Impedance Values Research Articles

Enhanced Grain Boundary Resistance Resulting in High Permittivity and Low Dielectric Loss in CaCu3Ti4O12/LaNiO3

Abstract (1-X) CaCu3Ti4O12 + (X) LaNiO3 composite ceramics were fabricated using pre-reacted calcium copper titanate CaCu3Ti4O12 (CCTO) and lanthanum nickelate LaNiO3 (LNO) and their crystallographic structure and morphology were studied to measure dielectric, impedance, and conductivity values. X-ray diffraction peaks show that CCTO/LNO composites are in a cubic structure. Scanning electron microscopy images show denser and more uniform grains with thin grain boundaries and a smaller average grain size. The permittivity of CCTO is stable in the range 102 -106 Hz, but the composites show huge progress in permittivity by space charge polarization and relaxation in the range 103 -104 Hz, demonstrating improved dielectric properties. The 0.98(CaCu3Ti4O12)+0.02(LaNiO3) sample showed a dielectric constant of 2.58×104 at 1 kHz , which is superior to pure CCTO (2.28×104 at 1 kHz). The electrical behaviour of the metallic filler on the composites was investigated using impedance spectroscopy analysis. The resistance of grain boundary increases with LNO. Activation energies were found to be 0.92, 0.95, and 0.90 eV for x=0.1, 0.2, and 0.3, respectively, and these values are better than that of pristine CCTO (0.85 eV) sample. These results indicate that the prepared CCTO/LNO samples could be useul for high energy applications.

Mobile brain imaging in butoh dancers: from rehearsals to public performance.

Dissecting the neurobiology of dance would shed light on a complex, yet ubiquitous, form of human communication. In this experiment, we sought to study, via mobile electroencephalography (EEG), the brain activity of five experienced dancers while dancing butoh, a postmodern dance that originated in Japan. We report the experimental design, methods, and practical execution of a highly interdisciplinary project that required the collaboration of dancers, engineers, neuroscientists, musicians, and multimedia artists, among others. We explain in detail how we technically validated all our EEG procedures (e.g., via impedance value monitoring) and minimized potential artifacts in our recordings (e.g., via electrooculography and inertial measurement units). We also describe the engineering details and hardware that enabled us to achieve synchronization between signals recorded at different sampling frequencies, along with a signal preprocessing and denoising pipeline that we used for data re-sampling and power line noise removal. As our experiment culminated in a live performance, where we generated a real-time visualization of the dancers' interbrain synchrony on a screen via an artistic brain-computer interface, we outline all the methodology (e.g., filtering, time-windows, equation) we used for online bispectrum estimations. Additionally, we provide access to all the raw EEG data and codes we used in our recordings. We, lastly, discuss how we envision that the data could be used to address several hypotheses, such as that of interbrain synchrony or the motor theory of vocal learning. Being, to our knowledge, the first study to report synchronous and simultaneous recording from five dancers, we expect that our findings will inform future art-science collaborations, as well as dance-movement therapies.

New method for graphing impedance values as an analytical tool suitable for electrochemical impedance spectroscopy

A new method for graphing electrical impedance values named a “differentiation-based Bode plot” is proposed. This method facilitates the analysis procedure and reduces the arbitrariness of the interpretation of electrochemical impedance spectroscopy (EIS) data. Among the various methods for graphing impedance values, Nyquist plots are commonly adopted (primarily in the field of EIS) because of the apparent correlation between their shape and the corresponding equivalent circuit. However, because Nyquist plots do not contain frequency information, Bode phase and magnitude plots are frequently utilized. Although such plots are suitable for determining the absolute magnitude and phase of the impedance, they are not always useful for selecting the structure of an equivalent circuit, which is a hypothetical model for electrochemical cells. In the proposed method, instead of the real (Z’) and imaginary (Z’’) parts, two functions of the impedance derivatives with respect to frequency, i.e., dZ’/d(log f) and dZ’’/d(log f), are plotted. As substitutions for the Bode phase and magnitude plots, arctan{dZ’’/d(log f) ÷ dZ’/d(log f)} and log[sqrt{(dZ’/d(log f))2 + (dZ’’/d(log f))2}] are plotted against log f. Unlike the classical Bode plot, the differentiation-based Bode plot is independent of the lateral shift in the Nyquist plot, which is advantageous for determining an equivalent circuit. To demonstrate this advantage, the impedance values of typical equivalent circuits used in electrochemistry are calculated and plotted to compare differentiation-based Bode plots with Nyquist and classical Bode plots.

