Time Of Electrification Research Articles

Effect of stray current on corrosion of concrete structure and improvement experiment of reinforcement coating

Concrete structures are often subjected to harsh environmental conditions, and problems such as corrosion will greatly limit their service life and safety. Stray current is one of the factors that can be easily ignored but seriously affect concrete structure. Therefore, the study of the influence of stray current on concrete structure is conducive to understanding the performance and corrosion mechanism of concrete structure, providing technical support for protecting concrete structure, and improving its service life and safety. In this experiment, the effect of stray current and chloride ion interaction on the corrosion of reinforced concrete structure was studied, and the protective effect of the coating on reinforced concrete was studied by using Zn-Ni alloy plating solution. Electrochemical workstation, silver nitrate spraying, scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and direct observation were used to simulate and compare the corrosion experiments under different current intensities. By analyzing the influence of 0.05 and 0.10 A stray currents on concrete corrosion, the chloride penetration resistance of concrete structures was evaluated, and blank control experiments were set for different current intensity and different energizing time. The corrosion resistance of the steel bar coated with Zn-Ni alloy is compared with the steel bar without changing the coating under the same corrosion conditions. The results show that the corrosion tendency of concrete structures will be further increased under the action of stray current and chloride ion coupling, and the corrosion reaction will be accelerated. In addition, at the same time, the higher the simulated current, the more serious the corrosion of concrete structure; Under the same simulated current, the longer the electrification time, the worse the resistance of concrete structure to chloride ion erosion. Moreover, the corrosion resistance of the steel bar coated with Zn-Ni alloy is better. In summary, this study concludes that the coupling of stray current and chloride ion causes damage to the corrosion of concrete structures, and the current intensity and energized time are proportional to the corrosion degree, and the modified Zn-Ni alloy coated steel bar has better corrosion resistance

Electroosmotic flow in soft clay and measures to promote movement under direct current electric field.

Electroosmosis has been proposed as a technique to reduce moisture and thus increase the stability of soft clay. However, its high energy consumption and uneven reinforcement effect has limited its popularization and application in practical engineering. This paper presents the results of some electrokinetic tests performed on clayey specimens with different electrification time and anode boundary conditions. The results indicate that the timing of the formation of electroosmotic flow (EF) by the water originally contained in different soil cross sections, from the anode to the cathode, varies. The measuring soil cross section nearest the anode first reached the limiting water content of 22%±3% and electroosmosis had to be stopped. Water injection into the anode during electroosmosis enhanced further drainage of other four measuring soil cross sections until the second soil cross section from the anode reached the limiting water content of 30%±2%. Electroosmosis with water injection into the anode technique provides more uniform reinforcement, increasing EF, and environmental protection. The experimental results highlighted the relevant and expected contribution of water injection into the anode on the effectiveness of the electroosmotic treatment as a soft clay improvement technique.

Insights into electro-bioremediation of PAH-contaminated soil under polarity reversal conditions: Effect of effective current intensity and soil properties on microbial function

Electrical stimulation during electro-bioremediation has the potential to enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soil. In this study, we investigated the effective current intensity, referred to as the “window condition,” which promotes the activity of functional microflora. Electro-bioremediation was performed on PAH-contaminated soil using various polarity reversal frequencies (PRF) to study the remediation mechanism. The “window condition” in this study was 20–40 mA. The enhancement of PAH degradation, particularly that of high-PAHs, increased with higher PRF, which accompanied the increasing ratio of the “window condition” to the overall electrification time (RWC). Electro-bioremediation with a 10-minute (EBPR-10 m) and 30-minute (EBPR-30 m) polarity reversal (PR) periods achieved the highest ratios of PAH degradation at 43.9±2.3 % and 37.9±1.8 %, respectively, with RWC of 0.4919 and 0.4056, respectively, after 60 days. The increase in PRF improved the soil physicochemical properties, which were conducive to maintaining effective electrokinetic and biodegradation processes. Redundancy analysis (RDA) and Pearson correlation analyses demonstrated that soil electrical conductivity (EC), dissolved organic carbon (DOC), temperature, and the proportion of macroparticle components (0.195–2.500 um) in soil colloids (Ps/Po) were key factors in explaining the persistence of microbial abundance and community structure. Structural equation models (SEMs) further illustrated the mechanism behind the enhanced PAH biodegradation, including (i) the direct stimulation of microbial activity because of increased RWC and (ii) the indirect optimization of microbial function by improving soil physicochemical properties under optimal PRF.

