Papers by Keyword: Electrical Conductivity

Abstract: Mechanical strengths and electrical conductivity are the very important engineering properties of lightweight aluminum (Al) alloys used in automobiles, especially for battery-powered electric vehicles (BEV). However, the main issue is that the mechanical properties and the electrical conductivity of Al alloys are mutually exclusive. This study aims to simultaneously improve both the tensile properties and the electrical conductivity of the squeeze as-cast Al-6wt% Si-3wt% Cu by modifying its microstructure with the addition of nickel (Ni) and strontium (Sr). In comparison to those of the alloy free of Sr and Ni, the additions of 0.03 wt.% Sr and 0.5 wt.% Ni in the Al-6Si-3Cu alloy significantly improved the ultimate tensile strength, yield strength and electrical conductivity. This was because the addition of Ni element, as a transition element, collaborated with Cu to form fine intermetallic Al-Cu-Ni phases for dispersion strengthening. Also, the modification of the Si morphology from micron needles to nanoparticles by the Sr addition enhanced both the strengths and electrical conductivity of the developed alloy.

Abstract: Carbon-based materials are widely used in various fields such as wastewater treatment, gas sensing, and energy storage applications. In this study, waste peanut shell (PSH), available in Egypt, were transformed into useful materials by physical, chemical, and thermal treatments. The physical properties of materials from the different processing combinations were investigated. The activated (APSH), carbonized (CPSH), and activated/carbonized (A/CPSH) forms were successfully prepared. The prepared solids were characterized by SEM, FTIR, XRD, and nitrogen gas adsorption. Ball milling at 5 runs for 45 min resulted in 84 wt% of the ground PSH passing through the 212 μm mesh. Accordingly, the activation, carbonization, and activation/carbonization increased the surface areas of resulting solids by 6, 34, and 580 times, respectively. Among the materials prepared, the activated/carbonized PSH had a mean pore diameter of 1.9 nm, mesoporous material, and the highest electrical conductivity of 0.0042 Ω^-1cm^-1. This PSH is available as adsorbent in water treatment and materials for gas sensing and energy storage.

Abstract: Conductive polymer composites (CPCs) based on polypropylene (PP)/epoxy (EP) and high-density polyethylene (HDPE)/EP blends filled with synthetic graphite (SG) were produced and characterized to explore their potential for high electrical conductivity applications. The polymer blends were chosen as matrices due to their immiscibility and potential to enable co-continuous morphology formation and preferential distribution of filler, which allows formation of maximized conducting networks. In-plane and through-plane resistivities of PP/EP/SG composites decreased from 0.083 Ω.cm to 0.015 Ω.cm and 10.16 Ω.cm to 0.31 Ω.cm, respectively, while for HDPE/EP/SG composites, in-plane and through-plane resistivities decreased from 0.086 Ω.cm to 0.014 Ω.cm and 5.02 Ω.cm to 0.24 Ω.cm, respectively, when SG content was increased from 30 to 80 wt%. The immiscible blend-based composites produced in this study have the potential to achieve significantly higher conductivity than filled single polymers due to concentration of filler in one of the polymer phases and the co-continuous structure of the blends. Also, resistivity anisotropy of the PP/EP/SG and HDPE/EP/SG composites generally decreased with increase in SG content, with HDPE/EP/SG composites showing lower resistivity anisotropy than PP/EP/SG composites at the same SG content.

Abstract: Graphene aqueous dispersion is difficult to be prepared as conductive film by simple solvent evaporation deposition, not only because of the agglomeration in its aqueous solution, but also caused by the “coffee ring” phenomenon during solvent evaporation process. Herein, as a derivative of graphene, graphene oxide (GO) would be used as film forming material due to its good dispersion in aqueous solution and its liquid crystallinity. If GO can self-assemble as a compact pseudo-photonic crystal film by solvent evaporation deposition, it will be converted into a conducive graphene film after thermal reduction. In order to prepare a flexible and conductive elastomer material covered with graphene film, compact GO pseudo-photonic crystal film can be transferred onto the surface of a 10% stretched silicone rubber plate. After releasing the stretched force, GO pseudo-photonic crystal film can form a lot of folds, which provide allowance of shrinkage for this GO pseudo-photonic crystal film to avoid cracking during the high temperature reduction. Benefiting from transferring the GO film onto a stretched silicone rubber, a flexible, colored and conductive graphene/SR can be obtained.

Abstract: Controlling the polymerization of polypyrrole (Ppy) in presence of Zr-based metal organic-framework (Zr-MOFs) using sodium dodecyl sulphonate (SDS) as a dopant, leads to the formation of a new class of thermoelectric materials based on conducting polymer and highly porous MOFs with enhanced properties for energy production applications. The polymerization of polypyrrole in the Zr-Fumerate pores leads to the formation of homogenously coated MOF-spheres with high crystalinity and a high degree of improvement in many electrical properties such as conductivity and carrier mobility. The figure shows the movement of the electrons from the hot to the cold side in the aligned polymer inside the MOF pores.

