Influence of Cr content on the micro-structural and tribological properties of PLD grown nanocomposite DLC-Cr thin films

• DLC with different Cr concentration was deposited on to AISI SS304 substrate by PLD.
• Cr concentration was varied through 5, 10, 15 and 20 at% and was confirmed by EDAX.
• Adhesion improved due to formation of Cr3C2 nanoclusters, confirmed by HR-TEM and XPS.
• Internal stress reduced to 3 GPa for lower Cr concentration in DLC film.
• Low friction coefficient of 0.07 obtained for DLC with low Cr concentration.

Improved adhesion and low friction coefficient of diamond-like carbon (DLC) films has been a major challenge which otherwise would have opened door to many engineering applications. Amorphous DLC films doped with different concentrations of Chromium (Cr) (5, 10, 15 & 20 at%) were deposited on to stainless steel (AISI SS304) substrate using Nd-YAG pulsed laser deposition technique (PLD). Raman spectroscopy was used to calculate the internal stress of the films. DLC with lower Cr concentration (5 at%) showed significant internal stress reduction (3 GPa) compared to DLC with higher Cr concentration. Formation of Cr3C2 nanoclusters in the DLC matrix was confirmed by XPS and TEM analysis which enhanced the adhesion strength of the film. DLC films with lower Cr concentration exhibited ultra-low friction coefficient (0.04–0.09) and the value increased significantly in higher Cr concentration. An optimum metal concentration in DLC film leads to improved adhesion and friction behaviour that houses many engineering applications.