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This paper presents the results of the application of new unique techniques based on plasma nanotechnology in metallurgy and materials science. In recent years, a team of authors have developed the solutions for extraordinary problems arising in the conditions of metallurgical enterprises related to the production of synthetic materials and control of manufactured products, namely, the methods for the production of various structural materials and optimization of methods for their non-destructive testing by atomic emission spectral analysis (AESA). The paper points out some aspects of ongoing research, in particular, an innovative technique that allows obtaining ultrapure samples of white corundum by plasma melting of alumina in a reactor. This method also allows obtaining ultrapure aluminum at the output, which can be used for the purposes of hydrogen energy. In the course of the research, the criteria for thermal protection, temperature conditions and optimal parameters of the plasmatron were determined. In order to carry out the studies of metals and alloys by AESA method, a new global analytical method was developed, which made it possible to take into account the influence of various important parameters, including third elements, background plasma radiation, etc. This method has been preliminary tested on emission spectrometers made in Russia and can significantly reduce the error in the determination of low concentrations of elements. In addition to the consideration of these parameters, the method makes it possible to perform high-precision calibration of atomic emission spectrometers of the same type (produced in series), using not a set of several tens of approved standard samples, but only two standard samples. For each area, patent applications were formed and filed.

The paper presents the results of mining and primary approbation of plasma method for producing pure white corundum. Upgrading ways of pure corundum production is an important task for industry as part of reducing the energy consumption and environmental contamination. The purposes of the research at this stage are as follows: the selection of raw materials, formative evaluation for characteristics of the technology, conducting an experiment on melting and assessment of the sample. The corundum melting is conducted in the reactor using high-voltage plasmatron. Mixture of argon and 25–30 percent of nitrogen is used as the working fluid. The authors suggest using a four-layered protection of a melting reactor in order to ensure both thermal insulation properties and strength characteristics. This is especially relevant under temperature difference of the order of 2000 K and elimination of defective crystallization of the melt from the walls of the reactor. As a result of an experiment on melting alumina marked G-00 using high-voltage air powered plasmatron, the sample with alumina oxide in the amount of 99.79 percent and with absolute hardness equal to 500 was obtained. Further experiments make it possible to determine the prospects of using the proposed technology to obtain samples with an increased content of aluminum oxide. The paper discusses the application of the described technology for industrial production of pure corundum single crystals. The technology will make it possible to obtain samples to be used as abrasives for optical systems and for the production of sapphire glasses and scalpels.

This paper presents the results of one of the stages in the development of a plasma technology for producing ultrapure white corundum. This technology involves the melting of alumina in a reactor under the influence of plasma. To create the plasma, a plasma-forming gas is needed; in other words, the plasma torch working gas. To implement this technology, the chosen working gas must meet certain requirements. More precisely: 1) the gas should not form explosive or toxic compounds either with the reactor materials or the material of the electrodes; 2) it should not accelerate their erosion. An important requirement that a plasma torch working gas must have is minimal interaction with surrounding substances, even at high temperatures. This will reduce the likelihood of contamination of the melt with materials of the reactor itself. We consider using hydrogen, nitrogen and argon. Taking into account the requirements for the working gas, we opt for the mixture of nitrogen and argon at a concentration of 25÷30% N2 – 70÷75% Ar. Keywords: plasma torch, corundum, plasma technology, ultrapure materials