Effect of heat input on the microstructure and performance of dissimilar welded joint between Q345B low-alloy steel and 2205 duplex stainless steel

Q345B/2205 dissimilar steel multi-layer multi-pass welded joints were prepared using gas metal arc welding (GMAW). The effects of heat inputs on the microstructures and properties of welded joints were studied. The morphology and composition distribution of Q345B base metal near the fusion line were investigated. The results showed that the welded joints under different heat inputs were all present “carbon depleted zone” and “carburized zones” on both sides of the Q345B base metal and transition layer interface. The microstructure of the “carburized zones” was composed of martensite phase and granular bainite phase. It was found that only the welded joints with heat inputs of 1.765 kJ/mm and 2.860 kJ/mm met the usage requirements. The corrosion behavior and characteristics of the welded joint with a heat input of 1.765 kJ/mm in a 3.5 wt % NaCl solution were investigated intensively. During the soaked process of 14 days, the total impedance value of the welded joint showed first increasing and then decreasing. The maximum value of 8.7 kΩ cm2 was obtained on the 5th day. As the soaked time increased, the corrosion products of the welded joint underwent the formation, thickening, cracking and detachment, which was the main reason of the change in the corrosion resistance. The research results of this article have significant implications for the application of low-alloy steel and stainless steel welded joints in engineering.

Assessing Pain Levels Using Bioelectrical Impedance in Low Back Pain Patients: Clinical Performance Evaluation

Background/Objectives: Musculoskeletal pain is one of the leading causes of years lived with disability worldwide and has a negative impact on daily life and quality of life. Methods: The purpose of this study was to analyze the electrical characteristics of back pain by measuring and calculating bioelectrical impedance variables (R, Z, PA) in 85 subjects (45 in the Healthy group and 40 in the LBP group). Additionally, impedance measurements were conducted on 20 subjects (10 in the Young group and 10 in the Older group) to assess the impact of aging. Results: Bioelectrical impedance parameter values were higher in cases of back pain, and correlation analysis showed that there was a statistically significant difference between the Healthy and LBP groups (p < 0.05). A positive correlation was found between impedance parameters and pain related indices (ODI, RMDQ, VAS) (mean R, Z, PA: 0.68, 0.54, 0.75), with BMI positively correlating only with PA (0.493). Diagnostic accuracy for detecting back pain exceeded 95% (R, Z, PA: 0.984, 0.984, 0.963). Conclusions: Results indicated that aging did not significantly affect impedance values. The bioelectrical impedance measurement device used in this study, with its simultaneous diagnostic and therapeutic capabilities, proved useful for real-time pain diagnosis and treatment monitoring, highlighting its potential clinical utility.

Effect of Gd doping on the microstructure and electrical characteristics of Maghemite (γ-Fe₂O₃) ceramics

