Search Results (163)

Researchers increasingly agree that livestock farming is the leading cause of air pollution with ammonia (NH₃) gas. The existing research suggests that 30–80% of nitrogen is lost from slurry and liquid manure in the gaseous form of ammonia. Most studies have focused on environmental factors influencing ammonia volatilization and manure composition but not on controlling the moisture level on the surface of the excreta. Applying the principles of convective mass exchange, this study was undertaken to compare different types of organic covers that mitigate NH₃ emissions and offer recommendations on how to properly apply organic covers on the surface of manure. Data was obtained from research in laboratory conditions comparing well-known coatings (chopped straw) with less commonly used organic materials (peat) or waste generated in other industries (sawdust, hemp chaff). This research demonstrated that applying bio-coatings can reduce ammonia (NH₃) emissions at coating thicknesses of ≥5 cm for sawdust, ≥3 cm for peat, ≥10 cm for hemp chaff, and 8–12 cm for straw. These reductions are linked to the ability of the coatings to lower manure surface moisture evaporation, a key driver of ammonia volatilization, highlighting the role of surface moisture control in emission mitigation. 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

The precision casting of nickel-based single-crystal superalloys imposes stringent requirements on the high-temperature stability and chemical inertness of ceramic shell face coats. To address the issue of traditional EC95 shells (95% Al₂O₃–5% SiO₂) being prone to react with the alloy melt at elevated temperatures, thereby inducing casting defects, this study proposes a lanthanide oxide-based ceramic face coat material. Three distinct powders—LaAlO₃ (LA), LaAlO₃/La₂Si₂O₇ (LAS), and LaAl₁₁O₁₈/La₂Si₂O₇/Al₂O₃ (LA11S)—are successfully prepared through solid-phase sintering of the La₂O₃-Al₂O₃-SiO₂ ternary system. Their slurry properties, shell sintering processes, and high-temperature performance are systematically investigated. The results demonstrate that optimal slurry coating effectiveness is achieved when LA powder is processed with a liquid-to-powder ratio of 3:1 and a particle size of 300 mesh. While LA shells show no cracking at 1300 °C, their face coats fail above 1400 °C due to the formation of a La₂Si₂O₇ phase. In contrast, LAS and LA11S shells suppress cracking through the La₂Si₂O₇ and LaAl₁₁O₁₈ phases, respectively, exhibiting exceptionally high-temperature stability at 1400 °C and 1500 °C. All three shells meet the high-temperature strength requirements for CMSX-4 single-crystal alloy casting. Interfacial reaction analysis and Gibbs free energy calculations reveal that Al₂O₃-forming reactions occur between the novel shells and alloy melt, accompanied by minor dissolution erosion without other chemical side reactions. This work provides a high-performance face coat material solution for investment casting of nickel-based superalloys. Full article

In this study, a production method for ceramic shell macrocapsules and a high-temperature-resistant, polymer agent-based self-healing system was developed. Two types of macrocapsules were created by filling hollow ceramic capsules with high-temperature-resistant diallyl phthalate (DAP) resin, known for its thermal stability, and a peroxide-based curing agent. These capsules were incorporated into epoxy and DAP matrix materials to develop polymer composite materials with self-healing properties The macrocapsules were produced by coating polystyrene (PS) sacrificial foam beads with raw ceramic slurry, followed by sintering to convert the liquid phase into a solid ceramic shell. Moreover, FTIR, TGA/DTA, and DSC analyses were performed. According to the thermal analysis results, DAP resin can effectively function as a healing agent up to approximately 340 °C. In addition, quasi-static compression tests were applied to composite specimens. After the first cycle, up to 69% healing efficiency was obtained in the epoxy matrix composite and 63.5% in the DAP matrix composite. Upon reloading, the second-cycle performance measurements showed healing efficiencies of 56% for the DAP matrix composite and 58% for the epoxy matrix composite. Full article

