This study investigates how UV-induced surface oxidation of PEEK coatings influences the capillary-driven penetration of liquid, uncured epoxy resin in rectangular capillaries formed by PEEK-coated hairpin wires, as well as the dielectric breakdown strength measured under a modified test configuration. UV irradiation was applied at various intensities and exposure times, and the resulting changes in surface chemistry were characterized by FTIR, Raman spectroscopy and XPS, while AFM was used to visualize nanoscale topographical variations. Resin penetration behavior was evaluated at 40, 60 and 80 degrees C. Dielectric breakdown strength was assessed using a setup based on the voltage-ramp prescriptions of IEC 60851-5 but employing a modified ground-electrode configuration (water medium) rather than full standard compliance. UV irradiation induced the formation of carbonyl and carboxyl/carboxylate groups, which correlated with a reduction in resin penetration time of up to similar to 30%. Nanoscale surface features disappeared after UV exposure, although roughness parameters did not show a consistent trend due to substrate waviness. Breakdown strength decreased already at the lowest UV irradiation specific energy indicating a threshold-like behavior with no significant changes at higher exposures. As the tests were performed in tap water, the measured dielectric values may reflect the combined influence of surface oxidation and the ionic test environment. Overall, UV-induced oxidation enhances resin penetration but is associated with a reduction in dielectric breakdown strength under the present test conditions, highlighting a non-linear trade-off between impregnation efficiency and electrical robustness.

Steel is a critical material in many industrial applications, particularly in the petroleum sector, where components are often exposed to water-containing crude oil. The presence of water in crude oil can accelerate corrosion processes that compromise extraction, transportation, and export operations, resulting in increased maintenance costs, operational downtime, and negative environmental impacts. Wettability, defined as the tendency of a liquid to spread on or adhere to a solid surface, provides essential insight into the interaction between liquid phases and metallic surfaces such as pipe steel, and can influence corrosion behaviour and adhesion characteristics. Contact angles are commonly used to quantify wettability, and are affected by both the properties of the liquid and the composition of the solid materials.This study reviews previous research and analyses experimental results to evaluate the influence of oil and water wettability on the surfaces of four steel pipe materials. The experimental investigation involved the measurement of contact angles of glycerin oil, hydraulic oil, petroleum, and a hydraulic oil/petroleum mixtures on four steel surfaces (1.4050 steel, 1.4301 steel, C60, and 42CrMo4) using KSV software to record dynamic changes in contact angle over a period of 5 minutes for each sample. The main observations were that the wettability of hydraulic oil and petroleum was better than that of glycerin oil and water measured on all types of steel surfaces. Moreover, the wettability of petroleum and hydraulic oil increased while water and glycerin oil decreased when the Cr content of the steel increased (for example, when Cr content was 18wt.%, Θ petroleum = 8°, but Θ water = 76° ).

Oil–water separation is of enormous importance because it has practical implications for addressing corrosion problems in the oil industry, arising from direct contact between the inner surfaces of pipelines and water containing oil. Therefore, the development of functional materials for handling oil–water mixtures is crucial and has significant economic benefits in the future. Using metal meshes remains a complex process because the properties of the extracted oil mixture (emulsion) vary across fields, which can affect the efficiency of the separation process and the required mesh size for optimal results. Still, it is considered a promising approach for separation. In this study, stainless steel meshes of various mesh sizes (180, 200, 300, 400, and 500 meshes) were coated with a 0.1-micron-thick layer of nickel by physical vapour deposition (PVD). The separation efficiency of stainless steel meshes, both with and without Ni coating, was examined at room temperature using an emulsion (50% vol. petroleum and 50% vol. water) prepared in the laboratory. The Ni-coated meshes achieved high separation efficiencies of 97% and 92% for mesh sizes 400 and 300, respectively. An 8% increase in the separation efficiency of the 200 mesh size resulted in about 80% efficiency with a Ni coating. Hence, it can be concluded that the prepared meshes have potential for high-efficiency oil–water separation, which may help reduce water transport to subsequent processing stages and mitigate corrosion-related issues.

