V. A. Vlasov

Processing line for industrial radiation-thermal synthesis of doped lithium ferrite powders

The paper considers the issues of industrial production of doped lithium ferrite powders by radiation-thermal method. A technological scheme of the processing line is suggested. The radiation-thermal technological scheme enables production of powders with technical characteristics close to the required ones under relatively low temperature annealing conditions without intermediate mixing. The optimal conditions of the radiation-thermal synthesis are achieved isothermally under irradiation by the electron beam with energy of 2.5 MeV in the temperature range of 700-750 0C within- 120 min.

Microwave properties of Li-Zn ferrite ceramics

The work presents results of a study of the electromagnetic properties Li-Zn ferrite ceramics in a wide frequency range. It is shown that a homogeneous composition of such ceramics typically appear good radio-absorbing properties in the low-frequency range of microwave. The method of solid-phase radiation-thermal synthesis with preparatory mechanical activation of reagent mixture for obtain a homogeneous composition of ferrite powders is proposed.

Effect of powder compaction on radiation-thermal synthesis of lithium-titanium ferrites

Effect of powder compaction on the efficiency of thermal and radiation-thermal synthesis of lithium-substituted ferrites was investigated by X-Ray diffraction and specific magnetization analysis. It was shown that the radiation-thermal heating of compacted powder reagents mixture leads to an increase in efficiency of lithium-titanium ferrites synthesis.

Ultrasonic Surface Treatment of Titanium Alloys. The Submicrocrystalline State

The paper presents the results of the research on improvement of physical-and- mechanical properties of titanium alloys VT1-0 and VT6 by modification of surfaces using ultrasonic treatment, and a comprehensive study of the microstructure and mechanical properties of modified surface layers. It has been established that exposure to ultrasonic treatment leads to formation in the surface layer of a structure with an average size of elements 50 - 100 nm, depending on the brand of titanium alloy.

The investigation of carbon oxidation in gas-Discharge plasma under external magnetic field

The low-temperature plasma is currently widely used in various technological processes. However, the influence of an external magnetic field on the plasma processes is not studied enough. The low-temperature plasma processes including dissociation of molecular gases, oxidation, and disperse phase formation are researched. The results of experimental investigation of processes associated with carbon oxidation in high-frequency argon- oxygen plasma under external magnetic field (<;1 Tesla) are shown. An insertion of carbon atoms to plasma are realized with graphite electrode evaporation. The basic chemical reactions in neutral-radical composition are defined in temperature range 1500-3500 K. The basic products of plasma processes are carbon oxide, carbon dioxide and superdispersed soot. An external magnetic field promotes displacement of plasma chemical reaction rate relations to disperse phase formation. A possibility of isotopic selective plasma processes is shown. An isotopic composition of gaseous reaction products is measured by quadrupole mass-analyzer. The isotopic composition changing tendencies of gaseous and disperse phases (according to carbon isotopes) reaction products versus magnetic field scope are established. The best results are achieved by superposition of magnetic field scope and product reaction quenching area.

Microstructure and thermal analysis of lithium ferrite pre-milled in a high-energy ball mill

AbstractIn this work, the effect of ball milling of synthesized LiFe5O8 ferrite powders on the microstructure and properties of ferrite ceramics was studied by XRD, laser diffraction and SEM analysis as well as thermal analysis. The mechanical milling of LiFe5O8 was carried out in a Fritsch Pulverisette 7 planetary mill using the zirconia or steel grinding balls. The process of ferrite sintering was investigated using dilatometric analysis. In addition, ferrite ceramics electromagnetic properties, including magnetization, Curie point and electrical resistivity, were investigated. The results showed a strong difference in the structure of ferrite ceramics obtained from ferrite powders pre-milled by zirconia or steel grinding balls. Thus, the milling results in a decrease in the particle size of the ferrite powders to ultrafine range. The ferrite ceramics, obtained from powder milled by steel balls, is characterized by high density and low porosity as well as good electromagnetic properties and the main presence of a disordered β-LiFe5O8 phase. However, the mechanical milling using zirconia balls leads to the contamination of ferrite by zirconia, resulting in the formation of β-LiFe5O8/ZrO2 composite ceramics during sintering.

Influence of reagents mixture density on the radiation-thermal synthesis of lithium-zinc ferrites

Influence of Li2CO3-ZnO-Fe2O3 powder reagents mixture density on the synthesis efficiency of lithium-zinc ferrites in the conditions of thermal heating or pulsed electron beam heating was studied by X-Ray diffraction and magnetization analysis. The results showed that the including a compaction of powder reagents mixture in ferrite synthesis leads to an increase in concentration of the spinel phase and decrease in initial components content in lithium-substituted ferrites synthesized by thermal or radiation-thermal heating.

High energy effect in Li-Ti-Zn ferrite syntesis

Lithium-zinc-titanium ferrite synthesis under the high energy action, including mechanical activation of initial reagents mixture in a planetary mill and subsequent heating of reaction mixture by a high-energy electron beam, is investigated using x-ray diffraction and thermal analyzes. The composition of initial reagents mixture corresponds to lithium substituted ferrite formation with a stoichiometric spinel formula: Li0.65Fe1.6Ti0.5Zn0.2Mn0.05O4. The synthesized ferrites were examined by saturation magnetization and Curie temperature measurements. It was shown that the mechanical activation for 60 min and radiation-thermal heating at 800°C of the initial reagents mixture significantly increase the reactivity of solid phase systems, and thereby, decrease the temperature and time of synthesis, improving the homogeneity of the end product. The obtained lithium-titanium-zinc ferrites are characterized by the high values of both the specific magnetization and Curie temperature.

Study of the dielectric polarization in Li-Zn ferrite ceramics

Paper presents the results of dielectric properties investigation in radio frequency range for lithium-zinc ferrite ceramics. Dielectric parameters of ferrite was obtained using mathematical processing (for Debye type polarization) of experimental data. It is shown that the observable ceramics composition has dielectric anomalies characterized by ferroelectric type.

Non-equilibrium melting processes of silicate melts with different silica content at low-temperature plasma

This article is devoted to research the possibility of high-temperature silicate melts producing from different silica content at low-temperature plasma taking into account nonequilibrium melting processes.