Effect of Al additions in WC-(Cr1?xAlx)N coatings on the corrosion resistance of coated AISI D2 steel in a deaerated 3.5 wt.% NaCl solution

Multilayered WC-(Cr1−xAlx)N coatings were deposited on AISI D2 steel using cathodic arc ion plating (CAIP) process. Five kinds of WC-(Cr1−xAlx)N coatings were prepared: WC-Cr0.6Al0.4N, WC-Cr0.57Al0.43N, WC-Cr0.53Al0.47N, WC-Cr0.48Al0.52N and WC-Cr0.45Al0.55N. The Al concentration could be controlled by using evaporation source for Al targets and fixing the evaporation rate of the other metals (WC alloy and Cr). In this study, the corrosion behavior in deaerated 3.5 wt.% NaCl solution was investigated by electrochemical corrosion tests (potentiodynamic polarization test, galvanic corrosion test, electrochemical impedance spectroscopy (EIS)) and surface analyses (glow discharge optical emission spectroscopy, X-ray diffractometry, scratch adhesion test, scanning electron microscopy, electron probe micro-analyzer).