Effectiveness of using pure copper and silver coupon corrosivity monitoring (CCM) metal strips to measure the severity levels of air pollutants in indoor and outdoor atmospheres

Abstract

Severity levels of air pollutants rich in oxides, chlorides and sulphides were successfully measured in indoor and outdoor atmospheres using pure copper and silver coupon corrosivity monitoring (CCM) metal strips when the maximum exposure periods were limited to thirty days for indoor and ninety days for outdoor environments. Resultant corrosion products from air pollutants which were successfully measured were copper oxides (CuO and Cu2O), copper sulphides (CU2S), silver chlorides (AgCl) and silver sulphides (Ag2S). The total film thickness measured for copper corrosion products were as low as 36A for indoor atmospheres (G1, mild) and as high as 6019A for outdoor atmospheres (GX, severe). The total film thickness measured for silver corrosion products were as low as 98A for indoor atmospheres (G1, mild) and as high as 3464A for outdoor atmospheres (GX, severe). Coulometric/cathodic reduction current densities used for both copper and silver were 0.05mA/cm2 (indoors) and 0.5mA/cm2 (outdoors). Coulometric/cathodic reduction potentials for Cu) were between minus 0-600mV, between minus 600-900mV for Cu2) and between minus 900-1200mV for Cu2S. AgCl was reduced between minus 0-700mV and Ag2S between minus 700-1200mV. The hydrogen evolution stages for both copper and silver were observed at -1200mV for indoor and -800mV for outdoor environments.