Electroless nickel–phosphorus (Ni–P) coatings were deposited on steel substrates for 20, 40, and 60 min to examine the effect of deposition time on their pseudocapacitive behavior in an alkaline electrolyte. The coatings were characterized by scanning electron microscopy (SEM/EDS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). Although coating mass, thickness, and roughness increased monotonically with deposition time, the electrochemical response showed a pronounced maximum at 40 min. The 40 min coating exhibited the highest areal capacitance in both CV and GCD measurements, reaching 33.1 ± 1.8 mF cm−2 at 10 mV s−1 and 426.5 ± 9.8 mF cm−2 at 5 mA cm−2, whereas the 60 min coating showed substantially lower capacitance. SEM and AFM confirmed progressive nodular coarsening and increasing surface roughness with time, but these geometric parameters alone did not explain the non-monotonic capacitance trend. In contrast, XPS revealed that the 40 min coating possessed the highest surface Ni content, while prolonged deposition led to a more P-enriched outermost surface. EIS further showed that the 40 min coating had the most favorable local high-frequency interfacial response, whereas the 60 min coating exhibited the highest local polarization. The results demonstrate that the electrochemical performance of electroless Ni–P coatings is more closely associated with the composition and accessibility of the activated near-surface region than with coating thickness or roughness alone, and that 40 min represents an interfacial optimum under the applied deposition conditions.

The growing demand for flexible and wearable energy storage systems calls for sustainable and mechanically robust substrates that overcome the limitations of conventional rigid and nonbiocompatible materials. Here, we present a binder-free and flexible supercapacitor fabricated on mulberry paper, integrating electrostatically engineered carbon nanotubes (CNTs) and covalently cross-linked poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). CNTs modified with a cationic surfactant, cetyltrimethylammonium bromide (CTAB), uniformly adhere to the hydroxyl-rich fibers via electrostatic interactions, enhancing interfacial stability and minimizing resistance. PEDOT:PSS is cross-linked using divinyl sulfone (DVS), simultaneously improving electrical conductivity and aqueous stability. The resulting device exhibits an areal capacitance of 30.4 mF cm(-2) at 50 mV s(-1) and maintains 95.9% of its capacitance over 80,000 cycles at 4.0 mA cm(-2). This study provides a scalable and low-cost platform for high-performance, durable, and flexible energy storage, highlighting a novel interfacial engineering strategy for natural fiber substrates.

Liquid metals (LMs), with their unique combination of high electrical conductivity and mechanical deformability, have emerged as promising materials for stretchable electronics and biointerfaces. However, the practical application of bulk LMs in wearable sensors has been hindered by processing challenges and low stability. To overcome these limitations, liquid metal particles (LMPs) encapsulated by native oxide shells have gained attention as versatile and stable fillers for stretchable and conductive composites. Recent advances have focused on the development of LM-based hybrid composites that combine LMPs with metal, carbon, or polymeric fillers. These systems offer enhanced electrical and mechanical properties and can form conductive networks without the need for additional sintering processes. They also impart composites with multiple functions such as self-healing, electromagnetic interference shielding, and recyclability. Hence, the present review summarizes the fabrication methods and functional properties of LM-based composites, with a particular focus on their applications in wearable sensing. In addition, recent developments in the use of LM composites for physical motion monitoring (e.g., strain and pressure sensing) and electrophysiological signal recording (e.g., EMG and ECG) are presented, and the key challenges and opportunities for next-generation wearable platforms are discussed.

Herein, the impregnation dynamics of the space between rectangular, polymer‐coated copper hairpins in electric motors, using polyester‐based and epoxy‐based liquid resins, are described both experimentally and theoretically. The rectangular capillary is formed along its sides by two copper hairpins coated with a polymer, with paper along its bottom and air along its top. The following properties of the two test liquid resins are measured from 25 to 80 °C: their contact angles on the hairpin and on the paper, their dynamic viscosities, densities, and surface tension. Dynamic viscosity is modeled by the Vogel–Fulcher–Tammann model, while surface tension is modeled by the Eötvös model, used also to estimate the molar masses of the resins. Penetration times of the test liquids are measured into the capillaries for ten penetration lengths. A model is derived for the penetration length as a function of time for a liquid penetrating into horizontal, rectangular, and thin capillaries. The resulting model is similar to that of the Lucas–Washburn but the geometrical parameters differ. The temperature dependence of the penetration rate is modeled by the extended Vogel–Fulcher–Tamman model.

