Search Results (161)

This study investigates the dripping and leakage problem in kitchenware known as the “teapot effect” through a multidisciplinary experimental approach encompassing fluid mechanics, material science, and ergonomic design. Unlike previous studies confined to idealized geometries and single-fluid analyses, this work systematically examines 32 distinct spout geometries from commercially available teapots, coffee pots, and milk jugs under realistic operating conditions. Experiments were performed using three fluids with contrasting rheological properties: boiling black tea, cow’s milk, and Turkish coffee on a precision rotating platform operating at quasi-static (1°/s) to isolate surface tension, gravitational, and geometric effects from inertial forces. Three quantitative parameters were measured for each specimen: capillary dome angle, teapot effect angle range, and optimum pouring angle. Results demonstrate that spout tip geometry is the dominant controlling parameter. Thin-lipped elliptical cross-sections effectively suppressed dripping, whereas triangular and wide curved geometries produced the teapot effect across broad pouring angle ranges reaching up to 70°. A spout outlet extension length of 4–5 mm combined with a spout tip radius below 4 mm was found necessary and sufficient for clean flow separation. Furthermore, suspended particles and proteins in milk and Turkish coffee were shown to intensify the teapot effect by disrupting contact line dynamics at the spout tip. These findings provide quantitative design thresholds directly applicable to industrial kitchenware development. Full article

Al/Mg bimetallic composites have drawn considerable attention for their promising lightweight applications in sectors such as the aerospace and automotive industries. In these systems, the interfacial behavior critically governs the overall performance and reliability. In this research, the molecular dynamics (MD) simulation was employed to systematically study the effects of pouring temperatures (923 K, 973 K, and 1023 K) and preheating temperatures (373 K, 473 K, and 573 K) on the interfacial diffusion behavior and fracture mechanism of the polycrystalline Al/Mg bimetallic system. The results indicate that the influencing rule of pouring temperatures and preheating temperatures on the interfacial diffusion behavior is consistent. Specifically, the diffusion coefficient of Mg atoms is higher than that of Al atoms, while the diffusion distance of Al atoms is significantly greater than that of Mg atoms. As the temperature increases, the thickness of the interfacial transition layer correspondingly rises. However, the effects of these two parameters on tensile fracture behavior demonstrate notable discrepancies. Specifically, the fracture mode evolves with pouring temperature, transitioning from being mediated solely by dislocations to being co-mediated by twins and dislocations. In contrast, the fracture mechanism remains solely dislocation-controlled, regardless of the preheating temperature. In addition, all the models fractured at the interface between the diffusion layer and the Mg matrix. The optimal tensile strength of 1.850 GPa was achieved at a pouring temperature of 923 K and a preheating temperature of 473 K, representing an improvement of approximately 52% compared to the lowest value recorded in the study. This research offers significant theoretical insights for the rational optimization of preparation parameters and an in-depth understanding of fracture mechanisms in Al/Mg bimetallic systems. Full article

This study investigates the synthesis and physicochemical characterization of biolubricant base oils derived from sunflower oil methyl esters (SUNOMEs) via transesterification with trimethylolpropane (TMP) using guanidine carbonate (GNDC) as a green and efficient catalyst. The transesterification process was optimized to achieve high conversion and desirable physicochemical properties suitable for lubrication applications. The synthesized esters were characterized by viscosity, density, pour point, and oxidation stability, confirming their suitability as environmentally friendly lubricants. Reaction parameters, such as catalyst concentration (3.0–5.0 wt%), were optimized under both solvent-free and vacuum-assisted conditions. The use of guanidine carbonate achieved enhanced physicochemical properties with significantly reduced reaction times (≈6 h) and eliminated soap formation. The resulting TMP triesters exhibited kinematic viscosities in ranges of 41.27–52.73 cSt (40 °C) and 8.668–10.02 cSt (100 °C), a viscosity index in the range of 180–196, and excellent oxidation stability (RSSOT: up to 54.27 min). Fourier transform infrared (FTIR) analysis confirmed the formation of complete triester structures with characteristic carbonyl and C–O stretching bands at 1735 cm⁻¹ and 1050 cm⁻¹, respectively. Spectra showed also distinct stretching vibrations near 1640–1670 cm⁻¹ and 3300–3400 cm⁻¹, which correspond to amide carbonyl and N–H characteristic groups. The tribological performance was evaluated using Four-Ball Standard Test Method, demonstrating significant improvements compared to commercial mineral oils. The results indicate that guanidine carbonate is an effective catalyst for producing sunflower-oil-derived esters with favorable lubricating properties, highlighting their potential as sustainable biolubricants for industrial applications. Full article

