Oxidizing pretreatment for oxide-coated indirectly heated cathodes

摘要

The surface of a cathode core metal is oxidised to a depth of 600-1300 A by annealing in air. The oxidised surface is then coated with nickel formate or oxalate, dried and reduced by annealing in a reducing atmosphere to metallic nickel; some of the nickel oxide of the core is also reduced to nickel. The cathode is then treated in the conventional way.