Nano-titanium dioxide ceramic coatings exhibit excellent wear resistance, corrosion resistance, and self-cleaning properties, showing great potential as multifunctional protective materials. This study proposes a synergistic reinforcement strategy by encapsulating micron-sized Al₂O₃ particles with nano-TiO₂. A core-shell structured nanocomposite coating composed of 65 wt% nano-TiO₂ encapsulating 30 wt% micron-Al₂O₃ was precisely designed and fabricated via a slurry dip-coating method on Q235 steel substrates. The microstructure and surface morphology of the coatings were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Comprehensive performance evaluations including densification, adhesion strength, wear resistance, and thermal shock resistance were conducted. Optimal coating properties were achieved under the conditions of a binder-to-solvent ratio of 1:15 (g/mL), a heating rate of 2 °C/min, and a sintering temperature of 400 °C. XRD analysis confirmed the formation of multiple crystalline phases during the 400 °C curing process, including titanium pyrophosphate (TiP₂O₇), aluminum phosphate (AlPO₄), copper aluminate (Cu(AlO₂)₂), and a unique titanium phosphate phase (Ti₃(PO₄)₄) exclusive to the 2 °C/min heating rate. Adhesion strength tests revealed that the coating sintered at 2 °C/min exhibited superior interfacial bonding strength and outstanding performance in wear resistance, hardness, and thermal shock resistance. The incorporation of nano-TiO₂ into the 30 wt% Al₂O₃ matrix significantly enhanced the mechanical properties of the composite coating. Mechanistic studies indicated that the bonding between the nanocomposite coating and the metal substrate is primarily achieved through mechanical interlocking, forming a robust physical interface. These findings provide theoretical guidance for optimizing the fabrication process of metal-based ceramic coatings and expanding their engineering applications in various industries. Full article

B₄C is beneficial for forming a glassy film that is effective at impeding oxygen diffusion and improving the oxidation resistance of coatings at high temperature. The effect of B₄C content on the oxidation resistance of a B₄C-SiO₂–Albite/Al₂O₃ (BSA/AO) double-layer coating by the slurry brushing method at 900 °C was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and differential scanning calorimetry (DSC) with thermogravimetric analysis (TGA) in this work. It is indicated that the composite coating with 20 wt% B₄C exhibits excellent oxidation resistance at high temperature, which shows a mass loss of only 0.11% for the coated carbon block after being exposed to 900 °C for 196 h. This is attributed to the in situ formation of a thin, dense glass layer with good self-healing ability at the interface of the B₄C-SiO₂–Albite/Al₂O₃ composite coating within 1 h and the persistence and stability of the dense glass layer during exposure. The mechanism is discussed in detail. Full article

Valve leakage mainly comes from worn sealing surfaces caused by abrasive particles. This study uses plasma beam spraying to create Fe55 alloy coatings with CeO₂ and TiN added to improve microstructure and wear resistance. Five coatings were prepared: Fe55 with 0.02% CeO₂ (FC2), 0.04% CeO₂ (FC4), 1% TiN (FT1), 2% TiN (FT2), and 2% TiN/0.02% CeO₂ (FC2T2). These coatings were tested for wear and erosion using wet sand and slurry experiments. Results showed that FC2T2 had the most uniform microstructure with fully equiaxed grains (20.32 μm size) and no columnar grains. This was due to CeO₂ and TiN co-working effect: CeO₂ was adsorbed onto TiN surfaces, reducing TiN decomposition and acting as nucleation sites. The FC2T2 coating also showed the highest hardness uniformity (no large changes with depth) and the lowest surface roughness after wear (41% lower than pure Fe55). In wear tests, FC2T2’s Cr₇C₃ hard phases blocked abrasive cutting, while the γ-Fe matrix prevented Cr₇C₃ from breaking off. Erosion tests confirmed FC2T2’s superior performance, as its uniform structure limited deep grooves. Adding both CeO₂ and TiN improved wear resistance by providing a balanced microstructure, reducing leakage risks in valve sealing surfaces. Full article

High-entropy silicide (MeSi₂) coating was prepared by the slurry method and silicon infiltration method using Mo, Cr, Ta, Nb, W, and Si elemental powders as raw materials. The coating consisted of four layers, including a porous MeSi₂ layer, a (CrTa)Si layer, a TaSi₂ layer, and a Ta₅Si₃ layer from outside to inside. At 600 °C, Si was preferentially oxidized to form SiO₂ oxide film. The mass gain rate of the coating was 0.2 mg/cm² over a period of 100 h oxidation, eliminating the phenomenon of low-temperature pulverization. At 1200 °C, MeSi₂ coating had a protection time of 20 h. During the oxidation process, the coating generated metal oxides, forming a thin SiO₂ oxide film. TaSi₂ and Ta₅Si₃ gradually transformed into Ta₂O₅, and the coating eventually failed. Full article