AbstractThis paper presents a novel study on the microstructure and electrical properties of gadolinium (Gd) doped maghemite (γ-Fe₂O₃) nanoparticles, emphasizing their significance for advanced applications in efficient materials. X-ray diffraction analysis confirmed that both pure and doped samples crystallized in a cubic structure (P4332 space group) with high purity. Gd doping significantly increased crystallite size and altered particle morphology, as shown by transmission electron microscopy (TEM), which revealed larger nanoparticles with cubic shapes. Thermal analysis (TGA and DTG) indicated that higher Gd concentrations enhanced thermal instability, affecting structural integrity. FTIR spectra showed shifts in Fe-O bond vibrations, suggesting lattice distortions and increased disorder. BET measurements indicated that higher Gd doping led to greater mesoporosity and surface area, countering expectations of densification. Electrical conductivity and impedance studies revealed two distinct regions: a constant conductivity at low frequencies and an exponential increase at high frequencies, attributed to small polaron hopping. Activation energy values below 200 meV support this mechanism. Gd doping decreased overall conductivity due to disrupted atomic arrangements, increased electron scattering, and modifications in the electronic band structure. Complex impedance spectroscopy illustrated higher real impedance values for doped samples, with increased Gd concentration leading to enhanced impedance. These findings elucidate the impact of Gd on the electrical properties of maghemite nanoparticles and highlight their importance in meeting the growing demands for highly efficient technologies in energy storage and electronic devices. Graphical Abstract

Green Film Forming Technology Based on Polydopamine Galvanized

At present, the mainstream passivation agent is chromate passivation agent, but it has the disadvantages of high toxicity and high price, so this project seeks to find a safer, cheap and green chromium-free passivation agent. Because dopamine and chitosan derivatives have certain corrosion inhibition properties on metals in acidic media, these polymer corrosion inhibitors can achieve high corrosion inhibition rates at high concentrations. Therefore, in this experiment, dopamine was added on the basis of sodium silicate, and the sample was passivated to explore the potential enhancement effect of dopamine on the passivated film performance. After the sample was treated, the impedance value could be fitted by electrochemical impedance spectroscopy and Zsimpwin software, and then the Tafel polarization curve was drawn. It was found that the addition of dopamine significantly improved the corrosion resistance of the passivated film. By promoting the positive shift of self-corrosion potential and greatly reducing the self-corrosion current density, the protective barrier effect of passivation film on metal matrix is effectively enhanced. Finally, the experiment successfully proved that the corrosion resistance of the passivation film after adding dopamine was better

Standardization of transthoracic impedance values for estimating heart failure and its utility

Abstract Background The use of intrathoracic impedance for examining pleural effusion in heart failure patients has been explored previously. However, due to concerns about its accuracy and complexity, transthoracic impedance values have had limitations in quantifying extravascular lung water. Our dual objectives were to clarify the relationship between intrathoracic conditions and percutaneous transthoracic impedance values, and to establish a basic model for a new machine learning-based estimation system for assessing intrathoracic conditions in patients with heart failure. Methods First, we developed a live porcine congested lung model that induced pleural effusion by substantial fluid loading, and then longitudinally evaluated its correlation with percutaneous transthoracic impedance values. Second, we conducted multi-frequency bioelectrical impedance analysis to simultaneously collect electrical, physical, and hematological data from 63 hospitalized heart failure patients and 82 healthy volunteers Results In the porcine model, pleural effusion correlated with a concurrent decrease in SpO2 and a gradual decrease in impedance. We indexed and generated features from the measured values and developed an intrathoracic estimation model based on electrical measurements and clinical findings using a decision tree-based machine learning approach. Among the 286 features collected per individual, the model used 16 features. Notably, the model demonstrated high accuracy in discriminating patients with pleural effusion, achieving an AUC of 0.905 (95% CI: 0.870-0.940) in cross-validation, significantly outperforming the conventional frequency-based method. Conclusions Transthoracic impedance values, when indexed, reflect intrathoracic conditions and improve estimation. Our results highlighted the potential of machine learning and thoracic impedance measurement for accurate estimation of pleural effusion. This approach provides an effective means of assessing intrathoracic conditions. Figure: The upper figure shows the relationship between impedance values and pleural effusion in the congested lung model. On these results, human data were collected to construct the estimation model. The lower illustrates the accuracy of the model and provides a comprehensive view of the system.

