International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Compositions of mechanoactivated silicatecontaining particles used as modifiers of polymer matrices have been developed. The morphology, particle sizes of the modifier, the nature of their distribution in the polymer matrix, as well as the topography of the friction surface of samples from modified polymers were studied using scanning electron and optical microscopy. Introduction of mechanically activated particles in concentrations from 0.01 to 2 wt. % into the polymer matrix of a reactoplastic polymer based on epoxy resin leads to multilevel modification, expressed in a change in the morphology of the test sample at the supramolecular, intermolecular and molecular levels. The effect of additives of nanophase modifiers on the wear rate of the developed nanocomposite materials is investigated. The introduction of composite mechanically activated nanodispersed particles into a reactive polymer based on epoxy resin leads to a decrease in the coefficient of friction in the studied range of modifier concentrations, loads and test speeds. Studies of the morphology of the surface of the analyzed samples have shown the presence of a separation layer on the surface of rubbing bodies, contributing to a significant decrease in the coefficient of friction. In the structure of this coating, the presence of nanophases is observed, which have a positive effect on the wear resistance of the developed composite material.

Chromium coatings were obtained from spent (waste) chromium electrolyte with the addition of nanosized aluminum oxide. The recovery of the waste chromium electrolyte is carried out by the activation of the chromium ions using the addition of Al2O3 nanoparticles. Electrochemically thin chromium films were deposited directly on S235 steel. The recovered chromium electrolyte has a concentration of nanoparticles of Al2O3 up to 10 g/l, which particles act as intensifiers of the electrochemical process. Analysis was performed with a “Polyvar Met” metallographic microscope and a Bruker D8 Advance powder X-ray diffractometer (XRD). The microstructure of the layer and the matrix were examined and the main phases were determined. SEM-EDS analysis of the chromium layer and the steel matrix was performed. The thickness of the obtained chrome coating with aluminum oxide nanoparticles was determined, which varies between 5 – 10μm.

The article presents the results of studies of the structure and properties of nanodispersed silicon carbide particles using the method of infrared spectroscopy of disturbed total internal reflection, as well as electret thermal analysis. Temperature ranges of the occurrence of TST in the polymer matrix have been established, which may be due to the processes of melting and oxidation of the polymer matrix, accompanied by the release of charge carriers. The activity of silicate-containing particles used to modify polymer matrices has been analyzed. It has been shown that the introduction of SiC particles into the polymer increases the intensity of TST peaks. The prospects of using ultrafine SiC particles obtained from natural raw materials for the modification of polymer materials are considered.

The article considers the influence of various technological methods for obtaining nanosized silicate-containing particles. Each of the methods has its advantages and disadvantages, none of them is universal. It is shown that, depending on the methods of formation of particles, their activity changes. Silicon carbide particles obtained as a result of the thermolysis process with preliminary chemical treatment from natural raw materials of organic origin are of interest for further research. These particles have an increased charge activity in relation to other studied classes of charged particles.

Removal of heavy metals ions from water sources still represents a challenge and different materials are being developed in order to overcome it. Iron oxide nanomaterials receive a lot of attention because of their small size, high surface area, biocompatibility and low cost. However, most of the reported synthesis methods are multi-step and time-consuming. We investigated the co-precipitation method for the synthesis of nanostructured hematite prepared at different temperatures and different calcination times. The obtained materials were characterized by X-ray powder diffraction, scanning electron microscopy and infrared spectroscopy. The adsorption capacity for Pb(II) ions was found to be about 6–12 mg of adsorbed Pb(II) per gram of adsorbent.

Nanotechnology has grown in popularity due to the enormous potential for producing materials and products with diverse properties, allowing significant advancement of existing technology and the development of new innovative technologies. Nanomaterials behave differently at the nanoscale than their conventional counterparts, opening exciting new possibilities in a wide range of construction applications. Nonetheless, the lack of information on nanomaterials’ suitability, high costs, and health risks limits their use in construction and structural engineering. As a result, research must be conducted to provide accurate information and facts about the properties and performance of nanomaterials under various load conditions, as well as information on the advantages of using nanomaterials over other construction materials. This paper provides information on nanomaterial properties and how they affect structural materials’ microstructure and mechanical properties. It also demonstrates the benefits of using nanotechnology and suggests new possibilities.

