The Role of Mass Transfer in the Rate of Electropolishing of Conical Copper Cavities under Natural Convection

Rates of mass transfer during electropolishing of conical copper cavities were studied by measuring the limiting current of anodic dissolution of copper in phosphoric acid. Parameters studied were physical properties of the solution and dimensions of the cavity. It was found that cavity dissolution takes place through a turbulent flow mechanism. The rate of polishing was expressed in terms of the mass transfer coefficient which was related to different variables by the following dimensionless correlation: Sh = 0.686(Sc × Gr) 0.313 . A comparison was made between the present results and those obtained earlier with other cavity geometries.