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.
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