Silicon nitride powder is a crucial raw material for fabricating silicon nitride ceramics, with its properties exerting a decisive influence on the final product’s performance. This study investigates the influence of polyvinyl alcohol (PVA) and polyacrylic acid (PAA) as binder additives on the characteristics of the resulting ceramics. Silicon nitride powder was treated with varying concentration ratios of PVA and PAA, followed by spray granulation to produce granulated powder. Subsequent hot-pressing sintering was conducted, and the performance of the sintered silicon nitride ceramics was evaluated. The results indicate that the optimal ratio of PVA to PAA is 2 wt.% : 2 wt.%, which yielded superior comprehensive properties, including thermal conductivity, mechanical strength, hardness, and volume resistivity.

The arc contact is the core component of the circuit breaker arc extinguishing chamber, and its performance is one of the key factors affecting the reliability of SF6 circuit breakers. Circuit breakers for AC filter banks must withstand mixed AC and DC voltages and interrupt capacitive loads 3 to 4 times a day during peak demand. The current arc contacts in service cannot meet the performance demands of frequent switching, including inrush currents and wear. To improve the overall performance of arc contacts, this paper utilizes a vacuum infiltration sintering process to prepare graphene-modified copper-tungsten contacts with high electrical conductivity, wear resistance, and arc erosion resistance (designated as CuW70-Gr, CuW75-Gr, CuW80-Gr, and CuW85-Gr for copper-tungsten 70, 75, 80, and 85, respectively). The study investigates the changes in arc erosion and wear resistance behaviors of different CuW-Gr alloy compositions in an SF6 atmosphere. The results show that the excellent electrical and mechanical properties of graphene enhance the electrical conductivity and hardness of each CuW-Gr alloy composition. The addition of graphene, due to its effect on improving the viscosity of molten Cu and dispersing arcs, reduces the mass loss of the contacts and improves arc erosion resistance. The axial dimension change of the CuW80-Gr stationary contact is the smallest, at 2.48mm. Furthermore, the addition of graphene significantly enhances the friction and wear resistance of CuW, and as the W content increases, the material's hardness and strength improve, and the wear amount decreases. This research provides solid technological support for promoting new material productivity, enhancing the intrinsic safety level of the power grid, and facilitating the construction of new types of power systems.

Silicon nitride (Si3N4) ceramics, combining excellent resistivity and high-temperature stability, are widely used in SF6-insulated high-voltage DC electrical equipment. This study attempted to fabricate Si3N4 insulating ceramics with superior dielectric and good mechanical properties using the stepwise pressureless sintering method, Y2O3-Al2O3 as a sintering additive, and four types of raw Si3N4 powders. The latter's characteristics were found to strongly influence both the mechanical and electrical properties of the ceramics. Specifically, powders with higher alpha-phase content, lower oxygen content, and a uniform particle size distribution contribute to obtaining dense ceramics with excellent mechanical properties. Furthermore, powders with a higher alpha-phase content and uniform particle size distribution enhance the volume resistivity of the Si3N4 ceramics, while smaller average particle sizes and lower oxygen content further improve the temperature stability of the ceramic resistivity.

Ultra-High Voltage (UHV) transmission technology, as a key method for global energy transmission, places higher demands on the performance of materials used in core equipment. This paper reviews the new materials employed in UHV equipment, including insulation materials, conductor materials, magnetic materials, and noise reduction materials. It analyzes the main characteristics, current research status, and limitations of each material, with a focus on the progress of domestic substitution for these materials. The aim of this paper is to provide a comprehensive reference for material development and equipment manufacturing, while proposing future directions to address the increasingly stringent service conditions and performance requirements of UHV equipment

The closing resistor is an important component of high-voltage circuit breakers. Its function is to withstand the L-C oscillation in the power grid during line closing, convert electrical energy into thermal energy, and release it to the external environment to achieve the purpose of suppressing closing overvoltage. The ceramic resistors currently used in circuit breakers are mainly resistance sheet products from a British company. The sintering method for preparing resistance sheets is pressureless sintering, but it cannot be ignored that this sintering method has problems such as high sintering temperature, long insulation time, and abnormal grain growth. Considering that hot pressing sintering can produce ceramic products with higher density and better performance, this paper uses hot pressing sintering to prepare carbon ceramic closing resistors, and compares their performance with resistance sheets of the same specification from a British company. The experimental results show that the density of resistance sheets prepared by hot pressing sintering is much higher than that of British company products, and their conductivity is better. Compared to products from British companies, the thermal conductivity has doubled and the bending strength has increased by nearly twice.