Modeling and Simulation of Wide-Frequency Characteristics of Electromagnetic Standard Voltage Transformer

To achieve the broadband applicability of standard voltage transformers in “dual high” power systems, an equivalent circuit model of the standard voltage transformer is first established. Using the complex magnetic permeability method and utilizing existing core parameters, the excitation impedance values are obtained. Next, based on the equivalent circuit model, the no-load error function of the standard voltage transformer is analyzed, and through simulation, the no-load error response curve of the standard voltage transformer in the frequency range of 20 Hz to 3000 Hz is derived. The simulation results indicate that within the 20 Hz to 700 Hz range, both the no-load ratio error and the no-load angular error meet the accuracy requirements, with the ratio error within ±0.05% and the angular error within 2′. Additionally, the derivation of the error transfer function demonstrates the correlation between the no-load error values and the number of turns and cross-sectional area of the standard voltage transformer. Simulation results, obtained by increasing and decreasing the number of turns and cross-sectional area by 10%, provide valuable insights for the error compensation and structural design of standard voltage transformers.

Corrosion mapping of intermetallic in a dissimilar weldment using in-situ alternating current scanning electrochemical microscopy

In the present work, in-situ corrosion activity mapping across explosively welded 304 L SS-Zr-4 dissimilar joint interfaces was performed using intermittent contact alternating current-scanning electrochemical microscopy (IC-AC-SECM). Two weld joint samples, one with a regular interface and another with an irregular interface, were examined for their local surface activities at an open circuit potential in tap water without using a redox mediator. The SEM micrographs showed the formation of intermetallics at localized regions of the irregular interface weld sample but not in the regular interface sample. The 304 L SS regions of the welds were relatively anodic, with current and impedance magnitude values of 270 ± 20 nA and 380 ± 20 kΩ respectively, when compared to the Zr-4 regions with the corresponding values of 160 ± 20 nA and 630 ± 20 kΩ, due to galvanic coupling effect. The IC-AC-SECM technique enabled the in-situ determination of corrosion activity of localized intermetallic region within the weldment. The current and impedance magnitude values of the intermetallic region were ∼ 240 nA and ∼ 450 kΩ, respectively, showing only a slightly lesser anodic activity as compared to the 304 L SS base metal. The results obtained from the IC-AC-SECM mapping showed a good correlation with the EDS elemental mapping of the dissimilar weldment with intermetallic. The findings indicate the effectiveness of the IC-AC-SECM technique for the in-situ localized corrosion mapping of dissimilar weld joints, showcasing its potential for various applications in assessing weld integrity.

Ensemble LVQ Model for Photovoltaic Line-to-Line Fault Diagnosis Using K-Means Clustering and AdaGrad

Line-to-line (LL) faults are one of the most frequent short-circuit conditions in photovoltaic (PV) arrays which are conventionally detected and cleared by overcurrent protection devices (OCPDs). However, OCPDs are shown to face challenges when detecting LL faults under critical detection conditions, i.e., low mismatch levels and/or high fault impedance values. This occurs due to insufficient fault current, thus leaving the LL faults undetected and leading to power losses and even catastrophic fire hazards. To compensate for OCPD deficiencies, recent studies have proposed modern artificial intelligence (AI)-based methods. However, various limitations can still be witnessed even in AI-based methods, such as (i) most of the models requiring a massive training dataset, (ii) critical fault detection conditions not being taken into consideration, (iii) models not being accurate enough when dealing with critical conditions, etc. To this end, the present paper proposes a learning vector quantization (LVQ)-based ensemble learning model in which three LVQs are individually trained to detect and classify LL faults in PV arrays. The initial LVQ vectors are determined using the k-means clustering method, and the learning rate is optimized by the adaptive gradient (AdaGrad) optimizer. The training and testing datasets are collected according to the PV array’s current–voltage (I–V) characteristic curve, and several features are extracted based on the Canberra and chi-squared distance techniques. The model utilizes a small training dataset, considers various critical detection conditions for LL faults—such as different mismatch levels and fault impedance values—and the final experimental results show that the model achieves an impressive average accuracy of 99.26%.