Liquid–Liquid Triboelectric Nanogenerator for Harvesting Distributed Energy

AbstractAs one of the most widely distributed water resources, rainwater contains tremendous energy that cannot be effectively utilized by the conventional electromagnetic generators. Triboelectric nanogenerators (TENGs) represent a distributed method to convert trivial mechanical energy into electricity based on contact electrification. Benefiting from the large and replenishable contact interfaces in liquid–liquid systems, liquid–liquid TENG further promises efficient charge transfer. However, the limited understanding of liquid–liquid contact electrification has restricted its development. In this study, the mechanisms of contact electrification in various liquid–liquid systems is comprehensively investigated and thus a liquid–liquid TENG with optimized materials and structures to harvest energy from rainwater is demonstrated. The proposed liquid–liquid TENG generates a high charge density (3.63 µC L−1) with high output stability (crest factor ≈1.1) and long effective contact electrification time. Based on the direct current characteristics, energy harvested from rainwater can be fed directly to electronic devices and a self‐powered rainfall sensor can also be implemented. This study highlights the promise of all‐liquid systems in distributed green energy and passive sensors, offering a new perspective on self‐powered devices.

Electrical swing adsorption on 3D-printed activated carbon monoliths for CO2 capture from biogas

Direct, resistive or Joule heating of the adsorbent allows for the intensification of Thermal Swing Adsorption processes by reducing process cycle time and reducing heat losses. In this work, an electrically conductive activated carbon monolith was 3D-printed using a potassium silicate binder. The monolith was assessed for biogas upgrading, using Joule heating for regeneration of the monolith. The electrification of the 3D-printed monolith resulted in very rapid and homogenous heating, to 150 °C in less than 30 s at a potential of 8 V. Next, the monolith was subjected to cyclic adsorption-desorption experiments for CO2 capture from a synthetic biogas mixture (30 v% CO2 – 70 v% CH4). The main parameters in ESA, namely voltage, electrification time, purge conditions and an additional rinsing step were investigated by determining the impact on the heating, regeneration efficiency and purity. Increasing the voltage from 4 V to 8 V step is preferred for recovery (82–95%) as well as for energy consumption, as it increases the efficiency (27.1–28.4%). It was also found that using the same amount of purge gas, it is preferred to use a higher purge flow rate for a shorter time (100 Nml/min for 15 s) over a lower purge flow rate for a longer time (50 Nml/min for 30 s). This benefits both recovery (87.3% vs 84.0%) and purity (84.5% vs 83.4%). Lastly, the benefit of adding a rinse step to increase the purity was demonstrated, where having a rinse step prior to electrification allowed to augment the total purity from 58% to 81.2%, while the regeneration of the monolith was as efficient.

Electrolytic accelerated corrosion morphology for structural steel based on an improved solution

Abstract Atmospheric corrosion degrades the mechanical properties of steel structures mainly because of stress concentrations caused by an uneven corrosion topography. Electrolytic corrosion is regarded as one of the most efficient indoor accelerated corrosion approaches, while, the uneven atmospheric corrosion topography usually cannot be well simulated by electrolytic corrosion. This study aims to introduce an electrolytic corrosion solution suitable for simulating atmospheric corrosion. The surface morphologies of the structural steel specimens after electrolytic corrosion in three different solutions under various electrification time and magnitude of the current were compared. The surface characteristics of the corroded steel plates were measured by a 3D noncontact surface topography scanner, and analyzed based on surface roughness theory and fractal theory. The results showed that the mixed solution of 0.5% CH3COONa and 0.2% NaCl will produce pitting corrosion on the steel surface, and the surface morphologies of the steel specimens after electrolytic corrosion were consistent with that of neutral salt spray accelerated corrosion test. It is verified that the electrolytic accelerated corrosion in such a solution can simulate actual atmospheric corrosion reasonably.

