Search Results (26)

In this study, we examined how printing temperature affects the microstructure and mechanical properties of polylactic acid (PLA) composite reinforced with iron oxide i.e., magnetite manufactured using a material extrusion technique. The composite was printed at temperatures from 185 °C to 215 °C. Microstructure analysis via synchrotron radiation X-ray microtomography revealed changes in both iron oxide and porosity contents within the printed structures. Mechanical testing results demonstrated a limited effect of the printing temperature on tensile performance. Finite element computation is considered to predict the elasticity behavior of the printed composite by converting 3D images into 3D structural meshes. When implementing a two-phase model, the predictions show a leading role of the iron oxide content, and an overestimation of the stiffness of the composite. A three-phase model demonstrates a better matching of the experimental results suggesting a limited load transfer across the PLA-iron oxide interface with Young’s moduli in the interphase zone as small as 10% of PLA Young’s modulus. Magnetic actuation demonstrates that experiments on PLA-iron oxide plates reveal a pronounced thickness-dependent limitation, with the maximum deflection observed in thin strips of 0.4 mm. Full article

Snack foods (e.g., extruded flour-based products) are widely favored by consumers because of their convenience, affordability, and time-saving attributes. However, with the growing demand for high-quality snacks, several challenges have emerged that hinder industry development, such as relatively underdeveloped industrial standards, limited raw material diversity (primarily starch and soy protein), and, consequently, insufficient nutritional value. In this study, a novel type of puffed snack was developed using Alaskan pollock surimi and wheat flour using extrusion puffing technology. The effects of varying ratios of surimi to wheat flour (0:10, 1:9, 2:8, 3:7, and 4:6, which served as SFBC, SFB1, SFB2, SFB3, and SFB4, respectively), on the physicochemical properties, apparent morphology, microstructure, thermal stability, and protein structure of spicy strips were systematically investigated, and the interaction between extruded protein and flour mixtures was analyzed. The results indicated that increasing the proportion of surimi led to decreases in hardness, elasticity, and chewiness, whereas the moisture content and water solubility index increased. The maximum expansion rate (202.2%) was observed in the SFB1 sample. Morphological and microstructural observations further revealed that a higher surimi content resulted in a denser internal structure and a reduced degree of puffing. The protein distribution was relatively uniform, with large pores. Moreover, increased surimi content increased the proportion of immobilized water and improved the thermal stability. These findings provide valuable insights into starch–protein-complex-based extrusion puffing technologies and contribute to the development of innovative surimi-based puffed food products. Full article

Ferronickel slag and ground granulated blast-furnace slag (GGBFS) are solid waste by-products from the metallurgical industry. When incorporated into concrete, they help promote resource utilization, reduce hydration heat, and lower both solid waste emissions and the carbon footprint. To facilitate the application of ferronickel slag–GGBFS concrete in 3D printing, this study examines how aggregate size and nozzle diameter affect its performance. The investigation involves in situ printing, rheological characterization, mechanical testing, and scanning electron microscopy (SEM) analysis. Results indicate that excessively large average aggregate size negatively impacts the smooth extrusion of concrete strips, resulting in a cross-sectional width that exceeds the preset dimension. Excessively small average aggregate size results in insufficient yield stress, leading to a narrow cross-section of the extruded strip that fails to meet printing specifications. The extrusion performance is closely related to both the average aggregate size and nozzle diameter, which can significantly influence the normal extrusion stability and print quality of 3D printed concrete strips. The thixotropic performance improves with an increase in the aggregate size. Both compressive and flexural strengths improve with increasing aggregate size but decrease with an increase in the printing nozzle size. Anisotropy in mechanical behavior decreases progressively as both parameters mentioned increase. By examining the cracks and pores at the interlayer interface, this study elucidates the influence mechanism of aggregate size as well as printing nozzle parameters on the mechanical properties of 3D printed ferronickel slag–GGBFS concrete. This study also recommends the following ranges. When the maximum aggregate size exceeds 50% of the nozzle diameter, smooth extrusion is not achievable. If it falls between 30% and 50%, extrusion is possible but shaping remains unstable. When it is below 30%, both stable extrusion and good shaping can be achieved. Full article

