scholarly journals Возможность синтеза наноразмерного карбида молибдена в атмосферной электроразрядной плазме

2019 ◽  
Vol 45 (17) ◽  
pp. 16
Author(s):  
А.Я. Пак
Keyword(s):  
Molybdenum Carbide ◽  
Arc Discharge ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Ambient Air ◽  
Transmission Electron Microscopy Data ◽  
Synthesis Product ◽  
Powder Synthesis ◽  
Two Phases ◽  
Microscopy Data

The paper presents the results of the experimental studies demonstrating the possibility of obtaining the crystalline phases of molybdenum carbide in a DC arc discharge plasma initiated inside a hollow graphite cathode under ambient air conditions. According to X-ray diffraction data in the powder synthesis product two phases of molybdenum carbide are identified: Mo1.2C0.8 and Mo2C, as well as graphite and metallic molybdenum. According to transmission electron microscopy data, molybdenum carbide particles are located in the carbon matrix, particles are characterized by sizes mostly not exceeding 5-10 nm.

scholarly journals Studying the influence of the energy parameters of the plasma dynamic synthesis process on the dispersed products of the W–C system

2021 ◽  
Vol 2064 (1) ◽  
pp. 012090
Author(s):  
A A Sivkov ◽  
I I Shanenkov ◽  
D S Nikitin ◽  
A Nassyrbayev ◽  
I A Rakhmatullin ◽  
...  
Keyword(s):  
Tungsten Carbide ◽  
Carbon Matrix ◽  
Initial Energy ◽  
Synthesis Process ◽  
Transmission Electron Microscopy Data ◽  
Plasma Dynamic ◽  
Energy Parameters ◽  
Dynamic Synthesis ◽  
Transmission Electron ◽  
Microscopy Data

Abstract Tungsten carbide and its different crystalline phases are widely used for production of metalworking tools due to their excellent physical and mechanical characteristics. However, there is still a problem of synthesizing the cubic modification of tungsten carbide. This paper demonstrates the results on studying the influence of the energy parameters of the plasma dynamic synthesis process on the dispersed products of the W–C system. It was revealed that the initial energy parameters directly influence the phase composition of synthesized products. There were found the optimal conditions for synthesizing the dispersed products from the standpoint of the high output of cubic tungsten carbide phase (more than 85 wt.%). According to transmission electron microscopy data, all the products are characterized by the presence of particles with a core-shell structure embedded into the amorphous carbon matrix.

scholarly journals Получение карбида титана в атмосферной электроразрядной плазме

2020 ◽  
Vol 90 (5) ◽  
pp. 805
Author(s):  
А.Я. Пак ◽  
Т.Ю. Якич ◽  
Г.Я. Мамонтов ◽  
М.А. Рудмин ◽  
Ю.З. Васильева
Keyword(s):  
Titanium Carbide ◽  
Discharge Plasma ◽  
Arc Discharge ◽  
Synthesis Method ◽  
Experimental Studies ◽  
Ambient Air ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbide Particles ◽  
Synthesis Duration

The paper discusses the experimental studies connected with development of scientific and technical foundations for the synthesis method of titanium carbide by electric arc discharge plasma under ambient air condition. According to the X-ray diffraction data, the dependences between the product phase composition and the synthesis duration was determined. According to the scanning electron microscopy and energy dispersive analyses data, a morphological types number of titanium carbide particles, which are formed as a result of uneven distribution of energy in the reaction volume, was identified.

Effect of energy on the phase composition of the product of arc discharge synthesis in the tungsten-carbon system obtained in a self-shielding autonomous gas environment

2020 ◽  
Vol 10 ◽  
pp. 79-87
Author(s):  
A. Ya. Pak ◽  
◽  
A. I. Kokorina ◽  
Keyword(s):  
Electron Microscopy ◽  
Phase Composition ◽  
Direct Current ◽  
Arc Discharge ◽  
Atmospheric Oxygen ◽  
Ambient Air ◽  
Synthesis Product ◽  
Powder Materials ◽  
Tungsten Carbides ◽  
Carbon System

