This study developed high-performance anti-flashover silicone coatings using sol-gel-synthesized CaCO3/SiO2 hierarchical fillers optimized via L-16(4(5)) orthogonal design. The optimal filler (Sample 5) was prepared under 70 vol% ethanol, with nTEOS:nCaCO(3) = 1:1 and 0.2 mol/L NH3H2O, at 45 degrees C, for 18 h, featuring covalent Si-O-Ca bonding, a dual-scale microstructure (2-4 mu m CaCO3 cores + 20-40 nm SiO2 nodules), a 14.44 m(2)/g specific surface area, and bimodal porosity (8-80 nm). Composite C7 (30 wt% filler, 3 wt% KH-570, 1:2 resin-to-filler ratio) achieved superhydrophobicity (a 153 degrees contact angle via Cassie-Baxter stabilization), ultrahigh electrical insulation (3.20 x 10(14) Omegacm volume resistivity, 1.60 x 10(13) Omega surface resistivity), and robust mechanical properties (Shore 3H hardness, 5B adhesion). Standardized IEC 60507:2020 tests showed that C7's flashover voltages (14.8 kV for KMnO4, 14.3 kV for NaCl/KMnO4, 13 kV for NaCl) exceeded that of neat silicone resin (NSR) and conventional CaCO3-filled composite (SR-CC) by >135%. Additionally, C7 retained superhydrophobicity after 500 h UV aging and maintained a 124 degrees contact angle after 12 months of outdoor exposure. The superior performance stems from synergistic hierarchical topology, tortuous discharge paths, and interfacial passivation. This work establishes a microstructure-driven design paradigm for grid protection materials in harsh environments.

Highlights What are the main findings? center dot Micro-nano SiC/ZnO fillers build efficient nonlinear conductive networks. center dot n-SiC enhances high-field nonlinearity via interfacial tunneling effects. center dot ZnO co-doping improves low-field stability and conductivity uniformity. What are the implications of the main findings? center dot Enables eco-friendly waterborne anti-corona coatings (WPU/EP system). center dot Improves electric field grading for high-voltage stator insulation. center dot Significantly enhances electro-thermal aging resistance and reliability.Highlights What are the main findings? center dot Micro-nano SiC/ZnO fillers build efficient nonlinear conductive networks. center dot n-SiC enhances high-field nonlinearity via interfacial tunneling effects. center dot ZnO co-doping improves low-field stability and conductivity uniformity. What are the implications of the main findings? center dot Enables eco-friendly waterborne anti-corona coatings (WPU/EP system). center dot Improves electric field grading for high-voltage stator insulation. center dot Significantly enhances electro-thermal aging resistance and reliability.Abstract With the demand for high-voltage electrical insulation systems increasing, the development of environmentally friendly anti-corona materials with reliable nonlinear electrical properties has become essential. In this work, a waterborne polyurethane/epoxy (WPU/EP) composite coating was fabricated using micron-sized SiC (alpha-SiC), nano-sized SiC (beta-SiC), and n-ZnO as multi-scale fillers. Its microstructure, nonlinear conductivity, flashover characteristics, and electro-thermal aging performance were systematically investigated. The results indicate that the incorporation of alpha-SiC significantly enhances conductivity under high electric fields by forming conductive pathways, while beta-SiC further improves nonlinear behavior through interfacial bridging effects. The addition of n-ZnO modifies interfacial characteristics and contributes to improved electrical response. Moreover, the flashover performance is strongly dependent on filler composition, showing a critical role of nano-fillers in charge trapping and transport regulation. Electro-thermal aging tests on simulated stator bars reveal that the developed coating exhibits improved resistance to degradation compared with conventional materials. These findings demonstrate the effectiveness of multi-scale filler design in tailoring the electrical and insulation performance of waterborne anti-corona coatings.

