Vol 38, No 3 (2016)

The lattice parameters of cubic diamond and rhombohedral graphite under the probable direct transformation synthesis conditions have been obtained by means of linear expansion coefficient and elastic constant. Based on the empirical electron theory in solid and molecules, the valence electron structures (VESs) of graphite and diamond, the covalent electron densities (CEDs), and the relative electron density differences (REDDs) of the diamond growth interfaces have been calculated. It has been found that the REEDs of graphite/diamond interfaces were awfully large and the CEDs were discontinuous at the first order approximation. Not any meaningful atomic state of graphite structure, which satisfied the bond length difference formula, existed on the detonation synthetic conditions. Accordingly, it was considered that the direct transformation from graphite to diamond could not come true from the perspective of VES. In addition, the mechanism of synthesis diamond by explosive detonation was discussed based on the VESs of graphite and diamond.

The effect of catalysts of the carbon nanotubes synthesis and of the technology of a Cu–Co–Fe active oxide mass deposition on the kinetic regularities of the CO oxidation reaction has been studied. It has been shown that the experimental data on both catalysts, bulk Cu–Co–Fe and deposited onto carbon nanotubes, agree with the Eley–Readil kinetic scheme. Based on the suggested mechanism, the effective reaction rate constants have been calculated by various methods. It has been shown that the use of Cu–Co–Fe catalysts deposited on carbon nanotubes offers considerable promise.

The effect of the conditions of cooling after the liquid-phase sintering of tungsten heavy metals have been studied. It has been found that to attain a high ductility of the tungsten heavy metal, the rate of cooling from the sintering temperature should afford removal of the major part of hydrogen, which was dissolved in the alloy volume in the temperature range of the liquid phase existence.

A study of the mechanism of formation of monocrystal planes of different crystallographic orientations has revealed that in polishing of sapphire the surface roughness parameters Ra, Rq, Rmax decrease in the series c > r > m > a with decreasing dielectric permittivity and thermal conductivity coefficient of the workpiece material, debris particle height, and Lifshitz constant that represents the energy of interaction between the polishing powder grains and the workpiece surface. The minimum allowable values of surface roughness parameters for atomically smooth surfaces have been defined, which linearly depend on interplanar spacings and decrease in the series r > a > c > m.

The paper addresses the simplest 3D model—a barrel made of parabolic and circular staves—for a diamond grain in the electroplated coating of dressing tools. It is shown that the proposed concepts of a diamond grain shape provide, on the one hand, an adequate description (including the quantitative one) the experimentally found relations between the parameters of an electroplated diamond coating and, on the other hand, a more detailed information in order to produce coatings with preset characteristics.

The evolution of topology of the B–B₂O₃ phase diagram has been studied at pressures up to 24 GPa using models of phenomenological thermodynamics with interaction parameters derived from experimental data on phase equilibria at high pressures and high temperatures.