Breakage behavior

The synthesis of carbonyls by the reaction of Ni, Fe or Mo with carbon monoxide is possible under low-temperature and low-pressure conditions. The apparent activation energy is reduced under milling conditions. The difference between non-acti-vated solid, pretreated solid and simultaneous reaction and milling is depicted in Fig. 14.15 [10]. At normal temperatures, a distinct decrease in activation energy and frequency factor can be seen this higher reactivity is derived from a high dislocation density. Below a critical temperature, the solid alters the breakage behavior from... 

Pitchumani, R., Meesters, G. M. H., Scarlett, B., 2003. Breakage behavior of enzyme granules in a repeated impact test Powder Technd. 130 138—146. 

Elastic-brittle breakage behavior is characterized by a failure which begins during elastic deformation and is attended by non-stationary cracks, where no external energy input is needed to grow the cracks with a rapid propagation velocity. 

Antonyuk, S., Palis, S., Heinrich, S., 2011. Breakage behavior of agglomerates and crystals by static loading and impact. Powder Technol. 206 88-98. 

The particle deformation and breakage behavior can be illustrated by means of the measured force-displacement curves. A typical force-displacement curve for the investigated sugar pellets is shown in Fig. 9. The force F characterizes the contact force between stamp and particle. The distance 5 shows the corresponding displacement of the particle. AH compression tests were carried out up to a compressive strain of 20%. 

To predict the real interactions of the particles in the FB, their material properties were obtained experimentally and used as parameters of DEM contact model. The deformation and breakage behavior of pellets were obtained with the help of single particle compression tests. The energy loss during the collisions was obtained by means of free-fall impact tests. 

It is important to differentiate between brittie and plastic deformations within materials. With brittie materials, the behavior is predominantiy elastic until the yield point is reached, at which breakage occurs. When fracture occurs as a result of a time-dependent strain, the material behaves in an inelastic manner. Most materials tend to be inelastic. Figure 1 shows a typical stress—strain diagram. The section A—B is the elastic region where the material obeys Hooke s law, and the slope of the line is Young s modulus. C is the yield point, where plastic deformation begins. The difference in strain between the yield point C and the ultimate yield point D gives a measure of the brittieness of the material, ie, the less difference in strain, the more brittie the material. 

The energy laws of Bond, Kick, and Rittinger relate to grinding from some average feed size to some product size but do not take into account the behavior of different sizes of particles in the mill. Computer simulation, based on population-balance models [Bass, Z. Angew. Math. Phys., 5(4), 283 (1954)], traces the breakage of each size of particle as a function of grinding time. Furthermore, the simu-... 

Specific interactions Chemical processes that involve the formation or breakage of intramolecular bonds. This behavior can be described by equilibrium constants and expressions. 

This enables one to use aliphatic systems as precursors to the radicals X-Y whose solvolytic (= redox) behavior can then be studied. Equations 2a, c describe what may be called oxidative solvolysis . This reaction sequence, the first step of which is in many cases induced by the OH radical, is of great importance in radical (and radiation) chemistry. It extends from /8-elimination reactions of monomeric radicals [6, 7] to the mechanism of DNA strand breakage [8]. An example for Eq. 2 in which it is shown that the radical XY can be produced by either step a or b is given in section 3.3. 

In brittle nonmetallics (such as porcelain, glass, impregnated graphite, etc.) and some thermosetting resins, the materials show rigid behavior and develop high displacement stresses up to the point of sudden breakage due to overstrain. 

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