Lateral flow tests (LFTs) had a pivotal role in combating the spread of the SARS-CoV-2 virus throughout the COVID-19 pandemic thanks to their affordability and ease of use. Most of LFT devices were based on nitrocellulose membrane strips whose industrial upscaling to billions of devices has already been extensively demonstrated. Nevertheless, the assay option in an LFT format is largely restricted to qualitative detection of the target antigens. In this research, we surveyed the potential of UV nanoimprint lithography (UV-NIL) and extrusion coating (EC) for the high-throughput production of disposable capillary-driven, foil-based tests that allow multistep assays to be implemented for quantitative readout to address the inherent lack of on-demand fluid control and sensitivity of paper-based devices. Both manufacturing technologies operate on the principle of imprinting that enables high-volume, continuous structuring of microfluidic patterns in a roll-to-roll (R2R) production scheme. To demonstrate the feasibility of R2R-fabricated foil chips in a point-of-care biosensing application, we adapted a commercial chemiluminescence multiplex test for COVID-19 antibody detection originally developed for a capillary-driven microfluidic chip manufactured with injection molding (IM). In an effort to build a complete ecosystem for the R2R manufacturing of foil chips, we also recruited additional processes to streamline chip production: R2R biofunctionalization and R2R lamination. Compared to conventional fabrication techniques for microfluidic devices, the R2R techniques highlighted in this work offer unparalleled advantages concerning improved scalability, dexterity of seamless handling, and significant cost reduction. Our preliminary evaluation indicated that the foil chips exhibited comparable performance characteristics to the original IM-fabricated devices. This early success in assay translation highlights the promise of implementing biochemical assays on R2R-manufactured foil chips. Most importantly, it underscores the potential utilization of UV-NIL and EC as an alternative to conventional technologies for the future development in vitro diagnostics (IVD) in response to emerging point-of-care testing demands. Full article

A large number of MIG welding tests were carried out on a 3 mm thick 7075 aluminum alloy plate prepared by the self-developed jet forming–extrusion–drawing process of 7075 high-strength aluminum alloy welding wire, and the welding process of the welding wire and the change in the performance of the welded joint after T6 heat treatment were studied. The results show that the self-developed wire has a good forming joint and a wide welding process window: the welding speed is 5–7 mm/s, and the welding current is 100–150 A. The main precipitated phases in the joint were η(MgZn₂), S(CuMgAl₂), Mg₂Si, and Al₁₃Fe₄, which were continuously distributed at the grain boundaries in the form of coarse networks or long strips, which was an important reason for the weak performance of the joints. After the heat treatment of T6, the precipitated phase in the joint was greatly reduced, the element segregation phenomenon was improved, and the residual precipitated phase was mainly Al₁₃Fe₄ and a small amount of insoluble phase Fe and Si, and the recrystallization size of the heat-affected zone was refined. Through heat treatment, the average microhardness of the joint was increased from 110 HV to 150.24 HV, and the tensile strength was increased from 326 MPa to 536 MPa, reaching 97.5% of the strength of the base metal, indicating that the softening phenomenon was significantly improved after heat treatment, and the joint had excellent performance. Full article

This study systematically investigates the influence of the composite addition of Ce, La, and Ca elements on the microstructure evolution and mechanical properties of Mg-3Zn-1Mn/Sn (wt.%) alloys. It indicates that the strength of Mg-Zn-Mn series alloys is superior to that of Mg-Zn-Sn series alloys, due to the stronger restriction of nanosized Mn particles on the recrystallization process and grain growth compared with Mg₂Sn phases. The addition of the Ca-La-Ce elements significantly enhances the strength of the Mg-3Zn-1Sn alloy (YS increased by approximately 92.5%, UTS increased by approximately 29.2%, and EL decreased by nearly 52.2%), while for the Mg-3Zn-1Mn alloy, a balanced effect on both the strength and performance can be achieved. This difference mainly lies in the more pronounced refined effect on the grain size and the formation of a bimodal grain structure with strip-like un-DRXed grains and surrounding fine DRXed grains for the Mg-3Zn-1Sn alloy. In contrast, the addition of the Ca-La-Ce elements has a less obvious hindrance on the recrystallization process in the Mg-Zn-Mn series alloy, while significantly weakening the extrusion texture while refining the grains. Through in-depth characterization and experimental analysis, it is found that Sn and Ca can promote the formation of brittle and fine secondary phases. A nanoscale Sn phase (Mg₂Sn phase) is more likely to accumulate at the grain boundaries, and the size of the nanoscale Ca₂Mg₆Zn₃ in Mg-Zn-Mn series alloys is finer and more dispersed than that in Mg-Zn-Sn series alloys, thus strongly hindering recrystallization and refining the recrystallized structure of the alloy. Full article

