Atmospheric Pressure Plasma Systems and Applications

Atmospheric-pressure plasmas have a wide variety of potential industrial applications. They are used in extractive metallurgy; metal recovery; novel nanomaterial synthesis; refractory and wear-resistant coatings deposition; chemical synthesis; energy conversion; industrial, medical, and nuclear waste destruction; engine combustion enhancement; and exhaust gas pollutants clean up. Atmospheric plasmas are produced by applying DC or AC high voltage between two electrodes designed as cylindrical in shape for jets and planar for the dielectric barrier discharge systems. This review presents an overview of the use of atmospheric-pressure plasma devices and industrial processes carried out in several of these areas.

Features of Machining Rotor Shafts of Diesel Engine Turbochargers with a Multilayer-Coated Tool

Introduction. The paper presents the results of experimental studies of power parameters when hard alloy steels are machined with tools, the cutting units of which have multilayer hard, heat-resistant and wear-resistant coatings. The obtained data will make it possible to optimize machining hard-to-machine materials. Materials and Methods. The aim of the study is to measure the power parameters of turning products and to create experimental formulas of power parameters for different technological modes. For this purpose, a special measuring multicomponent complex was used to estimate the influence of the mode parameters on the change in the cutting force components. Results. The numerically controlled machine tool was retooled by combining it with a three-component dynamometer and tooling. The cutting unit of the tool was coated with a multi-layer hard, heat-resistant and wear-resistant coating. The tool was equipped with instruments connected to a personal computer for measuring and processing experimental data. According to the results of the study, there have been obtained graphical dependences and empirical formulas, which take into account the influence of the mode parameters on the cutting force components when machining the units of alloy steels of high hardness, heat resistance and wear resistance. Discussion and Conclusion.The study allowed us to obtain experimental formulas of cutting force components for different mode parameters when machining parts by the tool equipped with cutting plates. The plates are coated with multilayer hard and wear-resistant coatings of titanium carbonitride, aluminum oxide and nickel nitride. The coating increases significantly the hardness, heat and wears resistance of the tool cutting unit and provides quality machining.

Assessment of tribotechnical properties and resistance to wear of plasma coatings

In order to determine the operating conditions of parts for which restoration of worn surfaces is acceptable by the method of plasma spraying of various powder alloys, contact fatigue tests were carried out under cyclic contact impulse loading. In addition, tribotechnical tests were carried out with various wear-resistant coatings under conditions of liquid sliding friction. Bench and operational tests showed the use of coatings obtained using modern plasma technologies, the feasibility of protecting parts operating in conditions of corrosion, waterjet and cavitation wear, as well as in sliding friction. The coating sprayed with Ni-Al intermetallic alloy powder provides the most reliable protection against shock cyclic impact and abrasion during liquid friction than other materials studied. Coating with wear-resistant self-fluxing powder Ni-Cr-B-Si-C alloy, hardened by solid carboboride phases, without its additional heat treatment for restoration of surfaces working in sliding friction pairs, is not recommended.

Synthesis of titanium carbide and titanium diboride for metal processing and ceramics production

Introduction. Titanium carbide and diboride are characterized by high values of hardness, chemical inertness and for this reason are widely used in modern technology. This paper provides information on the synthesis of titanium carbide and diboride by carbothermal and carbide-boron methods, respectively, on the use of titanium carbide as an abrasive and in the manufacture of tungsten-free hard alloys, carbide steels, wear-resistant coatings, as well as titanium diboride in the production of cutting tools and ceramics based on boron carbide The aim of this work is to study the processes of synthesis of highly dispersed powders of titanium carbide and diboride, which are promising for the manufacture of cutting tools, wear-resistant coatings, abrasives and ceramics. Research methods. Titanium oxide TiO2, nanofibrous carbon (NFC), and highly dispersed boron carbide were used as reagents for the synthesis of titanium carbide and diboride. Experiments to obtain titanium carbide were carried out in a resistance furnace, and titanium diboride in an induction furnace. X-ray studies of the phase composition of titanium carbide and diboride samples were carried out on an ARL X-TRA diffractometer (Thermo Electron SA). The determination of the content of titanium and impurities in the samples of titanium carbide and diboride was carried out by the X-ray spectral fluorescence method on an ARL-Advant'x analyzer. The total carbon content in the titanium carbide samples was determined on an S-144 device from LECO. The content of boron and other elements for titanium diboride samples was determined by inductively coupled plasma atomic emission spectrometry (ICP AES) on an IRIS Advantage spectrometer (Thermo Jarrell Ash Corporation). The surface morphology and particle sizes of the samples were studied using a Carl Zeiss Sigma scanning electron microscope (Carl Zeiss). The determination of the particle/aggregate size distribution was performed on a MicroSizer 201 laser analyzer (BA Instruments). Results. The paper proposes technological processes for obtaining highly dispersed powders of titanium carbide and diboride. The optimum synthesis temperature for titanium carbide is 2,000…2,100 oC, and for titanium diboride 1,600…1,700 oC. The content of the basic substance is at the level of 97.5…98.0 wt. %. Discussion. A possible mechanism for the formation of titanium carbide and diboride is proposed, which consists in the transfer of vapors of titanium oxides to the surface of solid carbon (synthesis of titanium carbide) and vapors of boron and titanium oxides to the surface of solid carbon (synthesis of titanium diboride). Due to the high purity and dispersion values, the resulting titanium carbide powder can be used as an abrasive material and for the manufacture of tungsten-free hard alloys, carbide steels, wear-resistant coatings, and titanium diboride powder can be used for the preparation of cutting tools and ceramics based on boron carbide.

Research and development of processes of vacuum ion-plasma parts surface treatment

The application of electron-ion-plasma technologies for increasing the service life of machine parts, tools and technological equipment has been investigated. The technology of vacuum ion-plasma surface treatment is proposed for the deposition of coatings, which makes it possible to create internal, external and combined coatings. The manufacturability of coating methods is largely determined by the level of the developed equipment. The entire technological process of deposition of wear-resistant coatings on parts of friction units is carried out in one cycle on a BRV600F vacuum unit, which is equipped with all the necessary technical means. A method has been developed for the technology of obtaining a superhard carbon-metal coating with desired properties, namely, improving the quality of diamond-like films by changing their structure and composition, while the lower layer should have high adhesion to the substrate material, the middle layer should have high hardness and increased wear resistance, and the upper layer should have good thermal conductivity and heat resistance with low coefficient of friction.

Modeling features of the technological process of forestry machines parts strengthening by the method of gas-thermal spraying

The efficiency of the working bodies of tillage forestry machines is determined by the sharpness of their soil-cutting elements. The purpose of the study is to substantiate the modes of the technological process of strengthening and recovery of cutting working forestry machines by the method of gas-flame spraying of wear-resistant coatings to increase their wear resistance and preserve the blade sharpness by implementing the self-sharpening effect, which allows increasing their life by 2-3 times. Technical and economic indicators of the gas-flame spraying process, as well as the scope of its application, depend on how well the technological modes of the spraying process are selected. The relevance of the topic is due to the need to increase the durability of tillage tools by strengthening their surfaces treatment. Such effective methods include the technology of recovery and strengthening of the working bodies of tillage machines using the technology of gas-flame spraying. In this regard, the issues of conducting research have become particularly relevant: to identify the relationships of technological parameters during the gas-flame application of wear-resistant coatings; to change the strength characteristics of the material of parts during their recovery, providing the necessary reliability and durability.