Effects of Iron(III) Ions on Corrosion of Stainless Steel in Concentrated Nitric Acid Solutions at High Temperature

摘要

Effects of Fe (III) ions on corrosion of stainless steel were examined in highly concentrated HNO_3 solutions at high temperature, using mass loss measurements, electrochemical measurements, and quantitative analysis of NO_x evolved during immersion.Addition of Fe(NO_3)_3 into HNO_3 caused the corrosion potential of stainless steel to become nobler gradually from the passive to trans-passive potential regions during immersion experiments. The average corrosion rate of stainless steel for 360 ks immersion increased with increasing Fe(III) concentration. Quantitative analysis of NO_x evolved during immersion suggested that Fe (III) ions adsorbed on the specimen surface act as catalytic centers in the reduction of HNO_3.