Influence of material structure on the electrochemical behavior of nickel–titanium carbonitride composites

Ni–TiC0.7N0.3 composites were prepared using direct current electrodeposition and hot pressing routes. Hot pressed Ni and sintered TiC0.7N0.3 were also prepared. In case of electrodeposition, the samples contained between 10.4vol.% and 20.9vol.% TiC0.7N0.3. The hot pressed composite contained 16.7vol.% TiC0.7N0.3. The Ni based materials exhibited active–passive behavior in de-aerated 0.1mol/l H2SO4 solution, while TiC0.7N0.3 exhibited active behavior. The corrosion rate and passive current density increased and critical current density decreased with increase in reinforcement volume fraction. Based on microscopic examination, the increase in passive current density has been related to the increase in matrix area due to selective corrosion at metal–ceramic interfaces.