Intensification of the rate of electropolishing and diffusion controlled electrochemical machining by workpiece oscillation

• Effect of electrode oscillation on the rate anodic processes was studied.
• Parameters studied were frequency, amplitude of oscillation and physical properties.
• Electrode oscillation enhanced the process by a factor up to a maximum of 7.17.
• The rate of mass transfer was related to the rate of energy dissipation.
• The mass transfer coefficient of the oscillating cylinder was correlated by all the parameters.

The effect of electrode oscillation on the rate of diffusion-controlled anodic processes such as electropolishing and electrochemical machining was studied by measuring the limiting current of the anodic dissolution of a vertical copper cylinder in phosphoric acid. Parameters studied were frequency and amplitude of oscillation, and phosphoric acid concentration. Within the present range of conditions, electrode oscillation was found to enhance the rate of anodic dissolution up to a maximum of 7.17 depending on the operating conditions. The mass transfer coefficient of the dissolution of the oscillating vertical copper cylinder in H3PO4 was correlated to other parameters by the equation: Sh=0.316Sc0.33Rev0.64.The importance of the present study for increasing the rate of production in electropolishing and electrochemical machining, and other electrometallurgical processes limited by anode passivity due to salt formation such as electrorefining of metals was highlighted.