Search Results (482)

This study presents the synthesis and ball-milling modification of titanite (CaTiSiO₅) powders to enhance the thermal stability and performance of polypropylene (PP) separators for lithium-ion batteries (LIBs). CaTiSiO₅ was synthesized using a ceramic route, and the experimental design varied the milling cycles and sphere sizes. Characterization techniques, including scanning electron microscopy, X-ray diffraction, Fourier-transform infra-red spectroscopy, surface area analysis, thermal analysis, and electrochemical tests, confirmed the production of high-purity monoclinic CaTiSiO₅. Ball milling effectively reduced the particle and crystallite sizes while increasing the specific surface area, total pore volume, double-layer capacitance, and ionic conductivity, while also reducing the cell resistance. Coating PP separators with the modified CaTiSiO₅ significantly improved their thermal stability and enhanced their electrochemical properties, including the electron transfer rate and Coulombic efficiency. These findings demonstrate the potential of ball-milled CaTiSiO₅ as a valuable material for developing safer and more efficient LIBs. Full article

This study investigates the impact of multilayer structures and drying strategies on the barrier properties of high-speed starch/bentonite-coated paperboard. The study examines the impact of drying at a high machine speed of 400 m min⁻¹, addressing a key knowledge gap. The hypotheses were that thin multilayer coatings reduce oxygen permeability more effectively than thick single or double coatings and that gentle infrared (IR) drying would be required to achieve this effect. The experiments comprised up to six consecutive coating applications, each providing a dry coat weight between 0.5 and 1.5 g m⁻². The IR dryer power ranged from 207 kW to 829 kW, and different IR frame positions were tested. The results indicated that thin multilayer coatings resulted in fewer pinholes, lower oxygen transmission rates, and improved grease resistance compared with one or two thick layers. However, the effectiveness of the multilayer-coated paperboard was influenced by the employed drying strategy. Specifically, gentle IR drying reduced pinholes, lowered oxygen transmission rates and enhanced grease resistance. Full article

Earthen immovable cultural relics, such as murals and painted clay sculptures, are prone to deterioration (e.g., efflorescence, flaking, and cracking) under long-term preservation conditions. While conventional restoration materials primarily offer reinforcement, they fail to regulate the migration of soluble salts within the relics, which is the main cause of such damage. Herein, aimed at protecting the painted sculptures and murals of the Yungang Grottoes, nano calcium-aluminum layered double hydroxides (Ca-Al LDHs) were prepared, and their effectiveness in regulating salt crystallization within the earthen ground layer, as well as their reinforcement performance were investigated. Simulated salt crystallization tests revealed that coating the ground layer with Ca-Al LDHs delayed salt-induced damage time by 150%. This can be attributed to the ability of Ca-Al LDHs to adsorb sulfate ions from soluble salts, thereby inhibiting the crystallization of magnesium sulfate on the surface of the ground layer. After curing Ca-Al LDHs-coated samples at 35 °C and 55% relative humidity (RH) for 7 days, their surface Leeb hardness increased by 3.1%, and the weight loss rate (measured via tape peeling test) decreased by 38.3%. These results indicate that the surface bonding strength was enhanced following Ca-Al LDHs coating, with the underlying mechanism being the transformation of part of the LDHs into calcium carbonate under the influence of water and carbon dioxide. This study demonstrates that Ca-Al LDHs not only suppress magnesium sulfate crystallization but also provide effective surface consolidation, showing promising potential for application in conserving painted sculptures and murals at the Yungang Grottoes. Full article

Background: Autologous arteriovenous fistula (AVF) is the most commonly used vascular access for end-stage renal disease patients. However, during the maturation process following AVF surgery, insufficient initial venous diameter often results in inadequate blood flow, leading to fistula maturation failure. Studies have indicated that implanting stents can enlarge the initial venous diameter and improve the success rate of AVF surgeries. However, stents made from metallic materials remain permanently in the body after implantation, posing risks such as in-stent restenosis. Methods: Our development and testing of magnesium alloy stents with a layered double hydroxide (LDH) coating to assist AVF maturation is presented in this paper. Firstly, AZ31 alloy was used as a benchmark to screen coating technologies, including anodizing, alkaline films, and LDH coatings. ZM21 tubes were then utilized to verify the transferability of optimized parameters across different substrates. Finally, the optimized coating was applied to ZM21 stents, followed by validation through in vitro degradation tests and biochemical simulations. Results: The results showed that LDH-coated AZ31 samples exhibited a 95% reduction in average corrosion rate compared to untreated samples. Additionally, the anion exchange property of the LDH layer effectively reduced the pH of the saline solution. Subsequently, LDH coatings were applied to ZM21 magnesium alloy stents, followed by in vitro degradation and biochemical simulation. Compared to untreated ZM21 stents, LDH-coated stents demonstrated a 94.9% reduction in average corrosion rate and significantly reduced the generation of soluble magnesium chloride, maintaining the solution pH below 8.0 and the Mg²⁺ concentration below 300 μg/mL. Conclusions: The results show LDH is the most effective corrosion-resistant coating and can control the degradation rate of magnesium alloy stents to enhance their support duration and biocompatibility. Full article

