Vol 52, No 2 (2016)

The results of experiments to reduce the instability of spark load parameters using a model of spatial electrospark dispersion for metal and graphite granules by varying the capacitance of a capacitor bank and charging voltage are presented. The conditions for spark process stabilization in a layer of metal and graphite granules are determined. The influence of the capacitance of a capacitor bank and charging voltage on the efficiency of energy distribution in the discharge circuit is shown.

Features of plasma electrolytic oxidation of the AL25 cast complex-alloyed aluminum alloy are discussed. It has been shown that a variation in the nature and concentration ratio of the electrolyte compo- nents provides the formation of mixed-oxide coatings containing the materials of the basic matrix and the dopant. An increase in the coating thickness and the manganese oxide content in the coating is achieved by the homogenization of the treated surface owing to the simultaneous formation of oxides and the removal of alloying components of the alloy from the surface layers. Current density intervals that provide a uniform distribution of elements in the coating and a high efficiency of the Faraday and thermochemical reactions are determined. It is found that the stoichiometric oxygen index in MnO_x oxides is x = 1.71–1.87. Testing of the synthesized oxide systems in the model oxidation of carbon(II) oxide to CO₂ shows that the ignition and complete conversion temperatures are at the level of values characteristic of platinum catalysts.

It is shown that, during the alloying of the D1 aluminum-based alloy using a tool electrode made of Al–Sn alloy, the surface layer of the electrode becomes enriched in oxides and the elements contained in the cathode material. The presence of the oxides leads to an increase in the electrical resistance of the electrode and to its excessive heating, which reduces the efficiency of alloying; this necessitates the recurrent modification of the working surface of the electrode.

A numerical experiment is used to study expansion of a plasma cloud with complex composition into a vacuum. Under the assumption that the density and temperature of the laser plasma are homogeneous throughout the cloud, the system of differential equations describing the plasma cloud expansion with allowance for inelastic processes is reduced to a system of ordinary differential equations for ions of five elements (Fe, Mn, Cr, Ni, Mo) with the charges z = 1, 2, 3, 4. The velocity of the plasma cloud boundary and its temperature as functions of the expansion time are determined. It is demonstrated that, after recombination stops, thermodynamically nonequilibrium plasma is created as a result of “quenching,” and in this plasma the residual degree of ionization and ion charge distribution depend on the initial plasma parameters T₀, N₀, and R₀. In the course of recombination, the dependence of ion charge distribution on ionization potential weakens.

This paper describes the general features of the functional methods of electrohydropulse, pulse electrocurrent, and magnetic pulse treatment processes of the melt in order to positively vary its crystallizaton ability.

This investigation highlights rationale of solvent bonding and adhesive bonding for fabrication of a transparent polymer such as polycarbonate with a high-throughput process. Studies under ultra violet spectra and visible spectra reveal that in comparison with adhesive bonding of a polymer, solvent diffusion bonding is more transparent. Polycarbonate is hydrophilic in nature resulting in a low contact angle of water as well as the presence of polar functional groups on the polymer surface. It is observed that a lap shear tensile strength of a solvent bonding polymer is significantly higher than that of an acrylic adhesive bonded polycarbonate, and fabrication of polycarbonate by solvent bonding merely takes few seconds. Solvent bonding of a polymer results in a cohesive failure from polymer as analyzed under the scanning electron microscopy, this is why solvent bonding shows a significantly higher bond strength.

The synthesis of lithium, sodium, and potassium bis(salicilato)borates (LiBSB, NaBSB, and KBSB) is carried out by a microwave method, whose application makes it possible to shorten the synthesis duration by 8–10 times and to obtain the product yield close to the quantitative one. The product purity and the nature of impurities are determined by thermogravimetric analysis. Additionally, the structure of the compounds is proved by the IR and NMR spectroscopy. The effect of complexing of salts with amide solvents is revealed.