| 摘要 |
PURPOSE:To maintain stable electron radioactivity of a base metal made of Ni containing a reducing agent for a long time, by treating the base metal at a high temperature in an atmosphere in which the reducing agent is hardly oxidized to make Ni crystal grains with a diameter of over a given value to be grown, before the base metal is heated in a wet atmosphere of hydrogen to make an oxide to adhere to the base metal. CONSTITUTION:A base metal made of Ni containing a reducing agent chosen out of Si, Mg, Al, Zr and W is heated at 100 deg.C for about 1hr in an atmosphere in which the reducing agent is hardly oxidized, for example, in vacuum at a pressure of below 10<-7> torr, thereby Ni crystal grains with a diameter of over 30m being grown. After that, the base metel is subjected to a decarburization treatment carried out, for example, at 950 deg.C in a wet atmosphere of hydrogen the dew point of which is 20 deg.C for 1hr, thereby an oxide working as an electron radiation source being made to adhere to the base metal. By the means mentioned above, any intermediate layer is hardly developed, and the electron radioactivity can be maintained for a long time. |