Two novel types of electrochemical sensors were obtained by chemical deposition of Pt and MoO2 nanoparticles onto multi walled carbon nano tubes (MWCNT) and used for determination of frequently used pesticides clomazone and oxyfluorfen in aqueous media via differential pulse stripping voltammetry (DPSV). Clomazone was determined in 0.1 M phosphate buffer solution at pH 7.0 in the concentration range 0.61-20.56 ng cm-3, with LOQ = 0.61 and LOD = 0.38 ng cm-3. Oxyfluorfen was determined with good reproducibility (RSD <2.4%) in the concentration range 2.5-34.5 ng cm-3, with r = 0.99 and a LOQ of 1.5 ng cm-3. Results were in the same range measured by HPLC/DAD, which was used as comparative method. Structural characterization of the dopped MWCNT performed by Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron (HR-TEM), and X-ray crystallography revealed a preserved MWCNT structure decorated with well dispersed species of the platinum and MoO2 nanoparticles

The structure of the bulk crystals allow to determine the habit of the nanocrystales on their base only as a source point. It is impossible to neglect the size, form and influence of surface. The liquids surface relatively quickly passes to equilibrium form when free energy is minimum. Debye’s temperature is rather arbitrary parameter. Its determination is based on some approach. However this parameter is introduced to the reference books and is broadly used in the crystal physics. Proposed strategy allows defining habit maximum size of nanoparticles on the base well known physics representations. The L–value is determined the bounder between sizes where it can be done value description and where it’s necessary to take into account the particle sizes.

The physical properties of nanoparticles as modifiers are depend on their geometrical characteristics. These objects have 5- and 10-axis symmetry which is forbidden for crystals. The 3×3 matrices-generators of point groups of rotation in crystallographical and crystallophysics basises have as matrix elements 0 and ±1, except groups hexa- and trigonal in H-basis crystals. But these lattices too have 0 and ±1 as matrix elements for matrical representation of point moving in crystallographical basis. For describing the point groups of pentagonal and decagonal symmetries, instead of crystal lattices the so-named general regular lattices (GRL). The two dimensional GRL is known as Penrose’s sets. For 3-d pentagonal sets there are 14 groups of point symmetry, which are not crystallographic because their elements may be golden ratio.

A methodology was developed for the casting of samples of AlSi7Mg alloy modified with nanocomposites (NCs). The following NCs were used: SiC + Cu, AlN + Cu + Al, TiN + Cu, SiC + Al, SiC + Ag Cu, where Ag and Al are cladding metals. The introduction of the nanocompositions takes place in the crucible of a furnace. A thin-walled cylindrical casting mould is used on whose axis is installed a protected thermocouple to measure temperature variation as a function of time. The effect of NCs on overcooling and on sample structure is established.

The influence of various factors on the processes of nonequilibrium crystallization of dipeptide (DPT) from its aqueous solutions has been studied. The nonequilibrium crystallization leads to the formation of spatially heterogeneous structures. Depending on the charge of the DPT molecule (neutral or anion), not only the morphology of the surface of the layers changes, but also its electronic structure. The important role is played by the properties of the substrate-layer interfaces, which are responsible for the formation of ferroelectrics on gold during the crystallization of the DPT anion. The structure of the solid layers is also significantly affected by charges on the substrate surface, which can partially or completely compensate for the charges of individual functional groups in the PT molecule. The observed effects of bipolar resistive switching in peptide layers and the formation of ferroelectrics can find practical application as a smart material of memristor organic lectronics.

The present work reports on a new silicotungstic acid catalyst supported on graphene (HSiW/G). The deposition was performed by sonochemical method proven as an effective technique for the synthesis of the supported catalysts. The catalyst (HSiW/G) was characterized using a variety of physico-chemical methods as TEM, HR SEM, DLS, FTIR and Raman spectroscopy. Homogeneous distribution of HSiW on the surface of graphene was demonstrated. Hydrolysis of biomass for the production of glucose was studied. The hydrolysis of glycogen was performed with a HSiW/G catalyst by hydrothermal treatment. The yield of glucose (65 wt%) obtained was about 8 times higher than that obtained with the same amount of bare HSiW. Stability of the HSiW/graphene even after 3 repeated uses was confirmed. The mechanism of enhancement of the catalytic activity was discussed in terms of a special interaction between the graphene support and HSiW and also the appearance of hydrophobic cavities on the surface of graphene.