Size segregation reduction

Another technique is to change the particle size distribution. There are, however, disadvantages. If segregation is occurring by the sifting mechanism, the particles must be almost identical in size before sifting is prevented. Alternatively, the mean particle size can be reduced below 100 p.m, but this size reduction (qv) increases the probabiUty of segregation by the too fine powder mechanisms. 

This Study has shown that reasonably uniform platinum crystallites can be made on y-alumlna, and that platinum and palladium can be segregated and maintained In that form for the most part even after exposure to high temperature oxidation-reduction conditions. Highly dispersed clusters of palladium, nickel, cobalt, and Iron can be observed. Cluster size determination could not be accurately made because of the lack of contrast between the cluster and the support. The marginal detectability by EDS for these clusters enabled elemental Identification to be made, however, mass uniformity determinations could not be made. 

Modified shearing locations for M55 rockets and a new shearing machine must be tested to show routine segregation of components and reduction in particle sizes to less than 1/4 inch in diameter. 

Separating Particle segregation based on size alone, without any significant particle size reduction (commonly referred to as screening or bolting)... 

Particle mixing is caused by the bubbles, partly be shear displacement or drift but also by the bulk transport of particles in the bubble wake. Bubbles may also cause segregation if there are different kinds of particles present. Unlike other kinds of mixers, segregation is insensitive to particle size difference but particularly sensitive to density difference. In a binary system of particles segregation increases approximately as particle density ratio to the power 5/2 but with particle size ratio only to the power 1/5 (11). This can cause problems in, for example, coal combustion where char has a markedly lower density than ash and also in some ore reduction processes using coke. 

A reduction in segregation size improves the draw-ability (after Takahashi et al., 1992). 

In the theories presented so far, a major driving force for segregation has been the fact that the surface is a region of reduced atomic coordination. In solids, there is a further driving force, namely the reduction of strain. Solute atoms that differ in size from the solvent lattice atoms create a strain in the lattice [41]. At a grain boundary, there are open sites where more space is available to the atoms. By migrating to these sites, a solute can reduce the strain energy. 

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