The quantitative evaluation of the impact of wax-solid deposition on the CO₂ displacement of high-pour-point oil has long been a challenge in gas-flooding experiments. This study employs slim tube experiments to simulate the displacement dynamics, and comprehensively evaluates the productivity/injectivity index formula and the GERG-2008 state equation. The results indicate that the fluctuations in this index remain stable within the 17–20 MPa range and become pronounced within the range of 30–40 MPa. The analysis of seepage velocity reveals an initial increasing trend for supercritical CO₂ under the conditions of 30 MPa, 35 MPa, and 40 MPa, followed by inflection points at different time steps. The observed decline in seepage velocity inflection is associated with the occurrence of wax-solid deposition in high-pour-point oil. Notably, there is a significant surge in CO₂ seepage velocity at 40 MPa during the latter stage of the experiment due to the release-blockage effect of supercritical CO₂. To systematically analyze the influence of wax-solid on the CO₂ displacement in high-pour-point oil, a methodological framework is established in this study. This approach enables precise analysis of displacement dynamic characteristics in the target areas and provides pressure parameters for oilfields. Full article

Porosity formation due to solidification shrinkage and inadequate liquid metal feeding during the casting of Sn-0.3Ag-0.7Cu (SAC0307) is a critical issue that impairs quality and subsequent processing. However, the opacity of the casting process often obscures the quantitative relationships between process parameters and defect formation, creating a significant barrier to science-based optimization. To address this, the present study utilizes finite element method (FEM) analysis to systematically investigate the influence of pouring temperature (PCT, 290–390 °C) and interfacial heat transfer coefficient (HTC, 900–5000 W/(m²·K)) on this phenomenon. The results reveal that PCT exerts a non-monotonic effect on porosity by modulating the solidification mode, which governs the accumulation of dispersed microporosity. In contrast, HTC plays a critical role in determining porosity morphology by controlling both the solidification rate and mode. Consequently, an optimal processing window was identified at 350 °C PCT and 3000 W/(m²·K) HTC, which significantly enhances interdendritic feeding and improves the ingot’s internal soundness. The efficacy of these optimized parameters was experimentally validated through macro- and microstructural characterization. This work not only elucidates the governing mechanisms of solidification quality but also demonstrates the value of numerical simulation for process optimization, offering a reliable scientific basis for the industrial production of high-quality SAC0307 alloys. Full article

Obtaining a good casting surface without defects requires proper preparation of the mould for the given metal alloy. It is important to select the appropriate moulding sand, which consists of a grain matrix and a binder. Due to the temperature and dynamics of the poured alloy, it is also important to apply a suitably selected protective coating to the surface of the mould. Depending on its chemical composition, the carrier used (water or alcohol), and the method of application, it is possible to create the most favourable conditions for obtaining a flawless casting. This article presents the impact of various protective coatings applied to moulding sand on a chromite matrix, comparing their technological parameters and selecting the best one for the given application conditions. During commonly used tests on moulding sand with a protective coating, its permeability, abrasion, and adhesion were determined. To verify the results obtained, microscopic photographs of the prepared surface layers of the moulding sand with a protective coating were also taken. It was found that, despite the same viscosity, the same carrier, and the same application method, the quality of the protective coating is determined by its appropriate composition developed by the manufacturers. The permeability of P^u moulding blocks after coating was found to be significantly reduced, from 255 to 37 [×10⁻⁸ m²/Pa × s]. The use of protective coatings significantly increased the moulding sand’s abrasion resistance, reducing the loss value from 0.826% to 0.330% for the weakest coating. In the group of protective coatings tested, the coating marked PC1M in the tests had the highest adhesion N_p and its value, depending on the application method, ranged from 0.30 MPa to 0.37 MPa. Full article

