Tribological and Corrosion Performance of CrAlN/CrN Coatings in Artificial Seawater under Varied Nitrogen Pressures

This study employed arc ion plating technology to deposit CrAlN/CrN coatings on stainless steel substrates, adjusting deposition pressures ranging from 1.0 Pa to 4.0 Pa. A detailed analysis of the coatings’ microstructure, wear, and corrosion features was performed using X-ray diffraction, scanning electron microscopy, nanoindentation, tribometers, profilometers, and electrochemical workstations. The study revealed that the crystalline structure of the CrAlN/CrN coatings primarily consists of cubic crystals of AlN, (Cr, Al)N, and CrN. Diffraction peak intensity analysis revealed preferential orientation in the CrAlN coatings along the (111) and (200) crystal planes. As the pressure increased to 3.0 Pa, the content of Al elements peaked, and the columnar structure became denser; at this point, the H/E* ratio reached a maximum of 0.079, indicating excellent delamination and fracture resistance of the CrAlN/CrN coating at this pressure. Tests in artificial seawater environments showed that with the increase in nitrogen pressure, the friction coefficient gradually decreased, reaching its lowest at 3 Pa, approximately 0.19. The wear rate trend aligned with the friction coefficient, recorded at a mere 2.20 × 10−7 mm3/Nm. Electrochemical polarization curve tests revealed that at 3 Pa pressure, the CrAlN/CrN coating had a corrosion potential of −0.04 V, a polarization resistance of 9.28 × 105 Ω·cm2, and a very low corrosion current of 4.81 × 10−8 A/cm2, demonstrating excellent corrosion resistance.