Abstract
Recently, AC arc plasma heating has been used for melting treatment of flyash and similar dusts and for temperature control of molten steel in a tundish of continuous casting process. But, in using AC arc plasma heating, there are some problems that the electrode erosion in plasma torch is severe and arc plasma is apt to be unstable at current zero.
This time, in order to catch hold of the electrode erosion and reduce it, the effects of electrode stem size and tip shape on the electrode erosion were clarified at a low current of 200 A by using an experimental plasma torch. The electrode was solid type and its material was Lanthanum-oxide-tungsten. The electrode tip was in touch with arc plasma and the electrode root was cooled with water. Main results are as folows. As the electrode was thickened radially and shortened axially and the electrode tip flat area was increased, the electrode erosion rate was decreased to 1ng/C of a commercial level. Then calculation of the temperature distribution along the electrode axis was carried out. As a result, there was a high correlation between the calculated temperature of the electrode tip and the measured electrode erosion rate. That is, as the tip temperature was decreased to 2, 700K, the electrode erosion rate was decreased to 1ng/C.
