For testing the determination of the reactivity of aluminum powders it is proposed to use the following parameters: temperature of the beginning of oxidation, maximal oxidation rate, degree of transformation (degree of oxidation) of aluminum, relative thermal effect. Parameters for an evaluation of the reactivity of powders were chosen following the analysis of results of a non‐isothermal oxidation of powders of different grain size under conditions of programmed heating (the oxidizer being air). According to the proposed method of testing, the sample of ultrafine powder UFAP‐4 produced by the electrical explosion of wires has the highest reactivity among the studied powders.

Plasma activated water is a chemically active aqueous medium characterized by the presence of reactive oxygen and nitrogen species created by plasma exposure. This particular chemical composition is the starting point of extensive research studies in several domains such as bio-disinfectant in biomedical applications or as fertilizer in agricultural applications. These various applications need adjustments of the PAW properties and consequently require a better control of the PAW chemical composition. To achieve this aim, a UV spectrophotometric method (190–255 nm) is implemented to simultaneously detect the nitrate and nitrite ions in plasma activated water by a gliding arc discharge reactor at atmospheric pressure. The method, tested in plasma activated distilled water (PADW) and in plasma activated tap water (PATW), shows significant increases of nitrite and nitrate concentrations. Preliminary results on PADW and PATW kinetics evolutions highlight a different behavior of the temporal post-discharge reactions leading to non-conversion of the nitrite ions in the case of PATW. The near non-existence of acidification during and after plasma activation encountered in PATW is due to high levels of carbonate species in tap water acting as a buffer solution. Indeed, the presence of hydrogen carbonate (HCO3−) leads to the acidity consumption during plasma activation whereas the presence of non-dissolved limestone in hard water (CaCO3) acts as carbonates reserve, and this induces the acidity consumption after plasma treatment.

Hydrocarbon dust-particles are formed and grown to a large size (around 1 μm) in a low pressure capacitively coupled radio frequency discharge in methane. The methane decomposition leads to the formation of both spherical dust-particles in the plasma bulk and coating on the electrodes. Under ion bombardment, the coating on the biased top electrode peels off, leading to the fall of flakes. To better understand the role played by the electrode surface state on the plasma chemistry and on the dust-particle growth, experiments are carried out in two different initial conditions for the electrodes: (i) without any coating and (ii) with a homogeneous hydrocarbon coating. Spherical dustparticle growth is followed using the temporal evolution of the DC self-bias voltage. At the end of the experiment, dust-particles and flakes are collected and observed by scanning electron microscopy. Using mass spectrometry, temporal evolutions of neutrals, ionic species, and positive ion energies are investigated. Between the two experimental conditions, no strong differences were observed on the plasma chemistry. However, the self-bias voltage is strongly modified as well as the dust-particle growth and dynamics.

We studied the epoxy polymer surface modification using air plasma treatment in a Gliding Arc (GA) plasma reactor and a pulsed Dielectric Barrier Discharge (DBD). We employed optical emission spectroscopy (OES) measurements to approximate the vibrational and rotational temperatures for both plasma sources, as well as surface temperature measurements with fiber optics and IR thermography to corelate with the corresponding hydrophilization of the epoxy material. Water contact angle measurements revealed a rapid hydrophilization for both plasma sources, with a slightly more pronounced effect for the air DBD treatment. Ageing studies revealed stable hydrophilicity, with water contact angle saturating at values lower than 50°, corresponding to a >50% decrease compared to the untreated epoxy polymer. ATR-FTIR spectroscopy studies showed an additional absorption band assigned to carbonyl group, with its peak intensity being higher for the DBD treated surfaces. The spectra were also correlated with the surface functionalization via the relative peak area ratio of carbonyl to oxirane and benzene related bands. According to SEM imaging, GA plasma treatment led to no apparent morphological change, contrary to DBD treatment, which resulted in nano-roughness formation. The enhanced surface oxidation as well as the nano-roughness formation on epoxy surface with the air DBD treatment were found to be responsible for the stable hydrophilization.

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The presence of hydrogenated carbon nitride a-CNx:H particles confined in an argon dusty discharge induces the appearance of instabilities. Those instabilities, also called plasmoids, are luminous regions which move through the plasma and rotate around the biased electrode circumference. Electrical characteristics of the plasma have been used to evidence the presence of dust particles and to demonstrate that plasmoid appearance is triggered by particles. The light emitted by the plasma is analysed by optical emission spectroscopy. This paper presents the spatial distribution of excited species, such as CN, Ar I… between electrodes both inside plasmoids and in the surrounding dusty plasma. Obtained results allow to get information for the electron energy distribution function. Moreover, the interplay between plasmoid behaviour and particle presence in the plasma is shown.

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