PURPOSE: To make it possible to obtain a stubborn holding structure to a cathode chip by sintering integrally a cathode chip of a hexaboride and a holder piece of a high melting point metal with a paste including a colloidal carbon and a high melting point metal powder.
CONSTITUTION: This cathode is made to reform to hold a cathode chip 4 of a hexaboride at the center of a tungsten wire 3, and the hexaboride is a hexaboride of an alkaline earth metal or a rare earth metal, whose tip is processed into a sharp conic form to make a minute cathode chip 4. A holder piece 5 is made of a high melting point metal to hold the base of the cathode chip 4 solidly in a high temperature, used by forming into U-shape with bending parts along the opposing sides surfaces of the cathode chip 4. To sinter the cathode chip 4 and the holder piece 5 integrally, a paste including a colloidal carbon and a high melting point metal powder is used. In such a way, a stubborn holding of the cathode chip 4 is made possible, and the service life can be extended.
Ishii, Masaji
Miyai, Akira
Hagiwara, Hirotoshi