In our study, supercapacitor electrodes were prepared by depositing electroless Ni-B coating on copper plates, followed by nitric acid etching. The composition and the micro- and phase structure of the coatings were investigated by ICP-OES, PFIB-SEM, and XRD techniques. The original pebble-like structure of the coating consists of 0.8–10 µm particles, with an X-ray amorphous phase structure. The surface morphology and porosity of the coating can be tuned simply by changing the etching time. The supercapacitive performance of the electrodes was evaluated by means of cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy measurements. The capacitance of the coating was found to vary on the etching time according to a maximum function, allowing for the determination of an optimal duration to obtain a specific capacitance of 157 mF/cm2 (at 0.5 A/g). An excellent charge storage retention of 178% was found after 5000 CV cycles at a scan rate of 50 mV/s owing to the evolved electrochemically active network on the surface of the electrode, indicating a long-term stable and reliable electrode.

The wettability of metal surfaces by different oils and water is a multifaceted phenomenon with significant implications for industrial processes, including lubrication, corrosion protection, and fluid transport; an understanding of the process is essential for optimizing the performance and durability of metallic components. The intermolecular interactions between oil molecules and the metal surface primarily influence the wetting of a metal surface by different types of oil. This paper introduces the concept of oil wetting on metal surfaces, exploring the factors influencing wetting behavior, the characterization techniques employed to assess wetting properties, and the implications for different industrial processes. This work aims to ascertain the contact angle of oil on various metal surfaces and subsequently establish a relationship between this contact angle and the attributes of the substrate. This is achieved through using the sessile drop technique. The results indicate that the wettability of petroleum was better than the hydraulic oil we used on all types of substrates (for example, on Ag surface, Θ-petroleum = 11°, but Θ-hydraulic oil = 20°). Also, we observed that the cosine of the oil/metal contact angle increases with the increase in the atomic radius of the pure metal substrate, and Becker’s broken bond model proved this linear relation. We then contrast this behavior with the wetting characteristics of water and glycerin on the same metals using the same conditions.

To date, batteries are the most widely used energy storage devices, fulfilling the requirements of different industrial and consumer applications. However, the efficient use of renewable energy sources and the emergence of wearable electronics has created the need for new requirements such as high-speed energy delivery, faster charge–discharge speeds, longer lifetimes, and reusability. This leads to the need for supercapacitors, which can be a good complement to batteries. However, one of their drawbacks is their lower energy storage capability, which has triggered worldwide research efforts to increase their energy density. With the introduction of novel nanostructured materials, hierarchical pore structures, hybrid devices combining these materials, and unconventional electrolytes, significant developments have been reported in the literature. This paper reviews the short history of the evolution of supercapacitors and the fundamental aspects of supercapacitors, positioning them among other energy-storage systems. The main electrochemical measurement methods used to characterize their energy storage features are discussed with a focus on their specific characteristics and limitations. High importance is given to the integral components of the supercapacitor cell, particularly to the electrode materials and the different types of electrolytes that determine the performance of the supercapacitor device (e.g., storage capability, power output, cycling stability). Current directions in the development of electrode materials, including carbonaceous forms, transition metal-based compounds, conducting polymers, and novel materials are discussed. The synergy between the electrode material and the current collector is a key factor, as well as the fine-tuning of the electrode material and electrolyte.

With the increasing demand for flexible energy-storage systems, mulberry paper has emerged as a suitable flexible substrate because its mechanical strength and chemical stability surpass that of A4 commercial printing papers. Mulberry paper can withstand deformation because of its high holocellulose content and low lignin content. Moreover, it is hydrophilic, which is advantageous for a simple dip-coating process. Herein, we propose a hybrid nanocomposite-coated mulberry paper, synthesized by dip-coating, as an electrode for flexible energy-storage devices. The electrode was successively coated with silver nanowires (AgNWs), carbon nanotubes, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate. The synergetic effect of the electric double-layer and pseudocapacitive materials as well as AgNWs, is to act as a current collector and increases conductivity, resulting in a gravimetric energy density of 14.64 W h kg −1 and gravimetric power density of 2.69 kW kg −1 at a current density of 1 A g −1 . This paper focuses on the fabrication of mulberry-paper-based electrodes with hybrid nanocomposite coatings and presents the electrochemical performance of the as-fabricated electrodes. These electrodes can be used in eco-friendly energy-storage devices because of the superiority of mulberry paper over commercial printing paper.

