Influence of TiC/a-C phase on tribological properties of composite coatings

Abstract

Gas phase carburisation of titanium in CH₄ atmosphere was carried out in a thermogravimetric analyser. The analysis revealed the formation of TiC phase embedded in an amorphous carbon (a-C) matrix. Raman scattering investigation revealed the evolution of two separate peaks corresponding to D and G band vibrational modes in a hexagonal sp phase of the graphite-like structure. The tribological properties of this coating relied significantly on the relative extent of D and G band modes with the evolution of TiC phase. A sharp transition of friction from lower to higher value was observed due to the wearing out of tribolubricant phases of TiC with disordered graphite-like structure present in the a-C matrix. In case of thicker coating, a lower regime of friction was observed with longer wear distances.

Keywords:

• TiC/a-C
• Composite coatings
• Friction
• Wear

The authors would like to thank P. K. Ajikumar, MSG/IGCAR, for preparing the TiC specimen, S. Kalavathi, MSG/IGCAR, for carrying out the GIXRD and Mr A. Bahuguna, MSG/IGCAR, for dimensional measurements of wear track by surface profilometry. The authors are also grateful to Dr C. S. Sundar, Director, Material Science Group, IGCAR, for providing encouragement and support.