Sliding tribological behavior of AlCrN coating

The sliding tribological behavior of the PVD AlCrN coating against Si3N4 ball have been investigated by using the CETR multi-functional UMT-2 test system under two sliding conditions (bidirectional and unidirectional). Reciprocating sliding tests (bidirectional) were performed under varied normal loads (5, 10 and 20 N) at sliding velocity of 0.48 m/min. Ball-on-disc tests (unidirectional) were performed at varied sliding velocities (0.48 and 5 m/min) under normal load of 5 N. The wear scars of the coating were evaluated by surface profilometer, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and the sliding wear mechanism of the coating was consequently discussed. The results showed that AlCrN coating had excellent anti-abrasion properties. Both the normal load in reciprocating sliding test and the sliding velocity in ball-on-disc test had significant influence on the sliding tribological behavior of the AlCrN coating. The combination of abrasion and oxidation was the main sliding wear mechanism for the AlCrN coating. The wear resistant and thermally stable oxides formed by the tribo-chemical reactions of chromium and aluminum protected the AlCrN coating against wear admirably.