Rotating Hull cell

Several authors have investigated the mechanism of the deposition of these alloys. Podlaha and Landolt suggested a model of catalytic electrodeposition. The main observations of these authors concern the dependence of composition on the concentration ratio, rotation speed, and current density. A rotating Hull cell was used for the experiments, which has already been described in Chapter 5, Figure 5.27. 

A very simple method to rotate an electrode is the rotation of an electrode rod or of an electrode cylinder. The calculation of the thickness of the diffusion layer is complicated but, in a first approximation, is proportional to an exponential dependence on rotation speed. An application of this method is the cell developed by Landolt for testing plating electrolytes. The standard equipment for such tests is the Hull cell (Figure 5.26). ... 

The Landolt cell (Figure 5.27) provides controlled convection conditions by the rotating cylinder electrode. A cylindrical shield surrounds a rotating cylinder, preventing direct current flux between rotating cylinder and counter electrode. The enforced longer way of the current lines simulates the variation of current density in a conventional Hull cell. 

Figure 11. Illustration of two alternative designs for the rotating cylinder Hull (RCH) cell, which allows the study of non-uniform current distribution on the cathode, under controlled mass-transport conditions. A anode, C cathode, IC insulating cylinder. Reproduced from Ref. 150 with kind permission of Springer Science and Business Media, and with permission from Ref. 95, Copyright (1996) The Electrochemical Society.

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