This study investigates the impact of varying extrusion ratios on the microstructure and mechanical properties of AlSiCuFeMnYb alloy. Following hot extrusion, significant enhancements are observed in the microstructure of the cast rare earth aluminium alloy. Within the cross-sectional microstructure, the α-Al phase is reduced in size, and its dendritic morphology is eliminated. The morphology of the eutectic Si phase transitions from long strips to short rods, fine fibres, or granular forms. Similarly, the Fe-rich phase changes from a coarse skeletal and flat noodle shape to small strips and short skeletal forms resembling Chinese characters. The CuAl₂ phase evolves from large blocks to smaller blocks and granular forms, while the Yb (Ytterbium)-rich rare earth phase shifts from large blocks to smaller, more uniformly distributed blocks. In the longitudinal section, the structure aligns into strips along the extrusion direction, with the spacing between these strips decreasing as the extrusion ratio increases. At an extrusion ratio of 22.56, the alloy demonstrates superior mechanical properties with a tensile strength of 325.50 MPa, a yield strength of 254.44 MPa, a hardness of 143.90 HV, and an elongation of 15.47%. These represent improvements of 27.8%, 36.5%, 38.9%, and 236.4%, respectively, compared with the as-cast rare earth alloy. In addition, the fracture surface of the extruded rare earth alloy exhibits obvious ductile fracture characteristics. Additionally, the alloy undergoes dynamic recrystallisation and dislocation entanglement during hot extrusion. The emergence of a twinned Si phase and a dynamically precipitated nanoscale CuAl₂ phase are critical for enhancing deformation strengthening, modification strengthening, and dynamic precipitation strengthening of the extruded alloys. Full article

Raman spectroscopy was used to detect low quantities of Vismodegib in the skin after its topical application via transfersomes. Vismodegib is a novel antineoplastic drug approved for oral administration for treatment of basal cell carcinoma. Transfersomes loaded with Vismodegib were prepared by thin film resuspension and extrusion, and were characterized physicochemically. Transfersomes were applied to human and pig skin specimens using the Saarbrücken penetration model. The skin was then sectioned by tape stripping, followed by penetration assessment by UV-Vis spectroscopy and Raman spectroscopy in a confocal Raman microscope. Raman signals from Vismodegib and transfersomes were recovered from skin sections, showing a similar distribution in the stratum corneum obtained by the other techniques. On the other hand, pig and human skin showed differences in their penetration profiles, proving their lack of equivalence for assessing the performance of these transfersomes. Raman spectroscopy appears as a potential non-invasive, direct tool for monitoring hard-to-detect molecules in a complex environment such as the skin. Full article

The processing quality of steel bar thread has a large influence on its performance. Using the traditional thread processing technology, it is difficult to meet the requirements of steel bar thread processing with large diameter and high strength. A technical process for HRB500 high-strength steel bar thread processing, including face milling, rib stripping, chamfering, necking formation, and thread rolling, was proposed. The influences of cutting parameters on the cutting force of steel bar surface in face milling were analyzed by the finite element method. For the necking formation process, the effect of springback amount on necking formation was studied. The main parameters in rolling formation were analyzed and calculated, including extrusion pressure, rolling speed, and rolling feed. Experiments for uniaxial tensile of the processed high-strength steel bar threads were carried out. The results showed that cutting depth has the largest influence on the cutting force; the second is feed rate. The effect of the spindle speed was lowest during the face milling. After the necking formation process, the values of the maximum springback amount along the X, Y, and Z directions were 0.05 mm, 0.06 mm, and 0.98 mm, respectively. The finished thread met the precision and quality requirements of a grade I joint. This study provides a high-quality processing technology for large-diameter and high-strength steel bar threads. Full article

