2021 Volume 70 Issue 5 Pages 145-149
The electropolishing behavior of Nb in a 30 wt％ sulfuric acid solution was investigated by controlling the potential of Nb using a three-electrode cell. The Electropolishing was performed with various combinations of cathodic pulse potential （Ec） and anodic one （Ea）. Almost completely mirrored surface was obtained after 120 minutes under the condition of Ec＝－3.0 V and Ea＝＋10 V with both pulse periods of 2.0 ms. The mirrored surface was also obtained within 60 minutes by shortening anodic pulse time （ta） to 1.0 ms at Ec＝－3.0 V and Ea＝＋10 V. This is due to the fact that anodic current decays so quickly at Ea＝＋10 V that anodic pulse time can be shortened to 0.25 ms with no change in anodic charge in one pulse. Thus the total number of cycles in a given time can be increased by shortening ta, which leads to faster electropolising rate: 0.92μm min－1 at ta＝2.0 ms and 1.52μm min－1 at ta＝0.25 ms.
