Papers by Keyword: Electrical Conductivity

Abstract: This study investigates the effect of introducing an intermediate solution treatment after cold drawing and before artificial aging on the mechanical and electrical properties of the 6201 aluminum alloy. The solution heat treatment was performed at 510 °C for one hour. Aging treatments were conducted at temperatures ranging from 150 °C to 200 °C for durations between 2 h and 30 h. This heat treatment route yielded comparatively softer materials, with a maximum ultimate tensile strength (UTS) of approximately 325 MPa. Electrical conductivity (EC) measurements demonstrated that the T6-temper method consistently produced higher EC values reaching values of around 63 %IACS compared to the conventional process, deomstrating inverse relationship between strength and conductivity. It was found that T6-155-30 condition produces the best combination of strength, ductility and EC of 325 MPa, 11.5% and 58.6 %IACS, respectively.

Abstract: The mechanical properties and electrical conductivity of the Al–0.15Fe–0.5Si–0.5Mg–0.2Mn alloy with a Mg/Si ratio of 1 were investigated using optical microscopy, scanning and transmission electron microscopy, tensile testing, Vickers hardness measurements, and specific electrical resistivity measurements. To analyze the electrical conductivity data, the unit % IACS was used, calculated as a percentage relative to the conductivity of annealed copper. The alloy was studied in the as-cast condition, in the deformed condition (following extrusion and drawing), and after heat treatments: HT1 — solution treatment at 530°C and aging at 140°C for 8 hours, and HT2 - solution treatment at 560°C and aging at 175°C for 6 hours. The microstructure of the investigated alloy varied depending on the condition and heat treatment parameters, consisting of an aluminum matrix and strengthening particles with different morphologies and chemical compositions. For rods in the as-cast state, the conductivity was 55% IACS, ultimate tensile strength (UTS) — 150 MPa, and elongation — 14%. After HT1: 51% IACS, UTS — 140 MPa, elongation — 19%. After HT2: 51% IACS, UTS — 195 MPa, elongation — 19%.

Abstract: Alumina (Al₂O₃) is a technical ceramic widely selected for demanding applications due to its excellent material properties, such as high strength, corrosion resistance, and thermal stability. In this study, the effect of the sintering temperature of 3D-printed alumina to its surface characteristics and its subsequent performance as a copper-metallized ceramic substrate was investigated. Green parts of alumina samples were prepared using stereolithography (SLA) 3D printing, debound, then sintered at temperatures ranging from 1660°C to 1740°C. Surface roughness was quantified using Atomic Force Microscopy (AFM), while the copper layer's adhesion was assessed via tape and burnishing tests. Electrical conductivity was measured with a four-point probe. A non-monotonic relationship between sintering temperature and surface roughness was observed. Roughness (Ra​) decreased as temperature increased from 1660°C to 1720°C, attributed to enhanced densification. However, increasing the temperature to 1740°C led to grain coarsening and a slight increase in roughness due to excessive grain growth. Stronger copper adhesion was achieved on smoother surfaces produced at optimized sintering temperatures. Electrical conductivity was also determined with a minimum sheet resistance of 0.089 mΩ/sq achieved.

Abstract: Bioplastics or biopolymers are being developed as an alternative to tackle the problem of polymer waste, which causes pollution and greenhouse gas emissions. Cellulose derived from corn cobs can be a biopolymer alternative to synthetic polymers. Cellulose derived from corn cobs can replace conventional petroleum-based polymers as an alternative plastic material. Incorporating ZnO into the biopolymer matrix is projected to result in favourable characteristics and allow for a wider range of applications. This study aims to investigate the changes in the characteristics of bioplastics derived from corn cob waste and starch upon the incorporation of ZnO, with a special emphasis on mechanical properties and electrical conductivity. FTIR analysis shows that the incorporation of ZnO exhibited no impact on the structure of the bioplastic. Scanning electron microscopy (SEM) analysis revealed that the ZnO microparticles' morphology is irregular and rough. The average size of ZnO particles incorporated into the biopolymer matrix was 0.623 μm. Mechanical tests showed a positive correlation between the amount of ZnO and the tensile strength of bioplastics. The assessment of the electrical conductivity of the Bioplastic/ZnO composite indicates a notable enhancement with the inclusion of ZnO. Electrical conductivity shows a progressive increase from 2.13x10^-15 S/m to 3.23x10^-12 S/m, 7.42x10^-11 S/m, and 2.03x10^-10 S/m with the incorporation of ZnO as much as 0.03, 0.06, and 0.09 g, respectively. Generally, incorporating ZnO into bioplastics can enhance their tensile strength and electrical conductivity.

Abstract: The paper explores the problem of optimizing groundwater sampling in areas affected by multiple rocket launcher systems (MRLS). Taking into account modern challenges to the safety of the population and the environment in the conditions of hostilities, an express method of preliminary zoning of groundwater pollution based on the measurement of electrical conductivity has been proposed. The method is based on modeling the spread of contaminants in combination with cluster analysis of these measurements. The results of the study can be used for operational monitoring of territories affected by hostilities and in management decision-making systems in the field of civil protection.

