Tuning the tribological property of PLD deposited DLC-Au nanocomposite thin films

Nonhydrogenated Diamond-like Carbon-gold (DLC-Au) nanocomposite thin films with various Au contents and cluster size (<10 nm) have been engineered using Excimer Pulsed Laser Deposition (PLD) on silicon (100) substrates with an aim to achieve reduced coefficient of friction (CoF). Structure, microstructure, chemical bonding and chemical composition of these films were comprehensively investigated using X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Raman and X-ray photoelectron spectroscopy (XPS), respectively. It is observed that the DLC matrix with lowest Au content sustained higher sp3 content due to enhanced interaction of carbon and smaller Au nano-cluster formed in these films. DLC-Au Nanocomposite formation takes place due to the low compatibility between carbon and gold which resulted in ultra-smaller Au crystallites in DLC matrix at lowest Au content. This enhanced the sp3 content in DLC films and induces tribofilm nucleation on the ball counter body with large amount of sp2 phase fraction which significantly reduced the CoF.