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In this paper, phenomena of general corrosion are assumed to be the results of three sequential processes: degradation of paint coatings, generation of pitting point, and progress of pitting point. A consistent corrosion model is proposed which can evaluate the generation and progress of corrosion quantitatively by introducing appropriate simple probabilistic models for each process. This probabilistic corrosion model can be identified by analyzing existing data collected from plate thickness measurements. Applicability of this model is verified by comparing the estimated behavior of corrosion progress and dispersion with those from actual data.

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This paper demonstrates that powerful laser radiation causes changes in the absorbance spectra of epoxy resin, polyethylene and polysulfone. Thin polymer films were located between IR AgBrCl optical fibres and exposed to the radiation of a CO 2 laser. The output of the laser source was varied in the range 0-8.5 W. The absorbance spectra were recorded using a Fourier transform infrared (FTIR) spectrophotometer. It was revealed that characteristic polymer absorbance peaks decay under exposure to the powerful IR light. The apparent dependence of peak magnitude on IR radiation power has been established. We showed that the phenomenon of the absorbance peak disappearances associated with the polymers-thermoplastic (including an engineering polymer such as polysulfone) and thermosetting-is of a threshold nature. The mathematical theory of the observed effect was derived. We propose that the effect under discussion is caused by the oxygen-free thermal action of IR radiation on the chemical structure of the polymer materials. The revealed effect could be effectively used to lower the losses in adhesive contacts of IR optical elements. The novelty of the proposed method lies in the fact that thermal treatment is localized strictly within the adhesive layer; optical elements to be contacted (fibres, lenses, etc) which are highly IR transparent do not experience the IR radiation, but the polymer adhesive is subjected to a temperature rise.