| 摘要 |
PROBLEM TO BE SOLVED: To delay the erosion rate at the tip in the transferable anodes for plasma heating, and to elongate the service lives thereof. SOLUTION: In a shift type plasma torch in which the d.c. electric current is supplied to molten metal in a vessel, and the molten metal is heated while generating Ar plasma, the anodes consisting of electrically conductive metal with internal water cooling structure, metallic protective bodies with internal water cooling structure at fixed intervals on the outsides of the anodes, and a gas feeding means for feeding Ar-containing gas to the gaps between the anodes and the protective bodies is provided. The material of the tips of the anodes consists of a sintered compact of tungsten and copper containing >=70 wt.% tungsten, and the radius R [mm] and thickness D [mm] of the tip of the anode satisfies the inequality (1): 0.08<D/R<0.22 (1). |
