Grain-oriented electrical steel (GOES) is characterized by a strong crystallographic texture, which is crucial for its magnetic properties. However, this texture also induces significant anisotropy in its elastic characteristics, which is less studied but important for manufacturing and application. This work investigates the anisotropy of the elastic modulus in GOES at different stages of its production - specifically after the first cold rolling (CR1), after subsequent decarburization-recrystallization annealing (DRA), and after the second cold rolling (CR2). The study employs a combined approach using Electron Backscatter Diffraction (EBSD) for texture analysis and Dynamic Mechanical Analysis (DMA) for direct measurement of storage modulus. Using the EBSD analysis the evolution of the crystallographic texture across the manufacturing stages was studied. The key texture components were qualified and quantified by 20 degrees deviation of standard crystallographic directions <100>, <110> and <111> from CR axes: RD, TD and ND. These data were compared to the spatial maps of Young's modulus, showing a uniform distribution in the rolling direction (RD) and the greatest dispersion of values in the normal direction (ND) for all processing stages. The maximum modulus values were consistently observed in the transverse direction (TD). A comparative analysis demonstrated a correlation between the elastic moduli values obtained via EBSD calculations and direct DMA measurements. A more significant divergence was noted for the thinner CR2 sheet (0.27 mm), which is attributed to the specific stress state during three-point bending in DMA, which amplifies the contribution of the near-surface layers.
Fluorinated nanometer-scaled diamond particles (NDs) C26F32, C84F64 and C148F96 have been theoretically investigated using the dispersion-corrected density functional theory. We justify that fluorinated NDs are more thermodynamically stable than fluorinated fullerenes of comparable size due to the stronger C-F bonds. Consequently, NDs are also more resistant to defluorination. The differences in lengths and energies of C-F bonds formed on the NDs edges and surfaces are discussed in details. We observe that fluorine atoms contribute significantly to both frontier molecular orbitals of fluorinated NDs. The HOMO-LUMO gap has a tendency to decrease with the ND size. The electron density transfer from the carbon core to the fluorine shell is found to be about 0.1 electrons per fluorine atom. Global optimization of the polymethyl methacrylate (PMMA) + ND configuration have been carried out with the genetic algorithm. A weak interaction of fluorinated NDs with PMMA polymer has been established. The concrete value and sign of the binding energy depends on the ND size. The electronic orbitals of NDs almost do not hybridize with those of the PMMA, so the optical properties of NDs into the polymer matrix remain unchanged. The paper discusses the effect of ND coating with fluorine and other functional groups on the mechanical and optical characteristics of the resulting NDs / polymer composite.
Ti-Zr-based alloys have a valuable property: the element ratio can be selected so that the neutron scattering length is reduced to zero, eliminating Bragg reflections. This property makes Ti-Zr-based alloys highly useful in neutron diffraction experiments, where certain devices must be placed directly in the neutron beam. This work studies the potential of as-melted Ti-32.4Zr alloy and thermomechanically treated and laser powder bed fused Ti-18Zr-15Nb shape memory alloy as materials in direct contact with specimens in a neutron beam - for example, in powder containers or pressure gas cells in neutron diffraction experiments. As a result, all tested alloys have no pronounced Bragg reflections of the neutrons. Their linear neutron attenuation coefficient is on similar level and about 1.7 times lower than those of commonly used vanadium. Reference silicon powder can be easily studied by neutron diffraction experiment in a custom-made container of the Ti-32.4Zr alloy with thick (2.5 mm) walls. Functional properties of Ti-32.4Zr and Ti-18Zr-15Nb alloys are on a similar level, while Ti-18Zr-15Nb alloy has a significant advantage due to ease of manufacturing and material availability. Thus, the Ti-18Zr-15Nb shape memory alloy is a promising candidate for devices staying in the direct contact with the specimen and placed in a neutron beam and which should be transparent to neutrons not to affect the results of the experiment, as for example fixtures, the powder container, pressure gas cells, high-pressure cell elements and gaskets in a neutron diffraction experiment.
A composite based on the conductive polymer PEDOT:PSS and unique graphene flakes has been developed, which can be used in various health monitoring technologies. Graphene's unique properties are due to the dry synthesis method. Using plasma generated by a direct current plasma torch at 350 Torr, the flakes were produced in uniform sizes. Modes for producing nanostructures with a minimum lateral size of 100 nm have been developed. A technique has been suggested for preparing the nanostructure suspension for two-dimensional (2D) printing of active films on substrates. The printed structures were tested as wearable sensors for human sweat glucose, and exhaled air analysis, as well as humidity and touch sensors. The possibility of analysis of various solutions using such sensor substrates as non-woven fabric (spunlace) and polycarbonate fishing line has been demonstrated. As a result, simple and accessible diagnostics of the human nervous system and detection of enhanced reactions to various external influences are offered. In the systems presented, the sensor conductivity surges in response to the chemical reactions occurring between the graphene surface and the liquid components. In general, due to the use of plasma-synthesized flakes, sensors that combine the simplicity and low production cost technology with high sensitivity have been manufactured.
The theoretical research of the potential existence and synthesizability of novel nanostructured diamond-like carbon clathrates has been carried out. Within the framework of density functional theory calculations, two previously unknown orthorhombic clathrate structures, C24 and C28, have been identified. The crystal lattices of these diamond-like compounds belong to the spa & scy;e group Pmmm and are characterized by five crystallographically inequivalent atomic positions. The C24 clathrate, composed of polyhedral blocks C20, C24, and C28, should be stable up to at least 500 K, whereas the C28 clathrate is stable only at low temperatures or high pressure. The cohesive energy of the most stable clathrate (C24) is less than the corresponding energy of diamond by 0.299 eV / atom. The densities of the new clathrates and their bulk modulus are lower than those of diamond by at least 14 % and 24 %, respectively. The orthorhombic clathrates are expected to be wide-bandgap semiconductors with bandgap in the range from 3.7 to 4.0 eV. The research has revealed that ultrathin hybrid carbon layers, consisting of sp2 and sp3 hybridized atoms, are the most plausible clathrate precursors. For the first time, it has been established that the structural variant of clathrate CA6 (carbon sodalite) can be obtained via high-pressure compression of crystals composed of layered or molecular precursors. In particular, CA6 clathrate can be formed by the process of strong compression of graphite consisting of L4-6-12 graphene perpendicular to the planes of the graphene layers when the pressure reaches approximate to 29 GPa. The pressure required for complete structural transformation of precursors into this diamond-like phase can be significantly reduced to 1.1 GPa if hydrostatic compression of dense fullerite composed of C24 clusters is applied. The experimental identification of the new carbon clathrates can be accomplished using calculated powder X-ray diffraction patterns and Raman spectra.