Conventional epoxy adhesives used in motor insulation structures still suffer from insufficient thermal resistance and difficulty in balancing heat resistance with mechanical reliability. In this study, BMI-modified E-51/MeHHPA/EMI-24 epoxy composites were prepared and evaluated as heat-resistant interfacial adhesives for simulated F-class pole windings. BMI/EP composites with different BMI contents were fabricated by melt blending and characterized in terms of curing kinetics, FTIR, mechanical properties, and thermal performance. The optimized formulation was then applied to bond Nomex insulation paper to the upright plate in a simulated pole winding. The results showed that BMI did not alter the main epoxy/anhydride curing pathway, but restricted segmental motion and improved thermal resistance. The 10phr BMI/EP composite exhibited a favorable balance among thermal performance, mechanical properties, and fracture morphology. The simulated winding prepared with this formulation showed no breakdown or flashover under 6800 V/60 s, with an insulation resistance of 64.49 GΩ. A lower-bound apparent temperature index of approximately 157 °C was obtained using the TGA-derived thermal life equation. These results indicate that this system has preliminary application potential as a heat-resistant interfacial adhesive for F-class motor winding insulation, although a complete thermal life assessment is still required.

In this work, a cerium-containing composite conversion film has been prepared on the PbSb alloy to improve its corrosion resistance. Batch studies have been carried out to address the influence of various process parameters. Systematic investigations were conducted to elucidate the film formation mechanism and evaluate the corrosion resistance property. The morphology and chemical composition were characterized with scanning electron microscopy, fourier transform infrared and x-ray diffractometry. The corrosion resistance of the samples has been measured by electrochemical and immersion tests. The results show that with the increase in the concentrations of H2SO4, (NH4)4Ce(SO4)4 and polyvinylpyrrolidone PVPk30, as well as the treatment temperature, the corrosion resistance of the film first increases and then decreases slightly. The film quality is greatly influenced by the processing time. Cracks begin to appear in the film after 12 h. Both PVPk30 and cerium ions act as synergistic surface modifiers; as a result, the film formed under the relative optimum process is very compact and completely covered the substrate. The film, mainly composed of PbSO4 with trace amounts of oxides, cerium compounds and organic materials, exhibits significantly superior corrosion resistance compared to the bare alloy in a carbonic acid solution.

PVDF is one of the most researched polymers for the development of high energy density film capacitors, and its crystalline structure and dipole motion are closely related to the energy density. In this work, the low-loss amorphous polymer PMMA was introduced as a reinforcing phase to blend with PVDF to form a matrix. PMMA/PVDF-BT nanocomposites were prepared by spin-coating method and subjected to quenching heat treatment in three media, namely, deionized water, ice water, and liquid nitrogen, respectively. The results showed that the quenching heat treatment achieved a synergistic increase in permittivity and breakdown strength without sacrificing the mechanical properties of the nanocomposites, while maintaining a low dielectric loss. The discharge energy density of the quenched heat-treated PMMA/PVDF-BT nanocomposite in ice water at 180 degrees C was 11.5 J/cm3 (3100 kV/cm), which was about 958.33 % of the best commercial BOPP film (1.2 J/cm3). This work has great potential as flexible dielectric substrates for advanced and sophisticated film capacitors.

Pb-Sb alloy is an excellent cutting rope material, however, easy to be corroded in CO2-containing environment. Hereby, the Pb-Sb alloy was heat-treated, and its microstructure and corrosion behavior in H2CO3 solution were investigated. The morphology and chemical composition were characterized with scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy, and x-ray diffractometry. The corrosion resistance of the samples has been measured by electrochemical and immersion tests. The hardness of the samples was also measured. The results showed that Sb was basically integrated into the Pb matrix after solution treatment at 290 °C for 1 h, and the grain size increased an order of magnitude. After aging treatment at 100 °C for 2 h, the hardness and corrosion resistance of the Pb alloy reached the highest, and the grain size of the alloy was larger than that of the original state, but was finer and more uniform than that of the samples after solution treatment and aging treatment for longer time due to the recrystallization. The decrease in the amount of large secondary phases and grain boundaries resulted in the improvement of the compactness of the corrosion products layer formed on the alloy surface during the corrosion test. In contrast, the excess of dispersed and fine secondary phases and coarser grains led to less protective corrosion products film and lowered the corrosion resistance after the solid-solution or longer-time aging treatment.

