Potassium-doped tungsten wire esp. for incandescent lamp filament

摘要

In tungsten wire prodn. by infiltrating blue tungsten oxide with a potassium-contg. dopant, reducing to tungsten powder and further processing to tungsten wire, the novelty is that (a) the blue tungsten oxide contains, as main constituent, a special hexagonal ammonium tungsten bronze of formula (I) (NH4)x(NH3)yWO3 (I) where x < 0.33 y< 0.05; and (b) infiltration is carried out with a potassium-contg. (pref. potassium nitrate) soln., pref. an Al- and Si-free soln. Also claimed are (i) a tungsten wire, esp. contg. 40-120 ppm. K and < 30 ppm. Si and Al, made by the above process; and (ii) an incandescent lamp with the above tungsten wire.