High‐entropy perovskite ceramics have become a topic of interest due to their unique properties and compositional versatility. This study pioneers the development of multifunctional high‐entropy perovskite ceramics by incorporating the rare‐earth element samarium (Sm) into the (Bi 0.4 Na 0.2 K 0.2 Ba 0.2 )TiO 3 matrix. The introduction of Sm 3+ increases the configurational entropy and introduces photoluminescence activation centers. Our results show that (Bi 0.4− x Sm x Na 0.2 K 0.2 Ba 0.2 )TiO 3 ceramics with x ≤ 0.12 retain pure perovskite phase and exhibit enhanced dielectric relaxation properties. The presence of Sm 3+ ions disrupts the long‐range ferroelectric order, resulting in lower maximum polarization and remanent polarization. In particular, the ceramic sample with x = 0.08 exhibits exceptional energy storage and photoluminescence properties. It achieves a recoverable energy storage density of 1.64 J cm − 3 and an efficiency ( η ) of 79.2% under a low electric field of 180 kV cm −1 . These properties position the material as a promising candidate for applications in electro‐optical devices.

High-entropy relaxor ferroelectric ceramics have recently attracted considerable attention owing to their versatile applications. Herein, we synthesized 13 lanthanide (Ln)-containing high-entropy perovskite oxides, specifically (Ba0.2Bi0.2K0.2Ln0.2Na0.2)TiO3. Our results demonstrate that only three of the 13 high-entropy compositions, characterized by a larger ionic radius of Ln3+, can be synthesized as pure perovskite phases. Notably, all three high-entropy perovskites exhibited robust dielectric relaxation behavior. Moreover, the temperatures corresponding to the maximum dielectric constants (Tm) consistently increased with increasing atomic number of the Ln elements. Additionally, these three high-entropy perovskites exhibit slim polarization-electric field curves, making them ideal candidates for use in dielectric energy storage.

Piezoelectric ceramics based on lead zirconate titanate are widely used in sensors, actuators, and transducers, but achieving high density and reliable performance for high-power applications remains a major challenge. This study explores optimization of high-power performance through hot-pressing. The combined effect of external pressure and sintering aids reduces the sintering temperature from 1175 °C to 900 °C, minimizing lead volatilization while promoting densification. Sintering in an inert atmosphere generates oxygen vacancies that act as domain-pinning centers, thereby enhancing the stability of piezoelectric properties under high-power conditions. Hot-pressed ceramics reach a maximum vibration velocity of 2.5 m/s, compared with 1.7 m/s for conventionally sintered samples, and the mechanical quality factor remains far more stable at elevated vibration levels. These results provide a practical pathway to improve the durability, efficiency, and reliability of piezoelectric devices in demanding high-power applications.

With increasing concerns about noise pollution, the pursuit of highly dependable piezoelectric acoustic sensors for real-time noise monitoring has come to the forefront of scientific research. Lead-based perovskite piezoelectric films, exemplified by lead zirconate titanate Pb(Zr,Ti)O-3 (PZT), surpass traditional piezoelectric materials such as ZnO and AlN in their piezoelectric properties, promising substantial advancements in next-generation acoustic sensor technologies. However, the toxic nature of lead in PZT materials poses formidable environmental and human health risks. In an unprecedented breakthrough, it presents the pioneering development of an environmentally benign lead-free piezoelectric Micro-Electro-Mechanical System (MEMS) acoustic sensor based on potassium sodium niobate (K,Na)NbO3 (KNN) film. High-quality <001> textured 3 mu m-thick KNN film is successfully integrated into commercially used Si substrate, rendering exceptional piezoelectricity (transverse piezoelectric coefficients e(31)* of approximate to 8.5 C m(-2)) with satisfactory thermal stability. The atomic-scale Z-contrast imaging and piezoresponse force microscopy characterizations reveal that the outstanding piezoresponse originates from the local coexistence of multiple phases and the enhancement of extrinsic piezoelectric contributions from in-plane polarization anisotropy. Finite element simulation is employed to design the triangular cantilever structure and annular diaphragm structure, each corresponding to different operating bandwidths. The resultant MEMS acoustic sensors stand out with outstanding acoustic performance (the high sensitivity and expansive receiving field of view), which are attributed to the microstructural engineering at multi-length scales for the excellent piezoelectric properties of KNN film. These features enable sensitive acoustic monitoring in various environments, including large-scale power grids and urban traffic.

This study investigates the long-term performance of novel aluminium alloy conductors in compression-type connections, aiming to enhance the efficiency and reliability of power cable systems. Through comprehensive experimental analysis, we evaluated the joint resistance and temperature management of these conductors under varied loads and conditions. Our findings indicate that the novel aluminium alloy demonstrates superior resistance stability and temperature control when compared to traditional materials, suggesting a significant potential to improve conductor longevity and energy efficiency. The implications of these promising results extend to the advancement of sustainable energy distribution, highlighting the critical role of innovative materials in the evolution of electrical power systems. This research contributes to the ongoing efforts to develop more efficient, reliable, and sustainable power infrastructure.

