Low Energy Milling to Produce Flake Powders
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)