Abstract: A directly heated cathode for electron tube having a stable electron emission characteristic and a low cut-off voltage is provided. The cathode comprises a base metal of an alloy consisting essentially of 20-30% by weight of tungsten and a trace amount to 0.25% by weight of zirconium, the balance being nickel, binder dots of metallic nickel powders distributed on a flat part at the front side of the base metal, and a layer of thermoelectron emission oxides laid on the flat part at the front side of the base metal. The layer of thermoelectron emission oxides is in direct contact with the flat part through clearances among the binder dots of the metallic nickel powders.

Abstract: The present cathode for cathode ray tube of directly heating type is characterized by comprising a cathode substrate body having two leg pieces extended in the same direction and a flat part connected to one end of each leg piece, prepared by shaping a flat metal plate of nickel- or cobalt-based alloy, a bonding layer having an uneven surface prepared by diffusion bonding by heating a powder layer comprising powders of alloy or mixture of nickel and cobalt formed on the flat part, to which a thermionic emission layer is to be bonded, and the thermionic emission layer, and has a very small deformation when used and a longer life.A cathode with much less deformation and much longer life can be obtained by using a cathode substrate body prepared from a flat metal plate provided with a thinner metal layer of at least one of nickel and cobalt on its surface than the flat metal plate by diffusion bonding.