Tribocorrosion Behaviors of CrAlN Coating in Seawater

The CrAlN coating was deposited on the 316 stainless steel by multi-arc ion plating. The composition and structure of coating was characterized by X-ray diffraction and scanning electron microscopy. The hardness and adhesion of the CrAlN coating was measured by using the nanoindentation device and the scratch tester. The tribocorrosion behavior of CrAlN was investigated in seawater environment. Tests were carried out in a triboelectrochemical cell using a ball-on-disk tribometer integrated with a potentistat for electrochemical control. It is found that the polarization curve of anodic area existed obvious passivated zone, which restrained further corrosion of coating during the sliding contact. The coefficient of friction decreased significantly at the anodic potential. Due to the synergism of the corrosion-wear, the wear-loss increased as the applied potential increased from –1 V to 0.5 V, synchronously. The total CrAlN coating loss at the anodic potential of 0.5 V (SCE) can be as large as 2.99 times of that at the cathodic potential of –1 V (SCE). Under the potential of 0 V, the wear-accelerated corrosion was generated, which accounted for about 13.71% of the total loss volume. At the potential (–1 V, –0.5 V, –0.25 V, OCP,0 V), the dominant wear mechanism was abrasive wear and plastic deformation while the fatigue pitting at the anodic potential (0.25 V, 0.5 V).