The paper presents the results of experimental studies on the preparation of ultrafine powder materials of the tungsten-carbon system in the plasma of a direct current arc discharge initiated in an ambient air. According to the results of X-ray diffractometry, transmission electron microscopy, scanning electron microscopy, and elemental analysis, the product identifies micro-sized and nanoscale crystalline objects that are carbon graphite-like materials gC, tungsten carbides WC and W2C with a hexagonal structure, tungsten W with a cubic structure. As a result of a series of experiments, the possibility of influencing the phase composition of the synthesis product by the amount of energy supplied, which is linearly dependent on the duration of the arc discharge, was established. In this case, tungsten oxide phases were not found in the composition of the synthesis products within the framework of the applied analytical techniques. The process of obtaining non-oxide materials during the generation of a direct current arc plasma in the presence of carbon and tungsten is possible due to the intense generation of carbon monoxide and carbon dioxide gases, which shield the reaction volume from atmospheric oxygen. Thus, in the framework of the presented work, the possibility of controlling the phase composition of the product of vacuumless arc synthesis in the tungsten-carbon system by changing the duration of the discharge burning at a constant direct current was shown for the first time.

The system of indicators of the quality of the carbon-carbon composite materials and technologies of their production

2018 ◽  
pp. 127-132
Author(s):  
T. N. Antipova ◽  
D. S. Shiroyan
Keyword(s):  
Composite Material ◽  
Low Cost ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Optimal Number ◽  
Laboratory Equipment ◽  
Carbon Composite Material ◽  
Carbon Composite Materials

The system of indicators of quality of carbon-carbon composite material and technological operations of its production is proved in the work. As a result of the experimental studies, with respect to the existing laboratory equipment, the optimal number of cycles of saturation of the reinforcing frame with a carbon matrix is determined. It was found that to obtain a carbon-carbon composite material with a low cost and the required quality indicators, it is necessary to introduce additional parameters of the pitch melt at the impregnation stage.

ARC DISCHARGE SYNTHESIS OF MATERIAL BASED ON GRAPHITE AND MOLYBDENUM CARBIDE

2019 ◽  
Vol 14 (11-12) ◽  
pp. 551-556
Author(s):  
A. Ya. Pak ◽  
P. N. Kononenko
Keyword(s):  
Molybdenum Carbide ◽  
Arc Discharge

Initial Dynamic Susceptibility of Maghemite Nanoparticles Dispersed in Surface-Treated Polymeric Template

2021 ◽  
Vol 21 (11) ◽  
pp. 5694-5697
Author(s):  
A. F. R. Rodriguez ◽  
R. F. Lacerda ◽  
L. E. Maggi ◽  
Hory Mohammadpour ◽  
Mohammad Niyaifar ◽  
...  
Keyword(s):  
Ex Situ ◽  
Transmission Electron Microscopy Data ◽  
Dynamic Susceptibility ◽  
Maghemite Nanoparticles ◽  
X Ray Diffraction ◽  
Chemical Treatments ◽  
Dynamical Susceptibility ◽  
Transmission Electron ◽  
Microscopy Data ◽  
Polymeric Template

Magnetic nanocomposites based on maghemite nanoparticles supported (ex situ route) on styrene- divinilbenzene (Sty-DVB) copolymer templates were produced and characterized for their structure and morphology. The as-produced nanocomposites were further chemically-treated with different oxidant agents and surface-coated with stearic acid. X-ray diffraction and transmission electron microscopy data show that the incorporated nanoparticles are preserved despite the aggressive chemical treatments employed. From the dynamical susceptibility measurements performed on the nanocomposites, the values of the saturation magnetization (76 emu/g) and the effective magnetic anisotropy (1.7 × 104 J/m3) were obtained, in excellent agreement with the values reported in the literature for maghemite. This finding strongly supports the preservation of the magnetic properties of the supported nanosized maghemite throughout the entire samples’ processing.

