Tribocorrosion behaviour of NiTiNOL60 alloy in an alkaline environment

NiTi-based alloys subjected to aggressive tribocorrosion working conditions can deteriorate by the combined action of mechanical and chemical wear. The synergistic interaction under sliding contact and corrosive environment formed the basis of the current study. This study employed a linear reciprocating tribometer coupled with an electrochemical cell of a three-electrode configuration to investigate the behaviour of NiTiNOL60 alloy sliding against an alumina ball (Al2O3) in a NaOH environment. The resulting wear track surfaces were examined using a scanning electron microscope, optical microscope, energy dispersive spectroscopy (EDS), and stylus profilometry. While the synergistic interactions reveal that abrasive and oxidative wear mechanisms exist concurrently, an increase in applied load reduces the corrosion potential, thereby leading to a higher wear volume and increased corrosion rate. The experimental results showed that a higher corrosion rate and wear volume occurred at a higher load. The wear track analysis illuminated the various wear mechanisms at play, including abrasion, debris adhesion, pitting, delamination, ploughing, and cracking. These mechanisms were influenced by both mechanical and chemical wear, the latter notably due to corrosive attacks. EDS elemental analysis showed an increase in oxygen content at higher loads, which suggests increased corrosion due to the delamination of the oxide layer during the reciprocating sliding.