Development of a new plasma technology for producing pure white corundum

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.