Average Particle Size Of Powders Research Articles

Preparation of powders on a planetary mill

1. An investigation of the kinetics of grinding powders Cr, Mn, Ni, W, ZrB2, TiC, NbC, and MoSi2 in a planetary mill shows that owing to its high intensity an average powder particle size of 1-2.6μ is obtained in a short time (5–20 min). 2. The optimal grinding time depends on the nature of the material and mainly on brittleness and ductility, with an increase of which the time increases. For brittle materials (Cr, Mn, ZrB2, TiC, NbC, and MoSi2) the optimal grinding time is 5 min, and for ductile materials Ni and W, 10–20 min. 3. When grinding brittle materials (Cr, ZrB2, TiC, NbC, and MoSi2) in the planetary mill practically no iron is ground off, which is particularly important when grinding pure materials. 4. There is a negligible yield of iron (up to 0.2%) when ductile materials (Ni, W) are ground.

空気透過法による粉体の平均粒度自動測定装置

An automatic apparatus for the direct indication of the average particle size of powder has been designed and subjected to practical tests. It consists of a device for determining the average particle size of powder from air-permeability as deduced through Kozeny-Carman's equation when the sample is formed into a compact bed, The design for the apparatus here described is based on the author's previous method, but with the addition of the automatic calculating circuit, so that the particle size of the sample as to surface average diameter may be indicated on the meter directly, in microns. The measuring range of particle size is from 50 microns to 0.5 micron. The measurement is rapid, simple and reproducible. The results obtained by this apparatus was compared with that measured by other methods.