As the communications industry continues to develop, low temperature co-fired ceramics are used as resonators in multilayer chip components of integrated circuits. In order to co-fire with the metal, it is necessary to reduce the sintering temperature of ceramics to below 960 degrees C. In order to rule out the impact of changes in the operating temperature of the ceramic material, we need to adjust the resonant frequency temperature coefficient to near zero. This paper discusses the application of a temperature-stable low-temperature sintered dielectric material derived from Li2ZnSiO4 (LZS) in low-temperature co-fired ceramics (LTCC). The addition of the low melting point oxide Bi2O3 resulted in a significant reduction of the sintering temperature and improvement of the densification of LZS ceramics, where the sintering temperature was reduced from 1200 degrees C to 900 degrees C. The relative density and microwave dielectric properties (dielectric constant epsilon r, quality factor Q x f and temperature coefficient of resonant frequency tau & fnof;) of LZS-xBi2O3 (x = 0, 3, 6, 9, 12 mol%) ceramics sintered at different temperatures increase and then decrease with increasing Bi2O3 content. The best performance was obtained when the Bi2O3 addition was 9 mol% (epsilon r = 6.87, Q x f = 28,151 GHz, tau & fnof; =- 85.2 ppm/degrees C). By increasing the amount of TiO2 added to LZS-9 mol%Bi2O3, the tau & fnof; value of the ceramic system can be continuously increased, which is effectively adjusted to near zero. The best integrated dielectric properties of the LZS-Bi2O3-TiO2 ceramic system (epsilon r = 8.9, Q x f = 22.982 GHz, tau & fnof; =- 8.34 ppm/degrees C) are obtained when the TiO2 addition is 30 wt%. This suggests that LZS-Bi2O3-TiO2 ceramics have potential for low-temperature co-fired ceramics (LTCC) applications.

This study resolves the challenge of balancing curing speed and performance in room-temperature-curing epoxy coatings by developing a novel system grafted with hexamethylene diisocyanate trimer (HDI trimer) and polyethylene glycol 200 (PEG200). Employing DMP-30 as the catalyst, the coating achieves efficient curing at 25 °C, with complete cure within 7.5 h. The cured material exhibits outstanding thermal stability (T50% = 380.83 °C) and mechanical properties. Fracture morphology analysis reveals a uniform ductile structure, confirming its high toughness and durability. Furthermore, kinetic models accurately predict curing behavior across different temperature curves, providing crucial guidance for optimizing industrial coating processes. This research offers a viable strategy for designing high-performance, rapid curing epoxy materials, demonstrating significant application potential in coating systems, composite surfaces, and electronic encapsulation.

Polyvinylidene fluoride (PVDF) is one of the most widely studied polymers for the development of film capacitors with high energy density. However, it is still challenging to modulate the polarization hysteresis phenomenon of PVDF in a simple and effective way to achieve a significant increase in energy density. In this work, a low-loss amorphous polymer poly(methyl methacrylate) (PMMA) was introduced as a reinforcing phase to be blended with PVDF to form a matrix. The dielectric and energy storage performance of PVDF is improved by integrating the high dielectric property of barium titanate (BaTiO3) with the low hysteresis property of PMMA. PMMA/PVDF-BaTiO3 nanocomposites were prepared by spin-coating process. It was shown that the PMMA/PVDF-BaTiO3 nanocomposites had a thin and flat macroscopic structure and a uniform and dense microstructure. The optimum dielectric constant of the nanocomposites was 12.9 at 100 Hz, and the optimum energy density was maximized to 6.5 J/cm3. Compared with the PVDF/PMMA composites, the dielectric and energy storage performance were significantly improved under the same conditions. This work provides a simple and effective strategy for obtaining polymer nanocomposites with high energy density and with potential as flexible dielectric substrates for film capacitors.

Improvement in the properties of interfacial regions in polymer-based nanocomposites is essential to enhance energy storage performance. In this paper, multistage interface optimization strategy was applied to nano-composite films, and core-shell structure BaTiO3@SiO2 nanoparticles were prepared and then surface-modified with KH550 coupling agent, which effectively enhanced the compatibility of filler BaTiO3 with the matrix PVDF/ PMMA. Among these nanocomposite films, the Eb of BaTiO3@SiO2-2/PVDF/PMMA ("2" is the mass fraction of KH550) nanocomposite film reached 500 MV/m, the highest Ucharge was 12.76 J/cm3, and the highest Udischarge was 4.41 J/cm3, which were 227 % and 238 % of the BaTiO3@SiO2-0/PVDF/PMMA nanocomposite film, respectively. In addition, the strategy can effectively reduce the dielectric loss (tans), in which the lowest tans of the nanocomposite films was only 0.047 in BaTiO3@SiO2-6/PVDF/PMMA nanocomposite film, which was 18 % lower compared to BaTiO3@SiO2-0/PVDF/PMMA nanocomposite film. Both experimental results and phase field simulations confirmed that the multistage interface optimization strategy proposed can effectively improve the dielectric and energy storage properties of nanocomposites.

