OBSERVATIONS OF PULSATING MARANGONI PHENOMENA DURING THE LOCAL OXIDATION OF DEOXIDIZED LIQUID STEEL

Studies have been made by means of a high-speed video technique of the surface of Al-Si-Mn deoxidized liquid steel at about 1600 degrees C d uring local reoxidation by gently impinging flows of CO2-containing ga ses. Expanding 'necklaces' of alumina oxidation product have been obse rved to form at frequencies of up to about 5 Hz and to travel at veloc ities of up to 250 mm s(-1) near to the gas inlet tube, depending on t he experimental conditions. The pulsation frequency appears to be cont rolled by the rate of diffusion of aluminium to the surface. The effec ts of additions of the surfactants sulphur and selenium on the velocit y of the moving front are shown to be consistent with the processes be ing surface tension driven.