Enhanced tribological behavior and corrosion resistance in AlSiC-based coatings through varied carbon content

Abstract

A series of AlSiC-based nanocomposite coatings with varying carbon concentrations were fabricated by filtered cathodic vacuum arc (FCVA) technology. These coatings featured an amorphous matrix with embedded Al4Si3C6 nanocrystals. With the increase in carbon content, the proportion of amorphous structure within the structure grew, which was accompanied by a rise in sp3 hybridized carbon bonds. This compositional change led to a significant enhancement in hardness and toughness. Notably, the AlSiC coating deposited at a flow rate of 50 sccm displayed exceptional mechanical properties, including a high hardness of approximately 23.2 GPa, toughness indices of H/E = 0.096 and H3/E2 = 0.216 GPa, a low friction coefficient around 0.18, a wear rate as low as ∼1.09 × 10−5 mm3 N−1 m−1, and a corrosion current density of approximately 1.08 × 10−9 A/cm2. The coating's superior tribological characteristics and corrosion resistance can be attributed to two main factors. The enhanced hardness and toughness indices (H/E and H3/E2) contributed to its improved deformability, which is essential for wear resistance. Secondly, the presence of a graphite layer formed during friction provided self-lubrication, further reducing wear. Additionally, the chemical inertness of both the amorphous SiC and the amorphous carbon phases within the nanocomposite structure significantly bolstered the coating's resistance to corrosion. The AlSiC nanocomposite coatings deposited by FCVA exhibit outstanding mechanical properties, tribological performance, and corrosion resistance, making them highly suitable for applications in environments where wear and corrosion are significant concerns.