Alexey Olegovich Khasanov

Influence of Ultradispersed Fraction of Boron Carbide Powder on Strength Properties of the Ceramics Manufactured by SPS Method

The experimental results for manufacturing ceramics from industrial boron carbide powder with 10 wt% of ultradispersed fraction of a powder of the same composition by spark plasma sintering have been presented. Under optimal process conditions such sintering results in a decrease of the sintering temperature and synthesis time, and the addition of ultradispersed fraction increases microhardness and fracture toughness of the ceramics.

Lower sintering temperature of nanostructured dense ceramics compacted from dry nanopowders using powerful ultrasonic action

Nanostructured high dense zirconia ceramics have been sintered from dry nanopowders compacted by uniaxial pressing with simultaneous powerful ultrasonic action (PUA). Powerful ultrasound with frequency of 21 kHz was supplied from ultrasonic generator to the mold, which was the ultrasonic wave-guide. Previously the mold was filled by non-agglomerated zirconia nanopowder having average particle size of 40 nm. Any binders or plasticizers were excluded at nanopowder processing. Compaction pressure was 240 MPa, power of ultrasonic generator at PUA was 1 kW and 3 kW. The fully dense zirconia ceramics has been sintered at 1345°C and high-dense ceramics with a density of 99.1%, the most grains of which had the sizes Dgr ≤ 200 nm, has been sintered at low sintering temperature (1325°C). Applied approach prevents essential grain growth owing to uniform packing of nanoparticles under vibrating PU-action at pressing, which provides the friction forces control during dry nanopowder compaction without contaminating binders or plasticizers.

Metal-ceramic composite development based on its modelling results

The modeling (and its experimental verification) of packing and deformation of the composites consisted of aluminum-magnesium alloy AMg6, B4C powder and W nano-powder has been performed. The powder compositions were determined using discrete element modeling of the composite particles packing based on the particle size distribution functions of real powders. The models of maximum mixture packing densities have been rendered.

Sintering of oxide and carbide ceramics by electron beam at forevacuum pressure

Novel approaches for electron beam sintering of zirconia and silicon carbide ceramics have been investigated: application of forevacuum pressure plasma-cathode to compensate the charge induced by the electron beam on the green compact surface, and previous dry powder compaction under powerful ultrasound assistance. Dense YSZ ceramics with submicron and micron grains have been consolidated by electron beam sintering after powder compaction using ultrasound.

Development of B 4 C nanostructured ceramics

The B4C ceramic samples have been manufactured by SPS method using mixed micrometric and nano-scaled powder. The microstructure, density, microhardness, fracture toughness of sintered ceramics have been investigated. The optimal processing modes have been determined.