The pre-oxidation process of electropolishing for the textured {113} <121> Ag substrate for Tl-1223 superconductor substrate

The surface roughness of a substrate is typically influenced by grain boundaries, grooves and voids. In an effort to improve the surface roughness, a textured {113} <121> Ag substrate was electropolished using a new method that causes the formation of an oxidation layer at the constant current density before electropolishing at a constant voltage of 1.75 V vs. SCE. The constant current density and potential were determined using the anodic polarization method. The pH effect for the optimized electropolishing condition was also investigated by adding phosphoric acid. The edges of the grain boundaries, grooves and voids became smoother when a constant current density was supplied with the pre-oxidation. A RMS (root mean square) value of 5.90-nm regarding the surface roughness of the Ag substrate was obtained without a final surface treatment before electropolishing, while a RMS surface roughness value of 34.12-nm was obtained for an Ag substrate that was given a final surface treatment for mechanical polishing.