Synthesis of Sustainable Binary Calcium Monosilicate Ceramics from Bio-waste: Effect of Sintering Temperature on Microstructure and Electrical Properties

This study was conducted to synthesise calcium monosilicate ceramics using rice husks and raw eggshells and investigated the effect of sintering temperature on the physical,microstructure and electrical properties of the final product. The high content of calcium and silicon in eggshells and rice husks, respectively promote the use of waste materials in the production of calcium monosilicates by mixing in a molar ratio 1CaO:1SiO2 and fired at different sintering temperatures for 2 hours with a heating rate of 10°C/min. A good correlation between sintering temperature, structural, microstructure, and electrical properties of calcium silicate was observed. The structural and morphological evolutions were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX). XRD analysis showed that the main crystalline phases of synthesised calcium monosilicate are pseudowollastonite (ICSD 98-005-2598) at 1250°C, and the phases of SiO2 also exist in different types of minerals. Besides, a small amount of larnite, Ca2SiO4 was traced at 1100°C and 1200°C. Fourier Transforms Infrared (FTIR) spectra showed the presence of characteristic functional groups in the precursor powder. In Nyquist plots, the summit frequency of the dominant arc decreases with increasing sintering temperatures. It may be attributed to the co-effect of the grain size and pore. A larger value of impedance at a lower frequency suggests an essential role of boundaries in governing the electrical properties of the sintered ceramics. As the sintering temperature increases, the microstructure of the sintered samples becomes denser while conductivity performance decreases. This is due to the reduction of particle interfaces and charge transfer.

Real-time in-situ coatings corrosion monitoring using machine learning-enhanced triboelectric nanogenerator

Current methods for monitoring coating corrosion are limited by their inability to provide real-time data and dependence on external power sources. This study presents a novel in-situ corrosion monitoring system using a solid-liquid triboelectric nanogenerator (TENG) that converts mechanical energy into electrical signals for self-powered sensing. TENG signals and electrochemical impedance spectra were measured on a dopamine-modified lignin-polydimethylsiloxane coating on steel in 1 M NaCl solution under no corrosion, indentation, pitting, and broken conditions, respectively. We extract time-frequency features from the TENG signals to predict the coating’s corrosion condition by applying a customised convolutional neural network (CNN). By extracting time-frequency features from the TENG signals and applying a custom CNN, a prediction accuracy of 99 % for corrosion classification was achieved. Furthermore, the CNN regression model predicted coating impedance values with a high coefficient of determination (R² = 0.98), demonstrating its effectiveness in tracking corrosion progression. The developed TENG also facilitates defect localisation via a matrix electrode beneath the coating. Our approach introduces a promising real-time technology for in-situ corrosion monitoring.

Electromagnetic scattering of a 3D spherical impedance cavity with a circular aperture by an arbitrarily located and oriented Hertzian dipole

The problem of the scattering of an arbitrarily oriented and located Hertzian dipole from an impedance cavity with a circular aperture satisfying different impedance values at inner and outer spherical surfaces is solved with a method of auxiliary sources (MAS). The study of that canonical problem with Leontovich boundary conditions answers the effects of the location of the excitation, aperture size, and boundary conditions on the resonance and radiation characteristics of the semi-opened spherical cavity. The proposed approach employs the distribution of the two perpendicular Hertzian dipoles on auxiliary surfaces representing the scattered field inside and outside the spherical cavity with a circular aperture. As the numerical results, the total radar cross section and the near field distributions are provided for different cases including the aperture size, source location, and boundary conditions. The resonance characteristics are analyzed. The method is validated by other approaches for the limit cases.

Towards multimodal visualization of esophageal motility: fusion of manometry, impedance, and videofluoroscopic image sequences.

