Materials Science Forum Vol. 1031

Abstract: Water dispersions of shungite carbon (ShC) nanoparticles were used for modifying the particle surface of ZnS:Cu, commercial electrophosphor. The EPR spectrum of ZnS:Cu powder has parameters consistent with the paramagnetic centers of Mn⁺². Modifying the phodphor surface with ShC nanoparticles results in a non-monotonic change in line width, amplitude and integral intensity caused by nanoparticle concentration, which correlates with variations in the brightness of electroluminescence. Variations in the parameters of spectral lines with nanoparticle concentration and UHF saturation power are interpreted in terms of modification and creation of additional dislocations in the subsurface layer of phosphor with new physico-chemical properties.

Abstract: The article presents the results of comparative studies of the stress-strain behavior of duck-foot tines made of steel and isotropic fiberglass. The studies were carried out on full-size 3D models of the SKP 01.08.080 (1) part being used on SZS-2.1 type seeders of various manufacturers widely spread in our soil and climatic zone. For the research, we used specialized software: CAD Autodesk Inventor and SolidWorks CAD/CAM system. Models were fastened and loaded using a distributed force of 650 N applied to the toe and wings of a duck-foot tine corresponding to the draught resistance of the part under conditions of its real operation at a speed of movement of up to 2.23 m/s. It has been shown that the deformations occurring in a duck-foot tine made of fiberglass 5...6 mm thick have a magnitude of 1.5...2 times less than those in a steel tine, the strength reserve factor of the steel and composite parts is the same and equals 15, however, its distribution over the part surface is uneven, so the predicted life cycle of the fiberglass part will be 2 times longer than that of the steel part.

Abstract: The article presents the technological scheme of the “stretching-over” hybrid technology, when the workpiece is simultaneously affected by two sources of loading: static and dynamic. It is proposed to use a pulsed magnetic field as a dynamic load. In this case, the tightening punch is equipped with an inductor connected to a magnetic-pulse unit. As a result of computer simulation, the distribution patterns of the stress-strain state in a tight-fitting workpiece were obtained both in the case of a conventional tight-fitting and with the proposed hybrid one. It was found that exposure to a pulsed magnetic field changes the stress-strain state, making it possible to intensify the stretching process.

Abstract: It is important to take into consideration the new fullerene derivatives genotoxicity. In the present is study, we analyzed the new water-soluble fullerene C70 (F350) effects on the human embryonic lung fibroblasts (HELF) oxidative damage and DNA breaks. We found that the studied compound causes cellular DNA damage and affects the transcriptional activity of cell cycle and cell apoptosis regulating genes.

Abstract: The procedure for determining the activation energy of conductivity Е_κ is analyzed depending on the temperature step ΔT. It is shown that with increasing ΔT, the error in the calculation of E_κ decreases, but the calculated value of E_κ decreases. In order not to lose the temperature dependence of the activation energy, it is necessary to choose the optimal value of Δt. In our opinion, this value should not exceed 5 – 10 °C. Taking into account the decrease in concentration with increasing temperature due to a decrease in density has virtually no effect on the accuracy of determining E_κ, provided that ΔT is 5 – 10 °C. It has been shown that in the temperature range 20 – 80 °C, the activation energy of conductivity decreases with increasing temperature. This decrease is due to the rupture of intermolecular hydrogen bonds of the solvent with increasing temperature. It was suggested that the movement of ions in an aqueous solution may be accompanied by the breaking of hydrogen bond of the solvent.

Abstract: Experimental studies of bending deformation of carbon - and fiberglass samples after 8-month exposure in full-scale conditions were performed and the modulus of transverse elasticity was determined. It was found that the influence of the external environment on fiberglass samples is more significant. For carbon fiber, there was an average decrease of 7.1%, and for fiberglass-by 14%. Modification of samples in ultrahigh frequencies (UHF) electromagnetic field reduces the negative influence of the environment: the values of the transverse elastic modulus of carbon fiber and fiberglass samples are reduced by 5% and 11%, respectively. It is shown that the UHF electromagnetic field in rational modes can increase the modulus of transverse elasticity of carbon fiber by (27-30)%, fiberglass – by (20.8-25.6)% with a significant increase in the uniformity of this parameter. Experimental studies of the bending deformation of carbon-and fiberglass specimens after 8-month exposure in natural conditions have been carried out, and the shear elastic modulus has been determined. It has been established that the influence of the external environment on fiberglass samples is more significant. For carbon fiber reinforced plastic, a decrease was noted on average by 7.1%, for fiberglass - by 14%. Modification of samples in a microwave electromagnetic field helps to reduce the negative influence of the external environment: the values ​​of the shear modulus of the prototypes of carbon fiber reinforced plastic and fiberglass are reduced by 5% and 11%, respectively. It is shown that the microwave electromagnetic field in rational modes allows increasing the transverse elastic modulus of carbon fiber reinforced plastic by (27-30)%, fiberglass - by (20.8-25.6)% with a significant increase in the uniformity of this parameter.

Abstract: The influence of electrolysis parameters on the structure and properties of iron coatings is shown. The dependencies of hardness of iron coatings upon the parameters of metal microstructure characterized by dilatation are established. It is shown that dilatation can be used as a checkup parameter for iron strength properties. The influence of some factors on the properties of iron deposits obtained under non-stationary deposition regimes is analyzed.