Disaggregation of ultrafine powders in conditions of ultrasonic cavitation
Use of high-dispersive additives as structure modifiers is one of the most effective instruments of cement composites required technical exploitation characteristics increase nowadays. However, use of high-dispersive powders is complicated by the fact that their particles are consolidated into aggregates. Thus, the major advantage of high-dispersive powder, which is its possibility to form more bonds when their content is very low, appears to be unrealized. One of the promising directions of dispersed phase fine grinding is use of ultrasonic cavitation. Ultrasonic exposure does not always provide the efficiency required due to insufficient information about the effect of conditions defining ultrasonic radiation intensity on amount of aggregates damage. In this regard, it is necessary to define factors and conditions of ultrasonic exposure, which provide effective high-dispersive powders disaggregation. In article аcoustic streaming in a fluid occurring due to cavitation and providing mass transfer intensification has been considered. The data about efficiency of cavitation bubble size and large-scale acoustic streaming effect on the distribution of powder particle size were obtained by calculation. The efficiency of high-dispersive powders disaggregation can be improved by using lowered hydrostatic pressure exposure.