Preparation and Characterization of Porous Si-Coated SiC Fiber Media

2004 ◽  
Vol 449-452 ◽  
pp. 233-236 ◽  
Author(s):  
Jun Suh Yu ◽  
B.S. Lee ◽  
Sung Churl Choi ◽  
Ji Hun Oh ◽  
Jae Chun Lee
Keyword(s):  
Electrical Conductivity ◽  
Silicon Content ◽  
Porous Si ◽  
Electrically Conductive ◽  
Electrode Distance ◽  
Sic Fiber ◽  
Effective Electrical Conductivity ◽  
The One ◽  
Fiber Preforms

Electrically conductive porous Si/SiC fiber media were prepared by infiltration of liquid silicon into porous carbon fiber preforms. The series rule of mixture for the effective electrical conductivity was applied to the disc shaped samples to estimate their silicon content, effective electrical conductivity and porosity. The electrical conductivity was estimated by assuming the disc sample as a plate of equivalent geometry, i.e., same thickness, electrode distance and volume. As the volumetric content of silicon in a sample increases from 0.026% to 0.97%, the estimated electrical conductivity increases from 0.17 S/cm to 2.09 S/cm. The porosity of the samples measured by Archimedes principle was in the range of 75~83% and 1~4% less than the one estimated by the series rule of mixture for the effective electrical conductivity.

scholarly journals Synthesis, Crystal Structures, and Spectroscopic Characterization of Bis-aldehyde Monomers and Their Electrically Conductive Pristine Polyazomethines

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1498 ◽  
Author(s):  
Abdul Hafeez ◽  
Zareen Akhter ◽  
John F. Gallagher ◽  
Nawazish Ali Khan ◽  
Asghari Gul ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Spectroscopic Characterization ◽  
Spectroscopic Techniques ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Electrically Conductive ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Ft Ir

Bis-aldehyde monomers 4-(4′-formyl-phenoxy)benzaldehyde (3a), 3-methoxy-4-(4′-formyl-phenoxy)benzaldehyde (3b), and 3-ethoxy-4-(4′-formyl-phenoxy)benzaldehyde (3c) were synthesized by etherification of 4-fluorobenzaldehyde (1) with 4-hydroxybenzaldehyde (2a), 3-methoxy-4-hydroxybenzaldehyde (2b), and 3-ethoxy-4-hydroxybenzaldehyde (2c), respectively. Each monomer was polymerized with p-phenylenediamine and 4,4′-diaminodiphenyl ether to yield six poly(azomethine)s. Single crystal X-ray diffraction structures of 3b and 3c were determined. The structural characterization of the monomers and poly(azomethine)s was performed by FT-IR and NMR spectroscopic techniques and elemental analysis. Physicochemical properties of polymers were investigated by powder X-ray diffraction, thermogravimetric analysis (TGA), viscometry, UV–vis, spectroscopy and photoluminescence. These polymers were subjected to electrical conductivity measurements by the four-probe method, and their conductivities were found to be in the range 4.0 × 10−5 to 6.4 × 10−5 Scm−1, which was significantly higher than the values reported so far.

scholarly journals Ionic Liquid as Dispersing Agent of LDH-Carbon Nanotubes into a Biodegradable Vinyl Alcohol Polymer

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 495 ◽  
Author(s):  
Valeria Bugatti ◽  
Gianluca Viscusi ◽  
Antonio Di Bartolomeo ◽  
Laura Iemmo ◽  
Daniela Clotilde Zampino ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Ionic Liquid ◽  
Polymer Matrix ◽  
Vinyl Alcohol ◽  
Mechanical And Electrical Properties ◽  
Dispersing Agent ◽  
The One ◽  
Double Hydroxides

A Zn/Al layered double hydroxides (LDHs) hosting carbon nanotubes (80% of CNTs) was synthesized and dispersed into a commercial biodegradable highly amorphous vinyl alcohol polymer at different loading (i.e., 1; 3; 5; 10 wt %). In order to improve the degree of dispersion of the filler into the polymer matrix, an ionic liquid (IL) based on 1-hexadecyl-3-methylimidazolium dimethyl-5-sodiosulfoisophthalate was added to the composites’ mixtures. Structural characterization of filler and polymeric composites was carried out. The analysis of thermal, mechanical and electrical properties of the composites, resulted improved compared to the unfilled material, allowed to hypothesize a good dispersion of the LDH-CNTs lamellar filler into the polymer matrix-assisted by the ionic liquid. This was demonstrated comparing electrical conductivity of composite at 5% of LDH-CNTs in the presence and in the absence of IL. The experimental results showed that the electrical conductivity of the sample with IL is four orders of magnitude higher than the one without IL. Furthermore, the percolation threshold of the whole system resulted very low—0.26% of LDH-CNTs loading, which is 0.21% of CNTs.

