Material Design & Processing Communications最新文献

Support structures are essential in additive manufacturing (AM) processes such as material extrusion, particularly for fabricating parts with overhanging features. However, conventional supports are typically removed after printing and cannot be reused, resulting in significant material waste and increased printing time. To address these limitations, this research introduces a novel multi-cell FDM build bed support system designed to minimize support-related challenges in fused deposition modeling (FDM). The proposed system employs an array of movable pins that function as a dynamically adjustable build platform controlled by an Arduino-based program. During the printing process, the pins elevate layer by layer, corresponding to the layer thickness. Each pin automatically stops at a predetermined height through an electromechanical control system. The lifting mechanism operates via a programmable stepper motor, whereas magnetic coupling between permanent magnets and metallic washers ensures stable support and protects the printed component from damage during detachment. Additionally, a hybrid support approach has been developed for printing curved geometries. This method combines traditional printed supports with the multi-cell FDM bed system, allowing the adjustable platform to provide sufficient support and significantly reduce the need for printed material. For highly complex overhangs beyond the bed′s adjustable range, conventional supports are selectively employed. Experimental results demonstrate that the proposed multi-cell FDM build bed system achieves up to 16.22% reduction in material consumption and 22.19% reduction in printing time compared with tree support and conventional FDM printing methods.

Friction stir spot welding (FSSW) effectively solves many problematic welding metals, such as dissimilar metals and thin alloy sheets. Carbon steel-AISI 1006 top sheet and an aluminum alloy AA2024-T3 bottom sheet were joined by FSSW with a cylindrical pinless tool. Joints are evaluated in terms of temperature, mechanical characteristics, microstructure, and macrostructure. With the other variables of the welding operation being constant, the influence of spindle speed, dwell duration, and penetration depth on the force of tensile shear failure has been studied throughout the welding process. The welding parameters were 10 and 15-s preheating time, 0.2, 0.4, and 0.6 mm plunging depth. Rotational speed was 710, 900, 1400, and 1800 rpm. A shear tensile test was utilized to examine the bonded specimens. At the optimal conditions, a microstructural analysis was conducted. Both interfacial and pullout fractures were found in the AA2024-T3 and carbon steel sheets. Intermetallic compounds (IMCs) located at the weld interface were evaluated.

This study utilized epoxy as a matrix for biocomposites reinforced with chicken feather fibers, which were produced by a manual mixing technique. Various loadings of feather fibers of 0.5, 1, 1.5, and 2 wt% were utilized following chemical treatment. Optical and scanning electron microscopies were employed to examine the morphological structure of biocomposites. Additionally, tensile, bending, impact, and hardness tests were conducted to assess the mechanical properties of biocomposites. Low fiber loadings of 0.5 and 1 wt% yielded enhanced mechanical properties relative to 1.5 and 2 wt% feather fiber loadings, attributable to better dispersion and integration within the epoxy matrix, as corroborated by morphological images. The manual mixing technique was more appropriate for feather loading below 2 wt%. Furthermore, the simulated results aligned well with the experimental tensile outcomes. The eco-friendly materials developed in this study could serve alternative applications, significantly reducing chicken feather waste in the environment and mitigating pollution issues.

Measuring corrosion in reinforcing steel embedded in mortar or concrete is a challenge that must always be considered. Electrochemical impedance spectroscopy (EIS) provides a useful estimation of corrosion rates, but its complexity and sensitivity mainly confine it to laboratory testing. On the other hand, the LCR meter, a small and portable device commonly used for testing circuits, measures impedance, capacitance, and inductance. Applying the EIS approach, which views elements as arrays of resistances and capacitances, allows inferring that it is possible to measure corrosion with the LCR meter by comparing it with EIS. To explore this, tests were conducted on cylindrical mortar samples with reinforcing steel, following a 2 × 3 factorial design with three replicates. After accelerated corrosion, a linear relationship was observed between the Rct parameter from EIS and the 100 Hz impedance from the LCR meter in samples subjected to impressed current. However, in samples subjected to carbonation, the techniques could not be correlated, possibly because the carbonation front had not yet depassivated the steel. The combination of chlorides and carbonation showed opposite effects: chlorides reduce the impedance of the mortar cover, while carbonation increases its resistivity. These results are a first step towards developing a new corrosion detection method based on the LCR meter, offering advantages in handling, time, cost, and portability.

