| 摘要 |
<p>PURPOSE:To obtain the captioned structure having high performance and a long life by a method, in which the base metal surface is coated with Ba and SiO2 through a mask having a controlled opening ratio for controlling the coating ratio and the thickness of a barium silicate layer while secondly coating the whole surface with Ni in order to control the depth of the barium silicate layer. CONSTITUTION:A smooth coppor mask chemically etched in the dotted shape is mounted on a base metal, in which a disk of the alloy of Ni-Mg.Si containing 0.06wt% of Mg and 0.03wt% of Si is welded on the tip of the cathode sleeve 5, a Ba film is evaporated, further the SiO2 film is evaporated on the Ba film followed by removing the mask and evaporating an Ni film 4 on the whole base metal surface for forming the base metal 2. An electron emissive substance 1 is applied to the surface of said base material 2, which is included into an electron gun for forming a diffusion control layer having about 60% of the coating ratio, for instance, in the position of the depth about 10mum by heat treatment. The coating ratio of the diffusion control layer shall be 30-95%, while it is desirable to have the depth of 3-20mum and the thickness of 0.05-0.5mum.</p> |
