Corrosion behavior of Ni3Al-bonded TiC-based cermets in H2SO4 and NaOH solutions

Abstract

Corrosion behavior of multicomponent Ni3Al-bonded Ti(C,N)-based cermets with various Ni3Al contents and Ti(C0.5,N0.5) addition was investigated in 1 M H2SO4 and 1 M NaOH solutions, using immersion tests, potentiodynamic polarization measurements, XRD, SEM and XPS. In 1 M H2SO4 solution, corrosion process of all cermets consisted mainly of their binder phase dissolution, and during potentiodynamic polarization, their passivation and pseudo-passivation corresponded to passivation of their binder phase and ceramic grains, respectively. Corrosion potential and current density decreased with increasing Ni3Al content, while corrosion potential increased and current density decreased with Ti(C0.5,N0.5) addition. In 1 M NaOH solution, corrosion process of all cermets consisted mainly of their ceramic grain dissolution, and during potentiodynamic polarization, their passivation and pseudo-passivation corresponded to passivation of their ceramic grains and binder phase, respectively. Corrosion potential increased and current density decreased with increasing Ni3Al content, while corrosion potential decreased and current density increased with Ti(C0.5,N0.5) addition.