| 摘要 |
PURPOSE: To manufacture a top layer having uniform constituent distribution by compressing and cohering together tungsten power with a first pressure which does not destroy the tungsten powder too extensively, followed by coating with a top layer of Sc2 O3 powder, and compressing the whole assembly with a second, high pressure to destroy the powder to a substantial degree. CONSTITUTION: A cavity in a holder 2 of a press 1 is filled with tungsten powder 9 and shaken several times to have the space between two dies to promote homogeneity filled and adhesion of the powder or pressed formed body. Next, a force F is applied to the die 3 to compress the tungsten powder 9, or a force F1 of at least 1×10<7> to 8×10<7> pa, which is sufficient to form a cohesive body 10 but of such a magnitude that substantially destroys powder particles. The top layer is applied using a brush, for example. Hydrogenated scandium or other scandium compound is used as an emission inducing material added to the tungsten powder. Here, a force F2 is applied to the whole assembly through the die 3, to obtain a compression formed body 12. This provides an average particle diameter of tungsten powder in effect in the range of 20 to 150 micrometers with the powder crushed to a considerable degree.
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