Electropolishing of niobium coatings on spherical shape samples

Selection of electropolishing parameters on rolled niobium samples (10 × 20 mm) in the mixed solution H₂SO₄ – HF was performed. The range of potentials and the duration of electropolishing were chosen. A special anode construction for the electropolishing of spherical shape samples from carbopyroceram coated niobium was used. Due to the small niobium coating thickness on the rotor, electropolishing was carried out in several stages. The duration of each stage was 2 minutes and totally five electropolishings were performed. It was found that the electropolishing of spherical shape samples should be carried out at a potential of 6.0 V relatively to the cathode from glassy carbon. (paper)