Preparing Potassium Doped in Round Tungsten Aluminum Strip from Ammonium Paratungstate—Preparation Method

Potassium doped in round aluminum tungsten is the raw materials in electric light manufacturing, electronic devices in ANTIDROOPING tungsten filament and vacuum spray plating tungsten hinge wire and other high-temperature heating body and resistance to high temperature components. A method for preparing potassium doped in round aluminum tungsten strip is introduced in this paper.

Specific steps:
1. Choice of materials: select special size of ammonium paratungstate distribution with crystalline in FSSS for 40 to 50μm and loose density in 2.1~2.5g/cm³ as raw material;
2 Mild reduction ammonium paratungstate: the raw material mild reduction in furnace in seven ranges of temperature to produce special intermediate ammonium tungsten bronze (ATB). Among them: seven ranges of temperature are 300, 360, 400, 420, 430, 450, 420℃, rate of hydrogen flow at 0.2~0.3m³/h,;
3. AKS doping: mix wet ATB with potassium silicate, aluminum nitrate solution dissolved in deionized water, and make potassium, silicon, aluminum adopted in the pores of ATB, doped ATB formed;
4. Direct reduction: ATB directly reduction in seven temperature reduction furnace a and fine grain tungsten powder B with FSSS 2.2 ~ 2.6μm generated; coarse grain tungsten powder D with FSSS 3.3~4.2μm generated in the same way;
5. Pickling: washing fine grain tungsten powder B, coarse tungsten powder D respectively with hydrochloric acid of concentration 6~8%, hydrofluoric acid of 6~8% to remove dopant and impurities;
6. Mixing powder: mixing the fine particles of tungsten powder B, coarse grain tungsten powder D according to a certain weight ratio after pickling;
7. Cool down and static pressure;
8. Pre-sintering: 120 ~45min under temperature of 40℃;
9. Vertical melting: directly electricity to sintering under the protection of hydrogen gas.

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