THE INFLUENCE OF THE RELATIVE HUMIDITY AND CORROSION PRODUCTS ON THE ADSORPTION

The adsorption of sulphur dioxide on metal surfaces has been studied using an S-35 isotope. Experiments have been performed with 0.10 PPM of sulphur dioxide at between 50 and 98 per cent R.h. The adsorption properties of polished iron, zinc, copper and aluminum samples were compared with those of pre-exposed samples of these metals. Measurements have shown a pronounced dependence of the adsorption rate on the humidity. Almost quantitative adsorption of sulphur dioxide was obtained on pre-exposed samples at R.H. greater than or equal to 80 per cent. Very low absorption capacities at humidities less than 90 per cent have been found for the corrosion products of copper and aluminum. Changes in the adsorption rate with time were used to study the corrosion initiation on polished iron surfaces. /TRRL/