Corrosion characteristic of pulsed electrodeposition nanocrystalline Ni-Co alloy coating

The microstructures, the surface morphology and the composition of nanocrystalline Ni and nanocrystalline Ni-Co alloy prepared by pulse electrodeposition have been studied by XRD, SEM and EDS. The corrosion behaviors of nanocrystalline nickel and Ni-Co alloys in the solutions containing 305% (mass fraction) NaCl and 5% (mass fraction) were investigated by soak method and electrochemical polarization method respectively. The experimental results indicate that typical nanocrystalline nickel and Ni-Co alloy coatings can be synthesized by pulse electrodeposition, and the alloying element Co had an effect of solution strengthening and grain size refinement. The nanocrystalline Ni-Co alloy is dense in nature and it exhibited better corrosion resistance in 3.5% (mass fraction) NaCl solution and 5% (mass fraction) HCl solution than the nanocrystalline nickel. The surface morphology of all samples after corrosion in 3.5% (mass fraction) NaCl solution show good corrosion resistance, however, the samples were uniformly corroded in 5% (mass fraction) HCl solution. © 2009, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.