Journal of the electrochemical society vol:153 issue:9 pages:C660-C667
To elucidate the role of the tangential interactions on the deposition of particles during electrodeposition, the orientation of prolate spheroidal particles during nickel deposition was studied on a rotating disk. Particle orientation distributions were determined at different radial positions on nickel coatings. The effects of rotation speed, current density, and electrolyte viscosity were investigated separately. The prolate spheroidal particles were observed to align due to the shear flow generated by the rotating disk. The alignment depends on the radial position on the rotating disk and on the rotation speed. The orientation angle of the particles tracks the direction of the streamlines of the flow field at the rotating disk. The critical Peclet number at which particle alignment sets in was used to calculate the tangential interaction energy between the particles and the electrode. Particle alignment is shown to be independent of the current density at which the nickel coatings are made, which indicates that the tangential interaction is dominated by the dispersion interaction. When metal was deposited using pulse plating, the ratio between the duration of the on and off pulses had almost no effect on the particle alignment. This means that the majority of particles is already oriented in the fluid flow before they contact the electrode or that particles align almost immediately after contact. (c) 2006 The Electrochemical Society.