Abstract
The Vacuum arc can remove the oxide layer and evaporate impurities on the metal surface. The removal by vacuum arc is expected to solve the problems of the current chemical and mechanical cleaning. In this paper, the removal of the oxide layer covering the circular hole on the stainless steel surface by using the vacuum arc was carried out by changing its diameter and depth. As the result, the oxide layer can be almost perfectly removed by using the vacuum arc. However it is difficult to remove the oxide layer on the inside of the fine and deep hole, even if the removal time and the arc current are increased. The removal time for the hole is longer than that for the plane without holes. The removal is done in turn of the surface area → the side of the hole → the bottom of the hole. The removal time is little influenced by the placement of the circular holes. But a removal is completed from the circular hole with the lower aspect ratio. A removal limit exists in the circular hole of the highest aspect ratio 1.67∼2.0. In this case, the surface metal is selected more preferentially than the oxide layer inside the hole. When the cathode spots inside the hole reach the critical aspect ratio, the cathode spots work well for “the re-removal” on the metal surface.
