scholarly journals The effect of modification diamond nanopowders detonation synthesis to change their electrokinetic and electrophysical characteristics

Surface ◽  
2020 ◽  
Vol 12(27) ◽  
pp. 169-178
Author(s):  
G. Bazaliy ◽  
◽  
N. Oliinyk ◽  
G. Ilnytska ◽  
◽  
...  
Keyword(s):  
Liquid Phase ◽  
Dielectric Loss ◽  
Electrophoretic Mobility ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Mass Fraction ◽  
Electrokinetic Potential ◽  
Thermochemical Treatment ◽  
Detonation Synthesis ◽  
Diamond Nanopowders

Development of methods for controlling the change in the functional cover and the energy composition of the surface of detonation synthesis diamond nanopowders is necessary to create stable suspensions and materials from them. The aim of this work is to study changes in the electrokinetic and electrophysical characteristics of the powder as a result of the modification of detonation synthesis diamond nanopowders using a liquid-phase thermochemical treatment. Diamond nanopowders of grades ASUD-75 - ASUD-99 with different sp2-hybridization carbon content, manufactured at the V.I. Bakul National Academy of Sciences of Ukraine from the product of detonation synthesis of diamond from the company "ALIT" (Zhytomyr) investigated. Diamond nanopowders of ASUD-90 grade after their modification by means of liquid-phase thermochemical treatment using: a melt of alkalis, a mixture of nitric and sulfuric acids, a mixture of chromic and sulfuric acids were investigated by electrophoresis using a device "Dzeta-potential-analizer" company "Mikromeritiks". Electrokinetic characteristics of diamond nanopowders: the magnitude and sign of the electrokinetic potential, electrophoretic mobility are determined. The methods were used to study the physicochemical characteristics of nanopowders: electrical resistivity, carbon content of sp2-hybridization, mass fraction of impurities in the form of an incombustible residue, and specific surface area. In this work, it was established by electrophoresis that the value of the electrokinetic potential and electrophoretic mobility of the powder decrease by 2-10 times with a decrease in the mass fraction of sp2-hybridization carbon from 23.6 to 0 wt%. Using the ASUD-90 nanopowder as an example, it is shown that the modification of the nanopowder by the liquid-phase method using thermochemical treatment with mixtures of oxidants leads to a decrease in the values ​​of electrophoretic mobility by 1.1-7.5 times and electrokinetic potential by 1.1-7.3 times. It was found by dielectric measurement that the tangent of the dielectric loss angle of diamond nanopowders of grades ASUD-90 - ASUD-99 is in the range 0.3046 - 0.3146. Modification of the ASUD-90 grade nanopowder using a liquid-phase thermochemical treatment leads to a change in the interval of the dielectric loss tangent, namely 0.2450-0.3249. According to the degree of increase in the ratio of the dielectric loss tangent from 0% humidity to 100% humidity, the methods for modifying nanopowders can be arranged as follows: modifying using a melt of alkalis (ASUD-90-1 sample, S = 12.8%) <mixture of chromic and sulfuric acids (sample ASUD-90-3, S = 13.8%) <mixture of nitric and sulfuric acids (sample ASUD-90-2, S = 20.8 %).

Electrophysical properties of mixtures of mineral oil and synthetic ester dielectric liquid

2021 ◽  
Vol 14 (2) ◽  
pp. 132-141
Author(s):  
M. N. Lyutikova ◽  
S. M. Korobeynikov ◽  
A. A. Konovalov
Keyword(s):  
Dielectric Loss ◽  
Breakdown Voltage ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Kinematic Viscosity ◽  
Mineral Oil ◽  
Flash Point ◽  
Power Transformers ◽  
Synthetic Ester ◽  
Insulating Properties

Power transformers are key equipment in power generation, transmission, and distribution systems. The reliability of power transformers is based on the performance of the insulation system, which includes solid cellulose insulation and a liquid dielectric. Modern power engineering requires liquid insulation to have excellent insulating properties, high fire resistance, and biodegradability. Mineral oil that has been in use for over 100 years does not meet certain requirements. Therefore, various methods of enhancing the insulating properties of the oil are currently being considered, including mixing it with other liquid dielectrics, which have excellent properties. Synthetic and natural esters are considered as alternative fluids.This article discusses the possibility of enhancing the insulating characteristics of mineral oil with a high content of aromatic hydrocarbons (for example, T-750 oil) by mixing it with synthetic ester Midel 7131. Assessment is given of insulating parameters of the resulting mixtures with an ester fraction in mineral oil from 0% to fifty%. The main characteristics of the mixtures are described, such as density, kinematic viscosity, flash point, dielectric loss tangent, relative dielectric permittivity, breakdown voltage, and moisture content. It is shown that with an increase in the proportion of ester, some parameters of the obtained insulating liquid improve (flash point, dielectric constant, breakdown voltage), while values of other parameters (density, kinematic viscosity, dielectric loss tangent) with an ester content of more than 10% in the mixture do not meet the requirements for mineral oils.

