抄録
A theoretical equation of the temperature difference (Δt) between electrolyte and electrode surface was derived as follows from the heat transfer theory and Joule's heat caused by electrolytic current and overvoltage:
Δt=K(iη)0.8
and K=(0.18ν1/4a1/4l1/4/λg1/4β1/4)0.8, where i: current density, η: overvoltage, ν: kinematic viscosity, a: thermal diffusivity, λ: thermal conductivity, g: gravimatric acceleration, β: coefficient of cubical expansion, l: length of specimen, the results of experiments were as follows: (1) The theoretical temperature differences calculated by the above equation fairly agreed with the data obtained in the electroplating experiments: however, when gas evolution occurred on the electrode, the experimental data were lower than the theoretical values owing to the agitation effects of the gas. (2) In the electropolishing experiments, the measured temperature differences were always higher than the theoretical values. The reason for this fact would be due to the changes in physical properties of electrolyte near the electrode surface; especially, changes in viscosity and specific gravity by addition of dissolved metal ions. (3) In case of anodizing of aluminum, the following equation of temperature rise was obtained considering the heat of formation of aluminum oxide.
ΔtA1=K{i(η+2.7)}0.8, the temperature differences calculated by the above equation was in good agreement with the experimental data.
