Inorganic Materials: Applied Research最新文献

Abstract—An original technique for modifying graphene oxide with iodine has been developed. It is shown that, when graphene oxide is treated with iodine, oxygen-containing groups are removed from the surface of graphene planes, which improves the electrically conductive properties of the material. The change in the structure and electrical conductivity of the modified graphene oxide, depending on the concentration of iodine, has been studied. According to Raman spectroscopy data, it can be seen that the composition of the modified materials includes molecular complexes of iodine ({text{I}}_{3}^{ - }) and ({text{I}}_{5}^{ - }). Changes in the structure of the crystal lattice of iodine-modified graphene oxide films were studied using X-ray diffraction analysis. According to IR spectroscopy, the effect of iodination on the change in the qualitative composition of functional groups in the material was analyzed. The specific electrical conductivity of graphene oxide as a result of modification increases from 9.6 × 10^–10 S/cm for the original material to 3.3 × 10^–7 S/cm for the material treated with an isopropanol solution containing 1 wt % I₂ relative to dry graphene oxide. The additionally modified films were heat treated at 80°C for 2 h. The resulting changes in the structure of the material are analyzed and an increase in electrical conductivity by one or two orders of magnitude is shown.

A process of plastic deforming polymer blanks is developed involving polytetrafluoroethylene (PTFE) and carbon fibers of the UVIS-AK-P grade. The production process is explored from the standpoint of increasing the strength and resistance to creep. The relationship is found between the physics, mechanical, and tribotechnical parameters and the structural composite properties. The composites obtained using various schemes of plastic deforming polymer blanks differ in the character of deformation under tension. They develop different structures and feature various wear patterns. A multidirectional approach to plastic deforming blanks based on PTFE allows obtaining isotropic polymer materials featuring improved strength properties and better resistance to deformation under load.

The influence of plasticizer content (rubber) on the density, microstructure, and properties of WC–15 Co alloy samples obtained using a plastic mold made with the help of additive technologies has been investigated. It has been experimentally found that, in molds made of polylactide with a strength of 70 MPa, the workpieces can be pressed at a pressure of up to 120 MPa. An increase in plasticizer concentration from 1 to 4 wt % leads to an increase in the density of workpieces from 61 to 90% after pressing and a decrease in the density of samples from 99.5 to 99.3% after sintering. This is 0.3–0.6% less than the density of products obtained after pressing in a steel mold at a pressure of 210 MPa. Deviations in density do not affect the microstructure and hardness of the obtained samples, which is 1140–1170 HV. Owing to the lower density and the presence of individual large pores up to 100 μm in length, the strength of products obtained using a plastic mold (1550–1980 MPa) turned out to be lower than the strength of products obtained using a steel mold (2230–2430 MPa). However, the density of blanks and the resulting hard-alloy samples turned out to be significantly higher than the density and hardness of samples obtained using existing additive technologies.

The paper presents the results of research devoted to studying the effect of the type of reinforcing phase on the structure and properties of an aluminum matrix composite material (AMCM) obtained by the method of self-propagating high-temperature synthesis (SHS) in a melt. In the course of the research, an analysis is carried out and a choice is made to use titanium carbide and titanium diboride as reinforcing phases. During the experimental synthesis of SHS in the melt, AMg2–10% TiC and AMg2–10% TiB₂ composite materials are obtained. In the course of further studies, microstructural, micro-X-ray spectral, and X‑ray phase analyses have been carried out, according to the results of which it is revealed that the technology used leads to the formation of the target TiC phase in the AMg2–10% TiC composite and TiB₂, Al₃Ti phases in the AMg2–10% TiB₂ composite. On synthesized samples of composite materials, an assessment is made of physical and mechanical characteristics: hardness, porosity, and electrical conductivity. It is found that the hardness of AMCM obtained by the SHS method based on the AMg2 industrial alloy reinforced with titanium carbide is higher than the hardness of AMCM reinforced with titanium diboride by 44 MPa. Also, the porosity of the AMg2–10% TiC composite is lower than that of the AMg2–10% TiB₂ composite by 6%. This paper also shows the effect of heat treatment on the physical and mechanical properties of AMg2–10% TiC and AMg2–10% TiB₂ composite materials. Carrying out additional heating leads to an increase in the hardness values of composite materials, as well as a decrease in porosity. According to the results of a complex of studies, the use of titanium carbide is recommended as a reinforcing phase.

