Mechanical properties and abrasive wear behaviour of Al-based PVD amorphous/nanostructured coatings

This study examines the mechanical properties and wear characteristics of aluminium-based nanostructured coatings produced by magnetron sputtering in an argon/nitrogen plasma. Compositional analysis of AlNiTiSiB(N) coatings was carried out by glow discharge optical emission spectroscopy (GDOES). Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the structure of the coatings; hardnesses and elastic moduli were also determined by nanoindentation. The abrasive wear behaviour of the coating-substrate system was studied using a slurry micro-abrasion wear test. Nitrogen-free (AlNiTiSiB) coatings were found to be surprisingly hard and wear resistant; however, nitrogen incorporation had a significant influence on mechanical properties and abrasion resistance, with increased hardness (from 8 to 15 GPa) and a significant reduction in wear coefficient - from 6 × 10− 3 mm3/Nm for a nitrogen-free coating (0B), to approximately 1.5 × 10− 3 mm3/Nm, for a coating deposited at 15 sccm nitrogen gas flow rate (15T) - being observed among the various AlNiTiSiB(N) coatings investigated. Several of the coatings were found to be comparable to convention ceramic PVD hard coatings (e.g. CrN) in terms of resistance to abrasion.