| 摘要 |
PURPOSE:To reduce dispersion of the electron emitting characteristic between different cathodes by producing a composite carbonate of scandium and alkali earth metal by coprecipitation method, and by covering the base metal of cathode with a layer of this composite carbonate. CONSTITUTION:5wt.% scandium nitrate is added to the total amount of barium nitrate, strontium nitrate, and calcium nitrate, and the mixture is dissolved in hot distilled water. This is mixed with another aqueous solution obtained by dissolving sodium carbonate in hot distilled water under agitation, and four- element carbonates are deposited, followed by dehydration and drying to yield powder of carbonate. Binder is added to this powder of four-element carbonate, followed by rolling, and a suspension is prepared and coated on base metal 1 by spray method. The cathode obtained is fitted to an electron tube, followed by encapsulation, and current is supplied to a heater 3 by vacuum exhaust process to heat the layer of coating. Thus pyrolysis is made from carbonate to oxides, and heat is applied to 900-1100 deg.C, followed by activating process, to accomplish a cathode to serve practical use. |
