Electrical Resistivity Behavior Research Articles

Electrical Contact Resistance Behavior of Reciprocating Slide Wear Test of Tin Plating Copper Alloy

Electrical Contact Resistance Behavior of Reciprocating Slide Wear Test of Tin Plating Copper Alloy

A new approach to investigate the ionic conductivity of NaCl and KCl solutions via impedance spectroscopy

Lima et al. [1] employed electrical impedance spectroscopy to analyze the electrical impedance behavior of dilute aqueous potassium chloride (KCl) and sodium chloride solutions in the frequency range of 10−1 Hz to 106 Hz (NaCl). The complex impedance Z* data from the solutions were modeled using an analogous electrical circuit that closely matched the experimental data. The electrical characteristics of the solutions were studied as a function of the cation types. The Debye model accurately describes the bulk effects of K+ and Na+ cations. However, it appeared that the analysis presented just the equivalent circuit components as a function of salt concentration. As a result, the current work used a simulation procedure to generate complex impedance (Z*) data from electrical parameters derived from the analogous circuit. To highlight the high-frequency relaxation processes occurring, extrapolation to a broader frequency range was performed. Furthermore, theoretical considerations were introduced in order to derive complex conductivity (σ*) from complex admittance (Y*). In the complex impedance (Z*) and admittance (Y*), there was a good correlation between all parameters derived from both processes. The key relaxation process characteristics, such as ionic strength, relaxation time, and conductivity values at low and high frequencies, were then retrieved. As a function of salt concentration, all of these parameters were evaluated and discussed.

Effects of the use of agricultural ashes, metakaolin and hydrated-lime on the behavior of self-compacting concretes

Self-compacting concrete (SCC) is an innovative product, which has fluidity and cohesion to cover the entire length of the piece and fill the spaces between reinforcement. However, currently, its use in construction sites is linked to a high consumption of cement. This generates a series of environmental problems such as depletion of natural resources and increased CO2 emissions. To mitigate these environmental problems, it is necessary to seek supplementary, locally available materials, to provide a sustainable and efficient way forward for the construction industry. In this perspective, this research investigates the effects of the use of metakaolin (MK), sugar cane bagasse ash (SCBA), rice husk ash (RHA) and hydrated-lime (HL) on rheological (slump flow, J-ring and V-funnel), mechanical (compressive strength) and durability (electrical resistivity, accelerated carbonation and mercury intrusion porosimetry) behavior in SCC. Portland Cement was replaced from 0% to 60% by mineral admixtures in mixtures with and without 10% HL. The results indicated that the SCC produced with agricultural ashes presented physical behaviors compatible with the standards and obtained compressive strength equivalent to the reference SCC (REF). Moreover, these concretes presented carbonation depth lower than the normative values and electrical resistivity significantly higher than the SCC-REF, reducing the probability of corrosion of the steel bars and, therefore, validating the use of ash obtained from industrial bio-waste in the production of SCC. The HL also presented itself as a good re-alkalizer of the cement matrix.

Bio-composites of rice husk and saw dust reinforced bio-benzoxazine/epoxy hybridized matrices: Thermal, mechanical, electrical resistance and acoustic absorption properties

