Studies on Electrode Connector Materials in the Electron Tube

Abstract

For the purpose of selecting materials for manufacture of electrode connector in the electron tube, Ni, Ni-Mn, Ni-Cr, Ni-Fe and Ni plated Fe were examined with respect to their embrittlement by annealing them in city coal gas, to the embrittlement of the stem lead wire in the stem making process, to the decrease in insulation resistance of inter-electrodes during their life, and to the fatigue of the cathode tab in the inverted pinched cathode due to the on-off cycling test.The results are summarized as follows;(1) Embrittlement by city coal gas firing can be evaluated by measurement of tensile strength and elongation. Embrittled Ni has low tensile strength and elongation, and its metallographic structure shows micro cracks formed along the grain boundaries.(2) Embrittlement and fracture of Ni stem lead and Ni cathode tab was caused by city coal gas firing in stem making process and in glass envelope sealing-in process. Metallographic structures of the embrittled lead wire and tab showed also micro cracks along the grain boundaries.(3) Ni-Mn, when used as cathode tab, decreased in insulation resistance of inter-electrodes during its life. But it was not the case with Ni, Ni-Cr, Ni-Fe and Ni plated Fe.(4) Ni plated Ni-Fe is recommended for the stem lead wire, because it is not embrittled and hardened by city coal gas firing, nor is it oxidized in the stem making process, nor does it wet glass.(5) 42% Ni-Fe is recommended for the cathode tab material, because it is not embrittled by city coal gas firing, nor does it decrease in insulation resistance of inter-electrodes, and it is strong resistant to fatigue.