As a ferroelectric polymer with excellent performance, polyvinylidene difluoride (PVDF) has an irreplaceable position in film capacitors. However, the problem of polarization hysteresis needs to be effectively improved. Consequently, linear polymer polymethyl methacrylate (PMMA) was introduced into the PVDF blend, and PMMA could inhibit the polarization behavior of PVDF in the amorphous region, thus weakening the local polarization field and reducing the coherent coupling between ferroelectric domains. In addition, high dielectric constant barium titanate (BaTiO3) nanoparticles were introduced to enhance the depolarization field inside the crystalline phase, and the synergistic effect of PMMA and BaTiO3 improved the polarization hysteresis and dielectric properties of PVDF. Preparation of PVDF/PMMA/BaTiO3 films was undertaken through the utilization of a spin-coating process, and the film thicknesses were uniform without obvious aggregation. The maximum discharge energy density of the 30 wt.% BaTiO3 nanocomposite film was 1.87 J/cm(3), and the dielectric loss (tan delta) can be stabilized at 0.12 and below. At 100 Hz, the E-b and tan delta of the 30 wt.% BaTiO3 nanocomposite film were 1400 kV/cm and 0.12, respectively. The favorable performance of the films has also been displayed by the phase field simulation results.

As dielectric film as the core device of capacitors, how to enhance its dielectric and energy storage performance is crucial for the application of film capacitors. To this end, we propose a solvothermal synthesis of metal-organic framework (MOF) material UiO-66-NH2 to explore the potential application of MOF materials in the field of dielectric energy storage. BaTiO3 nanoparticles and MOF fillers were selected to be introduced into the PVDF/PI matrix, and nanocomposite films were prepared by the spin-coating process, which showed a strong bonding at the micro-interface of the film and a uniform macroscopic thickness without obvious aggregation. The high porosity of UiO-66-NH2 and the high dielectric constant of BaTiO3, as well as the high breakdown strength Eb of the polymer matrix are utilised to synergistically promote the energy density and maintain good charge/ discharge stability. Notably, the BU-X/PVDF/PI nanocomposite films demonstrated good energy storage performance and stable charge/discharge efficiency eta. The results show that the BU-0.5/PVDF/PI nanocomposite film has an Eb of 2190 kV/cm, an energy storage density of 3.73 J/cm3, and stable eta ranging from 60 % to 94 %, which are superior to the pure BaTiO3/PVDF/PI nanocomposite film in terms of overall performance. In addition, the dielectric loss of the BU-0.5/PVDF/PI nanocomposite film is as low as 0.022. These findings indicate the good prospects for the development of MOF materials in the field of energy storage.

In this paper, the carboxylic acid modifier 2,3,4,5-tetrafluorobenzoic acid (F4C) was used to modify the BaTiO3 (BT) nanoparticles, which acted as a coupling agent. The modified BT(F4CBT) nanoparticles, polyvinylidene fluoride (PVDF), and polymethylmethacrylate (PMMA) were used to make the modified nanocomposite films: PVDF/PMMA-F4C-BaTiO3 nanocomposite films. The unmodified BT nanoparticles were used to make the unmodified nanocomposite films: PVDF/PMMA-BaTiO3 nanocomposite films. The modification effect of the F4C resulted in an increase in the amount of beta-phase and gamma-phase, a decrease in the amount of alpha-phase, and a decrease in the overall crystallinity of the PVDF-based nanocomposite films. The dielectric constant of the PVDF/PMMA-F4C-BaTiO3 nanocomposite films reached a maximum value of 16.7 at a frequency of 100 Hz at 4 wt% F4C, which was 40.3% higher than that of the unmodified PVDF/PMMA-BaTiO3 films. The F4C content of 2 wt% PVDF/PMMA-F4C-BaTiO3 nanocomposite films showed the lowest dielectric loss of 0.055, which was 56.7% lower than the unmodified PVDF/PMMA-BaTiO3 films. The breakdown strength of the PVDF/PMMA-F4C-BaTiO3 nanocomposite films increased and then decreased with the increase of the F4C content, and the highest breakdown strength was 2800 kV/cm at 4 wt% F4C, which was 55.6% higher than the unmodified PVDF/PMMA-BaTiO3 films. The charging density of the PVDF/PMMA-F4C-BaTiO3 nanocomposite films reached a maximum value of 20.65 J/cm(3) at 4 wt% F4C content, which was 394% higher than the unmodified PVDF/PMMA-BaTiO3 films.