The prime objective of the present work is developing cost competitive, less thermal conductive, electrical resistive, hydrophobic and acoustic insulation sustainable hybrid green composite materials using the hybrid bio-benzoxazines/epoxy matrix and bio-waste products. In this context, cardanol-melamine (C-m) and cardanol-aniline (C-a) based benzoxazines were synthesised using melamine, aniline and paraformaldehyde separately. The synthesized bio-benzoxazines were blended with (0:100 and 50:50 wt%) of bisphenol-A epoxy resin (DGEBA) and reinforced separately with rice husk and saw dust to obtain corresponding bio-composites for acoustic insulation applications. The breakthrough achieved in the present work is the cardanol benzoxazine is made in the form of hybrid matrix with epoxy resin, which cures significantly at lower temperature of 105 °C in the absence of any curatives. The specimens of composites prepared have been characterized for their thermal, mechanical, electrical resistance and acoustic insulation behaviour by different analytical methods. Among the composites, poly(50 wt% C-m/50 wt% Ep) based composites possess better composites than others. The tensile strength of the rice husk and saw dust reinforced poly(50 wt% C-m/50 wt% Ep) composites were observed at 7.5 and 7.1 MPa. The thermal resistivity of the rice husk and saw dust reinforced poly(50 wt% C-m/50 wt% Ep) composites were observed at 0.1 M2 k/w and 0.08 M2 k/w and roughness (Ra) were noticed at 5.1 and 5.6 µm. The electrical surface resistance of the rice husk and saw dust reinforced poly(50 wt% C-m/50 wt% Ep) composites were ascertained at 1.27 × 1010 Ω/sq and 7.29 × 109 Ω/sq. Data obtained from acoustic studies, it was observed that the highest value of sound absorption coefficient of 6400 Hz was noticed for composite specimens developed using both rice husk and saw dust reinforced with hybridized polymer composites.

Effect of the heat treatment on the electrical resistivity and magnetization reversal behavior of MnAl alloys

The casting Mn51Al47C2 alloy were undergone two distinct heat treatment processes, consisting of the heat treatment at 1000 and 925 °C. The process followed by quenching and annealing at 500 °C for 15 min. The low electrical resistivity for the heat treatment stage at 1000 °C (165* 10-4 Ω.m) can be described by the small fraction of the L10-ordered τ-phase (40 %). But the high resistivity for heat treatment at 925 °C (290.4* 10-4 Ω.m) originates within the large fraction (>95%) of the L10-ordered τ-phase with space inversion symmetry inhibiting the transport process. The magnetic characterization revealed higher Ms, Mr and Hc along with superior (BH)max for Mn51Al47C2 alloy heat-treated at 925 °C. Additionally, the derivative hysteresis loops assign narrow maxima to Mn51Al47C2 alloy when containing less amount of the L10-ordered τ-phase. Also, tracking the magnetization reversal behavior through the Henkel plots display the increasing negative-peak dominated curve for Mn51Al47C2 alloy when moving from the as homogenized sample (100% τ-phase) to those heat-treated at 1000 (40% L10-ordered τ-phase) and 925 °C (>95% L10-ordered τ-phase), respectively. This highlights the deterioration of the exchange coupling interaction between the grains when dominated with a highly ordered L10-τ-phase. The trend is best confirmed by the quantitative results gained from recoil loops for demagnetization, reversible and irreversible magnetization curves, indicative of a low degree of exchange interactions when the L10-ordered τ-phase is dominant. Furthermore, analyzing the nucleation field through the Kondürsky model gives a low value of 0.41 kOe for the alloy in the as homogenized state. This behavior can be attributed to the boosted propagation of the anisotropy field and enhanced magnetic exchange coupling in a structure with dominant regular τ-phase for which the deleterious effects of the interfaces for the L10-ordered τ-phase can be avoided.

Pressure effects on electronic structure and electrical conductivity of TiZrHfNb high-entropy alloy

Due to specific highly distorted crystalline structure, high-entropy alloys (HEAs) are expected to demonstrate interesting behavior under high pressures. However, this issue is not yet well studied. Here we address pressure effects on electronic structure and electrical conductivity of TiZrHfNb alloy. Among the multiplicity of single-phase HEAs explored so far, the TiZrHfNb one is an exemplar of thermally stable metallic material that crystallizes into body-centered cubic (BCC) structure and demonstrates excellent mechanical, corrosion, and friction properties compared to conventional alloys. We synthesize this material with BCC structure and analyze its electrical, superconducting, and magnetic properties. The alloy is a Curie-Weiss paramagnet and a type-II superconductor with the critical temperature of about 6.3 K. The estimated upper critical field and critical current density in the HEA are rather moderate compared to those observed in the superconductors based on Ti–Nb alloys. In the normal state, the alloy demonstrates high electrical resistance that practically independent of temperature but significantly dependent on pressure; it decreases linearly by 12.5% as the pressure increases up to 5.5 GPa. By analyzing the experimental data, we suggest that alloy resistance is mainly determined by two contributions: the residual resistance and Mott's s-d scattering. We show that a cooperative effect from changes in both the Debye temperature and electronic band structure near the Fermi level are the main factors responsible for the electrical resistance behavior of the HEA under pressure. Ab initio calculations performed at different pressures support this conclusion. The results show that TiZrHfNb alloy is a promising material for designing resistance pressure gauges.

