Search Results (283)

Planar heaters are designed to deliver uniform heat across broad surfaces and serve as critical components in applications requiring energy efficiency, safety, and mechanical flexibility, such as wearable electronics and smart textiles. However, conventional metal-based heaters are limited by poor adaptability to curved or complex surfaces, low mechanical compliance, and susceptibility to oxidation-induced degradation. To overcome these challenges, we applied a protein-assisted electroless copper (Cu) plating strategy to electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber substrates to fabricate flexible, conductive planar heating membranes. For interfacial functionalization, a protein-based engineering approach using bovine serum albumin (BSA) was employed to facilitate palladium ion coordination and seed formation. The resulting membrane exhibited a dense, continuous Cu coating, low sheet resistance, excellent durability under mechanical deformation, and stable heating performance at low voltages. These results demonstrate that the BSA-assisted strategy can be effectively extended to complex three-dimensional fibrous membranes, supporting its scalability and practical potential for next-generation conformal and wearable planar heaters. Full article

The slurry aluminizing process is widely employed to enhance the oxidation and corrosion resistance of nickel-based superalloys used in high-temperature environments such as gas turbines and aerospace engines. This study investigates the effects of the concentration of Al vapors in the reactor chamber and the initial slurry layer thickness on the microstructure, chemical composition, and phase composition of aluminide coatings. Coatings were manufactured on Ni-based superalloy substrates using CrAl powders as an aluminum source and chloride- and fluoride-based activator salts. The effect of the initial thickness of the slurry layer was studied by varying the amount of deposited slurry in terms of mg_slurry/cm²_sample (with constant mg_slurry/cm³_chamber). The microstructure and phase composition of the produced aluminide coatings were evaluated by SEM, EDS, and XRD analysis. Slurry thickness can affect concentration gradients during diffusion, and the best results were obtained with an initial slurry amount of 100 mg_slurry/cm²_sample. The effect of the Al vapor phase in the reaction chamber was then investigated by varying the mg_slurry/cm³_chamber ratio while keeping the slurry layer thickness constant at 100 mg_slurry/cm²_sample. This parameter influences the amount of Al at the substrate surface before the onset of solid-state diffusion, and the best results were obtained for a 6.50 mg_slurry/cm³_chamber ratio with the formation of 80 µm coatings (excluding the interdiffusion zone) with a β-NiAl phase throughout the thickness. To validate process flexibility, the same parameters were successfully applied to produce platinum-modified aluminides with a bi-phasic ζ-PtAl2 and β-(Ni,Pt)Al microstructure. Full article

Poly(vinylidene fluoride-trifluoroethylene) (PVTF) nanoparticles coatings with electrically heterogeneous microdomains were engineered to mimic the natural electromechanical microenvironment of bone tissue, offering a novel strategy to enhance osteogenesis. Through a biphasic solvent phase separation method, PVTF nanoparticles (NPs) were synthesized and spin-coated onto substrates, followed by melt-recrystallization to achieve high β-phase crystallinity. The substrates were then subjected to corona poling, a process involving high-voltage corona discharge to electrically polarize and align the molecular dipoles. Structural and electrical characterization revealed tunable microdomain surface potentials and piezoelectric coefficients, correlating with enhanced hydrophilicity. Notably, microdomain potential—produced by controlled polarization—was shown to directly regulate cellular responses. In vitro studies demonstrated that a corona-poled PVTF NP coating significantly improved bone marrow mesenchymal stem cell (BMSC) proliferation and early osteogenic differentiation. This work establishes a surface electropatterning approach and highlights the critical role of electrical heterogeneity in bone regeneration, offering a novel strategy for bioactive biomaterial design. Full article

Plasma electrolytic fluorination (PEF) of AZ31 magnesium alloy was carried out by adding different ratios of water to the ethylene glycol-ammonium fluoride electrolyte. The structural composition of the coatings was characterized using SEM, XRD, and EDS, and the effects of water content on the microstructure and corrosion resistance of the PEF coatings were analyzed. The results showed that the addition of water promoted the ionization of ammonium fluoride and increased the conductivity of the glycol electrolyte, which led to a decrease in the termination voltage. However, the coating thickness was not changed by the addition of water. The O element in water was not enough to compete with the F element in the electrolyte and had a small effect on the PEF coating composition, which was still dominated by MgF₂. The addition of water had an effect on the structure of the coating: with an increase in water content, the number of coating penetration holes decreases, and the continuity is enhanced. The pores on the surface of the coating tended to be levelled off and transitioned to the typical coating structure of PEO (plasma electrolytic oxidation). The addition of water to the glycol electrolyte was conducive to improving the corrosion resistance of the coatings. The corrosion resistance of PEF coatings in neutral NaCl corrosive medium firstly increased and then decreased, and the strongest corrosion resistance was obtained when the ratio of glycol and water is 6:4. Full article