Method of calculating the dielectric loss tangent of binary systems

1987 ◽  
Vol 52 (3) ◽  
pp. 310-312
Author(s):  
G. N. Dul'nev ◽  
D. P. Volkov ◽  
M. V. Dobrochasov
Keyword(s):  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Binary Systems

scholarly journals Dielectric and electrical properties of Cr substituted Mg ferrites

2015 ◽  
Vol 39 (1) ◽  
pp. 1-12 ◽  
Author(s):  
AKM Zakaria ◽  
Faizun Nesa ◽  
MA Saeed Khan ◽  
SM Yunus ◽  
NI Khan ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Lattice Parameter ◽  
Activation Energies ◽  
X Ray Diffraction ◽  
Constant E ◽  
Cr Concentration ◽  
Academy Of Sciences

The spinel ferrites MgCrxFe2-xO4 (0.0 ? × ?1.0) were prepared through the solid state reaction using conventional ceramic method at 1300°C in air. The homogeneous phase of the ferrite samples was observed from the X-ray diffraction study. Lattice parameter of the samples was found to decrease with increasing Cr concentration in the system obeying Vegard’s law. The ac electrical resistivity, measured as a function of temperature, decreases with the increase of temperature indicating the semiconducting nature of all the samples. The activation energies were calculated and found to decrease with increasing Cr content. The lower activation energies are associated with higher electrical conductivity. With the increase of temperature, dielectric constant (e`) and dielectric loss tangent are observed to be increased; while with the increase of frequency, dielectric constant (e`) and dielectric loss tangent decrease for all the samples.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 1-12, 2015

Multipurpose Nonwoven Viscose/Polypropylene Fabrics: Effect of Fabric Characteristics and Humidity Conditions on the Volume Electrical Resistivity and Dielectric Loss Tangent

2020 ◽  
Vol 21 (10) ◽  
pp. 2407-2416
Author(s):  
Koviljka A. Asanovic ◽  
Dragana D. Cerovic ◽  
Mirjana M. Kostic ◽  
Tatjana V. Mihailovic ◽  
Aleksandra M. Ivanovska
Keyword(s):  
Electrical Resistivity ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent

scholarly journals In-situ measurement of electric current and dielectric loss tangent during vulcanisation of nitrile rubber.

1998 ◽  
Vol 71 (5) ◽  
pp. 281-285 ◽  
Author(s):  
Toyohiko GONDOH ◽  
Yukiko MATSUOKA ◽  
Michiharu TOH ◽  
Daisaburo OKAI ◽  
Tetsuo MORI
Keyword(s):  
Dielectric Loss ◽  
Electric Current ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Nitrile Rubber ◽  
In Situ Measurement

Dielectric loss tangent of sapphire single crystal produced by edge-defined film-fed growth method

2002 ◽  
Vol 377 (3) ◽  
pp. 313-318 ◽  
Author(s):  
M. Kusunoki ◽  
M. Inadomaru ◽  
S. Ohshima ◽  
K. Aizawa ◽  
M. Mukaida ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Single Crystal ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Growth Method ◽  
Sapphire Single Crystal

scholarly journals Dielectric Behavior of Dysprosium Substituted Magnesium Ferrite

2018 ◽  
Vol 15 (1) ◽  
pp. 48-54
Author(s):  
Jeevan S. Ghodake
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Powder Diffraction ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Dielectric Behavior ◽  
Complex Dielectric Constant ◽  
Frequency Variation ◽  
Magnesium Ferrite ◽  
X Ray

Dysprosium substituted Magnesium ferrite weresuccessfully prepared by chemical combustion method. The as synthesized powder was presintered in air at 6000C for 1hr and finally sintered at 9500C for 1hr. From X-ray powder diffraction pattern of MgDy0.03Fe1.97O4, confirmed formation of single phase cubic spinel structure. The value of crystallite size obtained from X-ray powder diffraction (311) peak , it is found to be 46.38nm.The frequency and temperature variation of dielectric parameters such as real dielectric constant (ε′), complex dielectric constant (ε") and dielectric loss tangent (tanδ) were determined using Hioki LCR - Q meter. The frequency variation of dielectric constant shows a normal dielectric behavior of spinel ferrites. The dielectric loss tangent with frequency shows similar behavior as dielectric constant. The dielectric constant and dielectric loss tangent increases with increase in temperature

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