Abstract: The work investigates the effect of additives to the primary material of a current-carrying conductor on the heating temperature of an electrical wire, exemplified by a single-core aluminium wire with single-layer polyvinyl chloride insulation. It establishes the dependencies between the wire's heating temperature and its operating time under load currents that are lower, close to, and higher than the permissible levels set by regulations. The effect of chromium, vanadium, and titanium additives to the primary material of a current-carrying conductor on the wire's heating temperature during operation is also evaluated. Even small amounts of additives (less than 0.1%) to the primary material of a current-carrying conductor can affect the heating temperature of the loaded wire. Chromium additives have the most effect, while titanium additives have the least effect. The study demonstrates that during operation, a loaded electrical wire heats the least if the primary material of its current-carrying conductor has none of the additives considered in the article.

Abstract: Energy storage devices have become essential in modern life, and supercapacitors are among the prominent choices. Reduced graphene oxide (rGO) is a promising material for electrochemical double layer capacitors (EDLC). However, its drawback lies in its relatively lower electrical conductivity compared to pristine graphene. Doping mechanism utilizing nitrogen could enhance the electrical conductivity of rGO. In parallel, CuCr₂O₄ has been identified as a suitable material for pseudocapacitor. In this study, hybrid supercapacitors of EDLC and pseudocapacitor were fabricated through the utilization of N-doped rGO/CuCr₂O₄ composites. The fabrication process involved varying the duration of microwave-assisted solvothermal radiation at 180 W to synthesize N-doped rGO, with variations of 30, 45, and 60 minutes. The impact of varying radiation duration on the structures and morphologies of the materials was investigated using X-Ray Diffractometer (XRD), Fourier-Transformed InfraRed (FTIR), Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscope (EDS) instruments. The capacitive properties of the fabricated supercapacitors were evaluated through Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). From the CV measurements, the specific capacitances of the supercapacitors synthesized with radiation durations of 30, 45 and 60 minutes were found to be 397.72 Fg^-1, 245.79 Fg^-1, and 237.74 Fg^-1, respectively. The specific capacitance values were strongly influenced by the electrical conductivities of the materials, which were measured as 0.2, 0.18, and 0.13 Scm^-1 for radiation durations of 30, 45, and 60 minutes, respectively. It was observed that longer radiation durations appeared to induce structural damage to the material, leading to decreased conductivity in the resulting material.

Abstract: Out-of-furnace treatment of steel has many possibilities for correcting the iron-carbon semi-product obtained at the previous stage of steel production. This is ensured both by various methods of maintaining the temperature and by introducing the necessary correcting or modifying additives into the ladle with subsequent averaging stirring of the melt. At the same time, the bottom type of purging through one or more purging units became the most widespread. The paper presents the results of research on the nature of the flows created during bottom purging through a block with non-directional porosity. The research was conducted with the help of a full-scale physical model using water as a model fluid and using the conductometric method of establishing the homogeneity of the liquid bath and dissolution additives of the “heavy” type (using NaCl salt for modelling). Those additives dissolve mostly at the bottom and, for their volume distribution, require the creation of sufficient mixing flows. The study was carried out at different intensities of gas supply for purging according to the purging modes corresponding to industrial conditions. It was established that during purging in the bubbling mode through a block with non-directional porosity, the largest change in concentration during purging occurs in the volume of the liquid bath at the level of more than 25% from the bottom of the ladle. A large change in concentration indicates a significant volume of dissolution of “heavy” additives that dissolve at the bottom. This can be explained by the formation of conditions for the spiral rotation of the grouped bubble flow that breaks into individual bubbles at a distance of approx. 75% from the bottom of the ladle. Such flows create active horizontal mixing of the liquid bath. The best conditions for mixing the liquid bath, under conditions of addition of “heavy” additives that dissolve at the bottom, with the shortest homogenization time among the studied conditions were purging with an intensity of gas supply of 0.684-1.026 m³/t steel per h.

Abstract: This research investigates the effect of different particle sizes of recovered carbon black (rCB) on the electrical conductivity, flexural and fractured toughness properties and morphology of epoxy/rCB conductive composites. The rCB powder was a product from the pyrolysis process of waste rubber tires. This research aims for the application of tray production in semiconductor packaging. In this study, the composite was prepared by using a simple mechanical stirring method. The testing and characterizations carried out included electrical conductivity test, flexural test, fracture toughness test, Scanning Electron Microscopy (SEM) and viscosity. The epoxy/rCB conductive composite shows significant differences in electrical conductivity and mechanical properties when incorporated with different particle sizes of rCB. The conductivity percolation threshold was found at 1000 mesh with enhanced mechanical and electrical conductivity properties simultaneously.

Abstract: This study investigated the effects of mixing ratio and temperature on the electrical conductivity of a GNP-Al2O3 hybrid nanofluid. The results showed that an increase in the mixing ratio reduced the electrical conductivity ratio of the nanofluid, while an increase in temperature improved the electrical conductivity ratio. Additionally, an Artificial Neural Network (ANN) was used to predict the electrical conductivity of the nanofluid based on the mixing ratio and temperature. The optimal number of neurons in the hidden layer was found to be four neurons, with a low root mean square error (RMSE) value of 0.00696. The regression plot for the training, validation, and test data exhibited high correlation coefficients, indicating the reliability of the ANN model. These findings provide valuable insights into the behaviour of hybrid nanofluids and highlight the potential of using ANN for predicting their electrical conductivity.