Abstract
During the course of an investigation of nickel-alumina composites, it was observed for a rotating cylindrical copper cathode that the alumina content of the deposit on the cathode decreases with increasing revolution rate of the cathode. Further experiments were made to study the unusual deposit behaviours more in detail. At given revolution rates (N), the deposition rate of alumina (uAl2O3) calculated from the observed values of volume percent deposited is directly proportional to the alumina content in the bath (C*). Irrespective of C*, the ratio of uAl2O3 to the product of C* and current density shows an S shaped relationship to N in the range of 200 to 1000rpm. This relation-ship is well related to the observed particle distribution in the bath by a newly proposed “detaining function” under the assumption that the maximum size of alumina caught by the rotating cathode is inversely proportional to the revolution rate. This detaining function is calculated on the basis of attractive force due to London-van der Waals potential and repulsive centrifugal force.
