Electrodeposition of Laminar Metal Structures

As already stated above, multilayered laminar metal structures could be obtained by electrodeposition of individual metal layers from separate baths or from one bath containing ions of both metals. Only the second case is of interest for this chapter and such conditions will be discussed [1,5]. 

2 Formation of Laminar Deposits by Pulsating Current Regimes 

In the application of pulsating regimes [57-59], three types of pulses, schematically presented in Fig. 7.34, were used. 

The first attempt in theoretical treatment of the variation of the composition of the electrodeposit obtained by pulsating current from a bath containing two different metal ions, using complicated mathematical procedure, was presented in 1985 [60]. The quantitative theory of laminar metal electrodeposition based on fundamental concepts of electrode kinetics, using much simpler mathematical approach, was presented in a series of papers of Despic and co-workers [61-63]. 

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. 

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Fig. 7.34 Schematic presentation of pulsating regimes used for electrodeposition of laminar metal structures (Reprinted from Ref. [5] with kind permission from Springer)...

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