Evaluating partial pressure of vapors for various oxides

To improve control of the process of nano-powder production in the industrial plant based on electron accelerator, partial pressure of vapors was evaluated at evaporation for different reactions of aluminum, silicon, and titanium oxides. The performed experiments qualitatively proved the correctness of calculations. Besides, influence of water vapors added in gas-carrier on the productivity and average size of the particles of the obtained nano-powder were studied experimentally.     

Preparation of nickel nanopowder through evaporation of the initial coarsely dispersed materials on an electron accelerator

The experimental studies have shown that, during evaporation of coarsely dispersed carbonyl nickel, a nanodispersed powder of high purity can be obtained, which is promising for use in different technological applications. The process has a high efficiency and a relatively high output (of the order of 100 g/h). The specific feature of the synthesis is the separation of obtained nanoparticles into two fractions with average sizes of approximately 100 and 200 nm. The computer analysis of the system evolution has demonstrated that this separation can occur as a result of the aggregation of the initial clusters of sufficiently large sizes.     

Simulation of the structural state of amorphous phases in nanoscale SiO2 synthesized via different methods

The structural state in nanoscaled SiO₂ is probed experimentally via X-ray diffraction and the simulation method. The aerosil nanoparticles and nanoparticles synthesized via the electron beam evaporation are compared. The nanoparticles for all samples are shown to be in the amorphous state. The amorphous state of a SiO₂ unit lattice is simulated via the molecular dynamics. The full-profile refinement of parameters for a simulated SiO₂ phase (the Rietveld method) has allowed the complete structural information to be established at varying the specific surface. The unit cell parameters, the spatial atomic distribution and the degree of cell node occupation are determined, as well. The specific surface area is shown to decrease in aerosil nanoparticles and to increase in tarkosil nanoparticles with the increasing binding energy of atoms in a cell.

     

Use of hot-wire anemometry for measuring the nanopowder flow velocity

A new technique for measuring the flow velocity of nano-scale powders is used. The hot-wire anemometry method widely used in gas flows is employed for investigating nanopowder flows. By way of illustration, the flows of nanopowders of aluminum oxide C and silicon dioxide aerosil A-90 and A-380 in a vertical channel are studied. The results obtained show that nanoscale powder flow investigation by means of the hot-wire anemometry is promising.     

Investigation of acoustic waves propagation and flow in nanodispersed medium

Propagation of acoustic waves in nanodisperse powders and powder flow under the influence of acoustic vibrations have been investigated in the horizontal tube with the use of visualization and hot-wire anemometer methods.     

Stability of a nanopowder boundary-layer flow on a concave plate

Using hot-wire probe measurements, the mean and fluctuating velocities in a boundary layer on a concave plate immersed in the flow of a nanosized silicon dioxide powder are studied. A region of destabilization of disturbances is detected.