The paper investigates the effect of welding mode parameters on the uniformity of the deformation capacity of AISI 316 austenitic steel samples, namely, the influence of the welding current and purging gas consumption on the samples’ ability to perceive the force of cold cupping. Punch diameters of 3 and 8 mm were employed for the Erikson test to establish the dependence of the purge gas flow rate on the depth of the hole before the formation of cracks. The conducted metallographic studies confirmed an increase in the homogeneity of the dendritic structure in the weld zone due to the redistribution of heat input, as well as the absence of uneven grains and a decrease in the spread of grain sizes, which were in the range of 0.068–0.045 mm. The study resulted in determining the optimal range of technological parameters for the manufacture of flexible expansion elements to ensure their high operational properties. Full article

In this paper, regarding the example of concurrent extrusion of a round bar, the results of a comparative analysis of the impact of the extrusion ratio R on process parameters such as die wear intensity, extrusion force, stress intensity in the die, and its elastic deformation during extrusion are presented. The tests were carried out in a wide range of the R (1.5–11), assuming a constant outer diameter of the die. A comparative analysis of the wear was carried out in the area of the die corner radius and the calibration strip since the wear is the highest there. Based on the result obtained, it was shown that the increase in the extrusion force was not proportional to the increase in the extrusion ratio, and this could be described by a logarithmic equation. On the other hand, the value of equivalent stresses in the area of the die corner depends, to a relatively small extent, on the value of the extrusion ratio. However, due to the deformation of the die, it is most advantageous to use an extrusion ratio greater than or equal to three. Based on the wear analysis, it was estimated that the increase in the extrusion ratio R from 3 to 7 caused a more than 2.5 times increase in tool wear. In turn, the implementation of the extrusion process with the use of R = 11 caused a 4.5-fold increase in the average depth of die wear compared to its wear using the extrusion ratio R = 3. Full article

Antifriction alloys such as AlSn20Cu are key material options for sliding bearings used in machinery. Uniform distribution and a near-equiaxed granularity tin phase are generally considered to be ideal characteristics of an AlSn20Cu antifriction alloy, although these properties vary by fabrication method. In this study, to analyze the variation of the microstructure with the fabrication method, AlSn20Cu alloys are prepared by three methods: semi-continuous casting, semi-solid die casting, and spray forming. Bearing blanks are subsequently prepared from the fabricated alloys using different processes. Morphological information, such as the total area ratio and average particle diameter of the tin phase, are quantitatively characterized. For the tin phase of the AlSn20Cu alloy, the deformation and annealing involved in semi-continuous casting leads to a prolate particle shape. The average particle diameter of the tin phase is 12.6 µm, and the overall distribution state is related to the deformation direction. The tin phase of AlSn20Cu alloys prepared by semi-solid die casting presents both nearly spherical and strip shapes, with an average particle diameter of 9.6 µm. The tin phase of AlSn20Cu alloys prepared by spray forming and blocking hot extrusion presents a nearly equilateral shape, with an average particle diameter of 6.2 µm. These results indicate that, of the three preparation methods analyzed in this study, semi-solid die casting provides the shortest process flow time, whereas a finer and more uniform tin-phase structure may be obtained using the spray-forming process. The semi-solid die casting method presents the greatest potential for industrial application, and this method therefore presents a promising possibility for further optimization. Full article

