On the choice of criteria for the effectiveness of gas-vortex stabilization of plasma torches

A rationale of the principles of evaluating the effectiveness of gas-vortex stabilization of plasma torches has been provided. Taking into account the new possibilities of numerical modeling methods, new criteria have been introduced, their application allows both the developing of new gas-vortex stabilization methods and their using for evaluating the results of plasma equipment designing.

Design of a new gas-dynamic stabilization system for a metal-cutting plasma torch

The analysis of the influence of various design solutions of the gas-dynamic stabilization system in plasma torches for cutting metals on the efficiency of equalizing the velocities of gas flows along the cross-section of the gas path is carried out. It is noted that the efficiency evaluation method developed by the authors should be based on the calculation of the uniformity of the gas flow velocity distribution over the cross-section of the gas-air path of the plasma torch. A vortex stabilization system using two swirlers is proposed. The effect of improving the reliability and quality of plasma cutting is shown. The results of the efficiency studies for the proposed system of gas-vortex stabilization in metal-cutting plasma torches are presented. The calculating results of equalization coefficients for the velocity distribution in different parts of the gas-dynamic stabilization system in the plasma torch are presented. Based on the results of the calculations, a constructive optimization of the gas-air path in the plasma torch was performed. The experimentally obtained advantages of the new upgraded plasma torch in terms of the gas-vortex stabilization efficiency are demonstrated. The effects of improved cutting quality and reduced nozzle wear in the new plasma torch are shown. This is due to the higher degree of the plasma arc stabilization in the new plasma torch, which leads to a decrease in its oscillations, and, consequently, to an increase in the efficiency of the cutting process.

Processing of industrial waste by plasma-chemical method

In this paper, the results of the processing of magnesium fluoride by plasma-chemical method to obtain periclase and a solution of hydrogen fluoride (hydrofluoric acid) were presented. For the industrial implementation of plasma technologies, it is necessary to study the main parameters of plasma processes for obtaining reducing gases and processing metal oxides with them, to solve the issues of their hardware design, to increase the service life of plasma torches for their use in continuous metallurgical processes. The purpose of this work was to determine the conditions for the plasma-chemical process of processing magnesium fluoride. Thermal analysis of magnesium fluoride on a TGA/DSC2 thermogravimetric analyzer was performed. Thermogravimetric analysis showed that in the temperature range under consideration the process is endothermic, and at a temperature of ~1280°C a phase transition of the 1st kind is observed due to the melting of magnesium fluoride. The fractional composition of MgF2 and MgO powders was studied using the Analysette-22 Nanotech laser diffraction analyzer. The results of the evaluation of the fractional composition of powders have a significant difference. At the same time, the convergence of the data obtained using laser diffraction and electron microscopy methods was found.

Development and research of new technologies for precision plasma cutting of metals

Plasma torches of Russian origin concede to import metal-cutting plasma facilities by several parameters, in particular energy efficiency, quality of cut, degree of automation. To increase efficiency and safety of domestic electro-plasma technologies itь is necessary to perfect methods of analysis of known design solutions to provide new developments. The results of the plasma torch­es design widely used in metallurgical and machine-building technologies for air-plasma cutting of metals presented. It was noted that productivity, cutting quality and reliability of plasma equipment should be chosen as the main criteria of efficiency for plasma cutting technology. It was shown that special attention should be paid to improving the gas-vortex stabilizing method for the plasma forming gas, which ensures the efficiency of both the plasma torch and the plasma cutting process as a whole. Results of studies of a complex system for arranging the flow of plasma-forming gas through the channels of the gas-air path in the plasma torch and the subsequent creation of new systems for stabilizing the arc discharge of metal cutting DC plasma torches with high technological capabilities presented. The study was carried out by the methods of numerical simulation of gas-dynamic and thermo-physical pro­cesses for various designs of plasma torches. Optimized designs of plasma torches with various variants of gas-vortex stabilization systems were elaborated. A series of elaborated torches, which includes a single-stream plasma torches ПМВР-5 for precision cutting of medium thickness metals, as well as two-stream plasma torches ПМВР-9 for cutting metals of small and medium thicknesses presented. The last plasma torches use the technology of narrow-jet or compressed plasma and have no domestic analogues. A meth­odology of metal-cutting plasma torches designing by gas-dynamic, thermo-physical and acoustic criteria was elaborated. The results of experimental studies showed that the use of new ПМВР-5 plasma torches allows to obtain precision cuts corresponding to the 1st and 2nd quality classes according to GOST 14792-80 on steels of the 09Г2С type of medium thickness. It was also shown that the use of new plasma torches makes it possible to perform precision finishing plasma cutting on low-carbon steels of medium thickness (without additional mechanical processing of the cutting edge) in the production technologies of welded joints.

Plasma way to obtain ultrafine iron and aluminum oxides

The paper deals with two plasma-chemical synthesis installations based on alternating cur-rent plasma torches with power up to 30 kW, which can be used for production of ultrafine (nanosized) oxide and carbide materials. Some results obtained during experimental studies on the production of ultrafine powders of metal oxides (iron and aluminum) are presented.

Synthesis of Zinc Oxide (ZnO) Nanoparticle using Non-Transferred DC Thermal Plasma Method: A Morphology Review

The increase of nanomaterialusagesuch as nano-ZnO application indeveloping countries is a type of progressthat is beneficial from the engineering standpoint.Being able to controlthe results of nanomaterial production is crucialin this development. To control the outcome is to obtainZnO nanomaterialsproperties which are suitable and in accordance to its intended application.Thisstudy focuses on the morphology ofZnO nanomaterialswhich aresynthesized by non-transferred DC thermal plasmamethod. In this review,parameters of the apparatus regulating the outcomes of the synthesisis studied and analyzed to find certain guidelines that affect nanomaterial morphology. Some of the findings includethe influence ofnon-transferred DC thermal plasma torches main variables such as gas output and powerinputwhich are involved in plasma jet production. It also finds precursor input techniques in which affects the ZnO nanomaterial production outcome. The study indicates that each production parameters on the DC thermal plasma device have different ways in affecting the morphology of the synthesized nanomaterialand it is possible to control them

Study of the In-Flight Characteristics of Particles for Different Configurations of Cascade Plasma Torches

Cascaded plasma torches are becoming increasingly common, but the influence of geometry, notably that of the anode, is relatively unexplored. This work investigates the relationship between anode-cathode distance and plasma voltage fluctuations. The study was conducted using cascaded torches that can be configured with different numbers of neutrodes and commercially available Al2O3 powders. The powders were sprayed at different gas flow rates and current intensities while monitoring voltage fluctuations as well as in-flight particle temperature and velocity. The resulting alumina coatings were characterized based on microstructure, phase composition, porosity, and hardness. A frequency analysis of the arc voltage fluctuations revealed well-defined peaks at 60, 120, and 180 kHz that vary in intensity based on the number of neutrodes. The more neutrodes, the sharper and higher the peak. In contrast, the power spectra of the arc voltage generated by a conventional plasma torch contains no such peaks, indicating a random displacement of the arc root leading to less stability of the arc.