Preparation and Characterization of Gallium-Doped Zinc Oxide Nanopowders with High Electrical Conductivity

2007 ◽  
Vol 336-338 ◽  
pp. 2041-2043 ◽  
Author(s):  
Shang Feng Du ◽  
J. Liu ◽  
Yun Fa Chen
Keyword(s):  
Electrical Conductivity ◽  
Zinc Oxide ◽  
Volume Resistivity ◽  
Precipitation Method ◽  
High Electrical Conductivity ◽  
Electrically Conductive ◽  
Oxide Particles ◽  
Zinc Oxide Particles ◽  
Co Precipitation

Gallium-doped zinc oxide nanopowders with high electrical conductivity were prepared by calcining the precursor synthesized from ZnSO4·7H2O, GaCl3 and NH4HCO3 by co-precipitation method. The obtained samples were characterized by FE-SEM, TEM, XRD, XPS and BET techniques. The precursor particles were in the shape of sheet-like with size about several hundred nanometers. The electrically conductive zinc oxide particles, in the shape of sphere-like, were about 10~40 nm with low agglomeration, and the specific surface area was 28.7 m2/g. XRD and XPS results showed that all the doped Ga exists as the substitution form of Ga• Zn in the ZnO system. The volume resistivity of the product was as lower as 4.5 :·cm.

Detection and quantification of 3D hydraulic fractures with vertical borehole induction resistivity measurements

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. E259-E264 ◽  
Author(s):  
Kai Yang ◽  
Carlos Torres-Verdín ◽  
Ali E. Yılmaz
Keyword(s):  
Electrical Conductivity ◽  
Low Frequency ◽  
Hydraulic Fractures ◽  
Electrically Conductive ◽  
Resistivity Measurements ◽  
Effective Electrical Conductivity ◽  
Shale Formation ◽  
Logging Tool ◽  
Conductivity Contrast ◽  
Vertical Borehole

We have investigated the ability of low-frequency induction resistivity measurements to detect and appraise hydraulic fractures induced near vertical boreholes. Integral-equation-based simulations indicate that coplanar measurements can detect fractures when they are injected with electrically conductive proppant to increase their conductivity contrast with the shale background. Specifically, when a logging tool consisting of one transmitter and two receivers that are 1.2 and 1.5 m away is used to detect fractures with the effective electrical conductivity of [Formula: see text] in a homogeneous shale formation of [Formula: see text] conductivity, the measurements (1) can indicate the boundary of fractures intersecting with vertical boreholes by the signal spikes generated only when the tool enters/exits fractures, (2) can detect fractures as small as approximately 0.15 m and differentiate fractures up to approximately 10 m in width, (3) can detect fractures with height as small as 0.3 m, (4) can differentiate elliptical and rectangular fractures from each other if they exhibit the same width; e.g., they can discriminate if their widths are within approximately 0.4–10 m, and (5) are sensitive to the effective electrical conductivity of the fracture. A second logging tool consisting of one transmitter and two receivers that are 18 and 19.2 m away is found to be less useful in the detection and appraisal of hydraulic fractures induced near vertical boreholes.

scholarly journals Influence of Powdered Moringa oleifera Lam. Almonds Dried at Different Temperatures on the Physico-chemical Quality of the Pond Water

2020 ◽  
pp. 1-11
Author(s):  
Yerima Bako Djibo Aboubacar ◽  
Guero Yadji
Keyword(s):  
Electrical Conductivity ◽  
Moringa Oleifera ◽  
Chemical Characterization ◽  
Pond Water ◽  
Physico Chemical ◽  
Different Temperatures ◽  
The One ◽  
Moringa Oleifera Lam

The study focused on the physico-chemical characterization of raw water samples from the Kongou Gorou pond treated with almond powder from Moringa oleifera seeds. The powder which was used for the present study was dried in the oven for one month at the respective temperatures of 25, 40 and 50 ° C and then applied at a dose of 100 mg /L. The parameters studied are pH, iron, copper, electrical conductivity, rate of dissolved substances (TDS), hardness, organic matter; calcium, HCO3-, magnesium, the Complete Alkalimetric Title (TAC). The physico-chemical analysis showed that the waters studied have concentrations below the standards recommended by WHO in 2009. For the dose of 100 mg/L and stored at the respective temperatures of 50, 40 and 25 ° C, it was recorded: a pH close to neutrality, a reduction in iron content of 93.46% at 50 ° C, 90.76% and 90.76%, a decrease in magnesium of 27.21; 27.89 and 39.96%, a decrease in hardness of 37.98; 39.94 and 36.03%; a decrease in the TAC from 1.3 to 1.18; 1.29 and 1.23 ° F and finally a reduction of 9.26; 0.81 and 5.42% bicarbonate. At these respective temperatures of 50, 40 and 25 ° C, the electrical conductivity has increased by 33.63, 33.05 and 32.8µs.cm / L at 2 hours of settling and from 34, 64, 34, 28 and 36, 23 µs. cm / L at 24 hours of settling; an increase in the rate of Dissolved Substances from 15.21 to 16.32; 16.33 and 16.72 mg / L; an increase in the order of 34.48, 26.72 and 13.79% in calcium levels; an increase on the one hand of copper from 0.114 mg/L to 0.903 and 2.39 mg/L respectively at 50 and 40 ° C and on the other hand a total removal of the latter at 25 ° C. The results showed that the use of Moringa oleifera seeds effectively improves the physicochemical quality of the treated water, which not only meets the WHO drinkability standards but also the characteristics of water suitable for drip irrigation.

