| 摘要 |
PURPOSE:To provide hardness to the required part alone by performing local heating and blowing of gaseous nitrogen for a blank material simultaneously by means of plasma jets. CONSTITUTION:Mixed gases of nitrogen and argon are flowed from an operating gas passage 4 and gaseous nitrogen is flowed from a shielding gas passage 6 by using, for example, a plasma torch 1, to form an inert atmosphere, by which a blank material 7 is shut off from the atmosphere. Next, electric current is flowed between a tungsten electrode 2 and the nozzle 3, to generate plasma jets 8. The blank material 7 is heated by this, and at the same time, ionized nitrogen is ejected by the jets 8, whereby hardening reaction is accelerated. At this time, the jets 8 are maintained stably by keeping the nitrogen mixing rate of the operating gas 4 at <=30%. The flow rate of the operating gas is kept about <=10l/mm. in order to prevent the surface roughness of the blank material after the treatment from degrading. |
