Copper corrosion kinetics and mechanisms in the presence of chlorine and orthophosphate

Copper corrosion in the presence of orthophosphate and chlorine has indicated the formation of a protective scale containing either CuO or Cu₂O depending on the pH. Furthermore, the scale forms relatively quickly, after 15 days of immersion EIS showed very little change. The scale is initially porous, but after prolonged immersion, the porous structure disappears, as evidenced by SEM. The equivalent circuit that is used to model the EIS spectra fits the data well and yields useful information on values, such as Rct, which varies from 2 to 10 kΩ and R_film, which varies from 15 to 80 kΩ when the immersion time is extended from 2 to 30 days.