Effect of solutionization (two‐step vs one‐step solution treatment) and deformation (one‐step solutionization + deformation vs no deformation) on microstructural evolution and mechanical/electrical properties of an aged Al–Mg–Si alloy with microalloying Er + Sc co‐addition is studied, respectively, in comparison with its counterpart with a single Sc addition at the same total addition content. Experimental results showed that the Er + Sc co‐added Al–Mg–Si alloy displayed a combination of aging hardness and electrical conductivity superior to the single Sc‐added alloy, under either two‐step or one‐step solution treatment. This highlights an effective microalloying way to improve the Al–Mg–Si alloy by partially using cheap Er rather than full addition of expensive Sc. While the introduction of deformation yielded to a higher aging hardness but a lower electrical conductivity in the Er + Sc co‐added alloy apparently than in the single Sc‐added alloy. When comparing among the Er + Sc co‐added alloys, it is found that, although the one‐step solutionization leads to the highest aging hardness (≈102 HV in peak aging) and the deformation introduction results in the highest electrical conductivity (up to 57.3% IACS), the two‐step solutionization brought about the best combination of aging hardness (≈87 HV) and electrical conductivity (up to 56.7% IACS). Microstructural evolution under different treatments is analyzed to rationalize the variation in aging hardness and electrical conductivity especially in the Er + Sc co‐added Al–Mg–Si alloy.

Recently, high-entropy perovskites have attracted considerable attention due to their diverse chemical composition and multifunctionality. In this study, the high-entropy approach was employed in a (Bi0.4Na0.2K0.2Ba0.2)TiO3 matrix, and Nd3+ was introduced to enhance the configurational entropy and modify its dielectric and ferroelectric properties. Notably, despite Nd3+ doping, all samples maintained a tetragonal perovskite structure at room temperature. The configurational entropy increased with the Nd3+ concentration, consequently leading to a gradual decline in the ferroelectric properties along with the associated temperature (T-m) and maximum dielectric constant (epsilon(m)). The P-E loops of the ceramics also became thinner as Pm and Pr decreased, resulting in a slow decrease in the recoverable energy density (Wrec) and a simultaneous increase in the energy storage efficiency (eta). Especially, the energy storage performance reached its peak at an Nd3+ concentration of 12 mol%, exhibiting an energy storage efficiency of 85.8% and a recoverable energy storage density of 0.74 J/cm(3) at a low electric field of 100 kV/cm. These results highlight the potential of this material for dielectric applications in low electric fields and contribute to the advancement of alternative high-entropy energy storage perovskite ceramics.

The effects of homogenization parameters on the microstructure evolution and tensile behavior of a balanced Al-Mg-Si alloy were investigated using the optical microscope, scanning electron microscope, X-ray diffraction, electron probe microanalyzer, differential scanning calorimetry, electrical conductivity test, and tensile test. The results show that Mg2Si and /3-AlFeSi are the main intermetallic compounds in the as-cast structure, and Mg solute microsegregation is predominant inside the dendrite cell. The prediction of the full dissolution time of Mg2Si by a kinetic model is consistent with the experiment. The /3-AlFeSi in the alloy exhibits high thermal stability and mainly undergoes dissolution and coarsening during homogenization at 560 degrees C, and only a small portion is converted to alpha-AlFeSi. The optimal homogenization parameters are determined as 560 degrees C and 360 min, when considering the evolution of microstructure and resource savings. Both the strength and ductility of the alloy increased after homogenization.

Power cable plays a very important role in power transmission and is an important part of the national economy. The demand for power cables continues to increase with the rapid development of the economy. ‘Replacing copper with aluminum’ is an effective means to save copper resources and can save costs. However, aluminum has the disadvantages of low melting point, softness and poor mechanical strength, which makes the reliability of aluminum core cable low and prone to failure. Therefore, it is necessary to improve the comprehensive performance of aluminum alloy cables to ensure their reliability and safety. In this paper, two different kinds of rare earth elements are added to Al-Fe-Cu alloy, and the results are as follows. After rolling and drawing, the dispersed phase of rare earth microalloyed Al-Fe-Cu alloy ingot still shows a streamline in the same direction as rolling and drawing under scanning electron microscope. The mixed addition of rare earth elements La and Ce can form a fine phase, and the rare earth elements in the dispersion phase will be redistributed. The rare earth element Sc will enter the Al-Fe-Cu ternary phase during solidification.The strength of rare earth element Al-Fe-Cu alloy wire with a total mass fraction of 0.1 is about 160 MPa, and the microhardness exceeds 50 HV. The conductivity of Al-Fe-Cu-La-Ce alloy wire is 59.21

