Investigation on the effect of nitrate ion on the critical pitting temperature of 2205 duplex stainless steel along a mechanistic approach using pencil electrode

Investigation on influence of the nitrate ion on critical pitting temperature (CPT) of DSS 2205 in 0.6 M NaCl media is the aim of this research. Results revealed that 0.01 M NO3− has negligible effect on CPT, while 0.1 M NO3− causes CPT to shift to a value more than 85 °C. Then, a mechanistic approach using pencil electrode was sought based on proposed theory defining CPT as a temperature at which critical current density necessary for passivity (icrit) equals to limiting current density (ilim). Results indicate that nitrate ion increases CPT by increment in ilim and slight decrement in icrit.