Aluminum alloy 2024 (AA2024) is widely used in the aerospace sector, where a fine, uniform, and equiaxed grain structure is crucial for achieving enhanced mechanical properties. This study examines the effect of dynamic solidification, assisted by mechanical vibrations and conformal cooling, on the microstructural evolution and mechanical properties of permanent mold-cast AA2024. Mechanical vibrations were applied during solidification in the frequency range of 15–45 Hz and acceleration of 0.5–1.5 g. Process parameters, including pouring temperature, die temperature, vibration frequency, and acceleration, were optimized using an L9 orthogonal array based on the Taguchi method. Analysis of variance (ANOVA) was performed to determine the significance of the aforementioned process parameters. In addition, the alloy’s microstructure was observed through a microscope, which revealed a transition from dendritic to non-dendritic microstructure due to dynamic solidification. The average grain size of the alloy was significantly reduced by 40.9%. Moreover, the values of hardness and Ultimate Tensile Strength (UTS) of the alloy were improved by 13.5% and 10.6%, respectively. Optimal results were obtained at a pouring temperature of 750 °C, die temperature of 150 °C, frequency of 45 Hz, and acceleration of 1.0 g. Moreover, uncertainty analysis for all three responses was also performed. Full article

A series of poly(5-n-butyl-2-norbornene) oils with controlled molecular weights was synthesized via metathesis polymerization, fully hydrogenated, and characterized in terms of viscosity and tribological performance. In contrast to established lubricant base stocks—such as poly(α-olefins) and multiply alkylated cyclopentanes—these novel norbornene-based polymers remain underexplored, despite their promising anti-wear activity. Based on differential scanning calorimetry (DSC) data, all the synthesized products are amorphous compounds whose thermograms show a single glass transition temperature. The effect of molecular weight and temperature on the viscosity of poly(5-n-butyl-2-norbornene) oils was quantified over an extended temperature range, including extra-cold conditions down to −80 °C. The pour points of the oils were determined and can be as low as −66 °C, indicating excellent low-temperature fluidity. The tribological performance of the synthesized oils was evaluated using the four-ball test, with friction coefficient and wear scar diameter measured to assess anti-wear and antifriction properties. The tribological results were benchmarked against commercially available polyalphaolefin (PAO) oils (PAO-4, PAO-20, and PAO-80). Metathesis and hydrogenated poly(5-n-butyl-2-norbornene) oils outperform conventional PAOs by up to 67% in wear protection and 30% in friction reduction. These findings establish alicyclic molecular strain as a viable design parameter for next-generation lubricating oils, thereby expanding the toolbox for material development beyond conventional chemical functionalization. Full article

Recent research has focused on yogurts supplemented with plant-derived and apiculture ingredients to enhance functional properties. This study evaluates the symbiotic potential of provitamin A carotenoids, dietary fiber, and oligosaccharides from carrots, mangoes, and honeydew honey in probiotic-enriched bioyogurt. Formulations were assessed during fermentation (45 °C ± 1 °C for 5 h) and refrigerated storage (4 °C ± 1 °C for 21 days). Probiotic and starter culture viability was determined using pour-plate counts on MRS agar. Physicochemical parameters including pH, titratable acidity, total soluble solids, water-holding capacity, and antioxidant metrics (total phenolics and carotenoids) were analyzed. After 21 days of storage, the probiotic culture (VEGE 092) reached 10.26 log CFU/mL and the starter culture (YOFLEX) achieved 8.66 log CFU/mL, maintaining therapeutic thresholds. Total carotenoid content increased significantly (p < 0.05) from 2.15 to 3.96 µg β-carotene/g, indicating synergistic interactions between lactic acid bacteria and plant-derived bioactive compounds. These findings demonstrate that combining plant-derived carotenoids, prebiotic fibers, and honeydew oligosaccharides effectively maintains probiotic viability and enhances antioxidant stability throughout fermentation and refrigerated storage, supporting the development of functional dairy products with improved nutritional profiles. Full article