This study investigates friction-assisted spot joining (FASJ) of Ti6Al4V alloy and carbon fiber–reinforced polyphenylene sulfide (CF-PPS) composites using electrical discharge machining (EDM) surface pretreatment combined with process parameter optimization. EDM texturing generated superficial roughness that promoted mechanical interlocking between the molten polymer and the titanium surface. A central composite design was applied to evaluate the effects of rotational speed (RS) and plunge depth (PD), identifying optimal conditions that maximized lap shear strength while minimizing polymer degradation. Results showed that intermediate RSs favored bond formation by maintaining temperatures within the PPS melting range and preventing excessive thermal damage. Posttest characterization confirmed the formation of a bonded annular region that governed joint performance. The optimized process achieved lap shear strength values comparable to and, in some cases, exceeding those reported for other metal–composite joining techniques. Specifically, the EDM texturing process reached 33.1 MPa, outperforming most laser-welded Ti/CF-PEEK joints (2–37.3 MPa) and approaching the strength levels typically observed in aluminum–polymer benchmarks (≈55 MPa). These results demonstrate the effectiveness of the EDM-induced surface features in enhancing mechanical interlocking and interfacial adhesion. These findings demonstrate that combining EDM pretreatment with controlled thermal input enhances the reliability of FASJ for lightweight structural applications.

Refractory high-entropy alloys (RHEAs) have emerged as promising materials. They offer a viable alternative to nickel-based superalloys due to their excellent mechanical property stability at high temperatures, superior oxidation and corrosion resistance, and phase stability under extreme conditions. In this study, three different RHEA compositions of W_xTi_xMoNbTaV RHEAs (x₁ = (1, 0), x₂ = (0, 1), and x₃ = (0.5, 0.5)) were synthesized by partially or fully substituting titanium for tungsten under identical conditions to investigate the effect of this modification on the microstructure. Mechanical alloying was performed for 60 h to obtain powders with a single-phase BCC structure, followed by spark plasma sintering (SPS) at temperatures varying from 1200°C to 1400°C. XRD results indicated a relative stability of the BCC phase structure, with some phase segregations leading to the formation of some secondary phases in low percent. These secondary phases′ proportion and chemical composition varied depending on the alloy composition and sintering temperature. On the other hand, elevating the sintering temperature clearly enhances densification, although the extent of enhancement differs according to various alloy designs. Finally, the presence of the ductile-element–enriched phases is expected to significantly influence the microstructure and contribute to the enhancement of mechanical properties, which will be explored in a subsequent study.

This review paper provides a comprehensive analysis of the advancements and future directions in oil–water membrane technology, a critical solution for addressing environmental challenges associated with wastewater treatment and oil pollution. The review focuses on various membrane technologies employed in oil–water separation, including microfiltration, ultrafiltration, and nanofiltration, highlighting their effectiveness and operational mechanisms. It discusses key challenges encountered by these technologies, such as membrane fouling, high operational costs, and limitations in large-scale applications, which hinder their broader adoption. The paper further examines the characteristics of oil–water membranes, including hydrophilicity, oleophobicity, pore size, and surface roughness, which are crucial in determining separation efficiency. Commonly used materials for developing oil–water filtration membranes are also explored, encompassing polymeric, ceramic, and hybrid materials, with a focus on innovations that enhance performance and sustainability. Additionally, the evaluation of membrane performance is addressed through metrics such as flux, rejection rate, and fouling resistance, offering insights into their suitability for various applications. The review also investigates the parameters varied during oil–water filtration, such as pressure and temperature, and their impact on membrane efficiency and durability. This paper is aimed at providing a roadmap for future research and development in oil–water membrane technology, emphasizing the need for durable, fouling-resistant membrane designs and the exploration of cost-effective materials (such as quartz-based media) to meet global water treatment demands.

