Effects of titanium-based raw materials on electrochemical behavior of Ti(C,N)-based cermets

• Cermets with TiC0.7N0.3 and TiC + TiN raw materials are comparatively investigated.
• The cermet from TiC0.7N0.3 raw material shows higher corrosion resistance.
• Two cermets exhibit much higher corrosion resistance in NaOH than in H2SO4.
• In-situ formed corrosion products are characterized with good compactness.
• Based on the XPS analysis results, corrosion mechanism is discussed in details.

The electrochemical behavior of Ti(C,N)-based cermets with two different kinds of titanium-based raw materials, i.e. solid solution type TiC0.7N0.3 and single interstitial phase type TiC and TiN, was investigated in H2SO4 (pH = 1) and NaOH (pH = 13) solutions at 25 °C. Potentiodynamic polarization, electrochemical impedance spectroscopy and surface analytical techniques were used for the investigation. The results show that the cermet prepared from TiC0.7N0.3-based raw material exhibits higher corrosion resistance in the two solutions due to the differences in the chemical composition of the binder phase and hard phase and in the homogeneity of the microstructure. Both the cermets exhibit substantially higher corrosion resistance in NaOH than in H2SO4. Based on the X-ray photoelectron spectroscope analysis results, the corrosion mechanism was discussed in details.