The permeability of a certain mudstone interlayer in underground salt cavern gas storage (Jintan, China) is slightly high, as indicated by pressure tests (leakage rate of approximately 1~2 L/d). This layer is referred to as the “Micro-Leakage Interlayer (MLI)”. The MLI significantly impacts the tightness of gas storage, potentially leading to substantial losses. To address this problem, an experimental study was conducted. Initially, a method utilizing brine crystallization to plug the micro-leakage interlayer (MLI) was proposed. After crystallization, the porosity of the MLI cores exhibited a notable increase, and the permeability of the MLI cores increased significantly, further exacerbating the risk of gas leakage. These results indicate that the plugging solution requires further exploration. Finally, a combined plugging solution utilizing brine crystallization and ultrafine cement was proposed. Using saturated brine and waterproof coatings, an ultrafine cement slurry was prepared, and specimens were created for testing. The results indicate that the specimens exhibited a porosity of approximately 3%, a permeability below 10⁻¹⁹ m², and a uniaxial compressive strength of about 40 MPa. The ultrafine cement particles had an average particle size of 3 µm, and the ultrafine cement slurry exhibited extremely low porosity and permeability, as well as high strength. The results indicate that this solution is highly feasible and can be applied to field engineering. Full article

A multifunctional paper-based composite of paper coated with a polypyrrole@lignocellulosic slurry (PPy@LS) and carboxymethyl cellulose (CMC) was developed. PPy@LS was prepared via the polymerization of pyrrole onto a lignocellulosic slurry derived from hemp stalks prepared using deep eutectic solvents. The PPy@LS slurry was mixed with the required amount of CMC and vacuum-filtered onto filter paper to fabricate the composite (PPy@LS/CMC). The resulting composite paper exhibited excellent multifunctional properties, including electrical conductivity, photothermal conversion, and antibacterial properties. These properties are stable against external environments, such as water and abrasion, due to the addition of CMC. The electrical conductivity of PPy@LS/CMC varied in the dry (1.6 × 10⁻⁴ S/cm) and wet (4.8 × 10⁻⁶ S/cm) states, suggesting its potential application in humidity sensing. Notably, the PPy@LS/CMC paper achieved significant photothermal activity under light irradiation, as demonstrated by the measured surface temperature exceeding 80 °C in 10 min. Moreover, the composite paper exhibited > 99.9% antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The combination of the inherent characteristics of filter paper along with the photothermal property of PPy enable the PPy@LS/CMC composite appropriate for solar interfacial evaporation application. These multifunctional composite papers with innovative combinations of properties have great potential for applications in smart packaging, humidity sensing, biomedicine, and solar-driven water purifications. Full article

Evaluating the air purification performance of photocatalytic materials typically requires complex gas decomposition tests involving expensive analytical equipment and lengthy testing periods. In this study, photocatalytic performance evaluation methods involving resazurin (Rz) ink and fluorescence probe techniques were investigated as alternatives to conventional gas decomposition tests. TiO₂ films with varying performance levels were fabricated by controlling TiO₂ slurry concentration and the amount of photocatalyst deposited through spin coating. Photocatalytic performances of the synthesised films were then evaluated using the acetaldehyde decomposition method, Rz ink test, and fluorescence probe method for measuring OH radical generation. The acetaldehyde decomposition rate constants showed high correlation with both the Rz colour change rate in modified-pH ink (R² = 0.91) and the OH radical concentration (R² = 0.98). Conventional Rz ink testing for high-performance materials showed rapid colour changes, indicating its limited applicability. Our modified-pH Rz ink enabled facile analysis by ensuring controlled reactivity. Both the modified Rz ink method, which enables quantitative evaluation within five minutes even for high-performance materials, and the fluorescence probe method are suitable as reliable screening tools for photocatalytic air purification materials. These simplified evaluation methods will aid in developing more efficient photocatalysts and advancing environmental purification technologies. Full article

