Structure and tribological performances of CrAlSiN coatings with different Si percentages in seawater

Nanocomposite CrAlSiN coatings with different Si percentages were deposited using a multi-arc ion plating technique. The coating microstructures were characterized by SEM, XRD, XPS and TEM. The mechanical properties and tribological performances were measured. The results demonstrated that the microstructure of the CrAlSiN coatings was composed of (Cr, Al) N crystallites and an amorphous Si3N4 phase. With increasing Si content, the thickness of the as-deposited coating increased gradually, and the hardness, toughness and adhesion force first increased and then decreased. The CrAlSiN coating containing 5.5 at.% Si exhibited the optimal tribological properties in seawater. The significant improvement in the tribological performances is closely related to the formation of self-lubricating SiO2 and the enhancement of comprehensive properties.