METHOD FOR MANUFACTURING METAL-POROUS CATHODES FROM TUNGSTEN POWDER Russian patent published in 2007 - IPC H01J9/04 

FIELD: electronic engineering.

SUBSTANCE: method for manufacturing metal-porous cathodes from tungsten powder includes stepped annealing of source powder at temperatures ranging from 1650°C to 1750°C with lifting of temperature by 25-50°C, cracking of cake, control over quality of powder after each step of annealing by determining average diameter of particles of powder D_p, which is supposed, after not less than two annealing steps, to exceed 4,5 mcm (which is equivalent to passage of air through sample pellet, pressed at P_sp=2,8 t/cm², values of P≤0,45 kg/cm²), pressing of pellets from produced powder, baking of them in non-corrosive environment and saturating baked pellets with emission-active substance, in accordance to solution, powder quality control is based on diameter of particles D_pf, size of which is determined by means of measuring using "Fisher" type device, and which in accordance to ratio between D_p and D_pf, equal to D_p=D_pf-1, is supposed to match values not less than 5,5 mcm, but not more than 8,0 mcm either, interval of density values of baked pellets is computed ρ_{ba min} ÷ ρ_{ba max} from equations: ρ_{ba min} = 12,35 - 0,03(D_pf-1)+0,05(D_pf-1)², ρ_{ba max}=ρ_{ba min} + 0,20, where value ρ_bamin (g/cm³) satisfies condition of presence of minimal open porous channel in baked pellets, from interval of optimal values for current industry for aforementioned channel, while ρ_{ba max} (g/cm³) satisfies condition of presence of maximal open porous channel for current industry and on basis of standard dependency of density of baked pellets from specific pressing pressure ρ_ba=f(P_sp), where density equals ratio of pellet weight to its volume, for values ρ_{ba min} and ρ_{ba max}, pellet pressing pressure is determined.

EFFECT: increased lifetime of cathodes, decreased evaporation from them.

3 dwg, 3 tbl