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Home Material Sciences Production Of Highly Dispersed Extra Pure Powders And Extremum Mechano-Chemical Treatment Of Their Mixtures

Production Of Highly Dispersed Extra Pure Powders And Extremum Mechano-Chemical Treatment Of Their Mixtures

Description

Milling materials with various properties is expedient to carry out in the jet disintegrators (Fig.1). Principle of their operation consists in the following.

Two counter-current gaseous flows carry off the starting bulk material owing to ejection. In the accelerating tubes the particles are mixed and speeded. In the zone, where the flows meet, intensive milling of the starting material occurs due to collisions and intensive friction of particles. The rising flows carry off material to the zone of preliminary separation of rough fractions and then to the separator where the fine fraction is separated. At first it is caught in the cyclone and finally in the filter. The rough fractions are continuously returned from the separator to the milling chamber for further milling.

Advantages of the milling method using counter-current flows are:

  • the absence of friction elements eliminates the entry of impurities into the milled material and lowers specific energy consumption;
  • grinding dry vegetables and fruit occurs without destruction cellulose what favors the maximum preservation of their biologically natural structure;
  • possibility for milling both superhard materials (diamond, boron nitride) and viscous easily fusible plastics (caprone, fluoroplastic etc.);
  • mechano-chemical activation of material and milling occur simultaneously. Strenght of the cement produced in this disintegrator is increased; abrasive materials are abraded to powder without particles in the form of needles and plates; sintering temperature for ceramics is decreased.

Earlier authors have performed investigations on optimization of a milling unit in the existing jet disintegrator. This unit was used for the fine milling (particle dispersity of 5-200 μm) fruit and vegetable products.

To solve materials science problems, it is expedient to design a new jet disintegrator in with an inert gas is used as a carrier what makes it possible to eliminate oxidation of the material milled.

Innovative Aspect and Main Advantages

Positive results of investigations on improving hydrogen-sorption properties of intermetallic compounds with the use of mechanochemical treatment in a ball mill at their synthesis as well as the authors’ experience in optimizing parameters of jet disintegrators confirm expediency of designing a new jet disintegrator for solving a number of materials science problems including:

  • production of highly dispersed extra pure powders owing to the elimination of the “milling” effect. The use of an inert gas as a carrier instead of air in the jet disintegrator will make it also possible to eliminate oxidation of material in milling;
  • to give new useful properties to the materials milled as a result of mechanochemical treatment and activation. Free-flowing ingredients are in the zone where the flows meet under extremum conditions (near-sonic speeds at collisions and strong friction conditions).

Areas of Application

The new jet disintegrator, in which counter-current flows of inert gases are used, will find wide applications in several idustrials sectors, in particular:

  • in powder metallurgy for production of extra pure highly dispersed powders and activated homogeneous powder mixtures;
  • in hydride technologies: it is supposed that the compositions, which are produced by joint mechano-chemical treatment and activation of hydride-forming alloys and nanostructural carbon in the extremum conditions of the counter-current flows, would have improwed hydrogen-sorption properties that meet the current requirements of DOE, not less than 6 Wt.%. In this case reversible hydrogen saturation of the above composites under mild temperature and pressure conditions can be provided by selecting the compositions of a hydride-forming alloy as a catalist for hydrogen saturation of nanostructural carbon.


Fig. 1 Structural scheme of the jet air disintegrator.
1 – loading unit; 2 – separator; 3 – cyclon; 4 – filter; 5 – ventilator;
6 – milling unit; 7 – container for ready product; 8 – system for air preparation;
9 – compressor

Stage of Development

Technical feasibility of technology is studied. Also cooperations for futher development are sought.

Contact Details

Frantsevich Institute for Problems of Materials Science of NASU
3 Krzhyzhanovsky str., Kyiv, 03142 Ukraine
Vasiliy Pishuk
Phone: +38044 424-0081
Fax: +38044 424-0381
E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

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