Dysphagia is the inability or difficulty to swallow normally. Standard procedures for diagnosing the exact disease are, among others, X-ray videofluoroscopy, manometry and impedance examinations, usually performed consecutively. In order to gain more insights, ongoing research is aiming to collect these different modalities at the same time, with the goal to present them in a joint visualization. One idea to create a combined view is the projection of the manometry and impedance values onto the right location in the X-ray images. This requires to identify the exact sensor locations in the images. This work gives an overview of the challenges associated with the sensor detection task and proposes a robust approach to detect the sensors in X-ray image sequences, ultimately allowing to project the manometry and impedance values onto the right location in the images. The developed sensor detection approach is evaluated on a total of 14 sequences from different patients, achieving a F1-score of 86.36%. To demonstrate the robustness of the approach, another study is performed by adding different levels of noise to the images, with the performance of our sensor detection method only slightly decreasing in these scenarios. This robust sensor detection provides the basis to accurately project manometry and impedance values onto the images, allowing to create a multimodal visualization of the swallow process. The resulting visualizations are evaluated qualitatively by domain experts, indicating a great benefit of this proposed fused visualization approach. Using our preprocessing and sensor detection method, we show that the sensor detection task can be successfully approached with high accuracy. This allows to create a novel, multimodal visualization of esophageal motility, helping to provide more insights into swallow disorders of patients.

Corrosion resistance and forming mechanism of phytic acid conversion film on copper foil prepared by electrolysis

In this paper, the phytic acid conversion film was prepared on copper foil by electrolysis for the first time. Its morphology and chemical composition were characterized by SEM, EDS, FTIR and XPS, and its corrosion resistance was evaluated using electrochemistry. Finally, the formation mechanism of the phytic acid conversion film on the surface of copper foil and its corrosion resistance mechanism were revealed by quantum chemical calculations and molecular dynamics simulations. The results show that the phytic acid conversion film on the surface of copper foil prepared by electrolysis is uniform and dense. The electrochemical impedance value of copper foil in 3.5 wt% NaCl solution increased from 3956 Ω·cm2 to 24828 Ω·cm2 after the preparation of phytic acid conversion film, and the protection efficiency reached 91 %. During the electrolysis process, copper atoms are oxidized into copper ions, which can be coordinated with phytate ions to form negatively charged complexes. Under the action of electric field force, these complexes move toward the anode copper foil, and finally adsorbed on the surface of the anode copper foil to form phytic acid conversion film. The molecular dynamics show that the adsorption configuration of the phytic acid molecule on Cu(111) surface changed from perpendicular to parallel, and the binding energy increased from 234.87 kJ/mol to 354.23 kJ/mol after applying an electric field, Therefore, the phytic acid conversion film prepared on the surface of copper foil by electrolysis has good corrosion resistance. This study provides a new method for the rapid preparation of phytic acid conversion film with excellent performance on metal surface.

Preparation of the fluorinated graphene/epoxy resin anti-corrosion composite coating

In order to enhance the corrosion resistance of epoxy resin (EP) coating system, we put forward a facile approach to prepare hydrophobic fluorinated graphene (FG) filler for the EP coating by one-pot hydrothermal reaction in this work. Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), contact angle measuring instrument and scanning electron microscopy (SEM) were employed for the FG characterization. The SEM images of fracture morphology revealed that FG uniformly dispersed in epoxy resin matrix. Additionally, the excellent water resistance and the lower coefficient of friction of FG/EP coating was confirmed through the water absorption test and friction and wear test machine. The electrochemical impedance spectroscopy (EIS) demonstrated that the impedance value at the low frequency (|Z|0.01Hz) of 0.50 wt% FG/EP was 3.49 × 107 Ω·cm2 after being immersed in 3.5 wt% NaCl solution for 60 days, which was about 2 orders of magnitude higher than that of the pure EP coating (4.74 × 105 Ω·cm2). The 0.50 wt% FG/EP coating exhibited the superior anti-corrosion performance due to the FG with the two-dimensional sheet structure, uniform dispersion and hydrophobicity properties.