Abstract: The article considers the possibility of applying the eddy current method of non-destructive testing for measuring the electrical conductivity of new material - thin metal films. Copper films of various thickness obtained by physical vapour deposition were used as the measurement object. The deposition method and the hardware and software complex for measuring the electrical conductivity of the film were briefly described. A calibration curve that makes it possible to restore the values of the electrical conductivity of the material by the signal value of the eddy current probe was presented. The test results of films with different characteristics were given, and the distribution of the electrical conductivity of the films depending on the batch was shown. Based on different values of the electrical conductivity in a batch, the difference in deposition quality of various films was found.

Abstract: The article presents the results of studies of aluminum alloys connected by a welded joint obtained by friction stir welding. During this kind of welding a recrystallized fine-grained microstructure is formed in the joint. The pictures of the weld area microstructure are presented, and the eddy current probe signal variations when scanning the joint are shown. The resulting parameter of the eddy current probe was the local electrical conductivity of the weld area. It is demonstrated that the average grain size of the welded joint microstructure varies in the area of weld defects, which was determined by the signal variation of the eddy current probe. The microstructure peculiarities formed in the weld area where the defects are located, and their influence on the mechanical properties of welded joints are discussed. The results of a series of experiments allow concluding about the qualitative characteristics of the obtained welded joints.

Abstract: The materials of soil were affected by multi reasons; such as human activities, floods, tidal waves, ... etc. The change of the soil contents could be measured through different indexes; such as electric conductivities, salinity, concentration of the heavy elements, and concentration of essential elements ... etc. The land cover is affected by natural influences, like tidal energy, which plays a negative role in the salinization of land adjacent to the coasts, causing a problem for soils in all its details represented in changing of the dissolved elements in soil. One of the most important natural factors that cause soil salinity is human activity in all its forms, and one of the most important causes of salinity is the phenomenon of tides in the Arabian Gulf. Due to the lack of water imports for this governorate, the study area is located in the far south of Mesopotamia, specifically in the Basra governorate, represented by Al-Faw district and part of Abu Al-Khasib district, which is distinguished by its location in the region of Tails of the Rivers. To find the values of total dissolved salts and electrical conductivity for the year 2020 for the rainy season (field work outputs), where the values of total dissolved salts reached (7380-13380) mg / L . The electrical conductivity values reached (1217-2230) μS / cm for (11) soil samples randomly distributed over the study area, where the values of these samples were distributed on the sites within the cut map of the study area using (QGIS) program. (ENVI) program to calculate the salinity index values for the year 2020, then a regression method was used to correlate each of the spectral values of salinity with the values obtained in the field. Where it was found that the best equation for calculating salinity values is polynomial of the first degree because it links the field and spectral values with a linear relationship, and this process was completed using Matlab program to find salinity, for the 2010 dry season.

Abstract: The article discusses the spatial analysis of the chemical soil properties that is a key component of the agriculture ecosystem based on satellite images. The main objective of the present study is to measure the chemical soil properties (total dissolved salts (TDS), Electrical conductivity (EC), PH, and) and the ​spatial variability. On 13 November 2020 (wet season), a total of 12 soil samples were collected in the field through random sampling in the Sanam mountain-Al Zubair region south of Basra province, to contain its soil samples components of minerals and precious elements such as silica and sulfur. From experimental results, the soil sample in the sixth position has the highest concentration of TDS values, reached (5798.4 mg/l), and the soil chemical parameters (EC,and Sodium Adsorption Ratio (SAR), and the percentage of sodium dissolved in the soil (Na%)), which they exceeded the limit when compared with the Iraqi determinants and the World Health Organization determinants. Furthermore, the results showed spatial fitting and a high correlation between Salinity and Sodium Adsorption Ratio in the soil. Anomalies of the pH value (7.05) at the position_10 instead of position_11 (7.1) that has a very strongly saline soil, due to attributed to the presence of sulfur in this position. The article describes the spatial prediction for TDS values through the application of the curve fitting process using soil salinity index was done for the wet season years of (2000, 2005, 2010, 2015, 2018, 2020) and 2020_dry season for each position of the same field samples, to study the extent of the variation that occurred over these years. The highest concentration of TDS values was in positions (4, 6 & 8), as listed in table 5. The spatial analysis and data processing has been carried out using the Quantum Geographic Information System (QGIS 3.16) and Environment for Visualizing Images (ENVI 5.3).

Abstract: The effect of pre-aging on properties of Cu0.24Cr0.20Sn alloy before rolling and aging was studied in details. The results displayed the pre-aging was useful to improve the microhardness and conductivity of Cu0.24Cr0.20Sn alloy before cold rolling and aging, and the effect increased with the extension of pre-aging time. The microhardness and electrical conductivity of Cu0.24Cr0.20Sn alloy by first pre-aging at 400 °C for 2 h, second 85% rolling and then aging at 300 °C for 1 h can reach 189 HV and 85.4 %IACS, respectively. The TEM results indicated the density of precipitates increased with the increase of pre-aging time, and the interaction between precipitates and dislocations was gradually strengthened in the subsequent room-temperature rolling. The increase caused by pre-aging treatment before rolling and aging was mainly due to dislocation density strengthening.