Assessment of chemical exposures on ECC containing stone slurry powder

Generation of solid waste materials from various industrial sources is becoming a challenging issue for safe disposal. Durability performance of hydraulic structures under environmental loadings (aggressive substances) is also a concerning issue. The present paper investigated the durability performance of engineered cementitious composite (ECC) mortar containing stone slurry powder (SSP). SSP was used as partial subrogation of micro silica sand (MSS) and fine sand (FS) by 25% and 50% for each type of sand. Electrical resistivity (ER), compressive and tensile behaviour of various mixes were studied experimentally under chloride, sulphate and chloride-sulphate combined environmental conditions. Results obtained from various properties revealed that performance of fully MSS and FS containing ECC mixes was affected under aggressive substances at initial stages. The observations demonstrate that ECC containing SSP was durable and maintains better mechanical performance over fully MSS and FS containing mixes. This improvement finds a place in construction of hydraulic structures under aggressive environments.

Improvement of the Uniformity and Electrical Properties of Polyaniline Nanocomposite Film by Addition of Auxiliary Gases during Atmospheric Pressure Plasma Polymerization.

The morphological and chemical properties of polyaniline (PANI) nanocomposite films after adding small amounts of auxiliary gases such as argon, nitrogen, and oxygen during atmospheric pressure (AP) plasma polymerization are investigated in detail. A separate gas-supply line for applying an auxiliary gas is added to the AP plasma polymerization system to avoid plasma instability due to the addition of auxiliary gas during polymerization. A small amount of neutral gas species in the plasma medium can reduce the reactivity of monomers hyperactivated by high plasma energy and prevent excessive crosslinking, thereby obtaining a uniform and regular PANI nanocomposite film. The addition of small amounts of argon or nitrogen during polymerization significantly improves the uniformity and regularity of PANI nanocomposite films, whereas the addition of oxygen weakens them. In particular, the PANI film synthesized by adding a small amount of nitrogen has the best initial electrical resistance and resistance changing behavior with time after the ex situ iodine (I2)-doping process compared with other auxiliary gases. In addition, it is experimentally demonstrated that the electrical conductivity of the ex situ I2-doped PANI film can be preserved for a long time by isolating it from the atmosphere.

Electrical Properties and Strain Sensing Mechanisms in Hybrid Graphene Nanoplatelet/Carbon Nanotube Nanocomposites.

Electrical and electromechanical properties of hybrid graphene nanoplatelet (GNP)/carbon nanotube (CNT)-reinforced composites were analyzed under two different sonication conditions. The electrical conductivity increases with increasing nanofiller content, while the optimum sonication time decreases in a low viscosity media. Therefore, for samples with a higher concentration of GNPs, an increase of sonication time of the hybrid GNP/CNT mixture generally leads to an enhancement of the electrical conductivity, up to values of 3 S/m. This means that the optimum sonication process to achieve the best performances is reached in the longest times. Strain sensing tests show a higher prevalence of GNPs at samples with a high GNP/CNT ratio, reaching gauge factors of around 10, with an exponential behavior of electrical resistance with applied strain, whereas samples with lower GNP/CNT ratio have a more linear response owing to a higher prevalence of CNT tunneling transport mechanisms, with gauge factors of around 3–4.