The fast development of portable electronics demands electrodes for supercapacitors that are compatible with miniaturized device applications. In this study, an orderly aligned coaxial bilayer nanotube array made of transition metal/transition metal oxides was adopted as a nanostructure-integrated electrode for applications as miniaturized micro-supercapacitors. Using Ni and NiO as our model materials, the corresponding Ni/NiO-CBNTA electrodes were fabricated using templated growth and post-thermal oxidation. The Ni shells served as parts of the 3D nano-architectured collector, providing a large specific surface area, and the pseudocapacitive NiO layers were directly attached and electrically connected to the collector without any additives. The vertical growth of orderly aligned Ni/NiO-CBNTAs successfully avoided the underutilization of capacitive nanomaterials and allowed the electrolyte to be fully accessed, which manifested full charge storage capabilities under the miniaturizing. It was demonstrated that Ni/NiO-CBNTAs can serve as miniaturized electrodes with an improved specific capacitance of 1125 F/g ≅ 3 A/g, which is comparable to that obtained in a massive load electrode prepared by the conventional slurry-coating technique. Full article

The effects of substrate roughness and impact angle on the spreading behavior of Polyvinylidene Fluoride (PVDF) slurry droplets during the spraying process using a dispersing disk are investigated, aiming to enhance the quality of lithium-ion battery separators. In this study, through theoretical modeling and simulation analysis, mathematical expressions for the maximum spreading coefficient and the final shrinking coefficient of the droplets are derived. A simulation model for droplet impact and diffusion on the substrate surface is established based on the Lattice Boltzmann Method (LBM) and the Lagrangian function. Simulation results indicate that the maximum spreading coefficient of the droplet decreases with increasing substrate roughness and impact angle, while the final shrinking coefficient increases with substrate roughness but decreases as the impact angle increases. Finally, spray coating experiments for lithium-ion battery separators are conducted, and the results show that as the surface roughness and impact angle of the substrate increase, the average diameter of the droplets decreases, thereby validating the accuracy of the simulation results. Full article

Slot-die coating is widely used in the preparation of negative electrodes for lithium batteries. The thickness of the negative electrode has a significant influence on the battery performance and lifespan, and different manufacturers have different requirements for its thickness. In order to reduce the waste caused by trial and error in the electrode preparation process, a prediction model for the negative electrode thickness was established and verified through simulation and experiments. Based on the Landau–Levich film equation and the Ruschak model, a high-precision prediction model was constructed by taking into account the influence of factors’, such as temperature and slurry, spreading characteristics on the coating thickness. The minimum coating thickness and its influencing factors were explored. Meanwhile, the simulation analysis of the coating thickness was performed, and the theoretical values of three common process parameters were compared with the simulation results, showing a deviation of only 2.9%. An experiment on predicting the thickness of the negative electrode of lithium batteries was conducted. Thickness measurements were performed on the samples prepared through the experiment and compared with theoretical values. The accuracy rate of this thickness prediction model can reach 98.75%. Full article

Although materials with infrared camouflage capabilities are increasingly being produced, few applications exist in clothing fabrics. Here, graphene/MXene-modified fabric with superior infrared camouflage, Joule heating, and electromagnetic shielding capabilities all in one was prepared by simply scraping a graphene slurry onto alkali-treated cotton fabrics, followed by spraying MXene. The functionality of the modified fabrics after different treatment times was then tested and analyzed. The results indicate that the mid-infrared emissivity of the modified fabric decreases with an increase in the coating times of graphene and MXene. When the graphene/MXene-modified fabrics are prepared at loads of 5 and 1.2 mg/cm², respectively, the modified fabrics have very low infrared emissivity in the 3–5 and 8–14 μm bands, and the surface temperature can be reduced by 53.1 °C when placed on a heater with a temperature of 100 °C (surface radiation temperature of 95 °C). The modified fabric also demonstrates excellent Joule heating capabilities; at 4 V of power, a temperature of 91.7 °C may be reached in 30 s. In addition, customized materials exhibit strong electromagnetic shielding performance. By simply folding the cloth, the electromagnetic interference shield effect can be increased to 64.3 dB. With their superior infrared camouflage, thermal management, and electromagnetic shielding performance, graphene/MXene-modified fabrics have found extensive use in intelligent wearables and military applications. Full article