The damage impact of mechanical shocks on stator bar insulation is a key factor in high-voltage motor accidents. This study conducted electrical aging acceleration and breakdown experiments on damaged stator insulating materials to understand failure causes and evaluation methods. The relationship between sample defect area and depth and electrical properties was analyzed, along with the morphology of the damaged surface using a scanning electron microscope. Results show that the defect area correlates with impact mode but does not directly impact electrical performance. Effective insulation thickness is positively linked to electrical performance. This study serves as a valuable reference for evaluating mechanical impact faults in high-voltage motors.

(1-x) BaTiO3 - x Bi(Mg0.25Zn0.25Ti0.5)O3 (x = 0.00, 0.06, 0.12, 0.20,molar ratio) ceramics were prepared by solid sintering method. The effects of Bi(Mg0.25Zn0.25Ti0.5)O3 (BMZT) doping on microstructure, dielectric, ferroelectric and energy storage properties of BaTiO3 (BTO) were studied. With BMZT addition, the sintering temperature gradually decreases, the grain size reaches a minimum at x = 0.12 and the phase structure changes from tetragonal to cubic. And dielectric properties changed from temperature-dependent to temperature-insensitive. Additionally, higher cubic phase content induced slim polarization and electric field (P-E) loop and low remnant polarization (Pr). Therefore, 0.88 BaTiO3 - 0.12 Bi(Mg0.25Zn0.25Ti0.5)O3 ceramics achieved recoverable energy storage density (Wrec) of 702.7 mJ/cm3 and high energy efficiency of 87.3 % under electric field of 93 kV/ cm. It exhibited optimum properties, including a minimum grain size (0.620 mu m), superior dielectric properties (epsilon r = 1811.3, tans = 0.0552 at 1150 degrees C), a high maximum polarization strength (14.3 mu C/cm2), and the maximum dielectric breakdown strength (93 kV/cm), as identified in the present study. It simultaneously maintains high energy storage density and efficiency over a wide electric field range and large temperature range (room temperature - 90 degrees C). Thus (1-x) BaTiO3 - x Bi(Mg0.25Zn0.25Ti0.5)O3 ceramics are a promising material for energy storage applications.

Ceramic-polymer nanocomposites exhibit good dielectric constant, low dielectric loss and excellent storage capacity for energy. A spin-coating method was used to create 30 vol% BaTiO3 (BT) nanoparticles and polyvinylidene fluoride (PVDF) nanocomposite films with a homogeneous thickness of around 7 mu m. The findings indicated that, with increasing the quenching temperature, the dielectric constant of the nanocomposite films decreased at 100 Hz. The dielectric constant of the BT-PVDF nanocomposite film was 75.4 after quenched in air at 100(degrees)C, which was 21.4% greater than the that of the unquenched film. The breakdown strength of the films increased with increasing quenching temperature and reached the maximum values of 1400 kV/cm and 1600 kV/cm at 160(degrees)C, respectively. The breakdown strength of the film quenched in liquid nitrogen reached a maximum of 1600 kV/cm at 140(degrees)C. With increasing of quenching temperature, the charging density of BT-PVDF nanocomposite film increased first and then decreases, reaching the maximum value of 11.165 J/cm(3) at 140(degrees)C, which was 146% higher than that of the unquenched film. Heat treatment will be an innovative method for improving the dielectric and energy-storage capabilities of ceramic-polymer nanocomposite films.Highlights center dot The uniform thickness of the film prepared by spin-coating was about 7 mu m. center dot The dielectric properties of the composite film after quenching processes were improved.center dot The breakdown voltage and charging density were vastly enhanced after quenching processes.