In the process of rubber extrusion, the feed structure directly affects the extrusion quality, extrusion uniformity, screw lateral force, and feed power consumption. Until now, the feed structure was mainly based on empirical designs, and there was no theoretical model for the optimal design of a feed structure. This paper focused on the squeezing mechanical analysis and model establishment of the feeding process in which viscoelastic rubber strips are passed through feed-wedge clearance in cold-feed extruders. The screw flight rotation squeezing process was simplified into a disc rotation squeezing process; the instantaneous squeezing velocity $\dot{h}\left(t\right)$ in the disc rotation squeezing model was derived according to feed wedge clearance geometry and the disc rotating speed. By transforming rotation squeezing into differential slab squeezing, mathematical expressions of the velocity distribution, pressure distribution, total squeezing force, and power consumption in the feeding process were derived in a rectangular coordinate system under isothermal and quasi-steady assumptions and certain boundary conditions by using balance equations and a Newtonian viscous constitutive relation. Theoretical calculations and experimental values showed the same trend. Through comparison, it was found that the power consumption (P3) caused by sliding friction is about 200–900 W according to theoretical calculations, while the experimental test results show it to be about 300–700 W. Additionally, the difference between theoretical pressure value and the experimental pressure value can be controlled within 5–15%. This could reflect the main factors that affect the feeding process, so could be used for analyses of actual feeding problems, and to contribute to rough quantitative descriptions of the feeding process, finite element simulation, and the optimization of the feeding structure. Full article

Surface morphology affects cell attachment and proliferation. In this research, different films made of biodegradable polymers, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-HV), containing different molecular weights, with microstructured surfaces were investigated. Two methods were used to obtain patterned films—water-assisted self-assembly (“breath figure”) and spin-coating techniques. The water-assisted technique made it possible to obtain porous films with a self-assembled pore structure, which is dependent on the monomer composition of a polymer along with its molecular weight and the technique parameters (distance from the nozzle, volume, and polymer concentration in working solution). Their pore morphologies were evaluated and their hydrophobicity was examined. Mesenchymal stem cells (MSCs) isolated from bone marrow were cultivated on a porous film surface. MSCs’ attachment differed markedly depending on surface morphology. On strip-formed stamp films, MSCs elongated along the structure, however, they interacted with a larger area of film surface. The honeycomb films and column type films did not set the direction of extrusion, but cell flattening depended on structure topography. Thus, stem cells can “feel” the various surface morphologies of self-assembled honeycomb films and change their behavior depending on it. Full article

The comprehensive use of natural polymers, such as lignin, can accelerate the replacement of mineral oil-based commodities. Promoting the material recovery of the still underutilized technical lignin, polyolefin-lignin blends are a highly promising approach towards sustainable polymeric materials. However, a limiting factor for high-quality applications is the unpleasant odor of technical lignin and resulting blends. The latter, especially, are a target for potential odor reduction, since heat- and shear-force intense processing can intensify the smell. In the present study, the odor optimization of kraft and soda HDPE-lignin blends was implemented by the in-process application of two different processing additives–5% of activated carbon and 0.7% of a stripping agent. Both additives were added directly within the compounding process executed with a twin screw extruder. The odor properties of the produced blends were assessed systematically by a trained human panel performing sensory evaluations of the odor characteristics. Subsequently, causative odor-active molecules were elucidated by means of GC-O and 2D-GC-MS/O while OEDA gave insights into relative odor potencies of single odorants. Out of 70 different odorants detected in the entirety of the sample material, more than 30 sulfur-containing odorants were present in the kraft HDPE-lignin blend, most of them neo-formed due to high melt temperatures during extrusion, leading to strong burnt and sulfurous smells. The addition of activated carbon significantly decreased especially these sulfurous compounds, resulting in 48% of overall odor reduction of the kraft blend (mean intensity ratings of 5.2) in comparison to the untreated blend (10.0). The applied stripping agent, an aqueous solution of polymeric, surface-active substances adsorbed onto a PP carrier, was less powerful in reducing neo-formed sulfur odorants, but led to a decrease in odor of 26% in the case of the soda HDPE-lignin blend (7.4). The identification of single odorants on a molecular level further enabled the elucidation of odor reduction trends within single compound classes. The obtained odor reduction strategies not only promote the deodorization of HDPE-lignin blends, but might be additionally helpful for the odor optimization of other natural-fiber based materials. Full article