This work mainly explores whether the solubility product principle has a guiding role in regulating the composition of micro-arc oxidation (MAO) coatings. The MAO process was conducted on AZ31 Mg alloy in silicate electrolyte. Varying amounts of Potassium fluoride (KF) and Ammonium fluoride (NH₄F) were separately added to the basic electrolyte to regulate the OH⁻ and F⁻ contents in the electrolyte. The microstructure, phase composition and corrosion resistance of the MAO coatings prepared in different electrolytes were analyzed. Results showed that regardless of KF content, MgO was the main component for the MAO coatings obtained in electrolytes with KF. This was because the addition of KF not only elevated the F⁻ concentration in the electrolyte but also enhanced the OH⁻ concentration as a result of F⁻ hydrolysis. Based on the solubility product constants (Ksp) of MgO and MgF₂, a relatively lower concentration of Mg²⁺ was sufficient for the formation of MgO. Hence, Mg²⁺ consistently exhibited preferential reactivity with OH⁻, leading to the formation of MgO. The findings of the study demonstrated that the presence of KF electrolyte resulted in an enhancement of conductivity and an increase in the concentration of OH⁻. Conversely, the growth rate of the coating was observed to be low, and the coating-forming phases of the coating were identified as MgO and Mg₂SiO₄, and the coating had better corrosion resistance. NH₄F electrolyte with the increase in NH₄F concentration, conductivity decreases and then increases, OH⁻ concentration decreases, the growth rate of the coating is faster, the concentration of F⁻/OH⁻ is higher, the coating-forming phase is transformed into MgF₂, and the corrosion resistance of the coating is reduced. Full article

Titanium and its alloy scaffolds are widely utilized in clinical settings; however, their biologically inert surfaces and inherent mechanical characteristics impede osteogenesis and soft tissue integration, thereby limiting their application. Selective laser melting (SLM) was employed to fabricate scaffolds with matched cortical bone mechanical properties, achieving a composite coating of hydroxyapatite complexed with trace elements of silicon, strontium, and fluoride (mHA), along with type I collagen (Col I) and fibrinogen (Fg), thus activating the scaffold surface. Initially, we utilized the excellent adhesive properties of dopamine to co-deposit mHA and polydopamine (PDA) onto porous Ti-6Al-4V scaffolds, which was followed by immobilization of type I collagen and fibrinogen onto PDA. This bioinorganic/bioprotein composite coating, formed via PDA bonding, exhibits excellent stability. Moreover, in vitro cell experiments demonstrate excellent biocompatibility of the porous Ti-6Al-4V scaffold with composite bioactive coatings on its surface. Preosteoblasts (MC3T3-E1) and human keratinocytes (HaCaT) exhibit enhanced adhesion and proliferation activity, and the osteogenic performance of the scaffold is significantly improved. The PDA-mHA-Col I-Fg composite-coated porous titanium alloy scaffold holds significant promise in enhancing the efficacy of percutaneous bone transplantation and requires further investigation. Full article

Arsenic contamination in water demands effective, low-cost removal methods. This study introduces nanomagnetite-coated biochar derived from pecan nutshells for efficient arsenic adsorption. Utilizing a solvothermal method, uniform magnetite crystals were grown on biochar in a controlled process at 200 °C. The resulting bioadsorbent, characterized by XRD, SEM, and FTIR, exhibited a narrow size distribution and consistently high arsenic removal rates (97.30–98.76%). Biochar with varied particle sizes, synthesized at a short reaction time (6 h), showed the highest removal efficiency of arsenic (98.76%) and adsorption capacity (7.974 mg/g). This approach offers a sustainable for arsenic remediation, and ease of magnetic separation. Full article

Hydrogen chloride (HCl) is one of the most hazardous air pollutants and can cause significant damage to human health and the environment. Therefore, the continuous quantitative monitoring of HCl is of great practical importance. In this work, a novel triphenylamine derivative, named TPTc-DBD, with a Schiff base structure was synthesized. The molecular structure of TPTc-DBD was determined by NMR analysis, FTIR analysis and single crystal diffraction analysis. On this basis, a porous polyvinylidene fluoride (PVDF) film containing TPTc-DBD was then prepared by a spin-coating method, and its sensitivity to HCl was evaluated by naked eye and ultraviolet-visible absorption spectrum, respectively. The detection limit of the composite porous film for HCl molecules was determined to be 5.8 mg/m³. Interestingly, the composite films absorbing HCl can be reactivated by NH₃, which provides a cycle detection ability for HCl. After five testing cycles, the detection error remained below 1%. Furthermore, the microstructure of the film remained unchanged, highlighting its exceptional detection performance for HCl. Full article

