Surface modification by cathode spots of a vacuum arc

Cathode spots of a vacuum arc have the efficient property to remove oxide on the metal surface selectively. Analyses of the surface treated by vacuum arc revealed that various interesting surface modifications occurred during the removal of oxide. We have investigated these effects to open new applications of the vacuum arc. The cathode spots can remove inclusions, which often cause surface defects. They attack not only oxide but also carbide inclusions and eliminate them from the surface by evaporation. Removal of organic compounds is also possible. Degreasing (removal of grease) proceeds in parallel to the removal of oxide. The vacuum arc treatment results in the remarkable increase of hardness in the surface layer due to the rapid heating and quenching.