Vibratory Agitation to Enhance Mass Transfer in Electrodeposition

A study has been carried out employing a vibratory motor, offering amplitudes of 0·4–4 mm at 50 Hz in acid copper sulphate as a model electrolyte in which α‐Al2O3 particles are suspended for co‐deposition, yielding a composite electrodeposit. Using a horizontal disc vibrator at the bottom of the container, perforated discs have been shown to give superior agitation and a laminar/turbulent transition has been identified. Incorporation of particles is a maximum at the transition. In the laminar regime Sh‐Re0·037 and in the turbulent regime Sh‐Re0·82. Mass transport enhancement was measured for a variety of disc and tank diameters and enhancement factors for electrodeposition of 3–40 times were obtained. In these circumstances a modified Reynolds number Re1 was employed Re1 = 100 ad2(d1−d2)/υd2 and, assuming a conventional dependence upon Sc, a full correlation of the type Sh1 = constant Re1a Sc0·33 was obtained where the constant took values of 10–40 and ‘a’ took values of 0·83–1·1 depending upon precise location within the tank of the mass transfer probe.