The surface roughness of the machined parts is the most important parameter to predict the performance of mechanical components. Moreover, predicting the optimal machining parameters conditions is the preferable method for cost reduction and achieving the desired surface quality of the product. This study investigates three cutting parameters, such as depth of cut, spindle speed, and feed for the milling aluminium alloy AA6061, to predict the surface roughness quality. The experimental work utilized a manual milling machine with a coated carbide cutter. Furthermore, the experiments were arranged using the Taguchi L9 orthogonal array (OA) method. The average surface roughness (Ra) was measured and converted to signal-to-noise (S/N) ratio and then analyzed in the statistical method of analysis of variance (ANOVA). Finally, the optimal combination set speed, feed, and depth of cut was 2400 rpm, 30 mm/min, and 0.5 mm, respectively. Also, according to the ANOVA test, the most influential parameter was the spindle speed among the selected parameters, with the highest P value of (66.42%). In comparison, the lowest P value is a depth of cut (5.34%). Furthermore, spindle speed was the only significant factor statistically. By selecting a high spindle speed (2400 rpm), surface quality was enhanced, but the preferable level was low for depth of cut and feed.

Amorphous electroless Ni-B coatings were deposited on steel substrates with different surface morphologies and B contents (6.5–8.64 wt.%) that could be changed by altering the temperature and the composition of the baths. The supercapacitive behavior of the coatings was evaluated by cyclic voltammetry and galvanostatic charge–discharge measurements, and it was found that Ni-B coatings had higher capacitance than pure electroless Ni or the bulk Ni plate. A close relationship was identified between the microstructure, the B content, and the capacitive behavior of the coatings. The presence of the B alloying element had the most significant effect in determining the capacitance, while the surface area and particle size also contributed to its increase. A surface-specific capacity of 31 mF/cm2 was achieved by the coating containing the highest B content and largest AFM surface area. Furthermore, it was revealed that the particle size of the deposits was determined by the combined effect of the bath temperature and the B content under the applied experimental conditions. The obtained results indicate that Ni-B coatings are promising candidates for supercapacitive applications.

Experiments were carried out to investigate the wetting behaviour of liquid tin on two different steel substrates EN1.4301 stainless steel and 42CrMo4 low-alloyed steel. The experiments were carried out in a vacuum furnace at residual pressure (10 −8 bar) with the temperature raised till 1233 K (960 °C). The transition of the liquid tin droplet from a non-wetting to a wetting state was achieved on the surface of both steels after the spontaneous oxide removal. The transition temperatures in the Sn/EN1.4301 and Sn/42CrMo4 systems were nearly identical, 1140 K and 1130 K, respectively. SEM images showed the formation of the Fe–Sn intermetallic compounds at the Sn/steel interfaces above the transition temperature. Tin penetration into the grain boundaries of EN1.4301 and 42CrMo4 steels was also observed. Graphical abstract

Herein, we systematically demonstrate the synergistic behavior of GNP/CNT composite as an electrode material. Uniform dispersion of CNTs effectively inhibits the restacking of GNP sheets, resulting in enhanced specific surface area, porosity, and conductivity. Moreover, CNT intercalation provides a porous and interconnected network for electrolyte ion transportation. As a result, GNP composite having 1.0 wt% multi-walled carbon nanotube (MWCNTs) shows specific capacitance up to 143 Fg � 1 at 5 mVs � 1, an improvement of 150% compared to pristine GNPs. The improved electrochemical performance implies that the proposed composite electrode is a promising candidate for supercapacitor application.

Research on stretchable materials has gained momentum with the increasing commercialization of wearable and flexible devices. Among the materials used in stretchable electronics, polydimethylsiloxane (PDMS) is popular owing to its remarkable mechanical properties when subjected to deformation. Recent studies have shown that sponge-like porous PDMS is gaining attention, as it provides high surface area and strong absorption properties as well as facilitates mass transfer, making it ideal for use in electronics. This review primarily focuses on the production method and application of porous PDMS. The article describes the various processing methods used to produce porous PDMS, including 3D printing, gas foaming, and phase separation, each of which results in different characteristics. Thus, researchers can choose the most suitable method according to their desired application. Porous PDMS provides channels for mass transfer and strong absorption properties that enable addition of fillers such as carbon nanotubes (CNTs), graphene, and metal nanoparticles, which can further enhance the functionality of the material. In addition, the review covers applications according to the filler used, such as sensors using CNT, flexible electrodes using NiO/MnO2/CNT, and nanogenerators using ZnO. Choosing the right material for the filler is important for obtaining the desired characteristics as per its application.

