Powders
A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material. In particular, powders refer to those granular materials that have the finer grain sizes, and that therefore have a greater tendency to form clumps when flowing. Granulars refers to the coarser granular materials that do not tend to form clumps except when wet. (Wikipedia, Powders, 3/25/2011)
Fluidized Beds
Materials
Mixing Powders
Polyaryletherketone (PAEK) Powders
Powder Injection Molding
Recent US Patents
11/29/2011
8,066,422
Material moisture content adjustment method
Kobayashi et al of Kajima, Japan, adjusted the moisture content of powders by mixing with fine ice using liquid nitrogen to control temperature. (RDC 12/5/2011)
Recent Journal Articles
Mixing and Packing of Fine Particles of Different Sizes
(198–206) Industrial & Engineering Chemistry Research 50 #1 (2011)
Liu et al of the New Jersey Institute of Technology, New Jersey developed two different approaches for mixing different sizes of fine particles without segregation and simultaneously increasing the packing density of the mixture. The first application requires uniform mixing of 300 and 30 μm aluminum oxide particles acting as surrogates for the explosive RDX. The packing density needs to be as high as possible and the particles need to be well-mixed to prevent local hot spots. This was accomplished by adding moisture to uniformly mix the particles and then removing the moisture to increase the packing density. The second application requires mixing coarse (2.3 mm) and fine (65 μm) silica aerogel particles; the aerogels are very porous and light and have a very low thermal conductivity. Here we want to fill the voids between the coarse particles with fine particles so that the bulk (or packing) density of the mixture is increased, thereby further increasing their insulating properties. This was done by combining a negative pressure (vacuum) with an external force field, such as sound waves or vibration. (RDC 2/14/2011)