Mass transfer at rotating cone electrodes

Upright and inverted rotating cone electrodes (apex half angle 52°) have been studied using electrodeposition of copper from an acid electrolyte (Sc=1770) by means of limiting current mass transport techniques. The behaviour suggests that it is appropriate to regard these electrodes as modified disc electrodes. The upright rotating cone electrode exhibits a flow transition atRe=1×10⁵. In laminar flowSh=4.5Re ^0.48 and in turbulent flowSh=0.04Re ^0.95. The inverted rotating cone electrode exhibits a flow transition atRe=6×10⁴. In laminar flowSh=4.5Re ^0.45 and in turbulent flowSh=0.04Re ^0.88. The data have been interpreted in terms of a coating thickness affected by throwing power effects and the use of a conical cathode cell for control of high speed electrodeposition processes is indicated.Nomenclature A electrode area (cm²) - C _b concentration (of bulk solution) (mol cm^–3) - c concentration difference (mol cm^–3) - D diffusion coefficient (cm² s^–1) - f/2 friction factor - F Faraday's constant (96485 A s mol^–1) - i _L limiting current density (A cm^–2) - J mass transfer flux (mol s^–1 cm^–2) - K _L mass transfer coefficient (cm s^–1) - l slant height of the cone (cm) - U peripheral velocity (cm s^–1) - x local condition coordinate (cm) - z no. of electrons - apex half-angle of cone - angular velocity (rad s^–1) - wall shear stress (dyn cm^–2) - kinematic viscosity (cm² s^–1) - Re Reynolds number=Ud/v - Sc Schmidt number=v/D - Sh Sherwood number=K _L d/D