Erosion of needle electrodes in the pulsed corona discharge in water with a pulse energy of ∼ 2÷; 3 J was investigated in dependence on the electrode material (platinum, tungsten and stainless-steel) and the solution conductivity (100 and 500 µS/cm). Erosion of electrodes remarkable increased with the higher solution conductivity for all three tested metals. The highest erosion rates were determined for tungsten while platinum was the least eroded material. In addition to the dominant melting effect, release of anode material by the electrolysis significantly contributed to the total erosion of needle electrodes. The highest contribution of electrolysis was determined for stainless-steel electrodes that released up to 40-50 % of eroded metal in the form of iron ions. Peculiar protrusions were observed on the surface of eroded tungsten electrodes.

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Abstract:Titanium dioxide thin films are extensively studied for applications in solid state gas sensor devices. Their gas sensing properties are strongly dependent on deposition technique, annealing temperature, film thickness and consequent properties like crystalline structure, grain size or amount of defects and impurities. In this work we report the gas sensing properties of TiO 2 thin films prepared by reactive magnetron sputtering technique and subsequently annealed at temperatures 600°C and 900°C. The films were exposed to different concentrations of H 2 gas up to 10 000 ppm. Their sensitivity to gas at various operating temperatures, ranging from 250°C to 450°C, was obtained by measuring their resistance. 07.07.Df, 68.47.Gh, 73.25.+i, 82.47 PACS (2008):