Igor L. Shabalin

Pressure-dependent deuterium reaction pathways in the Li-N-D system

Neutron diffraction data from in situ deuteration and dedeuteration of Li(3)N are presented under different pressure regimes, whereby reaction pathways differing from the widely reported stoichiometric pathway of Li(3)N + 2D(2)<--> Li(2)ND + LiD + D(2)<--> LiND(2) + 2LiD are observed. At sufficiently high pressures, where the deuterium chemical potential is comparable with the heat of amide formation, the reaction appears to be driven straight to the amide plus deuteride phase mixture. At lower pressures, a cubic phase exhibiting a concentration-dependent variation in lattice parameter is observed. In dedeuteration, two sets of reflections from cubic structures with distinct lattice parameters are observed, both of which exhibit a continual decrease in cell volume. The reaction pathways are discussed in terms of the compositional variation.

Physicomechanical properties of ultrahigh temperature heteromodulus ceramics based on group 4 transition metal carbides

Abstract Abstract Highly densified TiC, ZrC and HfC based ultrahigh temperature heteromodulus ceramics (HMC), containing 10-50 vol.-% of low modulus phase in the form of particulate graphite, were prepared by hot pressing at 2700°C and 12 MPa in argon atmosphere. The microstructure, elastic characteristics, flexural and compressive static strength, fracture toughness, impact resistance, hardness and thermal expansion were investigated and compared with those available in earlier works for clear understanding the composition-property correlations and anisotropy of this type of HMC composites. Different thermal shock resistant parameters for the HMC were calculated on the basis of obtained experimental data. A new principle of optimum materials design for the compositions in the refractory carbide-graphite systems is exemplified by the TiC-C HMC materials.

Hydrothermal synthesis of zeolites from coal fly ash

The fly ash, from the combustion of coal to produce energy and heat, is an industrial waste, in which large accumulations represent a serious environmental threat. To reduce the environmental burden and improve the economic benefits of energy production, the science and industry focus on the transformation of coal combustion byproducts into new functional materials. The fly ash was studied by modern analytical methods. As a result of the hydrothermal reaction, several types of zeolites were synthesised from the fly ash: analcime, faujasite (zeolite X) and gismondine (zeolite P). It was shown that the experimental conditions (temperature, reaction time and alkali concentration) have a significant influence on the type of zeolite and its content in the reaction products. The series of experiments resulted in building approximate crystallisation field of zeolites and other phases as the first stage of the formation of ceramic membrane and other materials.

High toughness TiB2–Al2O3 composite ceramics produced by reactive hot pressing with fusible components

Abstract A manufacturing method of high toughness TiB2–Al2O3 ceramic composites by reactive hot pressing via exothermic reactions with Al, B2O3, C and TiB2 has been developed. The usage of fusible initial components (Al and B2O3) in the hot pressing procedure allowed forming dense ceramics with homogeneous fine structure at 1900°C and 20 MPa (after 8 min exposure) without any grinding of the initial powders. The hot pressed TiB2–Al2O3 composites exhibit the fracture toughness of 9 MPa m1/2, which is much higher than that of both single phase TiB2 (6 MPa m1/2) and Al2O3 (4 MPa m1/2) ceramics.

Carbon (Graphene/Graphite)

Carbon is the sixth element of the periodic table with the ground state level 3P0 and electron configuration 1s 2 2s 2 2p 2, which is hybridized to form sp 1, sp 2 and sp 3 chemical bonds between atoms.

Carbon Nano/Microstructures for Hybrid Hydrogen Storage Based on Specially Treated Carbon Fibers

The fabrication of carbon 3D-nano/microstructures based on the nanostructure deposition from gas phase on the surface of specially treated carbon fibres is proposed as an initial preparative stage to produce a carbonaceous scaffold for hybrid (adsorption-absorption) hydrogen storage materials. This materials design approach is focused toward the hybrids/composites, which could combine the capacity of compounds consuming hydrogen chemically with high specific surface area of systems adsorbing hydrogen intensively by physisorption. The fullerene molecules in the reaction zone can serve not only as a source of carbon pair (arc discharge) but as the catalyst of synthesis of carbon nanostructures (pyrolysis of hydrocarbons). In the present work the carbon fibres were impregnated by fullerene solution in toluene that catalyzed the process of carbon nanotubes growth at the fibres surface.