| 摘要 |
PURPOSE:To prevent a reducer on the surface of a base metal from being oxidized and thereby aim at a distinct improvement in emission characteristics, by pressing the base metal into a cathode sleeve at press-fit strength, and making the metal stick fast to the sleeve after heat-treating it in an oxygen ambience. CONSTITUTION:A base metal plate inclusive of a reducer is pressed into a disk form. In this case, to improve a state of press-fitting between the base metal and a cathode sleeve, a clearance between press metal molds is adjusted and a broken-out section of the base metal is held down to below 1/4 in thickness of its own. Next, the said base metal is pressed in the inner part of the cathode sleeve made of W-Ni or the like at a press-fit strength of 0.5kg/cm<2> or less. Successively, the cathode sleeve that has taken the base metal inside is heat- treated at a temperature of 800-1,100 deg.C in an oxygen ambience where a dew point is -60 deg.C and then both are stuck tightly. With this, not only emission characteristics can be well improved but also a cathode structure can be desiredly made up in a short time. |
