Tantalum powder, method for preparing the same, and electrolytic capacitor anode made of the tantalum powder

Abstract

The present invention relates to the tantalum powder and the process for preparing the same, and also relates to the electrolytic capacitor anode made of the tantalum powder. More particularly, the present invention relates to the tantalum powder having a BET surface area not more than 0.530 m 2 /g, Fisher mean particle size not less than 3.00 μm. The present invention relates to the process for preparing the tantalum powder, wherein the tantalum powder is prepared through reducing tantalum compound with a reducing agent, wherein the tantalum powder as seed is added during reduction, and said tantalum powder as seed is the tantalum powder that has been milled.

1 . Tantalum powder, wherein the tantalum powder has a BET surface area of not more than 0.530 m 2 /g, and Fisher mean particle size of not less than 3.00 μm. 
   
   
       2 . The tantalum powder according to  claim 1 , wherein said BET surface area is not more than 0.525 m 2 /g. 
   
   
       3 . The tantalum powder according to  claim 2 , wherein said BET surface area is not more than 0.520 m 2 /g 
   
   
       4 . The tantalum powder according to  claim 1 , wherein said Fisher mean particle size is not less than 3.05 μm. 
   
   
       5 . The tantalum powder according to  claim 4 , wherein said Fisher mean particle size is not less than 3.10 μm 
   
   
       6 . The tantalum powder according to  claim 1 , wherein said tantalum powder has a particle size distribution such that, the particles of −325 mesh comprise not more than 60 vol % of all particles. 
   
   
       7 . The tantalum powder according to  claim 6 , wherein said tantalum powder has a particle size distribution such that, the particles of −325 mesh comprise not more than 55 vol % of all particles. 
   
   
       8 . The tantalum powder according to  claim 7 , wherein said tantalum powder has a particle size distribution such that, the particles of −325 mesh comprise not more than 50 vol % of all particles. 
   
   
       9 . The tantalum powder according to  claim 1 , wherein said tantalum powder has an bulk density in a range of 0.5-2.0 g/cm 3 . 
   
   
       10 . A process for preparing the tantalum powder according to  claim 1 , wherein the tantalum powder is prepared by reducing tantalum compound with a reducing agent, wherein the tantalum powder as seed is added during reduction, and said tantalum powder as seed is the tantalum powder that has been milled. 
   
   
       11 . The process according to  claim 10 , wherein the particle size of the tantalum powder as seed is −60 mesh. 
   
   
       12 . The process according to  claim 10 , wherein said milling is continuous ball-milling for 5-40 hours, preferably for 10-30 hours in a stirring ball mill. 
   
   
       13 . The process according to  claim 10 , wherein the amount of the tantalum powder as seed added is 5-80 mass % of the theoretical reduction amount of the tantalum powder. 
   
   
       14 . The process according to  claim 13 , wherein the amount of the tantalum powder as seed added is 10-70 mass % of the theoretical reduction amount of the tantalum powder. 
   
   
       15 . The process according to  claim 14 , wherein the amount of the tantalum powder as seed added is 30-60 mass % of the theoretical reduction amount of the tantalum powder 
   
   
       16 . The process according to  claim 10 , wherein said process include the following steps:
 (a) mixing tantalum compound with dilution agent and tantalum powder as seed;   (b) adding reducing agent and reducing tantalum compound at a temperature of 700-1000° C.;   (c) soaking at a temperature of 700-1000° C.;   (d) removing the tantalum powder.   
   
   
       17 . An electrolytic capacitor anode, wherein said anode is manufactured from the tantalum powder of  claim 1 . 
   
   
       18 . The electrolytic capacitor anode according to  claim 17 , wherein the specific capacitance is in the range of 6000-30000 μFV/g. 
   
   
       19 . The electrolytic capacitor anode according to  claim 18 , wherein the specific capacitance is in the range of 10000-30000 μFV/g. 
   
   
       20 . The electrolytic capacitor anode according to  claim 17 , wherein the energizing voltage is in the range of 100-250V.