My research life about titanium and its alloys; from investigation about anomalous behavior of electrical resistivity to development of low cost beta type titanium alloys

My research life about titanium and its alloys; from investigation about anomalous behavior of electrical resistivity to development of low cost beta type titanium alloys

Aligned Carbon Nanotube-Based Sensors for Strain Monitoring of Composites

This paper presents a proof of concept of an aligned carbon nanotube (CNT) based strain sensor tested on the surface of a conventional aeronautic laminate. Two type of strain sensors were produced, type S and type T, in which the CNT alignment was parallel (Y) and transversal (X) to strain direction, respectively. Their electrical resistance response was thoroughly evaluated during cyclic tensile tests. Despite some disparities of the relative electrical resistance behavior in specific strain cycles, probably due to one-off interferences in the CNT conductive mechanism, the obtained gauge factor (GF) values were quite stable. Also, the electrical resistance anisotropy was evaluated and its opposite behavior when the samples were strained in Y- and X-directions may be used as strain direction indicator. Being able to quantify and indicate strain direction with just one 10×10 mm CNT patch, this sensor has proven to be suitable for strain sensing applications, namely for structure health monitoring of advanced composites.

A novel composite cotton yarn with phase change and electrical conductivity functions

PAN/PEG/CNT/cotton composite yarn (PPCCY) was fabricated by impregnating PEG2000–10000 into CNT/cotton yarn (CCY) and coating electrospun PAN around its surface. The effects of PEG type on the morphology, structure, electrical resistance and phase change behavior of the produced composite yarns were studied thoroughly by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetric(TG), electrical resistance tester and infrared thermal images. The experimental results indicated that the resulting compound yarn consisted of conductive yarn within which the spacing between cotton fibers was fulfilled by PEG, rendering phase transition enthalpy from 126–150 Jg−1. The composite yarn exhibited adjustable temperature and thermal storage and electrical conductivity abilities. The composite yarn demonstrated good responsive properties to external electrical and thermal stimuli and had reversible heat conversion and storage, which shows a promise for applications in electrical wearable fabrics.

Smart flame retardant coating containing carboxymethyl chitosan nanoparticles decorated graphene for obtaining multifunctional textiles

A revolutionary and straightforward technique with a dual functionality was manipulated for preparing graphene sheets (O-GRP) decorated with O-carboxymethyl chitosan nanoparticles (CMChNPs). Graphene was successfully exfoliated and decorated with CMChNPs through a simple ultrasonication tool. The developed graphene sheets were then utilized as the green binder for coating the surface of textile with the Ppy-Ag nanocomposite. A new vapor polymerization was used to synthesize the nanocomposite of polypyrrole-Ag on the graphene-modified fabric for acquiring ternary modified textiles (CT/O-GRP-Ppy-Ag). The structure and surface morphology of CMCh, O-GRP, and the various coated textiles have been carefully approved using various spectroscopic and microscopic analysis. The thermal stability, mechanical properties besides their electrical resistance, antimicrobial, and flame retardancy behaviors for the coated fabrics were investigated. The as-fabricated textile composites attained an inferior electrical resistance as 0.05 kΩ than that for the virgin textile (2770 kΩ) as an indication for the high conductive fabrics. The inhibition diameter zone for modified textiles was recorded as 24, and 28 mm for the E.coli, and S. aureus bacterial strains, respectively. Moreover, the rate of burning and LOI values for CT/O-GRP200-Ppy-Ag were significantly improved to 30.9 mm/min, and 22.8%, respectively compared to uncoated textile (149.3 mm/min, 17.8%), and the blank CT/O-GRP200 (79.2 mm/min, 19.9%) confirming the enhanced retardation against the fire growth.

