Pulse reverse current electrodeposition

Abstract Electrodeposition is a weU-known conventional surface modification method to improve the surface characteristics, decorative and functional, of a wide variety of materials. Now, electrodeposition is emerging as an accepted versatile technique for the preparation of nanomaterials. Work done in this direction is discussed in this chapter. The basics of electrodeposition are introduced, then the electrodeposition of nanomaterials using special techniques for reducing grain size. Methods such as pulse and pulse reverse current deposition, template-assisted deposition and use of additives and grain refiners are explained with suitable examples. Deposition of nanostructured metals, alloys, metal matrix composites, multilayers and biocompatible materials reported in the literature are discussed. Finally, there is a discussion of the improved corrosion resistance of electrodeposited nanostructured materials, quoting results reported in Uterature. 

Electrodeposition using pulsed currents is known as pulse plating. The pulsed currents can be unipolar (on-off) or bipolar (current reversal). Pulses can be used along or be superimposed on a DC feed. By using the bipolar pulse, metal deposition occurs in the cathodic pulse period, with a limited amount of metal being... 

For the electrodeposition of laminar metal coatings, two conditions must be fulfilled (1) The reversible potentials for metals A and B must be sufficiently different so that at a given current density, the less noble one (B) virtually does not electrodeposit during the electrodeposition of the more noble one (A) until complete concentration polarization with respect to ions of metal A takes place (2) within the duration of the current density pulse, Send s equation [15] for diffusional polarization is obeyed with respect to concentration change, resulting in transition from electrodeposition of metal A to electrodeposition of metal B after well-defined transition time. 

---