Wear and corrosion resistance of diamond-like carbon coatings deposited by filtered cathodic vacuum arc coupled with a high-voltage pulse power

Utilization of high-voltage pulse power aimed to supply high negative bias and short pulse duration prepares high-performance coatings with low stress by alternating ion bombardment and deposition on the substrate. In this work, hydrogen-free diamond-like carbon (DLC) coatings were deposited on Si (100) and AISI 304 L stainless steel substrates at a pulse frequency of 10-50 Hz by filtered cathodic vacuum arc coupled with a high-voltage pulse power. The structure, chemical bonding state, mechanical properties and wear and corrosion resistance were evaluated using atomic force microscope, Raman, x-ray photoelectron spectroscopy, nanoindentation, ball-on-disk tester and electrochemical impedance spectroscopy (EIS). The increase in pulse frequency from 10 to 50 Hz led to a decrease in sp3 fraction from 58% to 35%, together with a sharp decrease in compressive stress from 3.89 to 0.67 GPa. The highest hardness (H) and Young's modulus (E) were 42 and 387 GPa, respectively, at pulse frequency of 10 Hz. However, at 50 Hz, the coatings with lowest H/E* (E*, effective Young's modulus) and H3/E*2 ratios of 0.091 and 0.23 exhibited the lowest coefficient of friction of 0.091 and wear rate of 4.85 × 10−8 mm3 N−1 m−1 due to the formation of the sp2-carbon rich transfer layers on mating surfaces. Wear mechanism changed from abrasive wear at 10 and 30 Hz to solid lubrication at 50 Hz. The EIS results showed that polarization resistance of the coatings changed from 13.4 to 5.32 M cm2 with increasing pulse frequency from 10 to 50 Hz.