Characteristics and Production of Tantalum Powder on the amount of Diluent By Na Reduction Method

Abstract

High-pure tantalum powder was fabricated through Na reduction process and has been produced by using <TEX>$K_2$</TEX>TaF<TEX>$_{7}$</TEX>, and KCI, KF for raw material and diluent, respectively. A raw material and diluent were charged at the hestalloy bomb by the weight rate of 1:2, 1:1, 1:0.5 and 1:0.25 each other, investigated properties of morphology, chemical composition and yield and particle size after reduced. Ta metal has been achieved by reduction of <TEX>$K_2$</TEX><TEX>$TaF_{7}$</TEX> 500g with 1% sodium in excess of stoichiometric amount in the charge at a reduction temperature of <TEX>$850^{\circ}C$</TEX> for 3hours. According to amount of the diluent, a formation of the powder doesn't have an effect. The diluent prevented the temperature rising caused from the heat of reaction and it maintained the speed of reducing reaction. But in the mixture ratio of raw material and diluent in the 1 : 2 and 1 : 0.25, an oxide and partially not reacted K were detected. As the amount of diluent increased, the size of tantalum powder decreased. According as raw material and the mixture ratio of diluent change from 1:0.25 to 1:2, the size is decreased from 5<TEX>$\mu\textrm{m}$</TEX> to 1<TEX>$\mu\textrm{m}$</TEX>, and a particle size distribution which is below 325 mesh in fined powder increases from 71% to 83%. In the case of average size of Tantalum powder which is the mixture ratio (1:0.5), we would get the Ta powder with grain size about 3<TEX>$\mu\textrm{m}$</TEX>, which come close to the average size (2~4<TEX>$\mu\textrm{m}$</TEX>) of tantalum powder which is used commonly in the present is Ta powder about 3<TEX>$\mu\textrm{m}$</TEX>.