Sliding tribological behaviors of PVD CrN and AlCrN coatings against Si3N4 ceramic and pure titanium

CrN and high aluminum-content AlCrN (Al:Cr = 70:30) coatings were deposited by the multi-arc ion plating technique. Reciprocating sliding tribological behaviors of the CrN and AlCrN coatings against Si3N4 ceramic and pure titanium (TA2) balls were comparatively investigated. The wear scars of the coatings were evaluated by surface profilometer, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), and the wear mechanisms of the coatings were consequently discussed in detail. The results showed that the AlCrN coating showed significant improvement in wear debris removal efficiency and load-carrying capacity as compared to the CrN coating when sliding against Si3N4 ball. The CrN coating exhibited higher wear resistance than the AlCrN coating under normal wear conditions. However, the CrN coating suffered severe concentrated wear under high normal load conditions, which was characterized by a combination wear mechanisms of delamination, abrasive and oxidative wear. The CrN coating presented significantly better performance in anti-adhesion to titanium than the AlCrN coating when sliding against pure titanium ball. The AlCrN coating was unsuitable for the tribological applications related to titanium counterparts.