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The low-temperature low-pressure hydrogen based plasmas were used to study the influence of processes and discharge conditions on corrosion removal. The capacitive coupled RF discharge in the continuous or pulsed regime was used at operating pressure of 100−200 Pa. Plasma treatment was monitored by optical emission spectroscopy. To be able to study influence of various process parameters, the model corroded samples with and without sandy incrustation were prepared. The SEM-EDX analyzes were carried out to verify corrosion removal efficiency. Experimental conditions were optimized for the selected most frequent materials of original metallic archaeological objects (iron, bronze, copper, and brass). Chlorides removal is based on hydrogen ion reactions while oxides are removed mainly by neutral species interactions. A special focus was kept for the samples temperature because it was necessary to avoid any metallographic changes in the material structure. The application of higher power pulsed regime with low duty cycle seems be the best treatment regime. The low pressure hydrogen plasma is not applicable for objects with a very broken structure or for nonmetallic objects due to the non-uniform heat stress. Due to this fact, the new developed plasmas generated in liquids were applied on selected original archaeological glass materials.

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This paper presents results on electric discharge generation by high frequency high voltage (15-100 kHz) in NaCl solutions with different initial conductivity (100-1300 mS cm -1 ), and compares them with DC discharge in the same electrode configuration. A batch plasma reactor in the pin-hole configuration contained a ceramic dielectric barrier separating two planar stainless steel electrodes; barrier thickness of 0.6 mm and pin-hole diameter of 0.6 mm was used. Lissajous charts were evaluated from electric measurements for different discharge phases (electrolysis, bubble formation and discharge regular operation). Breakdown moments for different solution conductivities were determined from discharge power evaluation as a function of applied frequency. Breakdown voltage amplitude was decreased by the increasing conductivity in both regimes while frequency and current decreased. Changes of physical parameters (temperature, solution conductivity and pH) as well as production of hydrogen peroxide at different solution conductivities were compared. Solution conductivity was increased in both discharge regimes and with the initial conductivity value. Solution temperature was increased by the discharge in both regimes and with the increasing initial conductivity, too. Solution pH dropped to acidic conditions when HF or DC positive regime was applied while it was enhanced by DC negative regime.

Shrnutí Článek představuje vývoj nových numerických modelů kompozitních materiálů na mezi-úrovni. Modely jsou určeny k predikci mechanických vlastností v tahu, tlaku, smyku a impaktním zatížení různých konfgurací tri-axiálně pleteného uhlíkového kompozitu, přičemž využívá znalosti materiálových vlastností vlákna a matrice a zvolené geometrie pletení. Představené výsledky jsou porovnány s měřením na vzorcích materiálu a vykazují dobrou úroveň shody. Modely lze využít mimo predikce materiálových vlastností v detailních analýzách porušení laminátu.