Effect of pressure on the behavior of cathode spots in oxide removal by arc discharge

Abstract

The effects of pressure on the cleaning action of the cathode spots were investigated in a wide pressure range from 10 to 20 000 Pa of inert atmosphere. Experiments were carried out by using hot rolled steel plates, the surfaces of which were covered with thick oxide of 5-10 μm. Experimental observation revealed the following results: (1) The cleaning action by cathode spots is confirmed even under a pressure as high as 20 000 Pa. (2) The number of cathode spots on the oxide surface increased with the increase of pressure in the range of 10-20 000 Pa. (3) The removal rate of oxide decreased with the increase of pressure. (4) The energy density of the cathode spot decreases with the increase of pressure. (5) The higher the pressure increases, the smaller area the migration of the cathode spot was restricted to. The migration area decreased with the increase of pressure. © 2006 ISIJ.