Experimental study of the suppression of flaming combustion and thermal decomposition of model ground and crown forest fires

This paper presents an experimental study of heat and mass transfer and phase transformations in the suppression of flaming combustion and thermal decomposition of model ground, crown, and mixed forest fires due to local exposure to water. The experiments were carried out with typical combustible forest materials (mixture of leaves, needles, and twigs) and models of trunks and branches of trees. The conditions and characteristics of suppression of the flaming combustion and thermal decomposition of combustible forest materials were determined. It is shown that in the case of crown and mixed fires, local short-term (a few seconds) action of a liquid projectile does not suppress the thermal decomposition of the material (but can only lead to localization of flaming combustion). In the case of ground forest fires, this approach can be efficient with an appropriate choice of the water-irrigated area of the combustion zone and the rate and time of water spraying.     

Effect of thermal annealing on the properties of borophosphate systems containing simulated Cs + Sr radioactive waste fractions

The effect of thermal annealing on the resistance of borophosphate systems to crystallization and the effect of crystallization on the hydrolytic stability of the materials were examined. Systems containing simulated Cs + Sr fraction were studied. Annealing at 400–500°C leads to a noticeable decrease in the leach rate. Annealing at a higher temperature, 600°C, leads to crystallization of the glass and to a considerable increase in the leach rate.     

Effect of the Intensification of Mechanical Processing on the Conversion of the Mineral Matter of Coal Fuel

The influence of intense preliminary mechanical processing in a disintegrator on the conversion of the mineral matter of Kuznetsk black coal was determined. With the use of X-ray spectral fluorescence analysis and a method of coal sample separation based on density, a significant redistribution of the mineral components with the use of an energy-intensive mill (disintegrator) was found in comparison with standard mills utilized in heat-power engineering in terms of both particle-size fractions and density. Crushing in the disintegrator leads to a more uniform distribution of mineral substances over the fractions. A small fraction becomes enriched in mineral elements such as calcium- and iron-containing minerals bound to the organic matter. The separation based on density showed that crushing in the disintegrator leads to a significant decrease in the concentration of iron-containing minerals and a decrease in the portion of organic components in the heavy fraction, as compared with crushing in a ball–tube mill.     

Effect of heat treatment on corrosion of laser-textured aluminum alloy surfaces

The kinetics of electrochemical corrosion of aluminum alloy (AlMg6) surfaces with different wettability was analyzed. The surfaces were processed by three different methods, in particular, polishing, laser texturing, the combination of laser texturing and low-temperature heating. After laser processing, the dimple-like texture was formed on the surface, and the wettability significantly enhanced. Low-temperature heating of laser-textured AlMg6 alloy surfaces led to the wettability inversion from strongly hydrophilicity to superhydrophobicity. Microscopic and profilometric methods were used to estimate the surface degradation due to corrosion when aggressive solution droplets (a mixture of NaCl and hydrogen peroxide aqueous solutions) evaporated. The potentiodynamic polarization measurements of AlMg6 alloy surfaces were conducted. The typical modes of corrosion and evaporation of aggressive solution droplets were detected. The kinetics of corrosion was estimated by the behavior of the corrosion area evolution. In addition, when immersing laser-textured sample with strongly hydrophilic properties into aggressive solution, the higher corrosion rate was found in the liquid meniscus region (aggressive mixture / alloy / air interface) compared to the textured site immersed in the mixture. This was explained by convection increasing the rate of reaction products removal and promoting a stronger deviation from the equilibrium state in the aggressive mixture. Experimental results of the potentiodynamic polarization measurements revealed that laser-textured samples exhibit enhanced corrosion protective properties compared to polished samples.

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Electroreduction of the tantalum oxofluoride complexes in an equimolar mixture of sodium and potassium chlorides

The electrochemical behavior of the tantalum mono-, di-, and trioxofluoride complexes in the equimolar NaCl–KCl melt is studied. The trioxofluoride TaO₃F^2– complexes are shown to discharge at the potentials that are more negative than those of alkali metal cations; that is, they are electrochemically inactive against the background of the equimolar mixture of sodium and potassium chlorides.