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TiO2 film deposition by PAPLD with biased substrates is investigated into a wide range of laser fluence and oxygen pressure. It is established that plasma of the r.f. discharge excited inside PLD chamber strongly affects the films properties. TiO2 films deposited by PAPLD were found better than those produced by the conventional PLD with regard to their morphology, optical properties, and uniformity. So, at the high values of Knudsen number (lambda) /L < 1 with an r.f. power of 70 Watt, PAPLD markedly improves the TiO2 film stoichiometry for high laser fluence, and the deposition rate increases with it up to 2 A/s.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Silicon carbide ceramic seal rings are treated by KrF excimer laser irradiation. Surface characteristics, induced by lasertreatment, depend upon laser fluence, the number of laser pulses, their energy and frequency, the rotation rate of the ringand the processing atmosphere. It was ascertained that silicon carbide has to be processed under an inert atmosphere toavoid surface oxidation. Microstructural analyses of surface and cross section of the laser processed samples showed thatthe SiC surface is covered by a scale due to the melting/resolidification processes (at low fluence: 1 .8 J/cm2). At highfluence (7.5 J/cm2) there are no continuous scales on the surfaces; materials is removed by decomposition/vaporisation andthe ablation depth is linearly dependent on the number of pulses. Different surface morphologies (flat and rugged areas,deposits of debris and discontinuous thin remelted scales) are observed. The evolution of surface morphology and roughnessis discussed with reference to composition, microstructure and physical and optical properties of the ceramic material and tolaser processing parameters. Preliminary results on tribological behaviour ofthe treated seals are reported.Keywords: Silicon Carbide, SiC, seal ring, laser ablation, microstructure, roughness.