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Compared with minimum quantity lubrication, electrostatic spraying can greatly improve machining and environmental performances. However, the cooling and lubricating performance of electrostatic spraying needs to be further improved. In this paper, the composite electrostatic spray cutting approach is proposed, and the environment-friendly machining of titanium alloy by using this approach is investigated. An atomization test device for composite electrostatic spray cutting and a composite electrostatic spray milling system are developed. The atomization tests for composite electrostatic spray cutting are performed to study its atomization morphology and to determine the atomization parameters that guarantee a stable composite electrostatic spraying. The atomization current is measured by using a picoammeter under stable composite electrostatic spraying conditions, and the charging performance and atomizing stability of composite electrostatic spraying are evaluated. Milling experiments of titanium alloy and ambient oil mist concentration tests are also carried out under electrostatic and composite electrostatic spraying conditions. The effects of composite electrostatic spraying on milling force, tool wear, chip morphology, and oil mist concentration are analyzed. Results show that compared with electrostatic spraying, composite electrostatic spraying can effectively reduce tool wear and oil mist concentration. Under composite electrostatic spraying condition, an increase in the flow rates of internal and external fluids can further reduce tool wear. An increase in the flow rate of internal fluid does not affect ambient oil mist concentration. But an increase in the flow rate of external fluid significantly increases ambient oil mist concentration.

Electrostatic spraying technology can improve the efficiency of pesticide deposition on the surface of leaves and reduce the environmental pollution caused by pesticide drift, which has an important prospect in agricultural pesticide application. To improve the deposition and penetration of droplets in the crop canopy, we designed and optimized an air-assisted electrostatic nozzle and conducted the spraying performance experiment. Parameters, such as charge-to-mass ratio (CMR) and particle size, were tested and analyzed to obtain the suitable operating parameters of nozzle. The results proved that the improved air-assisted electrostatic nozzle has good atomization and chargeability. There is a good charging effect with a charging voltage of 3,000–5,000 V, the CMR increased 127.8% from 0.86 to 1.97 mC/kg as the charge voltage increases from 1,000 to 4,000 V, at an air pressure of 1.0 bar and liquid flow rate of 200 ml/min. Furthermore, we designed a multi-factor orthogonal experiment, which was conducted using a four-factor, three-level design to investigate the effects of operational parameters and canopy characteristics on droplet deposition and penetration. Analysis of variance (ANOVA) and F-test were performed on the experiment results. The results showed that the factor effect on droplet penetration, in descending order, was as follows: spray distance, leaf area index, air pressure, and air pressure × spray distance. The factor effect on abaxial leaf deposition, in descending order, was as follows: air pressure, spray distance, air pressure × charge voltage, spray distance × charge voltage, and charge voltage. For optimal droplet penetration and abaxial leaf deposition, option A 3 B 1 D 2 (air pressure 1.5 bar, spray distance 0.2 m, charge voltage 2,500 V) is recommend. The spray nozzle atomization performance and deposition regulation were studied by experimental methods to determine the optimal values of operating parameters to provide a reference for electrostatic spray system development.

Al/NH4CoF3-Φ (Φ = 0.5, 1.0, 1.5, 2.0, and 3.0) binary composites and Al-NH4CoF3@P(VDF-HFP) ternary composites are fabricated via ultrasonication-assisted blending and electrostatic spraying. The effect of equivalence ratio (Φ) on the reaction properties is systematically investigated in the binary Al/NH4CoF3 system. For ternary systems, electrostatic spraying allows both components to be efficiently encapsulated by P(VDF-HFP) and to achieve structural stabilization and enhanced reactivity through synergistic interfacial interactions. Morphological analysis using SEM/TEM revealed that P(VDF-HFP) formed a protective layer on Al and NH4CoF3 particles, improving dispersion, hydrophobicity (water contact angle increased by 80.5% compared to physically mixed composites), and corrosion resistance. Thermal decomposition of NH4CoF3 occurred at 265 °C, releasing NH3 and HF, which triggered exothermic reactions with Al. The ternary composites exhibited a narrowed main reaction temperature range and concentrated heat release, attributed to improved interfacial contact and polymer decomposition. Combustion tests demonstrated that Al-NH4CoF3@P(VDF-HFP) achieved self-sustaining combustion. In addition, a simple validation was done by replacing the Al component in the aluminium-containing propellant, demonstrating its potential application in the propellant field. This work establishes a novel strategy for designing stable, high-energy composites with potential applications in advanced propulsion systems. [Display omitted] •Effective encapsulation by electrostatic spray using P(VDF-HFP).•Corrosion-resistant encapsulation layer provides composites aging resistance.•Functional gases activate Al and increase the gas production capacity of the system.•Two fluorides enhance the combustion performance of composites.•Potential applications for high reactivity and high gas production.