Study on the durability of MOCRC under constant-current-accelerated corrosion

To investigate the durability of magnesium (Mg) oxychloride-coated reinforced concrete (MOCRC) and the deviation from the natural corrosion process of the electrified accelerated corrosion test in reinforced concrete, the authors used the electrified accelerated corrosion test with saline soil as an electrolyte. A quality test, a dynamic elastic modulus test, a crack-width test, an electrochemical performance test and a microscopic test were conducted regularly. The test results show that the relative quality evaluation parameter ω 1, the relative dynamic elastic modulus evaluation parameter ω 2 and the relative corrosion evaluation parameter ω 3, which characterise the degradation of MOCRC, all gradually decrease as the electrification time increases. Failure standards were reached at 24, 21 and 21 days, respectively. Analysis of morphology, corrosion current density and corrosion rate shows that the morphology of the coated steel bar under accelerated corrosion is consistent with natural corrosion. Using saline soil as the electrolyte of the accelerated corrosion system can simulate steel bar corrosion in a natural environment better than a traditional salt solution can.

Electromigration behavior of Cu/Sn–58Bi–1Ag/Cu solder joints by ultrasonic soldering process

Sn–58Bi–1Ag solder ribbon was prepared by twin-roll rapid solidification technology, and the ultrasonic soldering process was used to prepare Cu/Sn–58Bi–1Ag/Cu linear solder joints. Electron probe microanalysis (EPMA) and energy dispersive X-ray spectroscopy (EDS) were used to study the interface morphology of intermetallic compounds (IMC), Bi segregation, and solder joint matrix microstructure evolution with the current density of 1 × 104A/cm2 (25 °C). The result shows that the morphology of the anode IMC layer changes from scallop-like to hilly-like and then to flat-plate-like with the electrification time, and the thickness of IMC layer increases gradually. Bi is segregated toward the anode to form a Bi-rich layer. The cathode IMC layer is changed from a scallop to a zigzag, and its thickness is firstly increased and then decreased. The Sn is segregated toward the cathode to finally form a β-Sn-rich layer. Coarsening of eutectic microstructure (β-Sn+Bi) in solder joint matrix was caused by prolonged time. Based on linear fitting, the kinetic index n of the IMC layer of the anode and cathode is 0.432 and 0.491, respectively, and the growth mechanism is supposed to be volume diffusion. Ultrasonic soldering techniques can refine the Bi phase and increase the solubility of Bi in β-Sn, which slows down the formation of Bi-rich layers. The addition of Ag forms wedge-shaped and granular Ag3Sn intermetallic compounds, which hinders the growth of the Bi-rich layer and the Cu6Sn5 IMC, thus effectively inhibiting the electromigration process.

CO2 capture using a novel hybrid monolith (H-ZSM5/activated carbon) as adsorbent by combined vacuum and electric swing adsorption (VESA)

Electrical swing adsorption (ESA) is an interesting cyclic adsorption technology which relies on rapid Joule heating of the adsorbent to liberate adsorbed molecules such as CO2. In this study we used a novel hybrid zeolite/activated carbon honeycomb to implement ESA and compared it to conventional vacuum swing adsorption (VSA) for CO2 capture. We then combined electrical and vacuum swing adsorption (VESA) to assess the merits of this dual regeneration technology for recovering CO2 from a 15% CO2/N2 gas stream at low pressure. With a simple VSA-only cycle, a CO2 downstream purity of only 17–23% was achievable when the desorption pressures varied from 30 to 10 kPa. This was primarily due to the adsorbent’s poor adsorption characteristics which provided little change in CO2 adsorption capacity over this pressure range. A CO2 product purity of 15–34% and a recovery of 29–78% was achieved with ESA as the electrification time was extended from 30 s to 180 s. The combined VESA process provided a CO2 purity of 33% and recovery of 72% with a short electrification time of 30 s at a mild desorption pressure of 10 kPa. Energy calculations indicate that the total specific energy for VESA was lower than ESA alone but still higher than VSA, although the latter suffered from low purity.

