Materials Science Forum Vol. 970

Abstract: The effect of complex high-energy action, including mechanical milling of Li₂CO₃-Fe₂O₃-ZnO initial reagents mixture and its consistent heating by the pulsed electron beam on solid-phase synthesis was studied by X-ray powder diffraction and thermal analyses. The initial mixture Li₂CO₃-Fe₂O₃-ZnO corresponds to the ferrite with stoichiometric formula: Li_0.5(1–x)Zn_xFe_2.5–0.5xО₄, where х = 0.2. The same studies were carried out with thermal heating in a laboratory furnace for detection the effect of radiation on the formation of phase composition lithium-zinc ferrite. Initial mixture was milled in AGO-2S planetary ball mill with a milling speed of 2220 rpm for 60 min. Radiation-thermal synthesis of the milled mixture was carried out by the pulsed electron accelerator (ILU-6) at 600°C and 750°C. The maximum time of the isothermal stage was 60 minutes. According to the X-ray powder diffraction and thermogravimetric analysis, it was found that the complex high-energy action leads to decrease a temperature and time of obtaining lithium-zinc ferrite homogeneous in phase composition. The proposed high-energy regimes allow to synthesized lithium-zinc ferrites at 600 °C for 60 minutes, which is much lower compared to conventional ceramic technology.

Abstract: The article presents the study of factors affecting the ability to control the self-propagating high-temperature synthesis of nanomaterials. It is established that there are two steps in the combustion process nanomaterial: burning of surface layer and deep combustion area, which can be considered as the thermal explosion. It was found that the surface roughness and the thermal conductivity of the substrate do not affect the combustion front velocity. The presence of glass transition on the substrate surface also does not affect the velocity of the front. It was established that the parameters of the deep combustion area do not depend on the nature of the initiation of combustion, being the second stage of the development of combustion; in all cases this stage is characterized by the same parameters. When varying the type of ignition source, the length of the surface burning front can vary up to 33%. The time of induction of a thermal explosion increases when the bulk layer of powder ignites from above.

Abstract: The effect of intensification of the compaction rate of ferrite compacts under irradiation conditions with a high-power electron beam both in the heating regime and in the isothermal stage of sintering was established. The compaction mechanisms of the compacts are different at each of these stages. The intensification of compaction at the non-isothermal stage in radiation-thermal conditions is due to processes involving the liquid phase. The role of bismuth oxide in the compaction of the material at the isothermal stage of sintering is unessential, but its influence is significant in recrystallization processes. Under of Ivensen’s phenomenology, compaction curves are explained by the deceleration of annealing of structural defects responsible for the fluidity of the material. Dislocations are the most probable type of defects, satisfying the detected regularities.

Abstract: Superlattice formation in thin layers of oxidizing crystals and the effect of near-surface proton saturation on structure ordering, formation and periodical distribution of quantum wells have been discussed. The paper shows, it is necessary to develop non-Euclidean approach to the crystal’s internal geometry and consider, in consecutive order, the question of the four-dimentional Riemannian space into three-dimentional Eucliden space interpretation (R_E interpretation).

Abstract: The effect of the formation and heat treatment modes of silicon-carbon coatings deposited by ion-beam sputtering of silicon carbide on their morphology, chemical and phase composition is determined. It has been established that an increase in the power of the ion source from 432 W to 738 W leads to a decrease in the sp³/sp² phase ratio by 1.7 times and an increase in the ratio of Si-C/Si-O bonds by 1.9 times. It is shown that doping of carbon coatings with silicon carbide increases their heat resistance.

Abstract: A new automated smartphone-based assay for metals ions determination based on the color reaction with organic ligands was developed. Quantification was performed by measuring the color of the polymer optode. This offers a smartphone-based alternative to the colorimeric method for signal treatment usually employed in automatic methods. The technique enabled linear calibration within the range 1–500 ppb of metals ions. The sampling time used for this concentration range was 15 min. The method was also tested for the quantification of metals ions in water samples, followed by digital image treatment of the optode. The automated detection metals ions approach was demonstrated by applying smartphone to the analysis of metals ions. Relative recoveries of the analytes ranged from 87 % to 105 %. The described procedure has the potential to be a fully automated online smartphone platform for the purpose of routine onsite water analysis.

Abstract: The study focuses on the effect of low-frequency noise on resistance converter of teraommeters to test cable insulation. A mathematical pendulum was used to simulate low frequency electromagnetic interference. It was found that the greatest effect is exerted by dynamic effects of electrostatic charges that accumulate on the printed circuit board, electronic components, structural elements of the resistance-to-voltage converter, and on the test cable sheath. The effect of constant and alternating magnetic fields on measurement of resistance of insulating materials is insignificant.

Abstract: This paper describes the physics of the interaction of the eddy current probe and the delamination in multidirectional carbon fiber reinforced polymer (CFDR). Currently, there is an opinion that eddy current signals obtained due to delamination in multidirectional CFRP are caused by the redistribution of the vertical eddy current arising from the excitation of eddy currents in the sample by a rectangular coil whose surface is orthogonal to the surface of the sample. The analysis performed by us shows that the possibility of creation and deformation of the vertical eddy current is very questionable, and that the observed eddy current signals associated with the delamination are most likely caused by carbon fiber plies misalignment towards the sample surface. In this paper was compare eddy-current signals from the delamination in CFRP in samples where the existence of vertical eddy current is possible in theory and in samples where this is not possible. The obtained signals had similar measurements, and this indirectly indicates the doubtfulness of the hypothesis of the delamination detection in CFRP samples due to vertical eddy current.

Abstract: A comparative analysis of the structural characteristics of LiZnTi ferrites sintered at the temperature of 1280 and 1360 K was performed. The qualitative and quantitative X-ray diffraction (XRD) analysis of the samples, main phase structural analysis, and unit cell parameters were carried out using the non-standard method (Rietveld method). Diffraction patterns were recorded on an ARL X'TRA diffractometer in the CuKα₁₊α₂ and CuK_β scanning modes.

Abstract: Implants made of porous SHS-TiNi alloys are successfully used in medicine to replace solid tissues of the human body. Self-propagating synthesis reaction of TiNi alloy was carried out through layer-by-layer combustion. XRD analysis of the phase composition and structural parameters of porous N_i50Ti₅₀ alloy, as well as microscopic studies, were carried out. The structural methods employed in the study showed that the surface of porous SHS-TiNi alloys is a complex of dense layers of amorphous-nanocrystalline intermetallic oxycarbonitrides saturated with O, N, C intercalation impurities. The study of the surface layer S showed that the layer S consists of three layers: the foam layer F and two sublayers. Samples were studied for the nonuniform potential distribution in the cross section of interpore partitions. It was shown that they correlate with the structural phase inhomogeneity of the SHS-TiNi alloy. The structural studies carried out using different methods allowed us to reliably establish the presence of surface nonmetallic phases in the form of surface films and grain boundary inclusions formed during the self-propagating reaction synthesis of the porous TiNi alloy. High biochemical compatibility is ensured by specific surface layers of the porous alloy formed in the process of its metallurgy, which do not require additional surface modification.