Structural optimisation and electrochemical behaviour of AlCrN coatings

• Published in: Thin solid films 2016-08, Vol.612, p.400-406
• Main Authors: Chen, Mohan, Wu, Dongqing, Chen, Wanglin, Zhang, Shihong
• Format: Article
• Language: English
• Subjects: AlCrN coatings; Corrosion resistance; Multi-arc ion plating; Vacuum annealing
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2016.06.032

AlCrN coatings were deposited on 316L stainless steel by multi-arc ion plating. The phase structures were controlled and optimised by vacuum annealing at 700°C, 800°C, and 900°C, each for 2h. The microstructures and morphologies of these coatings were examined by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscope, in association with adhesion strength measurement, residual stress measurement and potentiodynamic polarisation with 3.5% NaCl and 10% H2SO4 solutions. Results show that the solid solution hcp-(Cr, Al)N phase of as-deposited AlCrN coatings decomposes into hcp-AlN and CrN phases, then further decompose into N and Cr with increasing annealing temperature. Metal particles and droplets on the coating surface were gradually removed simultaneously when compared with as-deposited coatings. The highest adhesion strength was obtained after annealing at 700°C. It decreased with increasing annealing temperature due to the σ-FeCr phase and Cr2N phases, and the residual stress decreasing. The potentiodynamic polarisation measurements showed that the corrosion resistance of such coatings was significantly improved after annealing: the coatings annealed at 800°C showed the best protective efficiency because some corrosion resistance phases (h-AlN, Al2O3, CrN, and Cr2N) were generated. •AlCrN coatings deposited on 316L stainless steel by multi-arc ion plating•Structural optimisation by vacuum annealing to improve corrosion resistance•Excellently protective efficiency to stainless steel in both acid and seawater environments