Additive manufacturing of bonded magnets using polymer extrusion, powder bed fusion, and stereolithography is established, but this paper focuses on the laser powder bed method. Magnetic particles mixed with polymer powders were consolidated into bonded magnets by selective laser sintering. External magnetic fields were applied to align particles during sintering, but with uniform powder compositions and fields, the effects of which were limited to bulk properties. Considering the point-wise material consolidation mechanics, we hypothesise that controlled dispersion of multiple powder materials and localised external magnetic fields in specific orientations and at specific times during sintering can lead to bonded magnets with controlled magnetic heterogeneity. Results from experimental research conducted and reported in this paper have shown this hypothesis to be true. The outcome of this research paves ways towards achieving bonded magnets with controlled placement of different magnetic materials. The as-printed samples exhibit relatively weak polarisation (≈ 1.5-2 mT flux), but magnetisation under external fields (1.5-1.9 T) raises flux values up to 6 mT N / 3 mT S for NdFeB/FeSi and 14 mT N / 6 mT S for NdFeB/FeCo, demonstrating strong amplification of polar strengths. Both NdFeB/FeSi and NdFeB/FeCo samples show 80-100 mT North and 50-100 mT South differential polarities under external fields, with minimal change from as-printed to magnetised states. Even when the external field is reversed, a persistent North-upward remanent tendency confirms an easy-axis alignment induced during laser consolidation.

A Ni-SiC composite coating was effectively synthesized on a stainless-steel substrate through a jet electrodeposition technique integrated with a magnetic field, and then utilized for oil/water separation. Guided by an external magnetic field, the magnetically responsive nickel components loaded with hydrophilic SiC were incorporated into the coating, creating a coral-like micro-nano hierarchical rough structure. The functionalized mesh demonstrated remarkable superhydrophilic properties and submerged low-adhesion superoleophobicity. Appropriate processing parameters were identified by analyzing how electrodeposition duration and voltage influence the surface topography as well as the wettability associated with the Ni-SiC-coated mesh. The results indicated that the Ni-SiC-coated mesh prepared at 30 V for 10 min exhibited a WCA of 0 degrees and a UOCA of 152.2 degrees. Ni-SiC-coated meshes fabricated at a lower voltage required a deposition time of 30 min to achieve superhydrophilicity and underwater superoleophobicity. The mesh achieved high efficiency along with superior purification levels for various oil/water emulsions and sustained a stable separation performance (exceeding 95%) after 50 cycles. The treated substrate maintained its functionality in aggressive media. In natural conditions, the Ni-SiC-coated mesh still retained its outstanding superhydrophilicity and underwater superoleophobicity after three months of storage. In addition, the Ni-SiC-coated mesh maintained a UOCA of more than 150 degrees after water erosion for 10 h.

Auxetic structures exhibit distinctive deformation characteristics that give rise to unconventional mechanical responses, characterized by a negative Poisson's ratio (PR) under deformation. While most designs emphasize auxetic behavior, less attention is directed toward resulting stress distributions. The present study addresses this gap by predicting the PR and stress-concentration characteristics of an S-shaped auxetic structure, which is observed to exhibit lower stress concentration than conventional re-entrant configurations. Two prediction models were developed using machine learning techniques, i.e., regression analysis and an artificial neural network (ANN), based on a full-factorial design of experiments comprising 27 simulations. The regression model produced high coefficients of determination, with R2 values of 99.43% for the PR and 92.91% for the von Mises (VM) stress, along with average percentage errors of 1.9023% and 9.6215%, respectively. The ANN model demonstrated stronger performance, achieving an overall correlation of 0.99962 and average percentage errors of 0.6585% for PR and 3.024611% for VM stress. Statistical evaluation confirmed the goodness-of-fit for both models at the 95% confidence level, indicating no significant differences between finite element modeling (FEM) and predicted responses. Overall, the the ANN model offers superior predictive accuracy, making it an effective alternative to resource-intensive simulations/experiments.

Fiber-reinforced plastics enable lightweight building systems through digitizable and automatable additive manufacturing techniques such as coreless filament winding (CFW). Replacing carbon fibers with low-CO2-impact natural fibers offers opportunities for sustainable structures. A prior CFW study using four-point bending demonstrated the eco-mechanical potential of Linum usitatissimum fibers but was confined to simple sample geometries, emphasizing material over structural performance. This study addresses this limitation by introducing a new structural sample fabricated with a 3D-printed winding fixture and hybrid CFW. Samples from Phormium tenax fibers were experimentally benchmarked against carbon and L. usitatissimum fiber samples. Carbon samples exhibited 2.15x the mass/CO2-specific stiffness and failure load of the natural fiber samples. L. usitatissimum slightly outperformed P. tenax due to greater raw material optimization. Projections suggest increasing fiber volume ratios, coupled with advances in fabrication, could close performance gaps while balancing lightweight and sustainability goals.

Additive manufacturing technologies have shown promising results over conventional methods in fabricating all components of energy devices. A relentless drive to fabricate all critical components in a single step is the core driving force. In the current work, monolithic microbial fuel cells (MFCs) are evaluated using Porolay series filaments, replacing multilayer cellulose paper substrates-based MFCs for the first time. Leveraging the benefits of 3D printing, different filaments of the Porolay series are employed for varying the thickness and internal architectures of critical components such as membranes, electrodes and reservoirs, targeting the maximum throughput. Amongst four different filaments, the Gel lay performed the best in terms of power output. The optimised thicknesses are membrane 0.4 mm, reservoir 1 mm, and layer above reservoir 0.6 mm. Further, facile electrodes are developed, combining screen printing and drop casting using an electric paint, which covers the surface as well as the internal strands of the printed substrate, enhancing the electron-capturing sites. Based on the optimised critical components and filaments, the monolithic printed substrate is able to generate a stable OCV of 0.49 V for approximately 90 min and deliver a power of 12.3 mu W/cm2 using E. Coli as the biocatalyst. This low-cost device can assist point-of-care testing as a freestanding power source.