Application of a simple method for determining the equilibrium resistivity of dielectric luiquids

For the design of the electrical insulation of an UHVDC (Ultra High Voltage Direct Current) converter transformer the resistivity of the pressboard and mineral oil has to be known. For solid insulation the resistivity is virtually constant, however, in liquids it is dependent on, e.g., applied electric stress and time of electrification. Several methods are discussed in the standards. One way to characterize the oil is the measurement of the equilibrium resistivity, in contrast to an apparent resistivity for oil under high electric stress. Measurements using a low voltage triangular shaped voltage form allow calculation of equilibrium resistivity. The oils investigated show equilibrium resistivity in the range 5E11 Ohm·m to 5.96E12 Ohm·m, which are typical values for transformer oil. There is good agreement between these results and reference measurements using dielectric response

Impact of operating parameters on CO2 capture using carbon monolith by Electrical Swing Adsorption technology (ESA)

Electrical Swing Adsorption (ESA) technology is an interesting option for rapid temperature swing adsorption to capture CO2 due to its highly efficient and rapid regeneration with the Joule effect. Electric current, electrification time and N2 purge rate have strong effects on ESA processing performance. In this study, these operating parameters were investigated experimentally and theoretically, for their effect on CO2 product purity, recovery, harvest time and energy consumption. For a feed stream of 15% CO2 balanced with N2 using a MAST© carbon monolith, CO2 purity and energy consumption significantly increased as electric current and electrification time increased; CO2 recovery increased as N2 purge rate increased; these three factors all impacted on CO2 productivity positively, that is, productivity increased with increase of each of electric current, electrification time and N2 purge rate. The optimal conditions obtained for CO2 capture using MAST© monolith in this study are electric current of 12A, electrification time of 80s and N2 purge rate of 600ml/min (0.088m/s). Under such optimal condition, a CO2 purity of 52%, and a recovery of 76% was achieved with an energy consumption of 5.64MJ/kg.CO2.

Electrical surface resistivity of conductive polymers – A non-Gaussian approach for determination of confidence intervals

Polyanilines doped with different acids (HCl, H 2SO 4 and dodecylbenzenesulfonic acid, DBSA) were prepared and their surface electrical conductivities were characterized in a four-probe device, connected to a real-time data acquisition board. Collected data were synchronized and conductivity calculations were performed. The conductive behavior of the polyanilines was investigated along the electrification time. This allowed for introduction of a non-Gaussian technique for determination of the confidence intervals of surface resistivity data. It is shown that the distribution of experimental surface resistivity data does not follow a normal probability distribution function (PDF). Thus, ordinary assumptions related to normal distribution of the experimental errors are wrong and must be corrected for proper determination of the confidence limits of measured resistivity values. It is shown here that confidence limits of resistivity values are asymmetrical and that distribution of experimental values can follow multimodal distributions.

SBS/Pani · DBSA mixture plasticized with DOP and NCLS – Effect of the plasticizers on the probability density of volume resistivity measurements

Plasticized mixtures of styrene–butadiene–styrene block copolymer (SBS) and Polyaniline (Pani) were prepared in a Haake internal mixer. Two different plasticizers were used: dioctyl phthalate (DOP) and cashew nut shell liquid (CNSL). Pani and plasticizers were characterized by FTIR and the resistive behavior of plasticized mixtures was investigated along the electrification time. It is shown that obtained experimental data are subject to deterministic dynamic fluctuations that cannot be described by single normal probability distribution functions (PDF) along the time. The PDF analysis shows that obtained PDFs must be described as sums of at least three distinct Gaussian distributions with different areas. It is also shown that the Gaussian component with larger area may provide better representation of the measured volume resistivity values.

Characterization of polyester films used in capacitors. I. Transient and steady-state conductivity

Charging and discharging currents flowing through polyethylene terephthalate (PET) ultrathin films (1.5–12 μm) were measured by the use of a two-electrode configuration involving opposite lateral contacts. A study of the influence of electrification time, applied electric field, film thickness, nature of electrodes, and water content was carried out on both transient and steady-state conduction. The transient behavior can be interpreted in terms of dipolar orientation and relaxation processes while steady-state conductivity can be mainly accounted for in terms of Schottky emission. A comparison between PET and polyethylene naphthalate films is also reported.