A simple strategy to significantly improve the anticorrosion and aging resistance of epoxy coatings by adding polyaniline modified multi-walled carbon nanotubes

Epoxy coatings are widely used for corrosion protection of metals, but under extremely harsh environments, the epoxy polymer chains such as the C-O bonds of epoxy ether and aromatic ether, and the -OH in the epoxy chain structure can also undergo aging and degradation, leading to the failure of the coating in service. How to extend the anti-aging capability of epoxy resins while maintaining their other properties unchanged has become a major challenge in the practical application of epoxy coatings. In this study, the polyaniline (PANI) modified multi-walled carbon nanotubes (MWCNT@PANI) were synthesized by polymerization in-situ and added to epoxy resin as an anti-aging filler. The various measurements have been adopted to characterize the composition and structure of MWCNT@PANI, and the anticorrosive performance of the composite coating for carbon steel were evaluated via salt spray, chemical aging and UV light aging. Results showed that the impedance value of the blank epoxy coating decreases by at least two orders of magnitude after the salt spray tests, and the contact angle decreases by about 30° and gradually changes from hydrophobic to hydrophilic, indicating a significant decline in corrosion resistance. In contrast, the composite coating confirmed the excellent anti-aging performance, while the impedance values increased by approximately 2-5 orders of magnitude compared to that in blank epoxy coatings, and remained around 1010 Ω·cm2. Given the dense encapsulation of MWCNT@PANI, the dispersion stability between the filler and EP can be improved, and the effective corrosion resistance performance was also supported by molecular dynamic simulation. Besides that, the ability of free radical quenching along with the labyrinth effect and hydrophobic interaction have also been investigated to explain the anticorrosion and anti-aging mechanism.

Effect of epoxy resin addition on the acoustic impedance, microstructure, dielectric and piezoelectric properties of 1–3 connectivity lead-free barium zirconate titanate ceramic cement-based composites

In this work, 1–3 connectivity barium zirconate titanate ceramic cement-based composites were fabricated using Portland cement and epoxy resin as the matrix. Barium zirconate titanate (BZT) of 40–60 % by volume was used while epoxy was used with cement at 0–7% by volume. Dielectric and piezoelectric properties, and other properties such as acoustic impedance, density and microstructure were investigated. It was found that epoxy resin can be used in combination with BZT to achieve a suitable acoustic impedance value (9–11 × 106 kg/m·s2) matching that of concrete for structural health monitoring application. Thus, when epoxy resin was used at 7 %, BZT volume can be increased to 60 % where the highest d33 value of 93 pC/N was found and remain within the acoustic matching range. In addition, when epoxy resin was increased, both piezoelectric charge coefficient (d33) and piezoelectric voltage coefficient (g33) were also found to increase. This is likely due to the lower porosity thus denser matrix when epoxy resin was used in addition to cement.

Constructing ZSM-5 loaded with 2-mercaptobenzimidazole on glass fiber for enhancing the anti-corrosion and erosion resistance properties of epoxy coating

Glass fiber reinforced polymer coatings (GFRPC) are used to protect steel structures in harsh Marine environments due to high mechanical strength and chemical stability. The composite coating not only suffers from impact damage by seawater and sediment but also experiences corrosion damage in the splash zone. However, the GF has weak interfacial adhesion with polymer resins due to the chemical inertia and smooth surface, which limits the service lifespan of GFPRC. Hence, ZSM-5 zeolites were in situ prepared on the surface of glass fibers by hydrothermal synthesis, and 2-mercaptobenzimidazole (MBI) was further adsorbed to obtain difunctional hybrid glass fibers (ZGFM) to enhance the interfacial adhesion strength of glass fiber/resin and also the erosion resistance and anti-corrosion ability of composite coatings. Compared to GF/EP, the interfacial shear strength of ZGFM/EP was increased by 104.39 %. After immersion under an alternating hydrostatic pressure of 20 MPa for 12 days, the impedance value of the ZGFM/EP composite coating remained at 6.40 × 109 Ω•cm2, demonstrating outstanding deep-sea anti-corrosion performance. Following the erosion test, the ZGFM/EP exhibited a reduction in mass loss and volume loss by 10.65 % and 12.55 %, respectively, in comparison to the pure EP coating. The excellent interfacial strength between ZGFM and EP ensured effective stress transfer, which prevented crack propagation, thus enhancing the mechanical properties and erosion resistance of the composite coating. Meanwhile, electrochemical experiment proves glass fiber with MBI loaded obviously inhibited the corrosion reaction.