Gastrointestinal strongyle infections are a common challenge in dairy goat farming, potentially impacting animal health and milk production. We, therefore, conducted a study to evaluate the efficacy of pour-on eprinomectin (EPM) in early-lactating dairy goats naturally infected with gastrointestinal strongyles and to verify the related effects on milk yield and quality. A total of 42 pluriparous Camosciata delle Alpi goats, from two farms (F1 and F2), were involved in the trial. In each farm, the goats were divided into two groups: untreated (CONTROL) or treated (EPM, 1 mg/kg BW). Following the treatment, faeces were individually collected weekly for one month, subjected to copromicroscopic analysis, a faecal egg count reduction (FECR) test, and coproculture; according to the same time schedule, individual milk yield was recorded, and individual milk samples were collected and analysed (fat, protein, lactose, and somatic cell count). Data were statistically analysed by a mixed-model procedure for repeated measures over time. The low efficacy of EPM was demonstrated at all experimental times; overall FECR percentages (90% CI lower and upper bounds) were 39.00% (30.12–50.53) for F1 and 38.82% (30.08–50.10) for F2. Coprocultures allowed the identification of larvae of the genera Haemonchus, Teladorsagia, and Trichostrongylus. Goats treated with EPM showed a lower prevalence of Teladorsagia and Trichostrongylus larvae, and higher prevalence of Haemonchus larvae, compared with CONTROL goats (p < 0.001). The treatment did not significantly improve milk yield or overall milk composition. Full article

In recent years, construction has started on several high arch dams in the southwestern region of China, and the problem of concrete crack prevention has become prominent. During the construction period of the foundation gallery of high arch dams, the stress is high and there are many influencing factors, making it more prone to cracking, and there is relatively little systematic research on this issue. This article focuses on the cracks in the 733 m gallery of the 7th section of a super-high arch dam. Using self-developed 3D finite element software, the stress spatiotemporal distribution and influencing factors during the construction period were analyzed. Research has shown that a decrease of 4 °C in the average annual temperature inside the gallery results in an increase of approximately 0.25 MPa in surface stress on the arch and bottom plates. When poured to an elevation of 870 m, the circumferential stress caused by the self-weight on the arch of the gallery is 2.3 MPa, but it decreases to 0.9 MPa at a distance of 0.3 m from the surface of the arch. The stress at both ends of the bottom plate before and after the arch sealing is always greater than that in the middle, with a maximum stress of about 2.4 MPa. The selection of material parameters has a significant impact on the evaluation of crack resistance. When calculating the mechanical parameters of fully graded concrete, the crack resistance safety of the arch crown and bottom plate is significantly reduced. It is recommended to focus on strengthening the water cooling and “winter period” insulation measures for the arch crown and bottom plate during gallery construction and to use fully graded test parameters in simulation analysis to improve calculation accuracy and structural safety. The research results can provide reference for similar projects. Full article

Resin-based binders are one of the main materials used in foundry molding and core sands. Self-curing sand with furfuryl resin is one of the most popular technologies in the production of molds and cores for complex, critical castings made of iron and non-ferrous alloys. It has dominated small-batch production and the production of large-sized castings. This work is part of the research on new molding sands for mold additive manufacturing (3D printing). Three-dimensional printing technology in the production of sand-casting molds and cores is finding increasing industrial application in the production of castings from non-ferrous metal alloys. The aim of the research presented in this paper was to determine the influence of furfuryl resin type (classical and designed for 3D printing of sand molds) on cast iron casting properties. The pouring parameters were elaborated on the basis of the MAGMA software. Microscopic observations of castings, produced in classical and 3D-printed molds, were conducted, as well as an assessment of the roughness of the samples. The gas emissions from molding sands with both types of furfuryl resin were tested and analyzed in the context of the roughness of the castings obtained. It was proven that molding sand with furfuryl resin designed for 3D printing was characterized by lower gas emissions, which, in the case of molding sands with organic binders, is beneficial from an environmental point of view. Full article

The freezing method is widely employed in the construction of a vertical shaft in soft soil and water-rich strata. As the construction depth increases, investigating the water–heat–force coupling effects induced by the hydration heat (internal heat source) of concrete is crucial for the safety of the lining structure and its resistance to cracking and seepage. A three-dimensional coupled thermal–hydraulic–mechanical analysis model was developed, incorporating temperature and soil relative saturation as unknown variables based on heat transfer in porous media, unsaturated soil seepage, and frost heave theory. The coefficient type PDE module in COMSOL was used for secondary development to solve the coupling equation, and the on-site temperature and pressure monitoring data of the frozen construction process were compared. This study obtained the model-related parameters and elucidated the evolution mechanism of freeze–thaw and freeze–swelling pressures of a frozen wall under the influence of hydration heat. The resulting model shows that the maximum thaw depth of the frozen wall reaches 0.3576 m after 160 h of pouring, with an error rate of 4.64% compared to actual measurements. The peak temperature of the shaft wall is 73.62 °C, with an error rate of 3.76%. The maximum influence range of hydration heat on the frozen temperature field is 1.763 m. The peak freezing pressure is 4.72 MPa, which exhibits a 5.03% deviation from the actual measurements, thereby confirming the reliability of the resulting model. According to the strength growth pattern of concrete and the freezing pressure bearing requirements, it can provide a theoretical basis for quality control of the lining structure and a safety assessment of the freezing wall. Full article

