V. I. Lysenko

Properties of ceramics prepared from nanopowders

Fine-grained (on the order of several microns in grain size) ceramics have been produced from various nano- and submicron-sized powders (silica, alumina, titania, aluminum nitride, and tungsten carbide). The compaction and sintering behaviors of various powder mixtures and the properties of the resultant ceramics have been studied. For a number of compositions, fine-grained, dense, high-strength ceramics have been obtained with a microhardness of up to 16–18 GPa.

High Volume Synthesis of Silicon Nanopowder by Electron Beam Ablation of Silicon Ingot at Atmospheric Pressure

The evaporation of high purity silicon ingot was performed in Ar, N2, and air atmospheres using a power electron accelerator. The obtained powders with primary particle sizes of 10–500 nm were investigated using Brunauer–Emmett–Teller analysis (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence measurement, and Raman spectroscopy. The structure and photoluminescence properties of Si(Ar) nanopowder obtained at a large quenching rate differ substantially from those of Si(Ar) and Si(N2) obtained at a smaller quenching rate. Photoluminescence peaks in the visible region of the spectrum are detected at room temperature for the Si(Ar) nanopowders.

Microhardness of ceramics produced from different alumina nanopowders by different techniques

Fine-grained ceramics (with a grain size on the order of a micron) have been produced by the spark plasma sintering (SPS) of various alumina nanopowders. We have compared the microhardness of ceramic samples prepared from 11 alumina nanopowders and that of composites based on such powders. The ceramics have been prepared by both SPS and a conventional technique (sequential pressing and sintering). We examine the effect of the phase composition and average particle size of the starting nanopowder on the microhardness of the ceramics.

Preparation and properties of ceramics from a zirconia nanopowder

The possibilities of preparing ceramics from a zirconia nanopowder have been investigated. A ceramic material with a fine-grained (of the order of 2–3 µm) structure is synthesized. A ceramic material with zircon predominant is produced using a silica nanopowder (tarkosil). The properties of the initial nanopowder and the ceramic material synthesized are investigated using transmission electron and scanning electron microscopies. The microhardness and strength of the ceramics are determined.

Ceramics prepared from silicon dioxide nanopowders

The possibilities for preparing ceramics from silicon dioxide nanopowders are analyzed. A ceramic material with a fine-grained structure (with grain sizes of the order of 10–20 μm) is synthesized, and its optical properties are investigated.

Creation and properties of ceramics from niobium oxide nanopowder

The possibilities of fabricating ceramics from the nanodispersed powder of niobium oxide have been investigated. Finely-grained (~100–150 nm), dense, and durable ceramics with a microhardness of up to 13 GPa have been created using the method of Spark Plasma Sintering (SPS).

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.

Gas filtration and separation with nano-size ceramics

Filtration and separation properties were studied for filters made from open-porosity ceramics (sintered from authors-developed silicon dioxide nanopowder “tarkosil”. Key parameters were measured for samples of ceramics produced at different sintering temperatures: porosity, gas permeability coefficient, relative time of standard volume fill-up, gas mixture separation coefficient. The possibility of using the described ceramics for helium enrichment was demonstrated with examples of helium-nitrogen and helium-methane mixtures.

Fabrication and Properties of Ceramics Based on Chrome Oxide Nanopowder

The fabrication of ceramics from nano-dispersed chrome oxide powder is investigated. Fine-grained (150–200 nm), compact, and strong ceramic samples of a microhardness of 8.3 GPa are obtained by the spark plasma sintering method.