Copper wires are the state-of-the-art materials which are widely used in almost every electric and electronic related field in civil lives or industry. One of the most active research topics consists of compounding carbon-based materials with copper, due to their performance advantage in density, electrical and mechanical properties. In this paper, graphene reinforced copper samples have been prepared in two different methods, namely metallurgy method and Chemical Vapour Deposition (CVD) method. Electrical conductivity measurements were performed on samples prepared via both methods. Technologies such as SEM was adopted in our analysis to Figure out the mechanism causes this difference from a microscope point of view. Analysis results indicate that, with properly controlled preparing parameters, graphene reinforced copper composite can achieve a distinctive improvement in terms of electrical conductivity over traditional copper material.

In this study, two existing fire stopping systems of the valve hall in the converter station were selected, and the heat transfer process in the key areas was simulated by the ANSYS software under the condition of a hydrocarbon temperature rise curve. The main thermal parameters, such as temperature field, thermal flux, and thermal gradient, were obtained, and the temperature rise characteristics of measuring points were tested through the Fire Test Furnace and the one-dimensional heat conduction model. The simulation results show that Model 2 exhibits superior thermal resistance performance compared to Model 1, and the maximum heat flux density occurs at the square steel (keel) position. During the fire resistance test, it is observed that the fireproof mortar at the connection of Autoclaved Lightweight Concrete board in Model 1 exhibits significant detachment and cracking, accompanied by the emission of white smoke. Compared with the temperature rise of the measuring points in Model 1 and Model 2, the heating rate of measuring points f1 and f2 is 0.0471 °C/s and 0.0159 °C/s, respectively. The temperature value obtained from the fire resistance test exceeds that calculated by the one-dimensional heat conduction model.

In this work, microstructures of two kinds of heatproof grain-oriented silicon steel were investigated by OM and EBSD technique, and the change evolution of microstructure and heatproof mechanism under different annealing temperatures were studied. The results show that small grains and ‘gap’ were formed in the strip surface by toothed roll groove method, and ‘V’ shaped groove was formed in the strip surface by laser irradiation method. The heatproof temperature of laser irradiation grain-oriented silicon steel was about 850 ℃, and the heatproof temperature of toothed roll groove grain-oriented silicon steel was about 800 ℃. The former has better heatroof. With annealing temperatures increased, the iron loss of two strips increased gradually. For toothed roll groove grain-oriented silicon steel, it’s mainly due to the decrease of misorientation difference between the notch area and the Goss grains on both sides, while for laser irradiation grain-oriented silicon steel may be related to the change of Goss orientation near the groove.

In this experiment, copper was coated on the surface of graphite by chemical process. Besides, the microstructure and crystal structure of copper-coated graphite were characterized by SEM and XRD. Copper-plated C/Cu composite was prepared by SPS sintering technique of powder mixture by two-step method. In order to test the dispersion state of graphite in the composites and the phenomenon of interfacial dispersion, the effect of graphite content on the properties of copper-coated C/Cu composites was also an important point. Therefore, the microscopic characterization and performance test were carried out. The results show that magnetic stirring and high-energy ball milling ensure the uniformity of copper-coated graphite in copper matrix, and conducted structural grain refining. The grain size of copper, and the properties of composite materials decreased with the increase of graphite content, such as relative density, conductivity and hardness. However, the further increase of graphite content leads to excessive grain size, the relatively long time of ball milling makes the fine grain become larger after sintering. When the graphite content is 1.0wt.%, the relative density, conductivity and hardness are 99.91%, 92.1%IACS and 67.7 HV, respectively. It is proved that copper-coated graphite and two-step powder mixing play an important role on improving the properties of the composites.

Owing to the overwhelming salt mist, high humidity and high temperature caused by the costal climate in Fujian, the abrasion and erosion issues on the surface of outdoors isolation switch contacts have raised serious concerns, which causes the heating problems of the contacts, and subsequently leads to the hidden risks of the power grid’s daily operating. It has been revealed that the various properties of silver-based composite coating could be enhanced after doping with additive phase graphene. Utilizing potassium iodide as complexant for silver-electrode position, a silver-graphene composite coating with excellent general performance was successfully synthesized via complex electrode position techniques in cyanide-free KI system. Moreover, the affecting patterns of working current density and graphene addition for properties such as binding strength of coating, contact resistance, abrasion resistance, erosion resistance, and surficial morphology.When the graphene addition stands for 1.5 g/L, and the current density shows around 0.4 A/dm2, the graphene will deposit into the composite coating, leading to the most magnificent performance of silver-graphene composite coating, which possesses valuable properties such as the excellent combination with matrix, compact surficial structure, well-performed contact resistance, abrasion resistance and erosion resistance, etc., as proved by the research.