Evaluating the corrosion behaviour of multilayer coatings in seawater conditions
Thursday, 12 November 2015
Cr/Cr2N nano-multilayer coatings with varied individual thickness of Cr2N layer were fabricated on 316L stainless steel substrates by multi-arc ion plating system.
The evolutions of microstructures and mechanical properties were investigated by scanning electron microscopy, X-ray diffraction, nanoindentation and scratch testing. The corrosion behaviors and tribological properties in seawater conditions were evaluated using polarisation resistance and reciprocating-sliding friction tests, respectively.
Corrosion behaviour depended on porosity
Results showed that the multilayer coatings with thicker individual Cr2N layer presented higher hardness at the expense of toughness, and the coating with thickness ratio of Cr and Cr2N layers at 0.45 possessed both high hardness and toughness. The dominant feature influencing the corrosion resistance of deposited multilayer coating was the porosity and interface effect. While the excellent tribological performances of coatings with high load bearing capacity were attributed to the optimisation of thickness ratio presenting high mechanical properties. Furthermore, the tribolayer formed during wear process, which small debris particles of chromium nitride embedded into the lubricative matrix and well adhered in the wear track, played a significant role in the anti-wear property. The superior anti-corrosion and anti-wear performances of nano-multilayer coatings made them good candidate protective materials in engineering applications in seawater environments.
The study is published in: Surface and Coatings Technology, Volume 282, 25 November 2015, Pages 78–85