The characteristic of an atomic membrane cathode is to adsorb a thin layer of another metal on the surface of one metal, which is positively charged to the base metal. This forms a double layer with positive charges on the outside, and the electric field of this double layer can accelerate the movement of electrons inside the base metal towards the surface, thereby reducing the electron escape work of the base metal and increasing its electron emission ability by many times. This surface is called an activation surface. The main materials used as matrix metals are tungsten, molybdenum, and nickel.
The formation method of the activated surface is generally powder metallurgy. Add a certain amount of oxide of another metal with lower electronegativity than the base metal to the base metal, and make it into a cathode through a certain processing process. When this cathode is heated under vacuum and high temperature, the metal oxide is reduced by the base metal to become a metal. At the same time, the activated metal atoms on the surface that are reduced rapidly evaporate at high temperature, while the activated metal atoms inside continuously diffuse to the surface through the grain boundaries of the base metal to supplement.
Post time: Oct-12-2023