The development of hybrid organic coatings for corrosion protection remains a key research priority. This study focuses on synthesising Layered Double Hydroxide (ZnGa-LDHs) intercalated with environmentally friendly disodium sebacate (SB) corrosion inhibitor, forming ZnGa-SB. To overcome the challenge of limited dispersibility in organic coatings, ZnGa-SB was combined with Graphene Nanoribbons (GNR), produced through the oxidative unzipping of multi-walled carbon nanotubes (MWCNT). The resulting composite, ZnGa-SB/GNR, was synthesised using an in situ hydrothermal method and incorporated into polyurethane (PU) enamel. The synergy between high-barrier GNRs and active ZnGa-SB creates a “labyrinth effect” that effectively inhibits the diffusion of corrosive species. Microstructural analysis, including XRD, FT-IR, Raman, TGA, FE-SEM, and EDS, confirmed the nanofiller structure. The nanofillers were embedded into acrylic resin (AC) for short-term anticorrosive testing in a 0.1 M NaCl solution and then into PU for long-term evaluation in a 3.5 wt% NaCl solution, using electrochemical impedance spectroscopy (EIS). The PU/ZnGa-SB/GNR coating exhibited a high impedance modulus of 5.90 × 10⁷ Ω cm² at |Z|_0.01 Hz, even after 2688 hours of immersion, indicating enhanced corrosion resistance. This coating demonstrated superior performance in cross-cut and pencil hardness tests and sustained less damage in salt spray analysis compared to other coatings. The synergistic effect offers a promising approach for developing next-generation hybrid anti-corrosive coatings. Full article

ZnAl and ZnAlCe layered double hydroxide (LDH) conversion layers modified with picolinoyl N4-phenylthiosemicarbazide (HL) are fabricated on hot-dip galvanized steel (HDG) to improve corrosion protection. X-ray diffraction (XRD) confirms that HL molecules are not intercalated within the LDH interlayers, whereas Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS) analyses reveal their surface adsorption. Moreover, scanning electron microscopy (FE-SEM) observations reveal that HL modification induces changes in surface morphology. After 168 h in 0.1 M NaCl, the LDH structure remains intact, and N and S signals are still detected, confirming the persistence of both the LDH layer and adsorbed HL molecules under corrosive conditions. During 168 h immersion in NaCl, electrochemical measurements indicate that the modified LDH layers exhibit higher corrosion resistance than the unmodified ones, with the ZnAlCe LDH/HL coating providing the most effective protection. Full article

Double-shell ZnO/Al₂O₃ submicron hollow fibers were successfully fabricated through a combined electrospinning and atomic layer deposition (ALD) approach. Polyvinyl alcohol (PVA) fibers were first produced by electrospinning and subsequently coated with a conformal Al₂O₃ barrier layer via low-temperature ALD employing trimethylaluminum (TMA) and deionized (DI) H₂O to preserve the integrity of the temperature-sensitive polymer core. The inner polymer was then removed using two different techniques—thermal annealing and water dissolution—to compare their effects on the fiber morphology. Finally, a functional ZnO layer was deposited by thermal ALD with diethylzinc (DEZ) and DI H₂O. It was found that the polymer removal method critically determined the final structural and morphological characteristics of the fibers. Thermal annealing resulted in smooth, shrunken fibers, while water dissolution led to diameter expansion and the formation of a highly rough, bubble-like surface structure due to swelling-induced micro-cracking. The selection of the polymer removal method offers a precise and controllable route for tailoring the fiber morphology. The resulting high-aspect-ratio (HAR) structures, particularly the rough and expanded fibers, exhibit enhanced specific surface area, making them highly promising for applications in sensing, catalysis, and filtration. Full article

