Study of Mechanical Grinding Effects on Niobium Surface

Study of Mechanical Effects on Niobium Surface*Mechanical grinding is commonly employed to eliminate surface defects such as scratches and pits from niobium cavity surfaces or sheets before cavity fabrication.Subsequently, chemically buffered polishing or electropolishing is often utilized to completely remove residues of the polishing media and any defects induced by mechanical grinding, ensuring a pristine surface.In this study, we conducted a systematic investigation to assess the influence of mechanical grinding using silicon carbide (SiC) and aluminium oxide (Al 2 O 3 ) polishing media on niobium surfaces.Additionally, the study examines the effects of post-mechanical grinding chemical treatments on surface quality.Nb samples were ground with SiC and Al 2 O 3 media.Coarse grit sizes inflict substantial surface damage, while finer grits embed more abrasives into the surface, a problem particularly pronounced with SiC.Although EP effectively removed these embedded abrasives, it creates pits.Al 2 O 3 proved to be a better polishing media, as it resulted in fewer embedded abrasives (fewer pits) on the niobium surface.The study suggests to used a finer grit, preferably better than grit size of 400, to finish an Nb surface to achieve a defect-free surface with comparatively lower material removal in EP.