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

Effect of the structure of cellulose acetate membranes on their permeability, electrical conductivity and rejection

1990 ◽  
Vol 55 (12) ◽  
pp. 2933-2939 ◽  
Author(s):  
Hans-Hartmut Schwarz ◽  
Vlastimil Kůdela ◽  
Klaus Richau
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Cellulose Acetate ◽  
Reverse Osmosis ◽  
Water Flux ◽  
Cellulose Acetate Membrane ◽  
Structure Parameters ◽  
Dc Electrical Conductivity ◽  
Cellulose Acetate Membranes

Ultrafiltration cellulose acetate membrane can be transformed by annealing into reverse osmosis membranes (RO type). Annealing brings about changes in structural properties of the membranes, accompanied by changes in their permeability behaviour and electrical properties. Correlations between structure parameters and electrochemical properties are shown for the temperature range 20-90 °C. Relations have been derived which explain the role played by the dc electrical conductivity in the characterization of rejection ability of the membranes in the reverse osmosis, i.e. rRO = (1 + exp (A-B))-1, where exp A and exp B are statistically significant correlation functions of electrical conductivity and salt permeation, or of electrical conductivity and water flux through the membrane, respectively.

Polypyrrole/PU hybrid hydrogels: electrically conductive and fast self-healing for the potential application in body-monitor sensor

2021 ◽  
Author(s):  
Zhanyu Jia ◽  
Guangyao Li ◽  
Juan Wang ◽  
shouhua Su ◽  
Jie Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Potential Application ◽  
Self Healing ◽  
Electrically Conductive ◽  
Sensor Application ◽  
Hybrid Hydrogels ◽  
Health Monitor

Conductivity, self-healing and moderate mechanical properties are necessary for multifunctional hydrogels which have great potential in health-monitor sensor application. However, the combination of electrical conductivity, self-healing and good mechanical properties...

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

scholarly journals Formation and Evaluation of Silicon Substrate with Highly-Doped Porous Si Layers Formed by Metal-Assisted Chemical Etching

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yijie Li ◽  
Nguyen Van Toan ◽  
Zhuqing Wang ◽  
Khairul Fadzli Bin Samat ◽  
Takahito Ono
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Contact Resistance ◽  
Power Factor ◽  
Chemical Etching ◽  
Porous Si ◽  
Si Substrate ◽  
Si Substrates ◽  
Output Performance ◽  
Metal Assisted Chemical Etching

AbstractPorous silicon (Si) is a low thermal conductivity material, which has high potential for thermoelectric devices. However, low output performance of porous Si hinders the development of thermoelectric performance due to low electrical conductivity. The large contact resistance from nonlinear contact between porous Si and metal is one reason for the reduction of electrical conductivity. In this paper, p- and n-type porous Si were formed on Si substrate by metal-assisted chemical etching. To decrease contact resistance, p- and n-type spin on dopants are employed to dope an impurity element into p- and n-type porous Si surface, respectively. Compared to the Si substrate with undoped porous samples, ohmic contact can be obtained, and the electrical conductivity of doped p- and n-type porous Si can be improved to 1160 and 1390 S/m, respectively. Compared with the Si substrate, the special contact resistances for the doped p- and n-type porous Si layer decreases to 1.35 and 1.16 mΩ/cm2, respectively, by increasing the carrier concentration. However, the increase of the carrier concentration induces the decline of the Seebeck coefficient for p- and n-type Si substrates with doped porous Si samples to 491 and 480 μV/K, respectively. Power factor is related to the Seebeck coefficient and electrical conductivity of thermoelectric material, which is one vital factor that evaluates its output performance. Therefore, even though the Seebeck coefficient values of Si substrates with doped porous Si samples decrease, the doped porous Si layer can improve the power factor compared to undoped samples due to the enhancement of electrical conductivity, which facilitates its development for thermoelectric application.

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