Tribocorrosion assessment of low-temperature plasma nitrided super duplex stainless steel

The tribocorrosion of low-temperature plasma nitrided UNS S32750 super duplex stainless steel was investigated according to procedures for passivating materials. Nitrided and non-treated samples were compared through two reciprocating sliding tests in NaCl solution: the continuous test, without significant passive layer growth, and the intermittent one, with repassivation. Open circuit potential and linear polarization resistance (LPR) characterized the electrochemical response. LPR was successfully introduced to evaluate the polarization resistance evolution during the continuous test. Corrosion and mechanical wear components were quantified. The mechanical wear dominated, and nitrided samples showed lower wear volume loss. After the intermittent test, their values were further reduced. Such improvement was explained by the higher load bearing capacity and repassivation ability of the nitrided surfaces.