The rechargeable metal-air battery technology is a well-interested smart method for eco-friendly and sustainable energy storage. Both of the two order of magnitude lower global market price per tonne of Zn compared to lithium and the multiple theoretical and practical specific energy density of rechargeable ZAB compared to the worldwide Li-ion designs contributes the developing continuously of rechargeable Zn-air battery. The air electrode as a cathode has a vital role in increasing the discharge-charge performance in ZABs, therefore different layers-order air electrodes were assembledwith the utilization of Ni-foam, graphite coating and carbon nanoparticles. The tri-layers cathode showed the highest voltage and performance values compared to the mono- (Ni-foam) and bi- (Ni-foam + graphite coating) layers architectures. The effect of electrolyte inorganic additives (e.g., 2 n/n% ZnCl2 and 0,05 wt% MnO2) was experienced especially at the no-load period.

Nanotechnology plays a vital role in all the scientific fields including environmental research due to their surface: volume ratio compared to bulk materials. Recent studies prove their effectiveness as pollutant removal and remediation practices. Zinc oxide (ZnO) nanoparticles a multifunctional material with distinct properties and their doped counterparts were widely being studied in different fields of science. However, its application in environmental waste treatment is starting to gain attention due to its low cost and high productivity. Heavy metal pollution is one of the major pollutants affecting aquatic and terrestrial life forms. Pollution in water bodies has also raised alarming concerns in the past decades. Most of the heavy metals are essential elements in trace amounts and omnipresent in the environment, causing toxicity for living organisms, for instance, nickel. In our work, we analysed the prospect of selective removal of nickel ions by different alkaline metals (K+, Rb+, and Cs+) doped zinc oxide nanoparticles fabricated by different treatment methods (as-prepared and heat-treated). We found morphological variations from flower like to rod like owing to the alkaline cations of the dopants. In addition, the crystal structure and its different fractions presented amorphous content of the fabricated samples increased from 2 to 10 wt% with respect to the atomic radius of dopant in as-prepared samples and not present in heat-treated samples. We report, how the structure and the sample composition directly affected their adsorption behaviour towards Nickel ions in aqueous solutions based on the micro and nano zincite ratio of the ZnO particles.

In this paper, the preparation of calcium oxide (CaO) nanoparticles (NPs) is reported by a precipitation method, using CaCl 2 and NaOH as starting raw materials. The produced NPs were characterized for chemical composition, phase composition, particle size distribution, morphological features, specific surface area, and crystallite sizes. It is shown that calcination of Ca(OH) 2 in vacuum takes place faster/at a lower temperature compared to the calcination in air due to the higher entropy of the gaseous product of calcination. It is also shown that when these CaO nanoparticles are kept at room temperature in air, they fully and spontaneously transform into CaCO 3 within 3 weeks. Therefore, if this material is disposed in open fields (not necessarily in industrial conditions), it is able to capture carbon dioxide from normal air slowly, but surely. However, when the CaO nanoparticles are kept in the air at 100–200 °C, they mostly capture water vapor from the air instead of carbon dioxide, and the resulting calcium hydroxide blocks the carbon dioxide capture by CaO nanoparticles.

In this paper, 50 … 680 nm thick AlN-Al 2 O 3 coatings are deposited by magnetron sputtering on the surface of a steel substrate and a piece of copper is melted on top of the ceramic. Upon heating the ceramic layer is cracked, and the phase inversion of the two top phases from steel/ceramic/copper configuration to the steel/copper/ceramic configuration takes place within 30 s of liquid time of copper. This phase inversion process is accompanied by a Gibbs energy change of about − 1.78 J/m 2 , due to good wettability of solid deoxidized steel by liquid copper in contrary to poor wettability of the ceramic by the copper. When copper is melted on AlN-Al 2 O 3 coating with its thicknesses smaller than a critical value of about 170 ± 60 nm, liquid copper droplets hanging down into the cracks within the ceramic reach the solid steel surface at the bottom of the cracks, thus the flow of Cu down along the cracks is enabled. However, when copper is melted on AlN-Al 2 O 3 with its thickness larger than the critical value of 170 ± 60 nm, Cu first forms a non-wetting droplet on top of the ceramics, and only after a certain incubation time it starts flowing down the cracks. This incubation time was found to depend linearly on the thickness of the ceramic, as cracks are filled from the bottom upwards by liquid copper via the evaporation–condensation mechanism. By the end of the process, the steel/copper/ceramic configuration is further stabilized by gravity. Graphical abstract