Electrochemical Polishing Process Conditions For NiW Alloy Substrates In Superconductivity Materials

The electrochemical polishing technology has been receive muchattention duo to its simple, high efficient, easy to control, good quality and wideapplications in polishing process compared to machinery polishing and chemistrypolishing processes. The polishing process in superconductivity coating conductor is akey step. The goal of this thesis is to develop a new electrochemical polishing process toapply to NiW alloy substrate surface in superconductivity (YBCO) coating conductor.This thesis includes a review section and a research section. In the review, generalintroduction to the electrochemical polishing including basic principle, polishingprocess, elementary theory, influence factor, merit and metal surface roughness werepresented. The current progress in electrochemical polishing technology was reviewedand the purpose of this work was described.The research section contains two parts. In the first part, the anodic polarizedbehaviors of NiW alloy was studied in different electrochemical polishing solutionsincluding concentrated sulfuric acid, phosphoric acid, lactic acid and dimethylglyoximeas the chemical additive. The conditions including the distance between anode andcathode, the area ratio of anode and cathode and initial composition of polishingsolutions were preliminary optimized. The result showed that a good quality wasobtained using a distance between anode and cathode of 1cm, the area ratio of anodeand cathode of 1:8 and the working potential of 0.8 V(vs, Hg/Hg₂SO₄). The polishingtemperature was examined.In the second part, based on designation factor and the level, the electrochemicalpolishing experiment was carried out according to the orthogonal experiment L₉(3⁴).The precise polishing quality was characterizied by atomic force microscopy. Theoptimum condition for this electrochemical polishing process was following (1) thedistance between anode and cathode of 1cm; (2) the area ratio of anode and cathode of1:8; (3) polishing solution formula: volume ration of concentrated phosphoric acid+concentrated sulfuric acid+lactic acid=4:8:3 and 15% (W/W) dimethylglyoxime; (4)working voltage of 1.4 V and polishing temperature of 60℃.This work provides some basic research material for the development of the new superconductivity material NiW alloy substrate surface electrochemical polishingmethod and the new polishing solution.