scholarly journals Процессы переноса заряда в легировaнном натрием углеродном композите на основе фуллеренов и терморасширенного графита

2019 ◽  
Vol 61 (10) ◽  
pp. 1971
Author(s):  
В.И. Берёзкин
Keyword(s):  
Carbon Composite ◽  
Charge Carriers ◽  
Free Electrons ◽  
Additional Increase ◽  
Undoped Material ◽  
Main Charge ◽  
Carbon Composite Material ◽  
Scattering Centers ◽  
Order Of Magnitude ◽  
Thermally Exfoliated Graphite

AbstractThe results of doping of a carbon composite material, in which fullerenes are located in a conductive matrix based on thermally exfoliated graphite, with a sodium dopant are presented. Charge transfer processes taking place in samples with different initial ratios of components are studied. It turns out that the electrical resistivity of the samples increases with the introduction of sodium and an increase in its content, since the mobility of the main charge carriers, which are holes as in the undoped material, decreases. The concentration of charge carriers in different types of samples varies in both directions and can increase by more than an order of magnitude. It is concluded that Na plays an ambiguous role. It can contribute not only to the generation of free electrons, but also to an additional increase in the concentration of various defects that can generate free holes and can affect, being effective traps and scattering centers, all types of charge carriers.

scholarly journals Electro-Thermal and Semiconductivity Behaviour of Natural Sintered Complex Carbonate Ore for Thermo-Technological Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Loutfy H. Madkour
Keyword(s):  
Energy Gap ◽  
Sintering Temperature ◽  
Thermal Analyses ◽  
Charge Carriers ◽  
Degree Of Crystallinity ◽  
Power Coefficient ◽  
Free Electrons ◽  
Dc Voltage ◽  
X Ray ◽  
Main Charge

The polymetal (Zn, Pb, Fe, Ca, Mg, Cd, Ba, Ni, Ti, and SiO2) complex Umm-Gheig carbonate ore is subjected to sintering treatment at 573, 773, 973 and 1273 K respectively for four hours. Chemical, spectral, X-ray and differential thermal analyses are applied for the native ore as well as for the samples preheated and sintered. The current versus applied DC voltage (I–V) characteristics, bulk density (Db), percent shrinkage (%S), activation energy (Ea) and energy gap (Eg) are established for the sintered ore. The electrical conductivity σ, thermal conductivity (K) and thermoelectric power coefficient α have been investigated as a function of applied temperature for the sintered ore materials. The electrical conduction is mainly achieved by free electrons near or in conduction band or n-type. As the sintering temperature (Ts) increases the conduction of the ore is also increased due to the recombination process taking place between the electrons and holes. Electrons hopping between Fe2+ and Fe3+ are the main charge carriers. The formation of Fe3O4 at high sintering temperature acts as an active mineralizer, thus inducing an increased degree of crystallinity and a more ordered crystal structure is produced.

scholarly journals Магнитные свойства легированных натрием композитов типа фуллерен-терморасширенный графит

2019 ◽  
Vol 61 (10) ◽  
pp. 1799
Author(s):  
В.И. Берёзкин ◽  
В.В. Попов ◽  
С.В. Кидалов ◽  
Н.В. Шаренкова
Keyword(s):  
Magnetic Properties ◽  
Magnetic Moment ◽  
Structural Features ◽  
Carbon Composite ◽  
Strong Increase ◽  
Initial Composition ◽  
Field Range ◽  
Brillouin Function ◽  
Carbon Composite Material ◽  
Thermally Exfoliated Graphite

AbstractThe magnetic properties (field range H = 0–50 kOe, temperature range T = 3–300 K), and structural features of a sodium-doped carbon composite material based on fullerene C_60 and thermally exfoliated graphite (TEG) are studied. The material is obtained with different ratios of the components by sintering at a pressure of 7 GPa and T = 600°C, at which it is found that significant amorphization of the crystal lattice of the initial C_60 occurs. The dia-, para-, and ferromagnetic components ( M _D, M _PM, and M _FM) were separated from the total magnetic moment of the samples under study. It is found that a sodium dopant has no effect on the magnetic properties of the composite. Analysis of the M _PM( H ) field dependences by using the Brillouin function for the fullerene-containing sample (i.e., without TEG) makes it possible to determine the quantum number of the total angular momentum of paramagnetic (PM) centers. Its value is found to be J = 1, which corresponds to elementary magnetic moment μ_PM = 2μ_B of a PM center. The concentration of PM centers is estimated at the level of N _PM ≈ (2–5) × 10^18 g^–1 for most samples, including the material without TEG. The introduction of TEG into the initial composition and an increase in its proportion in the composite leads to a strong increase in the magnetic moment, which is explained by an increase in both the J value and the concentration of PM centers.

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.

Dynamic Characterization and Modeling of Carbon Composite Ballistic Behavior

2016 ◽  
Author(s):  
Chian-Fong Yen ◽  
Robert Kaste ◽  
Jian Yu ◽  
Charles Chih-Tsai Chen ◽  
Nelson Carey
Keyword(s):  
Composite Material ◽  
Progressive Failure ◽  
Laminated Composite ◽  
Carbon Composite ◽  
Ballistic Impact ◽  
Impact Testing ◽  
Material Behavior ◽  
Failure Behavior ◽  
Failure Model ◽  
Carbon Composite Material

Design of the new generation of aircraft is driven by the vastly increased cost of fuel and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aircraft structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic impact conditions. Using a meso-mechanics approach, a laminated composite is represented by a collection of selected numbers of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by the strain-rate dependent layer progressive failure model using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA as a user-defined material subroutine. In this paper, the ballistic limit velocity (V50) was established for a series of laminates by ballistic impact testing. Correlation of the predicted and measured V50 values has been conducted to validate the accuracy of the ballistic modeling approach for the selected carbon composite material. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic and blast survivability.

scholarly journals Design and Construction of an Electric Guitar Body Made of Carbon Composite

2021 ◽  
pp. 101-106
Author(s):  
Radoslav Vandžura ◽  
Vladimír Simkulet ◽  
Michal Hatala
Keyword(s):  
Composite Material ◽  
Carbon Composite ◽  
The Body ◽  
Electric Guitar ◽  
Carbon Composite Material ◽  
Selection Of ◽  
Design And Construction

This paper presents the selection of technology, technological and working procedures to construct the body of an electric guitar (Stratocaster type.). The used material for the electric guitar construction was carbon composite material offset by standardly used components. The carbon composite was chosen because of its excellent properties suitable for guitar construction. Described and used technologies were Manual Wet Lamination Technology and Vacuum Bag Molding (VBM) technology, and both are affordable and uncomplicated methods.

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