G. Sh. Usmanova

Comparative Analysis of Extractive Methods of Porphyrin Separation from Heavy Oil Asphatenes

A comparative analysis has been made of the methods of porphyrin extraction from high-vanadium heavy oil asphaltenes using polar solvents and sulfuric acid. Chromatographic separation of the extracts, followed by analysis of the porphyrin fractions by UV spectroscopy, helped determine the main types of extracted porphyrins. The prospect of the method of getting porphyrin concentrates by sulfuric acid treatment of high-vanadium petroleum asphaltenes is shown.

Magnetic anisotropy induced in the nanocrystalline FeZrN films prepared by oblique-angle magnetron sputtering

Nanocrystalline Fe77Zr7N16 films are prepared by oblique-angle magnetron sputtering. The effect of the ion beam angle and subsequent annealing on the phase and structural states, the coercive force, the saturation magnetization, the remanent magnetization, and the induced in-plane magnetic anisotropy field has been studied. The possibility of natural ferromagnetic resonance in these films at gigahertz frequencies is estimated.

Sulfuric Acid Assisted Extraction and Fractionation of Porphyrins From Heavy Petroleum Residuals With a High Content of Vanadium and Nickel

Primary porphyrin extracts were obtained from carbon tetrarchloride solutions of different heavy oil residuals with assistance of sulfuric acid. According to data of chromatographic separation of extracts porphyrinic fractions appear in amount of 13.0–24.2%. Based on UV/visible absorption spectroscopy the presence of porphyrins of etio and phyllo types mostly with rhodo and deoxophylloerythroetioporphyrins in lower amount was established. The content of porphyrins in obtained fractions was determined at the level of 15.3–44.8% of the total weight. It was shown that a higher concentration of porphyrins in sulfuric acid extracts occurs for the case of the high vanadium and nickel content and low amounts relation of asphaltenes to resins.

Electron microscopy of phase and structural transformations in soft magnetic nanocrystalline Fe-Zr-N films

The effect of deposition conditions (film thickness) on the structure of soft magnetic Fe80–78Zr10N10–12 films formed by reactive magnetron deposition on a heat-resistant glass substrate has been investigated by analytical transmission electron microscopy, high-resolution electron microscopy, and diffraction analysis. The processes of evolution of the phase and structural state of films and the film-substrate interface upon annealing in the temperature range of 200–650°C have been analyzed taking into account the thermodynamic, kinetic, and structural factors and the specific features of the nanocrystalline state.

Evolution of the phase-structure state during annealing of Fe-ZrN films grown by magnetron sputtering

The evolution of the phase-structure state of Fe-ZrN films grown by RF magnetron sputtering and annealed at T = 200–650°C has been studied by transmission electron microscopy, high-resolution electron microscopy, and X-ray diffraction analysis. It has been found that the initial state of the film contains 1- to 5-nm crystallites of α-Fe-based solid solution supersaturated with nitrogen. The number of such crystallites increases, the concentration of nitrogen in them decreases and 2- to 10-nm nanocrystallites of ZrN and Fe2N nitride phases appear after annealing. The formation of zirconium nitride at the first stage (200–500°C) is associated with a decrease in the degree of supersaturation of the α-Fe lattice with nitrogen. At a higher annealing temperature (650°C), a decrease in the nitrogen concentration in the lattices of both the bcc Fe and zirconium nitride phase leads to the formation of iron nitride crystallites.

Effects of annealing on the magnetic properties and microstructure of Fe-ZrN nanocomposite films

We have studied the influence of thermal annealing on the magnetic properties and microstructure of 0.7-μm-thick Fe-ZrN nanocomposite films obtained by a reactive RF magnetron sputtering technique on non-conductive substrates. The near-surface and bulk magnetostatic characteristics of the films were studied using magnetooptical and vibrating-sample magnetometers, respectively. The microstructure was determined by X-ray diffraction. It was established that the magnetic characteristics strongly depend on the annealing temperature. These dependences are explained by structural changes induced in the films by the thermal treatment.

Role of C: Zr stoichiometry in the formation of a nanocrystalline structure and magnetic properties in Fe87-x Zr13Cx films

X-ray diffraction analysis was used to study the structure of as-sputtered and annealed Fe-13 at. % Zr-C films, which were produced by reactive magnetron sputtering and characterized by stoichiometric and nonstoichiometric (with respect to ZrC) at. % C to at. % Zr ratios. A special packet of programs was used to resolve wide reflections observed in X-ray diffraction patterns of the films. The as-sputtered films of all compositions were found to be amorphous in terms of X-ray diffraction. The thermal stability of the amorphous phase increases as the C: Zr ratio in the films departs from the stoichiometric ratio (1: 1) characteristic of the monocarbide ZrC. Annealing leads to the formation of a mixed (amorphous + nanocrystalline) structure. Depending on the carbon content and annealing temperature, the phase composition of the films is represented by different combinations of phases, such as bcc α-Fe (the basis phase), fcc ZrC, monoclinic Fe2C, monoclinic Fe2.5C, orthorhombic Fe3C, and Fe23Zr6. After annealing at 550°C, the best magnetic properties are characteristic of the films having the stoichiometric composition with respect to ZrC (at. % C: at. % Zr ∼ 1).

X-Ray diffraction study of the evolution of phase and structural state and macroscopic stress during annealing of soft magnetic Fe95 − xZr5Nx films prepared by ion-plasma deposition

The evolution of the phase composition, nanostructure parameters, and macroscopic stress in soft magnetic Fe95 − xZr5Nx films (prepared by ion-plasma deposition onto quartz substrates) during their annealing has been investigated by X-ray diffraction. During deposition, depending on the N content, either a mixed structure composed of an X-ray amorphous phase enriched in Zr and N and a crystalline phase (α-Fe(N) solid solution) or an X-ray amorphous phase enriched in Fe, Zr, and N is formed in the films. During annealing, depending on the temperature and nitrogen content, different combinations of crystalline phases (α-Fe(N) and Zr(N) solid solutions, α-Fe, Fe4N, Fe2N, ZrO2) are formed in the films. The large compressive stress formed in the films during deposition changes to a lower tensile stress during annealing.

Thin-film magnetically soft Fe-Zr-N alloys with high saturation induction

Thin films of magnetically soft nanocrystalline alloys of the Fe-Zr-N system with a high (1.6–1.8 T) saturation induction and a very low (record) coercive force (4–6 A/m) were obtained by magnetron sputtering followed by thermal treatment of the deposit. Direct magnetooptical observation of the domain motion revealed a high homogeneity of the film material and showed that remagnetization in the material proceeds by mechanism of the domain boundary displacement.

Composition and Properties of Oxidation Products of Heavy Oil Resid Asphaltenes

Asphaltenes of various heavy oil resids are oxidized by aqueous sodium percarbonate solutions at 200°C and 4 MPa pressure. The composition and properties of the obtained products are analyzed. Water-soluble oxidation products in the asphaltene oxidation products comprise 47.4-49.4%. Products of oxidative condensation of asphaltenes enriched with hydroxyl, ether, and carboxyl groups dominate in the composition of water-insoluble oxidation products. The water-soluble oxidation products represent carboxylic acid concentrate. The characteristics of the structural-group composition of the obtained oxidation products are disclosed. The possibility of practical utilization of asphaltene oxidation products as adhesion additives to road asphalt and for removal of phenol from water is demonstrated.