Corrosion behaviour of TiC/N coating prepared by plasma electrolytic saturation on NiTi

ABSTRACT

In this research, plasma electrolytic saturation of carbon and nitrogen was used to prepare TiC/N coating on NiTi alloy. In this regard, four types of urea-based electrolytes with various amounts of NH₄NO₃ were employed. The effect of electrolyte composition on the characteristics of the formed layer was studied using grazing incidence X-ray diffraction and scanning electron microscopy. The results showed that the TiC_0.2N_0.8 compound was formed in coating. The pore size of coating was increased by increasing the concentration of NH₄NO₃. To investigate the corrosion resistance of the coated samples, the potentiodynamic polarization test and electrochemical impedance spectroscopy were performed in Ringer's solution. It was observed that as the NH₄NO₃ concentration of electrolyte increased, the corrosion resistance of the formed layer was reduced. Such a behaviour was attributed to the operating current as well as discharge energy enhancement which caused the deep cracks and porosities formation in the coating.

KEYWORDS:

• Plasma electrolytic saturation
• TiC/N
• ceramic coating
• corrosion resistance
• NiTi shape memory alloy

Acknowledgements

The authors would like to acknowledge the financial support from the vice chancellor for research of Sahand University of Technology.

Disclosure statement

No potential conflict of interest was reported by the author(s).