Density and surface tension of molten alkali halides and their binary mxitures

The density and surface tension of molten alkali halides and their binary mixtures with common anions and cations are measured as a function of temperature and ionic composition. The equations are derived for their temperature dependences, with experimental error being given on a confidence level 0.95. The molar volume of the mixtures is found to deviate from additive quantities towards greater values, the deviation growing as the difference in the size of ions replacing each other increases. The relations of surface tension to molar volume of molten alkali halides were obtained. Their molar excess free surface energy, enthalpy and entropy in the surface monolayer are estimated from epxerimental data. The surface adsorption of ions in the mixtures is evaluated. It is shown to be governed by the difference in the size of ions substituting each other.     

Effect of Bound Water on the Fractal Geometry of Nanosized Cracks in Glasses Prepared by Vacuum Pressure-Assisted Sintering

The vibrational properties of fractal nanocracks in vitreous SiO₂samples prepared by vacuum pressure-assisted sintering are investigated by low-frequency Raman scattering spectroscopy. In the Raman spectrum, nanosized discontinuities with a fractal geometry manifest themselves in a specific frequency dependence of the scattering intensity: a monotonic decrease in the intensity according to the law of light scattering by acoustic vibrations localized on fractals is observed instead of the boson peak. The frequency dependence of the low-frequency Raman scattering intensity is analyzed for samples of different origins. A smoothing of the nanocrack profile with a decrease in the amount of bound water in the material is revealed.     

Patterns of extractive leaching of uranium and vanadium from an ore

The possibility of performing direct extractive leaching of uranium and vanadium from refractory ores that are preliminarily treated by the method of granular sulfatization, omitting the stage of sulfuric-acid leaching, was studied. The influence of the addition of water and the residual acidity of an ore on the process of extraction was determined.     

Plasma–melt processing of carbon-containing raw materials

The experimental and theoretical studies of the gasification of solid organic compounds by a melt technology were carried out for the two types of carbon-containing materials: slime and tar. The experimental works and the simulation showed that this gasification method can be used for the effective utilization of oilrefining and petrochemical-processing wastes with the simultaneous production of high-purity synthesis gas.     

Combustion synthesis and tribological properties of SiALON-based ceramic composites

β-Sialon-based composite ceramics with varied BN, TiN, TiB₂, SiC, and ZrO₂ contents were fabricated by infiltration-mediated combustion under high pressure of nitrogen gas. Friction and wear behavior of synthesized composites were explored as a function of their microstructure, phase/elemental composition, density, and pore size distribution.     

Combustion synthesis and luminescence properties of Eu-doped Ca–α-SiAlON

Investigated were the combustion synthesis of Eu-doped Ca–α-SiAlONs and their luminescence properties. Experimentally established were (a) green compositions ensuring maximal extent of conversion, (b) influence of elemental composition on phase composition and microstructure of synthesized Ca–α-SiAlONs, and (c) influence of elemental composition on the excitation and emission spectra of Ca–α-SiAlON luminophors.     

Thermal explosion of a mechanically activated 3Ni-Al mixture

Results of studying the thermal explosion of 3Ni-Al mixtures after their preliminary mechanical activation in a planetary ball mill are described. Reduction of the initiation temperature and effective energy of activation of interaction between the reagents to anomalously low values is found. Results of an x-ray diffraction analysis and an electron-microscope study of the thermal explosion products and initial mixtures with different times of mechanical activation are given.