| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a cathode for an electron tube allowing prevention of peeling of an electron emission substance layer from a substrate metal in operating for a long time and provision of stable cathode current. SOLUTION: A circular tungsten metal layer 55 having a diameter of 1 mm is deposited to a film thickness of 0.5μm at approximately central part of a substrate metal 1. A cathode base where the layer 55 is formed is applied heat treatment at 1000 deg.C for five minutes in the atmosphere of hydrogen. By this process, nickel which is main component of the substrate metal 1 and the tungsten metal layer 55 generate mutual diffusion to form a nickel-tungsten alloy layer 5. This layer 5 has fine irregular of nor more than 10μm and surface roughness bigger than that of the substrate metal 1, thereby the layer 5 has film adhesion with both the substrate metal 1 and an electron emission substance layer 2. Accordingly, peeling of the electron emission substance layer 2 from the substrate metal 1 in operating for a long time can be prevented and stable cathode current can be taken out.</p> |