Properties of indium tin oxide thin films grown by Ar ion beam sputter deposition

Indium tin oxide (ITO) thin films were grown by Ar ion beam sputter deposition under systematic variation of ion energy, geometrical parameters, and O2 background pressure and characterized with regard to the film thickness, growth rate, crystalline structure, surface roughness, mass density, composition, electrical, and optical properties. The growth rate shows an over-cosine, forward-tilted angular distribution with a maximum, which increases with increasing ion energy, increasing ion incidence angle, and decreasing O2 background pressure. ITO films were found to be amorphous with a surface roughness of less than 1 nm. Mass density and composition show only small changes with increasing scattering angle. The electrical resistivity behavior in dependence on the process parameters is complex. It is not only driven by the O2 background pressure but also very much by the scattering angle. The observed behavior can be understood only if competing processes are considered: (i) reduction of the number of oxygen vacancies due to the presence of O2 background gas and (ii) defect generation and preferential sputtering of oxygen at the surface of the growing films due to the impact of high-energy scattered particles. Even though absolute numbers differ, optical characterization suggests a similar systematics.

Fabrication of an IPL-sintered Cu circuit and its electrochemical migration behavior

Problems associated with the oxidation of Cu nanopaste have been widely studied in efforts to develop a replacement for Ag nanopaste. The intensive pulsed light (IPL) sintering process has been suggested to solve the oxidation problem because it is a method with a short processing time and is conducted at room temperature. Cu nanopaste was fabricated with Cu nanoparticles and a functional organic matrix. Cu nanopaste screen-printed onto a polyethylene terephthalate substrate was subjected to various IPL sintering conditions, and the effects of pulse power and pulse width on the microstructure, electrical resistivity, and electrochemical migration behavior of the printed Cu patterns were investigated. The electrical properties of the Cu patterns improved with increasing pulse power and pulse width because organic residues were removed by the IPL energy. The electrical properties of the Cu patterns improved with increasing pulse power and pulse width because organic residues were removed by the IPL energy. The electrochemical migration behavior was varied because of leaked ethylene glycol from organic matrix. The dendrites from lower pulse condition has finer microstructure and increased nucleation.

Mechanical and conductive performance of electrically conductive cementitious composite using graphite, steel slag, and GGBS

AbstractElectrically conductive cementitious composite (ECCC) can be utilized in traffic detection, structural health monitoring (SHM), and pavement deicing. Graphite is a popular conductive filler given its outstanding electrical resistance behavior, but its flat micro‐surface decreases the friction resistance, reducing mechanical strength. However, slag solids can substitute part of the graphite with their considerable conductivity and superior mechanical characteristics. In this research, 27 ECCC composites are developed incorporated by combined graphite powder (GP), blast furnace slag (GGBS), and steel slag (SS). Flexural, unconfined compressive strength (UCS) experiments, and resistance experiments with failure mode evaluations are carried out to explore the influence of proposed conductive fillers with different fractions. Results show the graphite strongly improves conductivity but dramatically reduces mechanical performance. Both steel slag and GGBS reduced the compressive and flexural strength after their replacement ratio exceeded 20%. Additionally, compared with GGBS, SS demonstrated a better influence on mechanical and conductive performance. A 15 wt% ratio of GGBS, 20 wt% of SS, and 4 wt% of GP are explored as the optimum design with 3.4 MPa of flexural strength, 36 MPa of compressive strength, and 7,779 Ω cm of resistance. Lastly, a microstructural investigation is conducted to explore the mechanical and conductive mechanism of ECCC.

