Investigation of corrosion resistance of CrN/Zn doped-CrN bilayer coating on 304 stainless steel by thermionic vacuum arc deposition method

This study aimed to investigate the deposition of single-layer CrN and bilayer CrN/Zn-doped CrN coatings on 304 stainless steel using the thermionic vacuum arc (TVA) technique and to reveal the contribution of these coatings to the corrosion resistance of the substrate. The coating surfaces were characterized by scanning electron microscopy, energy dispersive spectrometry, and atomic force microscopy, and it was determined that there were no defects such as microparticles and pinholes on the surfaces, and high smoothness was achieved. The results of contact angle measurements revealed that the coated surfaces had higher hydrophobicity than the bare surfaces. The potentiodynamic polarization measurements in 3.5 wt% NaCl solution determined that the corrosion potential of the CrN/Zn-doped CrN bilayer coating was higher than the bare substrate, and the corrosion current was smaller. It was observed that the coating provided 69.6% corrosion protection efficiency by improving the corrosion resistance. In the neutral salt spray test, according to EN ISO 9227 standard, no corrosion was seen, although stains and color changes occurred on the coated samples. In conclusion, 304 stainless steel coated with bilayer CrN/Zn-doped CrN using the TVA technique showed improved corrosion resistance. This research demonstrates the potential of TVA as a new technique to create stainless steel materials with increased corrosion resistance and contributes to the research results in this field.