Advanced Materials Research Vol. 1085

Abstract: This paper presents the results of development of ecological low-waste “dry” fluoride technology of magnetic material production on the basis of rare-earth metals of the Nd-Fe-B-system. The physicochemical fundamentals are stated and the basic stages of the proposed technology are experimentally examined: the fluorination of raw material with elemental fluorine, the production of compact ingot alloys and addition alloys by the calcium-thermal out-of-furnace reduction of fluorides, the production of magnets with the help of the powder metallurgy method using mechanical or hydride grinding, as well as waste processing.

Abstract: The results of researches of polymer composite materials are given in this paper. The fillers of composites were: hexaferrite BaCo_0.7Zn_1.3Fe₁₆O₂₇; and BaTiO₃, CaTiO₃, Bi₄Ti₃O₁₂ were chosen as the ferroelectric components. Results of the researches of complex permittivity and permeability showed that composite of W-hexaferrite BaCo_0.7Zn_1.3Fe₁₆O₂₇ and CaTiO₃ had the best electromagnetic characteristics.

Abstract: Novokuibyshevsk refinery vacuum gasoil (VG) with a high sulfur content (2.02 % wt.) thermocracking results are represented in abstract. Its density is 909.8 kg/m³. Material balance and fractional composition of liquid products cracking and reduction of sulfur containing in every component of it was established. Based on experimentally measured parameters we calculated gas, liquid, coke yields depending on process conditions. The amount of hydrocarbons and resins-asphaltens components increased in the vacuum gasoil cracking products, but these products have lower molecular weight in comparison to initial object. Cracking liquid products composition, which were gained after vacuum gasoil benzoyl peroxide (BP) oxidation pretreatment, specific differences from VG thermolysis products with BP used as radical forming addition were established.

Abstract: Experimental Stand for Testing Electrochemical Permeation (STEP) of hydrogen through metal foils was constructed and described in this paper. Hydrogen diffusion coefficients in different metal foils at room temperature can be determined by using STEP. Influence of pulsed electron beam irradiation on hydrogen diffusion coefficient in zirconium alloy E110 was investigated. It was established that treatment by pulsed electron beam with the energy density of 18 J/cm², by three impulses with duration 50 μs leads to a decrease in the diffusion coefficient of hydrogen on the order of one. This is due to the fact that structure with more branched crystals’ boundary formed after irradiation and such structure is effective trap for hydrogen. Also there is formation of protective oxide film after irradiation.

Abstract: The thermochemical processes of synthesis and purification of rare earth metals fluorides through the transfer of fluoroammonium complexes were discussed. By differential thermal calorimetry the temperature maxima of rates of formation and decomposition of complex compounds were defined and the values of the apparent activation energy processes were determined. It is possible the use of fluoroammonium systems to develop the preparation of anhydrous fluorides of rare earth metals.

Abstract: In the present work, the formation of the phase composition in the synthesis of lithium-titanium ferrite composition Li_0.6Fe_2.2Ti_0.2O₄ was investigated using thermo-magnetometry method based on thermo-gravimetric measurements in a magnetic field. Results of thermo-magnetometric analysis are compared with X-ray diffraction method data. It is shown that the thermo-magnetometry method better reflects the formation of the magnetic phase in the synthesis of ferrite, and therefore provides a more precise estimate the phase composition of the synthesis products.

Abstract: Multi-Walled Carbon Nanotubes (MWCNTs) cause suppression of rye seeds viability, however in high concentration (1 g/l) they stimulate increase in roots and stems by 20%. At the same time, in low concentrations of MWCNTs root growth suppression is observed, though stimulation of stem growth remains. MWCNTs affect activity of antioxidant enzymes of rye seedlings, thus the greatest stimulation is observed when low and average concentrations of MWCNTs are used. Activity of photosynthetic system of plants considerably increases only when the lowest of the studied concentrations of MWCNTs (0.1 mg/l) is used. Noted tendencies can be considered in further researches of phytotoxic and phytostimulating MWCNTs properties.

Abstract: The results of studies of fiber reinforced cement foam concrete with mineral and synthetic fibers are given in the article. Introduction of fibers in the amount of 0.1-2% of the weight of cement in the foam concrete mixture enables increase in the strength of the foam concrete in 28 days by 2.5 -fold, decrease in the thermal conductivity by 30-40% and the shrinkage strain by 42-90%.

Abstract: This paper introduces a new technique to test fatigue cracks in concrete that occur during its maintenance. The principle of the technique consists of exposing the object to pulsed mechanical excitation. As a result, acoustic waves start to propagate in the sample. Under the action of acoustic waves the dipole moments of double electric layers on the boundaries of components in concrete are changed and piezoquartz which is a part of sand and gravel is polarized. The external electric field occurs and is registered by a signal receiver placed near the object under study. The possibility of using this technique for crack nondestructive control is studied in the paper. The technique capabilities are shown by comparing the parameters of electric response on pulsed mechanical excitation when testing the defectless concrete and the same sample after developing the artificial crack in the concrete.

Abstract: The kinetic of lithium-zinc ferrite synthesis reaction up to temperatures 800°C was studied in air using non-isothermal thermogravimetric analysis. Mathematical treatment of thermogravimetric curves was carried out using Netzsch Thermokinetics software where the kinetic model with minimal adjustable parameters quantitatively describe the synthesis reaction of lithium-zinc ferrite was chosen. It was shown that the experimental TG curves clearly suggest a multi-step process for the ferrite synthesis and therefore a model-fitting kinetic analysis based on multivariate non-linear regressions was conducted. The complex reaction can be best described with a three-step reaction scheme consisting of parallel reaction steps. It is established that the best results were obtained with the using at the first stage the diffusion model of Yander, on the second and third stage were used the reactions of n-order. Kinetic parameters of lithium-zinc ferrite synthesis reaction were found.