Regression Analysis of Nano and Macrotribological Properties of Diamond-Like Carbon Films Deposited Through a Filtered Cathodic Vacuum Arc Ion-Plating Method

Diamond-like carbon (DLC) films have been extensively applied in industries owing to their excellent characteristics such as high hardness. In particular, there is a growing demand for their use as protective films for mechanical parts owing to their excellent wear resistance and low friction coefficient. DLC films have been deposited by various methods and many deviate from the DLC regions present in the ternary diagrams proposed for sp3 covalent carbon, sp2 covalent carbon, and hydrogen. Bend filtered cathodic vacuum arc (FCVA) approach with dc and pulsed bias voltage is used to produce diamond-like carbon (DLC) films. Atomic force microscopy was used to assess how changing the bias voltage affected the characteristics of nanoindentation and nanowear. The hardest DLC films had an average hardness of 50 GPa, a low dissipation modulus, a low elastic modulus to nanoindentation hardness ratio, and a strong nanowear resistance when they were deposited with a dc bias voltage of 50 V. Nanoindentation hardness was positively correlated with the Raman peak ratio Id/Ig, whereas wear depth was negatively correlated with this ratio. These nanotribological properties highly depend on the films’ nanostructures. The tribological properties of the FCVA-DLC films were also investigated using a ball-on-disk test. The average friction coefficient of DLC films deposited with dc bias voltage was lower than that of DLC films deposited with pulse bias voltage. The friction coefficient calculated from the ball-on-disk test was correlated with the nanoindentation hardness in dry conditions. However, under boundary lubrication conditions, the friction coefficient and specific wear rate had little correlation with nanoindentation hardness, and wear behavior seemed to be influenced by other factors such as adhesion strength between the film and substrate.