In order to solve the problems of low effective oxygen content, low density and high mechanical sensibility of ammonium perchlorate (AP) for propellant, potassium perchlorate (KP), which has a higher density and greater effective oxygen content, was introduced. An AP/KP composite oxidizer was prepared using electrostatic spraying. The morphology, structure, thermal properties, safety, and combustion performance of the samples were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and a quadruple coupling technique (TG-DSC-FTIR-MS). Comparative studies were performed with raw materials and physically mixed samples. The results indicate that the crystal structures of AP and KP remained unchanged in the composite oxidizers prepared using different methods. The electrostatic spray samples exhibited significantly improved safety compared to raw AP and physically mixed samples, with friction sensitivity reduced by 36% and 16%, respectively. Thermal analysis revealed that the electrostatic spray samples significantly enhanced the high-temperature decomposition of AP and KP, with decomposition peaks reduced by 49.15 °C and 9.67 °C, respectively. Additionally, the electrostatic spray method significantly reduced the activation energy of KP’s thermal decomposition from 448.32 to 440.62 kJ·mol − 1 to 222.80–226.11 kJ·mol − 1 . Compared to raw and physically mixed samples, the electrostatic spraying method reduced the ignition delay time of the composite oxidizer, increased the aluminum powder combustion rate, and enabled complete combustion of the Al powder. The electrostatic spraying method, with its adjustable process parameters and controllable sample morphology, enhances the overall performance of the composite oxidizer.

The trans-disciplinary aspects of the embryonic field of electrostatic spraying have provided a major motivation to researchers for the development of novel techniques for spraying of protective coatings to perishable food commodities for enhanced shelf-life, protective agents for health and hygiene in addition to other applications of sprays to manufacturing, transportation, agriculture, environment, medical facilities and devices. It has become the motives behind the renewed curiosity in the usage of the electrostatics in liquid based sprays. This provides an efficient and uniform transportation of liquid based agents which avoids the wastage of natural resource with enhanced performance. Edible coatings and incorporation of nutrition and active ingredients may improve fruit quality providing foodstuffs supplemented with extra flavour and a delicious, tantalizing and mouth-watering appearance. Electrostatic spray technology for coating of antioxidants and edible films for food products and fruits preservation is a sustainable development strategy in this revolutionary technology era that has gained a lot of attention owing to its importance in enhancing the shelf life of foods keeping its nutritional and sensory properties. Electrostatic disinfection and sanitization has gained a lot of attention and people became more alert about health and hygiene during the COVID-19 pandemic. Although few research initiatives have been taken over the past years, the work largely remains in the nascent stage as far as field-scale technology development and commercialization is concerned. These technological and life sustaining technologies will overall lead to improvement in the quality of life. A significant value of the charge-to-mass ratio (Q/M) of 4.83 mC/kg was achieved at applied air pressure of 4 bar and liquid flow rate of 130 ml/min at a target distance of 10 cm from the nozzle tip.

In order to improve the deposition and uniformity of the pesticide sprayed by the agricultural spraying drone, this study designed a novel spraying system, combining air-assisted spraying system with electrostatic technology. First, an air-assisted electrostatic centrifugal spray system was designed for agricultural spraying drones, including a shell, a diversion shell, and an electrostatic ring. Then, experiments were conducted to optimize the setting of the main parameters that affect the charge-to-mass ratio, and outdoor spraying experiments were carried out on the spraying effect of the air-assisted electrostatic centrifugal spray system. The results showed the optimum parameters were that the centrifugal rotation speed was 10 000 r/min, the spray pressure was 0.3 MPa, the fan rotation speed was 14 000 r/min, and the electrostatic generator voltage was 9 kV; The optimum charge-to-mass ratio of the spray system was 2.59 mC/kg. The average deposition density of droplets on the collecting platform was 366.1 particles/cm2 on the upper layer, 345.1 particles/cm2 on the middle layer, and 322.5 particles/cm2 on the lower layer. Compared to the results of uncharged droplets on the upper, middle, and lower layers, the average deposition density was increased by 34.9%, 30.4%, and 30.2%, respectively, and the uniformity of the distribution of the droplets at different collection points was better.

Electrostatic technology has emerged as a crucial tool for sustainable agricultural development due to its multifunctional characteristics. However, systematic and specialized investigations into its mechanism of action and application principles across diverse agricultural scenarios remain insufficient. Here, this review innovatively constructs a spatial scale classification framework and categorizes it into macroscale spray engineering and microscale plant biostimulation. At the macroscale, electrostatic spraying leverages charged droplets’ properties (high surface charge density, strong electrostatic interaction, enhanced adsorption) to improve canopy deposition efficiency and reduce agrochemical drift losses. At the microscale, electrostatic fields induce electron/ion directional movement, providing non-contact stimulation to regulate plant physiological processes such as seed germination and nutrient uptake. We systematically summarize the latest research progress in electrostatic spraying and electrostatic biostimulation, and further compare them in terms of their fundamental mechanisms, targets, and stages of technological development. Finally, the current limitations and challenges for each technology are overviewed and the forward perspective for the efficient application of electrostatics in agriculture are outlined. This review provides theoretical references and technical guidelines for the application research of electrostatic spraying and electrostatic biostimulation, holding significant importance for promoting the standardized development of electrostatic technology in sustainable and precision agriculture.

