A comparison of the corrosion behaviour over time in 0.5 M NaCl environment of TiCN spark plasma sintered with and without Si aids

The corrosion behaviour over time in 0.5 M NaCl of TiCN spark plasma sintered at low temperature (1400°C) with 5 vol% Si aids and its reference pure TiCN spark plasma sintered at high temperature (2100°C) were investigated by electrochemical techniques ( i.e., open circuit potential, current-potential curves, and electrochemical impedance spectroscopy) and microstructural characterisation ( i.e., optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy), and compared. It is shown that both TiCN materials are very resistant to corrosion in 0.5 M NaCl. After two months of immersion the surfaces remained pristine, without any signs of attack. Their impedance responses revealed capacitive behaviour and very high impedance at low frequencies. The protective passive films strengthened during anodic polarisation and the samples withstood considerable overpotentials before film rupture. The TiCN material fabricated with Si aids is preferable due to its slightly higher corrosion resistance and much lower sintering temperature. • The corrosion resistance of 95TiCN+5Si and its reference TiCN is investigated. • Both materials showed very high corrosion resistance in 0.5 M NaCl. • The passive films withstood considerable overpotential before breakdown. • The protective passive films strengthened during anodic polarisation. • 95TiCN+5Si is slightly more resistant and has much lower densification temperature.