Формирование состава и характеристик поверхности хромоникелевой стали 12Х18Н10Т при лазерном модифицировании в слое экспериментальной легирующей обмазки

The results of an experimental study of laser pulsed modification of the surface of stainless steel 12CR18NI10T in a layer of alloying compound made of graphite paste and nanodispersed titanium dioxide powder (anatase) and without coating are presented. A comparative analysis of the effect of the coating on the elemental and phase compositions, morphological characteristics and microhardness of the modified surface is carried out. It was found that as a result of the treatment, the processes of cementation and oxidation of the surface occur, which made it possible to obtain a mixture of iron carbide and high-strength oxides in the surface layer of steel. In the samples that underwent laser treatment in the coating layer, an increase in the intensity of the diffraction peaks of the graphite phase and the formation of iron oxides Fe3O4 and chromium Cr2O3 with the presence of titanium dioxide TiO2 were revealed, which created a mixed heterophase metal oxide structure with increased mechanical strength. An increase in the microhardness of the modified surface after laser pulsed scanning in the layer of the experimental alloying compound is established.

Anomalous evolution of the ion-induced surface relief of highly oriented pyrolytic graphite

The modification of the surface of highly oriented pyrolytic graphite (HOPG) under 10, 20 and 30 keV Ar+ ions irradiation with fluence 1018 cm−2 at the irradiation temperature of 250°C has been studied experimentally. An anomalous growth of the ion-induced surface relief of HOPG have been found. This effect, like the well-known effect of anomalous deep embedded argon ions in HOPG, is analyzed within the framework of plastic deformation mechanisms in graphite.

Investigation of the effect of laser surface modification on the hardness and wear resistance of a titanium alloy

The effect of laser modification of the surface on the value of the coefficient of elasticity, hardness, coefficient of friction and the amount of wear of the counter body when testing products made of a deformable titanium alloy was investigated. It was found that the indicators of hardness and wear resistance of a titanium alloy depend on the modes of laser modification. These dependencies are extreme in nature, they have maxima and minima. The quantitative values of hardness and wear resistance indicators for the specified material before and after laser treatment of its surface in various modes are given.

Effect of modification on the physical, mechanical and relaxation properties of the polymer - nanodispersed graphite system

The paper analyzes the physical, mechanical and relaxation properties of the polychlortrifluoroethylene (PCTFE) - modified nanodispersed graphite (TEG) system. It has been shown that the modification of the surface of conducting carbon nanoplates with ultradispersed dielectric silicon dioxide (SiO2) (30%) leads to a nontrivial effect - an increase in the electrical conductivity of the PCTFE - 2.5% TEG/30% SiO2 composite by more than two orders of magnitude in comparison with the PCTFE - TEG composites, containing unmodified carbon nanoplates. The functionalization of carbon nanoplates was carried out by treating the particle surface with an active solution of chlorosilane in an organic solvent, that in case of hydrophobization of the filler surface, leads to an increase in the system percolation threshold. It is shown that the method of hydrolyzation of the filler surface can be highly effective due to a directed change in some, in particular, shielding, properties of polymer composites based on nanocarbon. It is established that the modification of the nanofiller (dispersed thermoexpanded graphite) increases the intermolecular interaction of the filler-matrix. Depending on the concentration of the filler, the structure of the matrix and the system as a whole demonstrates dynamic transformations in the size of the heterogeneity of the structure. Ultrasonic studies of composites have shown that the smallest size of structure inhomogeneity is achieved in the range of concentrations of percolation development, and the change in the size of system structure inhomogeneity is associated with the transition from inhomogeneity as the size of crystallites activated by nanofiller at low concentrations associated with coagulation of nanoparticles at concentrations exceeding the percolation threshold. Thus, in the case of nanofillers, it is impractical to use concentrations that significantly exceed the percolation threshold, as this leads to coagulation of the filler particles and the relative loosening of the matrix.

Investigation of electrolysis-related modification of graphene films in biosensors

In this work, the modification of the surface parameters of graphene chips after electrolysis treatment in a NaClO4 aqueous solution has been studied. Two electrolysis modes have been analysed. In the first one, a negative potential (-0.2 V) is applied to the graphene chips, while in the second one the potential is positive (0.8 V). Investigation using a number of techniques including atomic force microscopy, Kelvin probe force microscopy, Raman spectroscopy, measurements of current-voltage characteristics and low-frequency noise has shown that the electrolysis mode with application of a positive potential on graphene chips decreases the 1/f noise and allows one to obtain a uniform surface potential distribution while leaving the graphene structure undamaged. The results of this study help to understand the efficiency and reproducibility of the procedure for electrolysis treatment of graphene chips.

FUNCTIONALIZATION OF THE SURFACE OF HYPERCROSSLINKED POLYSTYRENE FOR CATALYST SYNTHESIS

Нанесенные наноразмерные катализаторы широко используются в различных процессах химической технологии. При этом особые требования предъявляются к носителю, используемому при синтезе катализаторов. Сверхсшитые полимеры являются перспективными носителями, однако зачастую не имеют требуемых свойств (например, кислотности). Для придания дополнительных свойств возможно модифицировать поверхность полимеров различными веществами или функциональными группами. В данной работе проведено исследование способов модификации и веществ-предшественников кремнийсодержащей фазы для модификации поверхности сверхсшитого полистирола диоксидом кремния. The supported nano-scale catalysts are widely used in different fields of chemical engineering. For the catalysts, the certain requirements are specified fort the catalyst supports. Hypercrosslinked polymers seem to be the prospective materials for the catalyst synthesis. However, polymeric matrices often do not meet some standards for catalyst supports (i.e. polymers are inert materials and do not have the acidic or basic properties). To infuse the additional properties to polymers it is possible to modify its surface with different compounds or functional groups. In this work, the study of the ways for the modification of the surface of hypercrosslinked polystyrene and silica-phase precursors was carried out.

Physicochemical and Biological Properties of Graphene-Oxide-Coated Metallic Materials

In this article, we present graphene oxide (produced by a modified Hummers’ method) coatings obtained using two different methods: electrophoretic deposition on 316L stainless steel and chemical modification of the surface of gold applied to the steel. The coating properties were characterized by microscopic and spectrometric techniques. The contact angle was also determined, ranging from 50° to 70°. Our results indicated that GO coatings on steel and gold were not toxic towards L929 cells in a direct cell adhesion test—on all tested materials, it was possible to observe the growth of L929 cells during 48 h of culture. The lack of toxic effect on cells was also confirmed in two viability tests, XTT and MTT. For most of the tested materials, the cell viability was above 70%. They showed that the stability of the coating is the crucial factor for such GO coatings, and prove that GO in the form of coating is non-toxic; however, it can show toxicity if detached from the surface. The obtained materials also did not show any hemolytic properties, as the percentage of hemolysis was on the level of the negative control, which is very promising in the light of future potential applications.