Electrostatic spraying application is adopted in crop protection to prevent pest infestation, to improve product quality and to maximize yield. It involves a superposition of charges to pesticide spray droplets to attract substrate ions at obscured surfaces. The droplets wraparound effect reduces off-target deposition, enhances on-target spray and invariably improves spray efficiency. Electrostatic spraying system works effectively at optimum parameters in combination with charging voltages, application pressures, spraying height regimes, flow rate, travel speed, electrode material, and nozzle orientation. Many combinations of the system parameter settings have been systematically used by researchers for the electrostatic application, but there are unknown specific optimum parameters combinations for pesticide spraying. Since droplets chargeability influences the effectiveness of electrostatic spraying system, the parameters that produce ideal charge to mass ratio determine the functionality of the spraying deposition, retention and surface coverage. This article, therefore, analyses electrostatic system parameters that produce suitably charged droplets characteristics for effective impacting behavior of pesticides on substrates. Increasing applied voltages consequently maximizes charge-mass ratio to optimum and starts declining upon further increase in voltages beyond a critical point. This review further proposes the selection of an optimum electrostatic parameters combination that yields optimum droplets chargeability in pesticide application. Also, it is necessary to investigate the charge property of substrates prior to pesticide application in order to superpose the right opposite charge on spray droplets at rupture time during electrostatic spraying system.

Facile and ecofriendly loading of micro/nano function-specific substances to create functional materials is a trend being pursued by researchers. However, current micro/nano particles loading approaches are often hindered by issues such as uneven distribution, unsatisfactory stability and complicate procedure. In this work, we present an aqueous phase reshaping method that only utilizes the moisture to fabricate the “bubble particles”, which could perfectly cater to the topography of the substrate. The green preparation of bubble particles adopts an absolutely zero-pollution method, realizing the firm loading of particles on the substrate. Integrating the preparation and loading of particles overcomes the traditional complicate process, while the aqueous phase reshaping ensures uniform and firm loading of the “bubble particles” onto the substrate. Our mechanism demonstrates a significant enhancement in the interface relation after aqueous phase reshaping, with a 121-fold increase in contact surface area achieved by reducing the height by 1 µm. Furthermore, we explore for the first time the influence of the nature of the receiving substrate on the interface morphology of particles during electrostatic spraying, which has important guiding significance for the interface relationship of electrostatic spraying and even electrostatic spinning materials. We also screen out the natural antibacterial essential oil linalool as the effective specialized antibacterial agent, which can specifically inhibit the odor-producing Proteus in urine, with an antibacterial rate of up to 100%. Taken together, this simple, ecofriendly method for fabricating functional materials with optimal interface stability appears highly promising for use in various products formed by electrostatic spraying/spinning.

Stem cells cultured in cell aggregates exhibit higher cell survival rates and enhanced anti-inflammatory and angiogenic effects compared to single cells, constructing a stable and economical cell aggregate culture system that can accurately adjust the mass transfer distance of nutrients, which contributes to improving the therapeutic effects of stem cell aggregates. In this study, an alginate hydrogel microsphere culture system (Alg-HM) was prepared using electrostatic spraying technology and refined by optimizing the electrostatic spraying technology parameters, such as the sodium alginate concentration, voltage, electrospray injection speed, and nozzle inner diameter. Furthermore, by setting the Tip-dropped culture system (Tip-D culture system, created by dropping the resuspended hMSC aggregate–hydrogel solution with a tip to form the hydrogel microsphere) and Matrigel culture system (created by dropping the resuspended hMSC aggregates–Matrigel solution with a tip to form the Matrigel culture system) as the control group and Alg-HM as the experimental group, the culture effect of hMSC aggregates in the optimized Alg-HM culture system was tested; CCK-8 detection and Ki-67 immunofluorescence staining showed that the Alg-HM culture system significantly enhanced the cell proliferation activity of hMSC aggregates after 7 and 14 days of culture. The Calcein-AM/PI cell staining results showed that the Alg-HM culture system can significantly reduce the central necrosis of hMSC aggregates. The RNA sequencing results showed that the Alg-HM culture system can significantly activate the signaling pathways related to cell proliferation in hMSCs. This culture system is helpful for the culture of cell aggregates in vitro and efficient transplantation in vivo.