Through the application of advanced membrane modification strategies, high-performance membranes have been developed to effectively remove organic contaminants such as toluene and xylene from wastewater. These membranes demonstrate superior antifouling resistance and long-term operational stability, offering a competitive advantage for semiconductor wastewater treatment. This study introduces a novel approach to membrane fabrication using polyvinylidene fluoride (PVDF), recognized for its cost-effectiveness and distinct antifouling properties in contaminant removal. To enhance the performance of the membrane, the solvent (DMA, DMF, NMP) that dissolves PVDF and the immersion time (30 min, 60 min, 90 min) at which phase separation occurs were identified. Additionally, the membranes were treated with polyvinyl alcohol (PVA) through multiple dip coatings to enhance their hydrophilicity before a comparative analysis was conducted. The resulting optimized membranes demonstrated high emulsion fluxes (4412 $\mathrm{L}{\mathrm{m}}^{-2}{\mathrm{h}}^{-1}{\mathrm{bar}}^{-1}$ for toluene) and achieved oil-removal efficiencies exceeding 90% when tested with various organic solvents, including toluene, cyclohexane, xylene, benzene, and chloroform. The resulting optimized membranes prove to be a reliable means of producing clean water and of efficiently separating organic contaminants from wastewater. Showcasing remarkable antifouling capabilities and suitability for repeated use without significant efficiency loss, this solution effectively addresses cost and fouling challenges, presenting it as a sustainable and efficient wastewater treatment method for the semiconductor industry. Full article

A spin-coating technique was used to produce new thin films of fluoride-doped hydroxyapatite (HApF) and fluoride-doped hydroxyapatite in a dextran matrix (HApF-Dx) with the potential to be used as nanocoatings for various biomedical implants. The stability of the suspensions used in obtaining the thin films was confirmed by ultrasonic measurements with double-distilled water as a reference. The HApF and HApF-Dx thin films obtained by spin-coating showed diffraction patterns corresponding to hexagonal hydroxyapatite. The X-ray photoelectron spectroscopy studies confirmed the partial substitution of hydroxyl groups (-OH) by fluoride ions. The FTIR studies were conducted in order to highlight the presence of the functional group specific for the HAp in the samples and the influence of the dextran addition on the vibrational characteristics. The surface morphologies of the HApF and HApF-Dx thin films were explored using scanning electron microscopy (SEM), atomic force microscopy (AFM), and metallographic microscopy (MM). The surfaces of the HApF and HApF-Dx thin films were found to be smooth, homogenous, and nanostructured. The biocompatibility assays on HGF-1 cells confirmed that both coatings exhibited good cell viability for all the tested time intervals (24 and 48 h). The findings highlighted the potential of HApF and HApF-Dx coatings for biomedical applications. Additional information about the HGF-1 adherence and development on the surface of the HApF and HApF-Dx coatings was obtained using metallographic microscopy, scanning electron microscopy, and atomic force microscopy techniques. This research demonstrates that the spin-coating method can be successfully used to fabricate HApF and HApF-Dx nanocoatings for potential biomedical applications. Full article

This study aimed to evaluate the influence of different fluoride-containing toothpastes on fluoride uptake, surface roughness, and microhardness of six ion-releasing restorative dental materials, including glass hybrids (EQUIA Forte HT with and without coating), glass ionomer cements (Fuji IX), resin-modified GICs (Fuji II LC), alkasites (Cention Forte), and ion-releasing composites (Luminos UN and Activa). Specimens were prepared and subjected to a four-day brushing protocol using six toothpastes with varying fluoride formulations (NaF, SnF2, SMFP) and concentrations. Fluoride uptake was assessed by measuring fluoride release using an ion-selective electrode, while surface roughness and microhardness were assessed before and after brushing. Results revealed significant variations in fluoride uptake, with Fuji IX and EQUIA Forte HT showing the highest release, particularly when brushed with NaF-based toothpastes (Duraphat 5000 and 2800). Surface roughness increased post-brushing, with the greatest changes observed in Activa, while microhardness decreased across most materials, except for coated EQUIA Forte HT, which exhibited improved compactness. Resin-based composites, such as Luminos UN and Activa, demonstrated lower fluoride uptake and minimal changes in microhardness compared to GICs. The findings underscore the importance of material composition and toothpaste formulation in influencing fluoride dynamics, surface properties, and mechanical performance of restorative materials. Full article

Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent was evaluated as function of column flow rate, solution type, and sorbent recyclability. Adsorption column experiments included two column flow rates of 2 mL/min and 10 mL/min using two different solutions: deionized water and a synthetic solution representative of groundwater. Greater fluoride column adsorption capacity was obtained at the lower flow rate for both solutions, mainly due to longer contact times between solution and AMCCS sorbent. Adsorption of fluoride occurred through physical adsorption, which followed the Langmuir adsorption model and second-order kinetics for deionized water and synthetic solution. A lower AMCCS column fluoride adsorption capacity was observed for the synthetic solution due to the competition from adsorption of other ions in the synthetic solution, whereas fluoride adsorption by the AMCCS column was influenced by interphase mass transfer to a lesser extent using the synthetic solution than deionized water. The re-coating of spent AMCCS sorbent in the adsorption column resulted in effective recycling and reuse of the AMCCS adsorption column for both deionized water and the synthetic solution, rendering the AMCCS adsorption column a recyclable and sustainable flow through water defluoridation system. Full article

The 6061 aluminum alloy is a commonly used metal material for sports equipment but is vulnerable to the external environment and corrosion. A novel V-Zr-Ti composite conversion coating was successfully prepared on the surface of 6061 aluminum alloy, and a thorough investigation was conducted into the effect of the conversion parameters. Furthermore, the microstructure of the conversion coating, element contents of the coating surface, and dynamic evolution characteristics of the conversion solution were systematically investigated, and furthermore, the relationship among them was established. The results show that the optimal conversion time (CTI) and conversion temperature (CTE) for the VZrCC are 12 min and 45 °C. The VZrTiCC can gradually fill surface scratches during the coating-forming process, resulting in a relatively flat and even surface morphology. The conversion element contents on the VZrTiCC surface demonstrated a gradual increase, and the deposition rate was characterized by high Ti, medium Zr, and low V. The phase of the coating is predominantly constituted by metal oxides derived from conversion compositions, with a minor proportion of fluoride. Furthermore, the VZrTiCC can significantly enhance the corrosion resistance of an Al alloy matrix due to its low i_corr and average corrosion rate (ACR), and its corrosion resistance is about 5 times higher than that of the Al alloy matrix. Eventually, the formation process of the VZrTiCC with three key stages was proposed. In subsequent studies, to further establish a composition design framework for the conversion coating, a silane aqueous solution will be added to the existing V-Zr-Ti conversion solution, and a systematic study will be conducted on the V–organic composite conversion coating using computational molecular dynamics simulation combined with experimental characterization. Full article

This study aims to investigate the effects of different fluoride salts added in the PEO bath on the corrosion resistance and morphology of AZ31 magnesium alloy coatings. The PEO process was performed using a bipolar cycle with varying durations (4 and 30 min) in baths containing different fluoride salts (NaF, LiF, Na₂SiF₆) and a reference bath without fluoride. The coatings were characterised using SEM-EDS, XRD, and electrochemical impedance spectroscopy (EIS) to assess their morphology, chemical composition, and corrosion resistance. The results indicate that the presence of fluorides significantly influences the coating properties. NaF and Na₂SiF₆ coatings exhibited better corrosion resistance and more compact microstructures compared to LiF and the fluoride-free reference. The study highlights the importance of the fluoride counter ion in the PEO bath, demonstrating that NaF and Na₂SiF₆ provide superior protection against corrosion, making them suitable for biomedical applications where both porosity and corrosion resistance are critical. Full article

Effective and environmentally benign removal of polyvinylidene fluoride (PVDF) binders from spent battery electrodes remains a critical hurdle in sustainable recycling, primarily due to issues related to the mitigation of fluorinated compound emissions. This work evaluates PVDF binder removal from cathode active material using either a green solvent-based dissolution process or pyrolysis, analyzed by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The solvent pretreatment involved mixing dihydrolevoglucosenone (Cyrene™) with PVDF-coated NMC811 at 100 °C, followed by hot filtration to separate the Cyrene-PVDF solution. Pyrolysis was conducted at 800 °C under an argon atmosphere. Positive ToF-SIMS spectra for Cyrene showed characteristic peaks at ketene (42 m/z) and 1,3-dioxole (86 m/z), along with intense C₂H₃O⁺, C₃H₃O⁺, C₄H₇⁺, and C₃H₅O⁺ peaks. The characteristic peaks used to identify PVDF were C₃H₂F₅⁺ (133 m/z), C₃H₂F₃⁺ (95 m/z), and C₃HF₄⁺ (113 m/z). Both processes resulted in PVDF removal, with pyrolysis demonstrating higher effectiveness. Particle agglomeration was observed in both pretreated NMC811 samples, however agglomeration was more pronounced with Cyrene pretreatment due to PVDF redeposition. Following pyrolysis, PVDF was transformed into a defluorinated carbonaceous material. Full article