Combined role of molybdenum and nitrogen in Limiting corrosion and pitting of super austenitic stainless steel
Bingbing Li, Yuping Lang, Haitao Chen, Hanqiu Feng, Huapeng Qu, Sun Xu, Zhiling Tian
Abstract
The molybdenum and nitrogen content of super austenitic stainless steel in Cl − solution is shown to influence pitting resistance using immersion, electrochemical testing, and simulation. Variations in Mo and N content affect the defect density, resistance, and densification of the passive film, thereby reducing the number of pitting. A higher local pH associated with the pitting pits and an increase in NH 3 (NH 4 + ) are the results of increased N content, which also slows the rate of pitting expansion. The combined effects of fewer actively reactive spots within the passive film retarded pitting, and decreased corrosion rates due to NH 3 (NH 4 + ) mitigation of local acidity which serves to reduce the corrosion rate. The work function is improved to a greater extent when Mo and N are co-doped compared with individual Mo and N doping, and the adsorption energy is significantly increased when Mo and N are co-doped, indicating a synergistic role for Mo and N in the prevention of corrosion by Cl − .