Effect of Fe Content on the Microstructure, Electrical Resistivity, and Nanoindentation Behavior of Zr60Cu40-xFex Phase-Separated Metallic Glasses

Effect of Fe Content on the Microstructure, Electrical Resistivity, and Nanoindentation Behavior of Zr60Cu40-xFex Phase-Separated Metallic Glasses

Ti–Cu Coatings Deposited by a Combination of HiPIMS and DC Magnetron Sputtering: The Role of Vacuum Annealing on Cu Diffusion, Microstructure, and Corrosion Resistance

Titanium-copper (Ti–Cu) coatings have attracted extensive attention in the surface modification of industrial and biomedical materials due to their excellent physical and chemical properties and biocompatibility. Here, Ti–Cu coatings are fabricated using a combination of high-power pulsed magnetron sputtering (HPPMS; also known as high power impulse magnetron sputtering (HiPIMS)) and DC magnetron sputtering followed by vacuum annealing at varied temperatures (300, 400, and 500 °C). X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) data showed that Ti, Cu, and CuTi3 are mainly formed in the coatings before annealing, while Ti3O, Cu2O, and CuTi3 are the main compounds present in the annealed coatings. The cross-sectional TEM micrographs and corresponding EDS results provided evidence that Ti is mainly present on the surface and interfaces of the silicon substrate and the Ti–Cu coatings annealed at 500 °C, while the bulk of the coatings is enriched with Cu. The resistivity of the coatings decreased with increasing the annealing temperature from 300 to 500 °C. Based on self-corrosion current density data, the Ti–Cu coating annealed at 300 °C showed similar corrosion performance compared to the as-deposited Ti–Cu coating, while the corrosion rate increased for the Ti–Cu coatings annealed at 400 and 500 °C. Stable release of copper ions in PBS (cumulative released concentration of 0.8–1.0 μM) for up to 30 days was achieved for all the annealed coatings. Altogether, the results demonstrate that vacuum annealing is a simple and viable approach to tune the Cu diffusion and microstructure of the Ti–Cu coatings, thereby modulating their electrical resistivity, corrosion performance, and Cu ion release behavior.

Structure, electrochemical impedance and Raman spectroscopy of lithium-niobium-titanium-oxide ceramics for LTCC technology

Resultsof Electrochemical Impedance Spectroscopy (EIS) are reported for lithium-niobium-titanium-oxide (LNTO) ceramics synthesized by a solid-state reaction method with two functional additives (MoO3 or ZnO) in the temperature range 323 K - 573 K and frequencies between 10−1 Hz and 107 Hz. Scanning electron microscopy (SEM) reveals a textured morphology of rod and plate-like particles that are typical for M-phase LNTO materials, while X-ray diffraction (XRD) analysis confirms the formation of an M-phase member compound with an approximate structure of Li7Nb3Ti5O21. Complex impedance analysis indicates that its overall electrical resistivity behavior depends mostly on the grain boundary processes. EIS analysis shows a negative temperature coefficient of resistance behavior (NTCR) in a defined temperature range in two LNTOs and thermal activation of the conduction mechanisms. The low dielectric constants of 5.5 and 12.1 at 1 MHz were found for the first and second LNTOs, respectively. Complimentary Raman spectroscopic measurements, despite very large crystallographic unit cell of LNTO, reveal only a small number of lines, which is the consequence of a “molecular” nature of materials.

Structural Features, Anisotropic Thermal Expansion, and Thermoelectric Performance in Bulk Black Phosphorus Synthesized under High Pressure.

Black phosphorus (BP) allotrope has an orthorhombic crystal structure with a narrow bandgap of 0.35 eV. This material is promising for 2D technology since it can be exfoliated down to one single layer: the well-known phosphorene. In this work, bulk BP was synthesized under high-pressure conditions at high temperatures. A detailed structural investigation using neutron and synchrotron X-ray diffraction revealed the occurrence of anisotropic strain effects on the BP lattice; the combination of both sets of diffraction data allowed visualization of the lone electron pair 3s2. Temperature-dependent neutron diffraction data collected at low temperature showed that the a axis (zigzag) exhibits a quasi-temperature-independent thermal expansion in the temperature interval from 20 up to 150 K. These results may be a key to address the anomalous behavior in electrical resistivity near 150 K. Thermoelectric properties were also provided; low thermal conductivity from 14 down to 6 Wm-1K-1 in the range 323-673 K was recorded in our polycrystalline BP, which is below the reported values for single-crystals in literature.