Corrosion of Nanocrystalline Ni-W Coated Copper

Abstract

The present study is dealing with the corrosion of copper coated with nanocrystalline nickeltungsten coating. Different plating bath compositions and conditions were used in order to produce nickel-tungsten coatings of different tungsten content 30%, 40% and 50% wt, with a thickness of 20 μm. The corrosion resistance of nickel-tungsten alloy coated copper was examined by a potentiodynamic polarisation technique in NaCl solution (0.03 M, 0.3 M and 1 M) as a function of pH (3, 7, 10) and temperature (7˚C, 30˚C, 40˚C) of the solution. It has been found that the pH value did not seem to affect the corrosion behaviour of the coated specimen remarkably, while the increase of solution temperature increased the corrosion rate of the coated copper specimen. It was finally confirmed that the corrosion products mainly consisted of tungsten and nickel oxides.

Electrodeposition of multilayer Ni–W and Ni–W–alumina nanocomposite coatings

“…Since the corrosion behaviour of nanocrystalline Ni–W films is a correlation among grain size, tungsten content, and surface film formation 48 , with increasing tungsten content and consequently decreasing grain size, the anodic corrosion behaviour alters. On the other hand, the sudden increase in anodic curve was reported elsewhere 25,48,55,56 and it is also mentioned that this sudden increase diminishes by raising the W content in the coating structure up to about 22at.-%. 48 However, the exact reason for this manner is not clear, this behaviour may be due to the transformation and/or variation in crystal defects of oxide films produced at anodic potentials over the working electrode.…”