Effect of the Pulse Laser Radiation on the Stabilization of the ZrO2 and HFO2 High-Temperature Phases

2015 ◽  
Vol 245 ◽  
pp. 200-203 ◽  
Author(s):  
Maxim Alexandrovich Pugachevskii ◽  
Viktor Igorevich Panfilov
Keyword(s):  
High Temperature ◽  
Transmission Electron Microscopy Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Thermal Stability ◽  
Quantitative Content ◽  
Electron Microscopy Data ◽  
Cubic Phases ◽  
Transmission Electron ◽  
Microscopy Data

The conditions of formation of the ZrO2 and HfO2 high-temperature (tetragonal and cubic) phases in the ablated nanoparticles were investigated. X-ray diffraction and transmission electron microscopy data demonstrate that laser intensities above 109 W/m2 ensure the formation of the ZrO2 high-temperature phases, while intensities above 5·109 W/m2 do the formation of the HfO2 high-temperature phases. Quantitative content of the high-temperature phases in layers of the ablated nanoparticles increases with raising the intensity. The obtained nanoparticles exhibit good thermal stability.

scholarly journals Modeling of formation of carbon cluster groups in electric arc discharge plasma

2018 ◽  
Vol 80 (2) ◽  
pp. 108-113 ◽  
Author(s):  
A. N. Gavrilov
Keyword(s):  
Carbon Nanostructures ◽  
Arc Discharge ◽  
Experimental Studies ◽  
Particle Method ◽  
Cost Effective ◽  
Carbon Cluster ◽  
Collision Integral ◽  
Numerical Calculations ◽  
Plasma Synthesis ◽  
Interelectrode Space

The problem of modeling complex resource-intensive processes of plasma synthesis of carbon nanostructures (CNS) on the basis of mathematical and numerical methods of solution, focused on the use of parallel and distributed computing for processing large amounts of data, allowing to investigate the relationship and characteristics of processes to obtain an effective, cost-effective method of synthesis of CNS (fullerenes, nanotubes), is an actual theoretical and practical problem. This article deals with the problem of mathematical modeling of motion and interaction of charged particles in a multicomponent plasma based on the Boltzmann equation for the synthesis of ONS by thermal sublimation of graphite. The derivation of the collision integral is presented allowing to perform a numerical solution of the Boltzmann - Maxwell equations system with respect to the arc synthesis of CNS. The high order of particles and the number of their interactions involved simultaneously in the process of synthesis of CNS requires significant costs of machine resources and time to perform numerical calculations on the constructed model. Application of the large particle method makes it possible to reduce the amount of computing and hardware requirements without affecting the accuracy of numerical calculations. The use of parallel computing technology on the CPU and GPU with the use of Nvidia CUDA technology allows you to organize all the General-purpose calculations for the developed model based on the graphics processor of the personal computer graphics card, without the use of supercomputers or computing clusters. The results of experimental studies and numerical calculations confirming the adequacy of the developed model are presented. Obtained quantitative characteristics of the total pairwise interactions between the carbon particles and interactions with the formation of clusters of carbon with various types of ties in the plasma of the interelectrode space which are the basis of the synthesized nanostructures. The formation of carbon clusters occurs in the entire interelectrode space of the plasma with different intensity and depends on the process parameters.

scholarly journals Air Pollution Monitoring and Control System for Subway Stations Using Environmental Sensors

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Gyu-Sik Kim ◽  
Youn-Suk Son ◽  
Jai-Hyo Lee ◽  
In-Won Kim ◽  
Jo-Chun Kim ◽  
...  
Keyword(s):  
Air Quality ◽  
Air Pollutants ◽  
Linear Regression Analysis ◽  
Experimental Studies ◽  
Ambient Air ◽  
Pollution Monitoring ◽  
Scattering Method ◽  
Environmental Sensors ◽  
Monitoring And Control ◽  
Subway Stations

The metropolitan city of Seoul uses more energy than any other area in South Korea due to its high population density. It also has high emissions of air pollutants. Since an individual usually spends most of his/her working hours indoors, the ambient air quality refers to indoor air quality. In particular, PM10concentration in the underground areas should be monitored to preserve the health of commuters in the subway system. Seoul Metro and Seoul Metropolitan Rapid Transit Corporation measure several air pollutants regularly. In this study, the accuracy of an instrument for PM measurement using the light scattering method was improved with the help of a linear regression analysis technique to continuously measure thePM10concentrations in subway stations. In addition, an air quality monitoring system based on environmental sensors was implemented to display and record the data of PM10, CO2, temperature, and humidity. Through experimental studies, we found that ventilation fans could improve air quality and decrease PM10concentrations in the tunnels effectively by increasing the air flow rate.

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