Ivan Shanenkov

Effect of Energy on Plasmodynamic Synthesis Product in the Carbon-Nitrogen System

Carbon nitride (CNx) powders were synthesized in the high-speed carbon electric discharge plasma jet flowing into the chamber filled with the nitrogen atmosphere at normal conditions. A coaxial magnetoplasma accelerator (CMPA) was used to generate the plasma flow. The CMPA was supplied from the pulse capacitive energy storage. Effect of input to the CMPA energy value on powders was studied by using several analytical methods (XRD, TEM, XPS). According to XRD with the increasing of input energy value the content of CNx in the product increased about 1.5 times. Its in a good accordance with the XPS data according to which the presence of nitrogen increased from 0.5 to 1.4 mass percent. Furthermore, the particles morphology was noticeable changed with the energy increasing. The obtained results revealed that by changing the energy parameters of the capacity energy storage its possible to influence on the product synthesized in the carbon-nitrogen system.

Synthesis of ultra dispersed graphite–like structures doped with nitrogen in supersonic carbon plasma flow

In this paper the synthesis of ultra dispersed graphite-like structures doped with nitrogen by using a magneto plasma accelerator is shown. The synthesis of such structures is realized during supersonic carbon plasma jet flowing into the chamber filled with the nitrogen atmosphere. Plasma jet is generated by coaxial magneto plasma accelerator (CMPA) based on graphite electrode system. The CMPA is supplied from the pulsed capacitive energy storage with the maximum value of stored energy of 360 kJ. Electrical and energy parameters of plasma flow are recorded during experiment. According to X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) methods obtained particles with well seen triangle sectors are graphite-like carbon structures doped with nitrogen atoms. This is confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses in which carbon- nitrogen bonding configurations have been identified.

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.

Influence of Oxygen Concentration on Plasma Dynamic Synthesis Product in Fe-O System

In spite of being known for centuries, iron oxides are still important. Such modifications as magnetite Fe3O4 and epsilon phase ε-Fe2O3 are of great scientific and practical interest due to their promising electromagnetic properties. Nonetheless, only few methods allow synthesizing both of these phases, but they have some well-known disadvantages, which limit the possibility of using them widely. This work shows a unique method of synthesizing these materials in one short-duration plasma dynamic process using a coaxial magnetoplasma accelerator with iron electrode system. The plasma chemical reaction occurs between the iron-containing plasma and gaseous precursor (oxygen). The influence of oxygen pressure on the products of plasma dynamic synthesis was also studied in the framework of this investigation. It was found that the higher oxygen concentration leads to the formation of product with predominant content of epsilon iron oxide ε-Fe2O3, as well as lower oxygen concentration results in obtaining the product with the dominance of magnetite phase.

On the energy efficiency of coaxial plasma accelerator with graphite electrodes

Today the effectiveness of using of electromagnetic energy is a key issue in the creation and application of electrical devices. It is known that coaxial magneto plasma accelerator can be used to synthesize ultrafine powders of functional materials. The factors that influence on its efficiency are not studied enough. In this paper we demonstrate the possibility of achieving high (about 80%) efficiency of conversion of electromagnetic energy into the energy of combustion of high-current Z-pinch with using high-current pulsed accelerator with graphite electrodes.

Investigation of Ultradispersed Powders FexOy Obtained in the Electric Discharge Plasma

The paper shows the iron oxide powder production in the hypersonic jet of electro discharge plasma generated by a coaxial magnetoplasma accelerator with steel electrodes. The influence of gaseous atmosphere parameters has been investigated by carrying out experiments in normal atmospheric conditions and with the introduction of additional oxidant into the plasma discharge. Studies of the structure of synthesized powders and their magnetic properties have been carried out. It has been found that by introducing of additional oxidant it is possible to regulate the phase composition in the direction of increasing the yield of magnetite phase. Specific saturation magnetization decreases with decreasing of the magnetic nanoparticle sizes.

Effect of Oxygen Concentration in a Gaseous Mixture with Argon on the Phase Composition of Plasmodynamic Synthesis Products in an Iron–Oxygen System

The effect of a gaseous oxygen concentration in a mixture with argon on plasmodynamic synthesis products in an iron–oxygen system is described. X-ray diffractometry and scanning and transmission electron microscopy data showed that the products contain three different modifications of iron oxide: magnetite Fe3O4, hematite α-Fe2O3, and ε-Fe2O3 epsilon phase. A change in oxygen concentration leads to a significant change in the phase composition of the products and an increase in a yield of the ε phase.

Obtaining Intermetallic Compound Copper-Tin: Plasma Dynamic Synthesis and Spark Plasma Sintering

The intermetallic compound tin-copper (Cu-Sn) is widely used in the creation of high-quality bearings, electric conductive lubricants, 3D printers. However, when connecting two metals, the bond between atoms in the lattice becomes covalent or ionic. This leads to the fact that the material becomes more brittle. Additionally, the production of intermetallic compounds is cost-based in terms of both material resources and money. In this paper, the ceramics has been sintered based on the intermetallic copper-tin powders, obtained by plasma dynamic method. The raw powdered materials based on Cu-Sn were obtained using a coaxial magnetoplasma accelerator with copper electrodes by adding the crushed tin into the accelerator. Using X-ray diffractometry (XRD) and transmission electron microscopy (TEM) analyses, the presence of such phases as copper Cu and tin-copper Cu41Sn11 in the obtained material has been confirmed. Further, such-synthesized powdered products were used to obtain bulk samples using the spark plasma sintering technology at various sintering parameters. Images from scanning electron microscope showed a uniform sintering of the product at the sintering temperature of 440 °C under a pressure of 60 MPa. It was found that the sintered intermetallic ceramics has the Vickers hardness equal to 120 Hv. The obtained sample has the lower friction coefficient and the smaller wear area in comparison with the sample, made of pure copper.

Sintering of ceramics based on YBa2CuxOy Synthesized by plasma dynamic method

Yttrium-barium cuprates are of a great interest due their possible application in the manufacture of superconductors and devices on their basis. This paper shows the possibility to synthesize ultrafine powder of yttrium-barium cuprates using the system based on a coaxial magnetoplasma accelerator. Several methods, including X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy, are used to investigate the synthesized products. It is found that during working cycle with a duration less than 1 ms, all necessary conditions are created to synthesize the powder with the stoichiometries YBa2Cu3O696 and YBa2Cu4O8. These materials can be used for sintering the multilayer ceramics using the system of spark plasma sintering.

Influence of input energy on nanosized product of Ti-Si-N system obtained by plasmodynamic method

Composite ceramics TiN/Ti5Si3 is of a great interest due to its high hardness, fracture toughness, electrical conductivity and uniquely high resistance to erosion and oxidation up to 800 Celcius degree. The main problem is connected with the synthesis of necessary raw materials for ceramics sintering. Earlier it was shown the possibility to implement one stage synthesis of main components using plasmodynamic method. This paper shows the experimental results about the influence of input energy value on the products of the plasmodynamic synthesis, which were characterized using X-ray diffractometry and transmission electron microscopy methods.