The suspension arm is a crucial connecting component in the automotive powertrain system, required to withstand various working condition loads, thus necessitating high mechanical performance. With the continuous development of forming processes, the forming method of suspension arms has gradually shifted from traditional gravity casting to squeeze casting. Along with the demand for automotive lightweighting, there is an urgent need for lightweight requirements in suspension arm components. This study employs a multi-condition topology optimization method, incorporating the forming requirements of the squeeze casting process, to conduct lightweight design of a certain mounting bracket. The filling and solidification processes were numerically simulated using Anycasting, followed by mechanical property testing and microstructure analysis of the product. The results revealed that the topology-optimized suspension arm met the strength and stiffness requirements under all working conditions, with a mass reduction of approximately 54.7% compared to the pre-optimized version. Based on the forming process analysis of the suspension arm, the design of its squeeze casting mold was completed. Using AnyCasting software (AnyCasting 6.7), numerical simulations of the filling and solidification processes of the suspension arm were conducted. Combined with theoretical calculations, the forming process parameters for the suspension arm were finally determined as follows: extrusion speed of 15 cm/s-10 cm/s-5 cm/s (multi-stage speed), pouring temperature of 690 °C, mold temperature of 250 °C, extrusion pressure of 81.4 MPa, and holding time of 45 s. Through T6 heat treatment, the tensile strength, yield strength, and elongation after fracture of the suspension arm reached 326.05 MPa, 276.87 MPa, and 9.68%, respectively. Metallographic analysis showed that the eutectic silicon in the T6 heat-treated specimens was primarily spherical in shape, uniformly distributed without significant clustering. The reason for this difference may be that heat treatment affects the boundary dissolution degree of alloying elements. For eutectic Al-Si alloys, the boundary dissolution and diffusion of alloying elements are accelerated, which is beneficial for improving the mechanical properties of the alloy. Finally, in order to quantitatively analyze the microstructural properties of the material after heat treatment, analyses of secondary dendrite arm spacing and porosity were conducted, leading to the conclusion that the microstructure after heat treatment is more uniform and dense. Full article

Mineral oil-based lubricants contain harmful elements, such as sulfur and phosphorus, pose significant harm to the environment. In current research on the application of waste oils and fats in bio-based lubricants, most studies focus on single pretreatment processes or additive preparation, lacking systematic investigations into the combined use of composite pretreatment and additives on lubricant performance. Moreover, the decolorization efficiency of traditional physical adsorption methods for treating waste oils and fats is limited, making it difficult to meet the raw material requirements for bio-based lubricants. The purpose of this study is to conduct composite pretreatment processes on waste oils and fats, understand the impacts of parameters such as additive dosage and environmental factors on lubricant performance, establish an environmentally friendly and performance-compliant preparation process for bio-based lubricants, and provide a theoretical basis and technical support for its industrial application. Recent studies have shown that new decolorization processes for waste oil treatment significantly improve decolorization and recovery rates, as evidenced by research comparing new and traditional methods. Pretreatment with hydrogen peroxide, activated clay, and activated carbon significantly improved the color and odor of treated waste oil, meeting standards for bio-based lubricant production. The intercalation polymerization reaction between ethyl cellulose (EC) and montmorillonite (MMT) was employed to develop an additive (CTAB-MMT/KH560-EC). A thorough investigation was performed to analyze the impact of temperature, processing time, and additive concentration on the rheological behavior. The bio-based lubricant exhibited a kinematic viscosity of 200.3 mm²/s at 40 °C and 28.3 mm²/s at 100 °C, meeting the standard conditions as outlined in ASTM D2270-10e1. This lubricant achieved an improved low-temperature performance with a pour point of −22 °C, a friction coefficient of 0.081, and an average pitting diameter of 0.94 mm, indicating its suitability for a range of applications. These lubricants exhibit outstanding viscosity characteristics, meeting the relevant requirements for energy and environmental applications in green, eco-friendly, and biodegradable sustainable development strategies while expanding their application scope. Full article