Fine tungsten powders with an average particle size of 5 mu m were coated w
ith nickel and copper via high pressure hydrogen reduction from nickel sulp
hate and ammonia solution at 130-140 degrees C, 4000 kPa pressure and via f
ormaldehyde reduction of copper sulphate, ethylenediamine tetra acetic acid
(EDTA) and sodium hydroxide solution at ambient temperature respectively.
The nickel and copper contents coated on tungsten varied from 2 to 10 wt.%
and 2 to 30 wt.% respectively. As-coated tungsten powders were characterise
d using X-ray diffraction and scanning electron microscopy. It was found th
at nickel and copper were homogeneously distributed around the tungsten par
ticles in exceeding 4 to 5 wt.% of Ni/Cu content. No impurities, such as re
sidual chemical agents and oxides were detected by chemical and XRD analysi
s. However, the aggregation of tungsten powder became serious for copper co
ntents larger than 20 wt.%, which affects the fluidity of tungsten powders
during the subsequent press operation. The penetration depth of a perforati
on device prepared from coated tungsten powders increased by 20 compared wi
th that manufactured from conventionally blended elemental powders. (C) 199
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