Low Energy Milling to Produce Flake Powders

Abstract

A method for increasing surface area of a valve metal particle is provided as is an improved valve metal particle provided thereby. The method includes charging a mill apparatus with a valve metal powder and a media wherein the media has an average diameter of at least 0.01 cm to no more than 0.3175 cm. The valve metal powder is then milled at an average kinetic energy of no more than 3,000 ergs per media particle to obtain a milled powder.

1 - 30 . (canceled) 
     
     
         31 . A valve metal powder comprising:
 a CV/g of at least 30,000 micro-farad volts per gram;   a BET surface area of greater than 4 M 2 /g; and   an aspect ratio of at least 3.   
     
     
         32 . The valve metal powder of  claim 31  with an aspect ratio of at least 10. 
     
     
         33 . The valve metal powder of  claim 32  with an aspect ratio of at least 100. 
     
     
         34 . The valve metal powder of claim  30  with an aspect ratio of at least 200. 
     
     
         35 . The valve metal powder of  claim 31  with an aspect ratio of no more than 300. 
     
     
         36 . The valve metal powder of  claim 31  comprising no more than 30 ppm metallic impurity. 
     
     
         37 . The valve metal powder of  claim 31  comprising no more than 30 ppm impurity selected from iron, nickel, chromium, silicon and zirconium. 
     
     
         38 . The valve metal powder of  claim 37  comprising no more than 30 ppm impurity selected from iron, nickel and chromium. 
     
     
         39 . The valve metal powder of  claim 31  wherein said valve metal powder is selected from the group consisting of tantalum, niobium, tungsten, titanium, aluminum and alloys thereof. 
     
     
         40 . The valve metal powder of  claim 39  wherein said valve metal powder is tantalum. 
     
     
         41 . The valve metal powder of  claim 40  wherein said milled powder has a BET surface area of greater than 5 M 2 /g. 
     
     
         42 . The valve metal powder of  claim 41  wherein said milled powder has a BET surface area of greater than 6 M 2 /g. 
     
     
         43 . The valve metal powder of  claim 42  wherein said milled powder has a BET surface area of at least 7 M 2 /g. 
     
     
         44 . The valve metal powder of  claim 43  wherein said milled powder has a BET surface area of at least 8 M 2 /g. 
     
     
         45 . The valve metal powder of  claim 44  wherein said milled powder has a BET surface area of at least 9 M 2 /g. 
     
     
         46 . The valve metal powder of  claim 31  wherein said milled powder has a CV/g of at least 180,000 micro-farad volts per gram. 
     
     
         47 . The valve metal powder of  claim 46  wherein said milled powder has a CV/g of at least 200,000 micro-farad volts per gram. 
     
     
         48 . The valve metal powder of  claim 47  wherein said milled powder has a CV/g of at least 250,000 micro-farad volts per gram. 
     
     
         49 - 61 . (canceled)