Conventional waterborne polyurethane (WPU) has poor water resistance and poor overall performance, which limits its application in outdoor coatings. A solution to this problem is urgently needed. The introduction of fluorine-containing groups can effectively improve the water resistance of WPU. In this study, a new fluorinated chain extender (HFBMA-HPA) synthesized by free radical copolymerization and epoxy resin (E-44) were used to co-modify WPU, and five waterborne fluorinated polyurethane (WFPU) emulsions with different fluorine contents were prepared by the self-emulsification method. The effects of HFBMA-HPA content on the emulsion particle properties, coating surface properties, mechanical properties, water resistance, thermal stability, and corrosion resistance were investigated. The results showed that the WFPU coating had excellent thermal stability, corrosion resistance, and mechanical properties. As the content of HFBMA-HPA increased from 0 wt% to 14 wt%, the water resistance of the WFPU coating gradually increased, the water contact angle (WCA) increased from 73° to 98°, the water absorption decreased from 7.847% to 3.062%, and the surface energy decreased from 32.8 mN/m to 22.6 mN/m. The coatings also showed impressive performances in the adhesion and flexibility tests in extreme conditions. This study provides a waterborne fluorinated polyurethane material with excellent comprehensive performance that has potential application value in the field of outdoor waterproof and anticorrosion coatings.

Hyperspectral imaging poses great challenges to traditional camouflage materials, primarily because there is a huge difference between the reflectance spectra of camouflage materials and natural plants in the 1400-2000 nm band. The difficulty of simulating the natural plant spectrum lies in reproducing the absorption peak of water by increasing the water content in a camouflage material. Herein, a mesoporous (MS) material is used to simulate the plant spectrum because such material can absorb and retain a large amount of water. MS was prepared via a two-step method using tetraethyl orthosilicate and tetrabutyl titanate. The characteristics of the as-prepared MS were examined via X-ray diffraction, transmission electron microscopy, ultravioletvisible diffusion reflectance spectroscopy and nitrogen adsorption-desorption isotherms. In addition, a film was prepared using the fully absorbent mesoporous material, and the water content was determined via near-infrared spectroscopy and thermogravimetric analysis. The bonding between the mesoporous material and resin was examined via field emission gun scanning electron microscopy. The mechanical properties of the film were measured by a pendulum hardness tester and a cylindrical bending tester. The results indicate that low-temperature synthesis followed by high-temperature hydrothermal treatment is conducive to expanding the mesopore aperture, reaching a maximum of 23 nm. Moreover, the regular structure of the as-prepared titanium-containing mesoporous material is maintained under high hydrothermal temperature. The mesoporous film exhibits a good water absorption capacity of up to 80% by mass and can effectively simulate the spectrum of plants. The mechanical properties of the film are good, and the hardness of the film is related to the content of mesoporous powder. (c) 2023 Society of Industrial Chemistry.

Eco-friendly waterborne coatings frequently exhibit poor corrosion resistance, high solvent content, and extended curing times, attributed to the excessive employment of hydrophilic groups and petroleum-derived polyols. In this work, aniline trimer (ACAT) and polyethylene glycol (PEG) were used as chain extenders. E-44 epoxy resin was subsequently utilized to modify the system and an aniline trimer-modified waterborne polyurethane (AT-WPU) dispersion was prepared and characterized. The chemical structure of the synthesized ACAT was characterized employing 1H NMR, ESI-MS, and FTIR spectroscopy. The structure and coating performance of the AT-WPU dispersion were investigated utilizing FTIR, particle size analysis, thermogravimetric analysis, DSC, TEM, SEM, and electrochemical corrosion testing. The results demonstrate that the aniline trimer-modified waterborne polyurethane dispersion was successfully synthesized. Additionally, the DSC analysis results and thermogravimetric graphs indicate that the glass transition temperature and thermal stability of the coatings increased with the addition of aniline trimer. As the aniline trimer content increased, the hardness and adhesion of the coatings were significantly enhanced. In the electrochemical corrosion assessment, the corrosion current density of AT-WPU-3 attained 7.245 × 10−9 A·cm−2, and the corrosion rate was as low as 0.08 μm·Y−1, indicating excellent corrosion resistance. The present study provides promising practical applications in the domain of metal material protection.