Manufacturers, particularly those working in the mould and die industry, encounter several challenges in achieving the optimal surface finish. Approximately 40–60 HRC hardened hot working tool steel is used for the majority of the mould and die materials. Because of the tremendous strength of these materials, the conventional machining processes were limited in their capacity to machine them. When using conventional machining, it will encounter issues such as high tool wear rates and a poor machined surface finish. To address these issues, this research presented a hybrid machining method that incorporates ultrasonic vibration in an axial orientation into the conventional system tooling, referred to as ultrasonic vibration-assisted milling (UVAM), to solve the issues mentioned above. This research was undertaken to understand the effect of axial UVAM parameters on AISI H19 hardened hot working tool steel surface finish. To verify the efficiency of the suggested approach in improving the level of hardened AISI H19 tool steel machined surface roughness, we compared conventional milling (CM) to UVAM for various parameters, including milling spindle revolving speed, rate of feed and cutting depth. Axial UVAM dramatically reduced the machined surface roughness, with up to a 36.7% decrease in the value of Ra compared to the CM approach under the same cutting circumstances, according to the results of the milling tests. The surface prepared by UVAM was homogeneous and had proportionate peak-to-peak magnitude, which enhanced the surface quality, according to the macroscopic examination of the machined surface. Ra values have been strongly affected by the interlinkage between the cutting variables investigated. Continual hammering between the workpiece and cutter teeth greatly influences surface roughness, which is greatly influenced by frequency vibration. When ultrasonic vibration is applied, the level of surface roughness drops dramatically.

Recent research has shown a growing interest in refractory high-entropy alloys (RHEAs) due to the increasing demand for materials that exhibit exceptional mechanical strength, high ductility, excellent thermal stability and superior resistance to oxidation and corrosion. This study focuses on designing and fabricating three W_xTi_xMoNbTaV RHEAs to achieve an optimal balance between strength and ductility at room temperature. The selection strategy was based on leveraging the high strength of tungsten (W) and the excellent ductility of titanium (Ti) to develop an alloy with superior mechanical performance. Three distinct compositions (x₁ = [1, 0], x₂ = [0, 1] and x₃ = [0.5, 0.5]) were synthesised under identical conditions using mechanical alloying (MA), followed by spark plasma sintering (SPS). In our previous study, we conducted an in-depth characterisation of phase transformations during MA and the microstructural evolution after SPS. As a continuation of that research, this study explores the mechanical behaviour of these alloys, revealing exceptional properties. The results demonstrated that the combination of Ti and W is the most effective approach for developing RHEAs with an optimal strength–ductility balance, along with significantly high hardness values, achieving an impressive strength of 1300 MPa and ductility exceeding 20% at room temperature, underscoring their potential for advanced structural applications. These results locate W_xTi_xMoNbTaV alloys as strong candidates for applications in extreme refractory environments and present a promising alternative to conventional nickel-based superalloys for applications in turbines and nuclear reactor walls.

The reduction of fiber diameter from micro to nanolevel greatly enhances the surface area, thermal properties, filtration efficiency, reactivity, and overall functionality. Using a blend of polyacrylonitrile (PAN) and ethylene-co-vinyl alcohol (EVOH), solution electrospinning was employed to develop ultrafine nanofibers with a diameter of a few hundred nanometers. The impact of different weight percentages of EVOH blended with PAN on fiber diameters was studied. Fiber diameters drastically decreased with higher EVOH content in the blend, and a slight reduction was observed following isopropyl alcohol (IPA) treatment. The initial diameters of PAN-incorporated EVOH (POH) nanofibers were between 880 and 47 nm, which were reduced to 719 and 41 nm after IPA treatment. The smallest diameter of 102 nm was achieved by POH nanofibers with 75% EVOH after IPA treatment. Furthermore, the thermal properties demonstrate a synergistic effect with the melting temperature increasing from 290°C for pure PAN to 301°C for POH nanofiber with 75% EVOH. The fabricated ultrafine nanofibers with enhanced thermal properties can be applied in advanced air and water filtration systems.