W and 200 W. It was observed that lower plasma powers and higher pressures resulted in smoother films. The O/Al ratio of the films were found to decrease with increasing plasma powers and pressures. The thickness and refractive index of the films were significantly affected by the oxygen plasma treatment process, which could be related to the change in films’ packing density and the etching at the surface.

Abstract: Nature-inspired superhydrophobic surfaces have received immense industrial and academic interest due to their non-wettability and self-cleaning properties. To fabricate superhydrophobic silicone rubber surfaces, a simple, environmentally friendly atmospheric-pressure plasma treatment was applied. The effect of diverse plasma processing parameters on the final wettability behavior of the substrates, including plasma power, plasma frequency, number of passes, plasma jet speed, plasma cycle time and distance between the nuzzle outlet and substrate, were analyzed by means of design of experiments (DoE). Surface chemical characterization illustrated the influence of plasma treatment on the chemical composition of the produced silicone rubber. Furthermore, the presence of microstructures as well as the chemical composition of the surface was confirmed using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy analysis.

Abstract: Stiff coating on the phase-separated soft polyurethane substrate under the compression deformation is investigated by the finite element modeling (FEM). External strain leads to the wrinkling of layer surface, which is characterized by a set of wavelengths and amplitudes. The influence of the thickness and stiffness of the layer, elastic modulus of the substrate on the structural-mechanical properties of the deformed surface is studied. The results of the model are in good accordance with the experiment (plasma immersion ion impanation of nitrogen ions into the polyurethane substrate) and allowed to estimate the modulus of the coating and the deformation of the surface.

Abstract: The effect of the microwave (2.45 GHz) plasma power on the surface topography was evaluated on a commercially available epoxy composite. The plasma treatment was performed by varying the microwave plasma power from 200 W to 500 W at a constant oxygen flow rate at 20 sccm for one min treatment. Based on the Atomic Force Microscopy analysis, the surface roughness root mean square was changed from -2% to 21% by increasing the plasma power from 200 W to 500 W. In oxygen plasma, the interaction of plasma ions with the substrate surface leads to oxidation and etching of surface materials. More plasma ion density and ion current can be produced by increasing the plasma power. As a result, more interaction between plasma ion and substrate surface using high plasma power. The surface roughness can be considerably increased by plasma treatment using power above 400 W.