Koichi Takeda and Sunao Takeuchi
Advanced Technology Research Laboratories, Nippon Steel Corporation, Kawasaki 211-0035
The interesting properties of cathode spots were investigated in the removal of an oxide layer on metal substrate by a vacuum arc. The cathode spots attack the oxides selectively and remove them by evaporation. The observed removal rate of the oxide layer increases in proportion to the arc current and in inverse proportion to the thickness of the oxide layer. Considering the energy balance at the cathode spot, the authors have developed a simplified model to predict the removal rate. The theoretical results agree with the experimental ones qualitatively. The modeling reveals that there exists a critical current density below which the removal of oxides does not occur. The current density of the cathode spots produced in vacuum exceeds the critical value.
(Received July 21, 1998; In Final Form October 6, 1998)
vacuum arc, cathode spot, oxide layer, descaling, surface cleaning
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