Applications of thermoelectrometry to metal-ion modified polyimide films

As part of a research program to decrease the electrical resistivity of polyimide films with ionic additives a variable temperature three probe electrical resistivity measurement system has been designed and constructed. Sample temperature, electrification time, atmosphere, and measurement mode are computer controlled. As a data interpretation aid, temperature cycled analysis can be routinely performed. Surface resistivities in the range 103–1015 ohm and volume resistivities in the range 105–1018 ohm-cm are theoretically measurable under well controlled experimental conditions from room temperature to 250°. The electrical resistivity measurement system is useful for the evaluation of polymer films or films in general. Application of the system for analysis of cobalt, lithium and tin ion-modified polyimide films and some experimental considerations are presented. Correlation of the electrical measurements with differential scanning calorimetry, thermomechanical analysis, and thermogravimetric analysis is demonstrated.

Experiments on the Carnauba Wax Electret

The strength of the applied electric field, the thickness of the slab being electrified, the time of electrification and the low temperature holding time before removing the field were varied for carnauba wax electrets. After approximately one hour the discharge current varied inversely as a power of the time since turning off the forming field, the power being close to one. The magnitude of this current depended on both the forming field strength and on the thickness of the electret. A very large discharge was obtained when the wax was electrified and discharged while not completely solid. Dielectric constant measurements were made at temperatures between 27°C and 86°C, frequencies between 50 cps and 13 kc, and with superposed dc field strengths in the wax of zero, 3700 and 8100 volts per cm. The application of dc field was found to raise the dielectric constant at the higher temperatures. The case for permanent dipole orientation and that for ionic space charges as the cause of the stored charge of the electret is examined, and it is shown that there are objections to each mechanism. An alternate explanation is suggested.

The dielectric properties of varnished cloth at low voltage-gradients

Measurements of the dielectric properties of typical samples of varnished cloth have been made with the object of studying the laws governing the dissipation of power in the material when it is subjected to an alternating voltage. All the measurements were made under carefully controlled conditions. The samples were conditioned and tested in an enclosure, which was approximately airtight, and the temperature and humidity were regulated as required. An arrangement of mercury electrodes was generally used, but a number of control experiments made with graphite electrodes showed that the properties observed were those of the material itself, and were not peculiar to any one type of electrode. The most important measurements made were those of permittivity and power factor (from which the power loss was calculated), but measurements were also made, in certain cases, of the absorption and leakage currents produced by a constant applied voltage, with the object of correlating the results of alternating- and direct- current measurements. The permittivity and power factor were found to be independent of the voltage for all voltage gradients less than a certain critical value, and the present investigation was confined to this range of voltage gradients, which includes the values commonly employed in practice. The methods of measurement include the Schering bridge, a resistance bridge found to be more convenient in cases where the power factor was very large (values greater than 90 per cent were found), and an electro meter method for the d.c. experiments. The corrections and precautions necessary for high accuracy were studied in detail. The variations of the dielectric properties with atmospheric humidity, temperature and frequency of the applied voltage, have been investigated, and curves representing the more important results are given. Within the frequency range 50 to 4 000 cycles, the majority of the results obey the equations first given by Hopkinson and afterwards by Schweidler, and it is shown that the properties of such samples can be represented by four fundamental constants, the values of which are tabulated. These constants will represent d.c. as well as a.c. observations, but only when the time of electrification is short, i.e. of the same order as the periodic time of the alternating current. The general conclusion reached is that the current responsible for the power loss in varnished cloth is carried by ions or dipoles, the motion of which is opposed by a frictional force depending on the viscosity of the material or some similar property; that the displacement of such ions or dipoles conforms to Hopkinson's superposition principle, and that there is no dielectric hysteresis analogous to magnetic hysteresis. No existing theory gives a completely satisfactory explanation of the equations representing the observations, but the statistical explanation of K. W. Wagner, when applied to several possible theories, will account for them to some extent.