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A cold cathode plasma source is constructed for modifying PTFE surface characteristics. The source was easily built, had a consistent plasma discharge medium and acceleration system. A cylindrical Langmuir probe is also used to evaluate plasma parameters like density, temperature or even plasma potential. This probe is designed to be moveable so that it may approach any desired position in the plasma volume. The influences of nitrogen pressure and probe-cathode gap on plasma parameters were investigated. The electron temperature $T_e$ fluctuated from $7.73\times 10^4$ to $6.8\times 10^4$eV as the pressure rises from 0.2 to 0.4mbar. Further, by increasing the cathode-probe gap from 0.4 to 2cm, the electron densities increased from $0.46\times 10^{10}$cm${}^{-3}$ to $0.89\times 10^{10}$cm${}^{-3}$. Furthermore, the contact angles, work of adhesion and surface free-energy of pristine as well as irradiated PTFE films, were estimated. The results demonstrated that by extending the plasma exposure duration from 0 to 12min, the water contact angle is lowered from 82.2^∘ to 30.5^∘. At these conditions, the work of adhesion is raised from 81.9 to 134.1mJ/m², as the surface free energy is increased from 29.8 to 71.8mJ/m².

This study addressed the preparation of nanocomposites consisting of polyvinyl alcohol (PVA) and titanium oxide (TiO₂) for utilization in optoelectronics technologies. PVA/10%TiO₂ nanocomposite samples with a mean thickness of 0.1mm were created using the solution casting method. The PVA/TiO₂ films are irradiated with oxygen fluences of $0.4\times 10^{17}$, $0.8\times 10^{17}$ and $1.2\times 10^{17}$ ions/cm². The X-ray diffraction (XRD) and FTIR methodologies were employed to investigate the impact of ion bombardment on the structural characteristics and functional groups of PVA/TiO₂ substrates. Diffraction peaks are 20.1° for PVA and 25.4° for TiO₂, indicating the successful PVA/TiO₂ nanocomposite construction. The absorbance (A) of unirradiated and irradiated samples was measured using UV–Vis spectroscopy within a wavelength range of 200–1100nm. Band gaps ($E_g$) were calculated using Tauc’s formula for PVA/TiO₂ films, exhibiting a decrease from 4.56eV for unirradiated PVA/TiO₂ film to 4.16, 3.95 and 3.88eV at ion fluences of $0.4\times 10^{17}$, $0.8\times 10^{17}$ and $1.2\times 10^{17}$ ions/cm², respectively. Furthermore, the Ubrach tail has a rise of 1.23eV for unirradiated PVA/TiO₂ to 1.28eV, 1.4eV and 1.77eV for irradiated films with ion fluences of $0.4\times 10^{17}$, $0.8\times 10^{17}$ and $1.2\times 10^{17}$ ions/cm², respectively. Additionally, following ion irradiation, the PVA/TiO₂ absorption edge $E_e$, which was 3.56eV, decreased to 3.48, 3.37 and 3.23eV, with increasing ion beam fluences. This study demonstrated that the optical behaviors of the PVA/TiO₂ films were altered under bombardment, suggesting their potential applicability in optical devices.

In order to analyze the adsorption capacities of different solid substrates, we present a multi-step method to separately study the isotherm at different pressure ranges (steps). The method is based on simple gas isotherm measurements (nitrogen, methane, carbon dioxide, argon, and oxygen) and is tested to describe the adsorption process and characterize a graphitized surface (GCB) and two different granular activated carbons (GAC). The GCB isotherms are described as a sum of Fowler-Guggenheim-Langmuir shifted curves; isotherm behaviors are quite similar at different temperatures, but change below a certain threshold. In GAC the first steps show the same adsorption characteristics at low pressures (Dubinin's description), but this behavior changes at higher pressure regimes, which allows one to elucidate how heterogeneous the surfaces are or how strong the interactions between adsorbed molecules are for this marginal adsorption to occur. We tested different approaches (from BET multilayer to Aranovich) and found quite different features. We finally conclude that if the description of the adsorption on complex substrates, such as those presented here, is carried using only one model, e. g. Dubinin in case of GACs, the resulting characteristics of the adsorbent would be very biased.

Several researchers have recently expressed interest in additively manufactured electrodes for machining and surface modification applications. The additively manufactured AlSi10Mg tool electrode is one of the promising candidate materials for non-conventional processes. This research investigates the process parameters of laser powder bed fusion (L-PBF) processed AlSi10Mg tool electrodes for the electro-spark deposition process (ESD). The selected deposition parameters, namely, peak current (P_c), pulse-on time (P_on) and deposition time (DT) with various levels and experimentation, are based on the box-behnken design (BBD) of the response surface methodology. The deposition was carried out to analyze the output responses of material deposition rate (MDR), additive tool wear rate (ATWR) and surface roughness (SR). The multi-objective optimization was performed to minimize the ATWR and SR and maximize the MDR. The optimized ESD parameters of P_c = 6 A, P_on = 20$\mu$s, and DT = 5 min were found with predicted responses of MDR = 0.019 mg/min, ATWR = 0.095 mg/min and SR = 3.86 $\mu$m. The deposited surface witnessed the formation of debris, microcracks, and a solidified surface with a dark region and accumulated worn debris that has an elongated and flat shape. The workpiece substrate was exposed to a significant amount of additive tool electrode material (Si, Al, O, Mg, S), and different intermetallic (${\text{Al}}_{26}$ Si) 0.148, Al₂O₃, and Al₂S₃ formations have been recognized. This finding corroborates the efficient usage of L-PBF AlSi10Mg electrodes for ESD processes.

The effects of oxygen-containing functional groups on the surface roughness of graphene oxide are thoroughly studied using three-dimensional atomic force microscopy images, ball-and-stick model and wire-frame view results. Moreover, X-ray diffraction method and Fourier transform infrared spectroscopy are employed for characterizing the structural and chemical behavior of graphene oxide, respectively. Graphene oxide sheets show a clear concavity on one side when the aggregation of functional groups increased on the other side. This behavior could be the main reason for the surface fluctuation of graphene oxide sheets that is observed in microscopic images. In addition, the individual graphene oxide sheet presents greater values of mean roughness compared to multilayered sheets.