A. A. Evdokimov

Influence of the supplied energy on electroerosion recovery of material in an electrotechnical accelerator

The effect of the energy on the dynamics of electroerosive surface wear of the accelerating channel in a coaxial magnetic plasma accelerator is studied. The energy supplied to the accelerator is varied by cutting off the current pulse tail by a trigatron arrester at different instants of times. It has been ascertained that the dynamics of electroerosive surface wear of the accelerating channel is mainly determined by the behavior of the discharge power in the course of the process in the accelerator.

Studies of multiple and frequency operation of a coaxial magnetoplasma accelerator for production of superhard nanodispersed titanium compounds

It is demonstrated that a system based on coaxial magnetoplasma accelerator facilitates dynamic synthesis of nanodispersed titanium crystalline phases, such as cTiN and TiO2, during multiple use of a titanium barrel as a consumable material. The efficiency of material yield from the surface of the accelerating channel of a titanium barrel increases upon cyclic operation of an accelerator with duration of currentless pause less than 1.0 s.

Obtaining Ceramic Based on Si3N4 and TiN by Spark Plasma Sintering

The dependences of the microstructure and physical-mechanical properties of Si3N4–TiN-based ceramic in a wide range of mass ratios of the components are examined. The sintering process and the accompanying physical and chemical processes, viz. the dependence of the hardness and density of the material on the ratios of the conducting phase of titanium nitride and the dielectric phase of silicon nitride with values above and below the percolation threshold, are examined. A ceramic based on pure titanium nitride with high physical-mechanical characteristics (H = 21.5 GPa) is obtained.

Ceramics based on titanium nitride and silicon nitride sintered by SPS-method

The dependences of the microstructure and physical and mechanical properties of ceramic mixtures Si3N4/TiN in the full range of mass ratios of the components. Was also investigated directly, and the process of sintering occurring during a physical or chemical processes, in particular, has been obtained and the hardness of the material density on the ratio of the conductive titanium nitride phase and a silicon nitride insulating phase with values above and below the percolation threshold. Also obtained was pure ceramics based on titanium nitride with high physical-mechanical characteristics (H = 21.5 GPa).

Dependence of Physical, Mechanical, and Structural Properties of TiN Ceramics on Temperature of Spark Plasma Sintering

In this work the dependence of physicomechanical properties of titanium nitride ceramics on the temperature of the spark plasma sintering process is discussed. We study the behavior of the sintering process and find densification variances throughout the whole sintering process. The microstructure of the ceramics is studied and mechanisms of changes in grain structure depending on the sintering temperature are determined. The dependence of hardness of sintered material on sintering temperature is studied, and ceramics with a hardness of 17 GPa are obtained.

Direct dynamic synthesis of nanodispersed powder material on titanium-base in pulsed electric-discharge plasma jet

The possibility is shown to obtain a nanodispersed powder with the spherical shape particle and with the equal components distribution in a hypervelocity electrical discharge plasma jet generated by a coaxial magnetoplasma accelerator (CMPA). The developed method allows to obtain: nanodispersed (~ 50 nm), polymorphic crystalline TiO2 phases with the admixture of cubic TiN by the titanium plasma efflux in the air atmosphere; nanodispersed (10 ÷ 40 nm) TiO2 (rutile) crystalline phases with the TiC admixture by the titanium plasma efflux in the CO2 atmosphere; nanodispersed (30÷70 nm) cubic TiN by the titanium plasma efflux in the nitrogen atmosphere; nanodispersed composite powders by using electrodes of the CMPA made of several different metals, mixture of different gases and additional reagents introduction in the high-current discharge plasma jet. The process, including such stages as the electroerosive obtaining of the initial material, the dynamic synthesis, the nanodispersed particles formation, is fully realized in the short term (10-4 ÷ 10-3 sec.) cycle of the accelerator work. The basic initial material is generated by the electric erosion from the CMPA acceleration channel surface.

Direct plasmadynamic synthesis and preparation of superdispersed Ti–Si–N compositions

The preparation of nanodisperse titanium nitride and titanium carbide compositions by the direct plasmadynamic synthesis in the Ti–Si–N system is described in this paper. The use of the method of direct plasmadynamic synthesis allows one to achieve good mixing of the product and to create ceramic materials without areal defects produced by local agglomerations.

Time-Keeping Factor at a Constant Temperature in the Process of Spark Plasma Sintering

The dependence of the effect of time delay at a constant maximum temperature on the physicomechanical parameters of the sintered sample has been considered. Based on the results of the work, it can be concluded that it is necessary to reduce the duration of all sections of the sintering process in order to exclude the recrystallization factor, which worsens the parameters of the ceramics.

The Effect of Nitrogen Pressure in the Reaction Chamber on the Parameters of Titanium Nitride Obtained by Plasmodynamic Synthesis

In this study the influence of nitrogen pressure in the reaction chamber on the parameters of the synthesized nanosized TiN using plasmodynamic direct synthesis method has been investigated. It is shown that the pressure factor is not important in the synthesis of a nanosized product.