Using powder metallurgy methods by sintering in vacuum at temperatures from 1300 to 1500°C, materials with porosity from 67.5 to 82.5% are obtained from mixtures of titanium carbide powders and ammonium bicarbonate as a pore-forming agent. Using X-ray phase analysis, it is established that the crystal lattice parameter of the resulting porous materials decreases with increasing sintering temperature. This indicates a decrease in the content of bound carbon C/Ti in titanium carbide. As a result of a comparative study of the strength characteristics of materials synthesized from nano- and submicron titanium carbide powders obtained from bending tests, it is found that they have similar values. Ultimate bending strength is in the range from 2.6 to 18.1 MPa. As the porosity of the material increases, the tensile strength decreases. The destruction is fragile. In the fracture of materials obtained from titanium carbide nanopowder, destruction is observed both along the body and along the grain boundaries regardless of the sintering temperature. In materials obtained by sintering submicron titanium carbide powder at 1500°C, destruction occurs predominantly along the body of the grains. It is revealed that, under the same sintering conditions, the density of porous material obtained from titanium carbide nanopowder is higher than that of the material obtained from submicron powder.

A new monomer, benzamide methacrylate, is synthesized, and its free radical copolymerization with styrene in mass and in a solution in benzene in the presence of azobisisobutyronitrile (AIBN) is carried out and investigated. The ratio of comonomers is varied in a range of 90 : 10–10 : 90 mol %. The total concentration of comonomers is 1.7 mol/L at 70°C. The composition of the synthesized copolymers is determined by elemental analysis based on the nitrogen content. The monomer and copolymer are characterized by spectroscopic methods (IR, nuclear magnetic resonance (NMR)). The values of the relative activity constants of the monomer are determined, and the Alfrey–Price parameters are calculated. To assess the nature of distribution of the links in the macromolecular chain, the parameters of the microstructure are calculated. It is found that r₁ > r₂ (r₁ and r₂ are the relative activity constants) in all the cases; therefore, the copolymer is enriched in benzamide methacrylate links. It is shown that the composition of the formed copolymers depends on the composition of the initial monomer mixture. The obtained copolymer possesses quite high medical and biological activity, which opens up the possibility for its use as bactericides and fungicides. The obtained copolymers based on benzamide methacrylate are nontoxic and can be used as bactericidal agents. It is found that the biocidal effect is first of all associated with the presence of benzamide fragment links in the macrochain.

Boron-containing brushite cements (B-BCs) for bone grafting based on boron-substituted β-tricalcium phosphate (B-TCP) are developed. The phase composition and microstructure of B-BCs are studied. It is shown that the crystalline phase of brushite is formed as a result of hardening of the cements. The behavior of B-BCs in a physiological saline containing a TRIS buffer is studied. The compression strength of B-BCs within 5 days after blending is 22.5 ± 1 MPa. Studies of antibacterial activity against the E. coli gram-negative strain ATCC25922 and S. aureus gram-positive strain ATCC25923 show that boron-containing brushite cement exhibits antibacterial activity against both strains, causing a decrease in the number of colony forming units (CFUs) already after 3 h of incubation. In vitro studies of the developed B-BCs are carried out, and it is shown that the developed cements based on TCP and B-TCP are biocompatible and promising for use in bone tissue surgery.

Space charge-limited currents in Ti–TiO₂ thin-film structures have been studied. Using the experimental physical parameters of the TiO₂ dielectric, models of the formation of the space charge-limited injection currents have been constructed. The dependences of the injection current on the applied voltage, dielectric layer thickness, and parameters of electron traps have been explored. It is shown that the space charge-limited injection currents in the investigated structures depend significantly on both the depth and concentration of traps. The results obtained are compared with the dependences obtained previously for the BeO, Al₂O₃, and AlN structures.

Interaction of aluminum conductor alloy AlTi0.1 (Al + 0.1 wt % Ti) containing 0.01, 0.05, 0.1 and 0.5 wt % strontium additives with atmospheric oxygen in the range 723–823 K without formation of a liquid phase has been investigated by the thermogravimetric method. The kinetic parameters, true rate constants and activation energies of the oxidation process were determined for the studied compositions. It was revealed that, with an increase in the strontium content from 0.01 to 0.5 wt %, the oxidation rate of the initial alloy AlTi0.1 increases with a simultaneous decrease in the apparent activation energy of the oxidation process from 140.0 to 116.9 kJ/mol. An increase in the oxidation rate is explained by the interaction of strontium oxide with aluminum oxide with the formation of spinel, which simplifies the access of oxygen to the reaction surface. The oxidation kinetics of alloys is approximated by a hyperbolic law.

The crystal structure and composition of the Co–Ni–Fe films has been analyzed, and the effect of the deposition rate on the coefficient dB/dH of conversion of a weak magnetic field into the magnetic induction has been established. The presence of oxygen on the film surface indicates the porosity of the Co–Ni–Fe film structure, which is confirmed by the surface roughness. Electrochemical deposition from a chloride electrolyte has demonstrated the possibility of controlling the magnetic properties of the films by improving the deposition technique. The chloride electrolyte with filtration and boric acid, saccharin, and hydrochloric acid additives in a concentration ratio of C_Co : C_Ni : C_Fe = 1 : 1 : 1 ensures, at a temperature of 70°C, the reproducible electrochemical deposition of the Co–Ni–Fe films with low stresses, a uniform structure, and a high coefficient of conversion of a weak magnetic field into the magnetic induction.