| 摘要 |
PURPOSE:To make it possible to take out a higher current than before by applying an alkaline earth metal oxide containing zirconium carbide as the first layer to a substrate metal mainly composed of nickel while applying thereto the alkaline earth metal oxide containing one or plural kinds of nickel powder or the like as the second layer. CONSTITUTION:In a cathode formed by coating a substrate metal mainly composed of nickel with an electron discharge material layer consisting of an alkaline earth metal oxide containing barium, the alkaline earth metal oxide containing 0.1-2wt% of zirconium carbide is applied in adjacent to the substrate metal as the first layer. Then thereto, the alkaline earth metal oxide containing 0.1-2wt% of one or plural kinds of alloy powder consisting of nickel powder, or cobalt powder or nickel and cobalt are applied. When the amount of zirconium carbide to be added to the alkaline earth metal oxide is smaller than 0.1%, the reduction of the alkaline earth metal oxide is not sufficient while improving no electron discharge. When exceeding 2%, the reduction leads too far thus generating surplus Ba and being evaporated and shortening life. |