Background/Objectives: Laser has a prominent place in pharmaceutical industry, especially in the marking of solid dosage forms (SDFs). To combat falsified medicines, this study evaluates QR code marking on the surface of tablets as a supplement to serialization on packaging, using an ultrafast laser to achieve industrially relevant marking speeds while preserving the functional integrity of double film-coated ibuprofen tablets. Methods: Tablets were directly compressed and coated with a double film: the inner layer was a gastro-resistant coating (Acryl-EZE^® MP), while the outer one was a coloured, TiO₂-containing (TC) or TiO₂-free (TF) immediate-release coating (Opadry^®). QR codes were ablated on the tablet surface using various laser parameters (e.g., pulse energy and scanning speed), and the effects were physically, chemically, and microscopically examined to evaluate their properties after this processing. Results: No significant differences were observed between TC and TF coatings. In addition, the readability of QR code is strongly influenced by laser settings and coating types. Furthermore, the used laser has achieved the expected fast marking speed and high-precision coding, which may be economically feasible for pharmaceutical companies. According to the profilometry findings, the ablation depth could be compensated for with an appropriate coating thickness to enable the desired release properties. This was confirmed by the results of SEM, Raman analysis, and in vitro dissolution test. Conclusions: Ultrafast Ti:Sa laser-based QR code marking directly onto the dosage form offers increasing benefits in the healthcare field. However, it may undesirably affect the behavior of the dosage form. This requires careful consideration of formulation and laser processing conditions before application, especially in the case of delayed-release (DR) systems. Full article

In this study, oxide coatings with layered double hydroxide (LDH) nanosheets were prepared on AZ91 magnesium alloy by a one-step low-voltage microarc oxidation (MAO) process. The microstructure and composition of the coatings were characterized using SEM, EDS, XRD, FT-IR, and XPS. The corrosion protection performance of the coatings was evaluated by electrochemical analysis and hydrogen evolution tests. The results showed that oxide coatings with Mg-Al-LDH nanosheets are successfully produced by microarc oxidation at a voltage of less than 100 V. The coating with a higher density of Mg-Al LDH nanosheets exhibited enhanced corrosion resistance. Moreover, after modification with stearic acid, the coatings displayed high hydrophobicity and corrosion resistance. Full article

Simonkolleite (Zn₅(OH)₈Cl₂·H₂O), a layered double hydroxide, is used as a fast dry coating that can be applied onto different surfaces. Due to its rapid crystallization, some problems remain during its application, e.g., crack formation, low hardness, and limited compressive strength. To solve these challenges, we propose the harnessing of brown algae, a natural plague of the Caribbean, as a filler for Simonkolleite coatings. The influence of the addition of brown algae on the structural and morphological properties of the coatings was studied, with particular emphasis on their potential for improved durability and functional performance. The addition of the algae to the coatings favored microstructural compaction, resulting in a denser and mechanically more stable coating that exhibited higher hardness and compressive strength. Also, the presence of chlorophyll in the algae could promote light utilization for other emerging applications. Full article

During the vapor phase aluminizing process, protecting the joint regions of turbine blades remains a critical challenge, as the formation of the aluminide coating can significantly increase the brittleness of these areas. To address this issue, a novel double-layer anti-seepage coating was designed for the K4125 nickel-based superalloy. The coating employs a self-sealing mechanism, transforming from a porous structure into a dense NiAl/Al₂O₃ composite barrier at elevated temperatures, thereby suppressing aluminum penetration. Optimal anti-seepage performance is achieved at 1080 °C, reducing the transition zone width to 42 μm, which is a reduction of more than 70% compared to that of 880 °C. These results are attributed to the synergistic action of multiple mechanisms, including high-temperature densification, the formation of NiAl phase, and the growth of an oxide film on the substrate surface. Additionally, the thermal expansion mismatch enables easy mechanical removal of the coating after aluminizing without substrate damage. The coating system offers an effective and practical solution for high-temperature protection during vapor phase aluminizing in aerospace applications. Full article

At present, composite phase change materials are widely studied for battery thermal management. However, to ensure the battery’s thermal safety, it is necessary not only to control the temperature during regular operation, but also to prevent sudden thermal runaway. This basic function depends on the flame-retardant properties of the composite phase change materials. In this study, a hexagonal double-layer hollow nanocage S2 with defect orientation was prepared and combined with carbon nanotubes (PNT) derived from polypyrrole (PPy) tubes to form a high adsorption mixture. Multifunctional composite phase change material PNT/S2@PEG/TEP was prepared by adsorbing and coating polyethylene glycol 8000 (PEG-8000) and triethyl phosphate (TEP) with microfibrillated cellulose nanofibers (CNF) as the skeleton. The characterization shows that its thermal conductivity is 0.65 W/m·K and its phase transition enthalpy is 146.1 J/g, demonstrating its excellent thermal regulation. Microcalorimetric testing (MCC) confirmed its flame-retardant ability, attributed to the strong adsorption of PNT/S2 on PEG-8000 and TEP, the improvement in PNT’s thermal conductivity, and the contribution of CNF to flexibility. This composite phase change material, with excellent comprehensive properties, has broad application prospects in thermal safety for electronic equipment, significantly expanding its practical scope. Full article

Pipeline steels under cyclic loading in corrosive environments are prone to wear and corrosion–wear synergy. Low-dilution, high-reliability Ni-based Cold Metal Transfer (CMT) overlays are therefore required to ensure structural integrity. In this work, three overlay architectures were deposited on L415QS pipeline steel: a single-layer ERNiFeCr-1 coating, a double-layer ERNiFeCr-1/ERNiFeCr-1 coating, and an ERNiCrMo-3 interlayer plus ERNiFeCr-1 working layer. The microstructure, interfacial composition gradients, and dry sliding wear behavior were systematically characterized to clarify the role of interlayer design. The single-layer ERNiFeCr-1 coating shows a graded transition from epitaxial columnar grains to cellular/dendritic and fine equiaxed grains, with smooth Fe dilution, Ni–Cr enrichment, and a high fraction of high-angle grain boundaries, resulting in sound metallurgical bonding and good crack resistance. The double-layer ERNiFeCr-1 coating contains coarse, strongly textured columnar grains and pronounced interdendritic segregation in the upper layer, which promotes adhesive fatigue and brittle spalling and degrades wear resistance and friction stability. The ERNiCrMo-3 interlayer introduces continuous Fe-decreasing and Ni-Cr/Mo-increasing gradients, refines grains, suppresses continuous brittle phases, and generates dispersed second phases that assist crack deflection and load redistribution. Under dry sliding, the tribological performance ranks as follows: interlayer + overlay > single-layer > double-layer. The ERNiCrMo-3 interlayer system maintains the lowest and most stable friction coefficient due to the formation of a dense tribo-oxidative glaze layer. These results demonstrate an effective hierarchical alloy-process design strategy for optimizing Ni-based CMT overlays on pipeline steels. Full article

In this study, thin molybdenum nitride (MoN_x) layers were directly synthesized on molybdenum foil via thermal treatment under an NH₃ atmosphere, and their phase evolution, structural characteristics, and electrochemical performance were investigated. The thickness and morphology of the MoN_x layers were controlled by varying ammonolysis time and temperature, while subsequent annealing in N₂ converted the nitride layer into MoO₂. Meanwhile, oxidation in air yielded crystalline MoO₃ layers. X-ray diffraction and X-ray photoelectron spectroscopy confirmed progressive oxidation of molybdenum, with Mo 3d binding energies increasing in the sequence of Mo < MoN_x < MoO₂ < MoO₃, consistent with their nominal oxidation states. Electrochemical characterization revealed that both MoN_x/Mo and MoO₂/Mo electrodes exhibit notable pseudocapacitive behavior in 0.5 M H₂SO₄ electrolyte, with areal specific capacitances reaching up to 520 mF cm⁻² at 10 mV s⁻¹. Increasing layer thickness led to enhanced capacitance, likely due to an increase in the electrochemically accessible surface area and the extension of ion diffusion pathways. MoO₂-coated samples showed stronger faradaic contribution and superior rate capability compared to MoN_x counterparts, along with a gradual shift from predominantly electric double-layer capacitance toward hybrid pseudocapacitive charge storage mechanisms. Full article

Al–Si–Cu alloy is one of the aluminum die-cast alloys widely used in industry. Due to the presence of Si and Cu elements in the Al–Si–Cu alloy, the corrosion resistance of the Al–Si–Cu alloy is lowered. Thus, developing a corrosion-resistant film on the Al–Si–Cu alloy is necessary. A layered double hydroxide (LDH) film is recognized as a promising corrosion-resistant coating. LDHs exhibit a distinct structure where positively charged basic layers (metal hydroxides) are interleaved with intermediate layers that accommodate charge-compensating anions and hydration water. The positively charged layers allow for the exchange of anions as interlayers, enabling the incorporation of various anions into the interlayer. The difference in the anion species in the interlayer of the LDH films can affect corrosion-resistant performance. In this study, we aimed to prepare Mg–Al LDH films intercalated with different anions (NO₃⁻, MoO₄²⁻, VO₄³⁻, and PO₄³⁻) and investigate the corrosion resistance of the LDH films. The films were prepared on die-cast Al–Si–Cu alloys using steam coating and immersion processes. The prepared LDH films were characterized by XRD, SEM, FT-IR, and electrochemical measurements. The electrochemical measurements revealed that Mg–Al LDH films intercalated with MoO₄²⁻ showed the most superior corrosion resistance among all films prepared in this study. Full article