This study aims at the development and characterization of polylactic acid (PLA)—silicon nitride (Si3N4) composites for fused deposition modelling (FDM) 3D printing. Polymer ceramic composite filaments with varying Si3N4 concentrations (3

Solute segregation during conventional manufacturing restricts the development of Ti-Cu alloys despite their potential in biomedical applications. Here, we demonstrate that using core-shell Ti@Cu powders in laser powder bed fusion (PBF-LB/M) enables the fabrication of hypoeutectoid Ti-2.9Cu alloys with >98.4 % density, suppressed segregation, and enhanced chemical homogeneity. The resulting microstructure features equiaxed prior-beta grains with ultra-fine alpha laths and well-distributed nano-sized Ti2Cu precipitates at lath boundaries, contributing to grain boundary and precipitation strengthening. Compared to blended elemental powders, the core-shell strategy improves ultimate tensile strength by 17 % (from 857 +/- 15.9 MPa to 1004.5 +/- 18.7 MPa) and ductility by 6.4 % (from 12.6 +/- 0.01 % to 13.4 +/- 1.0 %). Flow3D simulations indicate enhanced laser-powder energy coupling and a more stable, symmetric melt pool with reduced thermal gradients and uniform convection for the Ti@Cu feedstock, rationalizing the suppressed segregation. This study establishes feedstock architecture as a powerful lever to unlock strength-ductility synergy in laser additively manufactured Ti-Cu alloys for biomedical applications.

Fused filament fabrication (FFF) in additive manufacturing has emerged as a potential technology in the development of tissue engineering scaffolds of precise, complex geometries. The choice of material and process parameters is significant in determining their properties, such as mechanical strength. Polymer-ceramic composites with exceptional bioactivity have the potential for FFF applications in fabricating scaffolds. In this study, polylactic acid (PLA) composite scaffolds reinforced with silicon nitride (Si3N4) particles in various weight ratios (97:03, 95:05, and 93:07 weight%) were developed using FFF technology. Taguchi's orthogonal array and grey relational analysis were employed to optimize three parameters (polymer-reinforcement ratio, infill density, and layer thickness) to analyze mechanical strength - through tensile, compressive, flexural, and impact tests - surface morphology using scanning electron microscopy, and biocompatibility through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay). The optimal formulation of 95:05 wt.%, 0.17 mm layer height, and 100% infill density demonstrated superior mechanical properties with a tensile strength of 47.52 MPa, flexural strength of 67.3 MPa, compressive strength of 71.57 MPa, and impact strength of 2.63 kJ/m2. Analysis of variance revealed layer thickness as the most influential factor (41.7%) impacting mechanical properties, followed by PLA: Si3N4 ratio and infill density. MTT assay and immunofluorescent staining analysis revealed that the optimal formulations enhanced cell viability and proliferation compared to controls.

In recent years, there has been a significant research effort in the laser powder bed fusion (LPBF) processing of Nitinol aiming potentially for stenting applications. To achieve superelasticity that Nitinol stents require, Ni content needs to be within f0.1at% of the optimal Ni content of 50.8at%, but the high thermal intensity of the laser in LPBF results in a Ni-loss. How to achieve the targeted Ni content in LPBF processed Nitinol alloys, whilst producing defect-free parts is not certain, requiring further evaluation. In the LPBF processing of a Nitinol powder with 51.2at% Ni herein, we exhibit defect-free processing obtaining the idealised Ni content with the use of a constant scan velocity and narrow power and thus energy (E) window. An exponential decay in Ni content with increasing E was observed and is correlated to the aspect ratio of the melt pool shape. Under optimum, defect free conditions, a primarily austenite structure with a tiny amount of twinned martensite is reported by room temperature. Sequential transmission electron micrographs taken between -80 degrees C to 0 degrees C on a defect-free sample have illustrated the transformation of twinned martensite to austenite with the major portion of the transformation taking place well below 0 degrees C.

Magnetism assisting the manufacturing process is well known within the energy coupled to matter realm and material processing assisting in the magnetic responses has also been in practice. The current research is an attempt to combine both approaches together in a multi-magnetic material consolidation process under the influence of external magnetic fields. Additive manufacturing by selective laser melting with controlled dispersion of multi-material magnetic powders and the application of controlled magnetic fields during material melting and consolidation are key features of the methodology. The melt-pool geometries, sub-granular structures, and the crystallographic orientations showed distinct responses with the use of external magnetic fields during laser consolidation of NdFeB and FeCo systems and their combinations with and without a third non-magnetic material matrix. As per the energy coupled to matter mechanisms and mechanics, the multi-magnetic material substrates consolidated by laser melting under external fields demonstrated patterned polar formations and predefined magnetic orientations. The directions and intensities of the north and south poles at different regions of the printed samples depend on the strengths and orientations of the external fields applied during consolidation and magnetisation fields employed after printing.

In the ever-increasing quest for alternative energy sources, hydrogen emerged as a promising green option, but efficient and economical production and management have been the primary constraints. Converting wastewater into H2 and other forms of energy attracted significant attention in terms of simultaneously and sustainably managing both the wastewater and the energy generation problems. Microbial Electrolysis Cells (MEC) evolved recently as promising options for converting wastewater into H2 and electricity but with serious constraints on scalability. The current research aims to explore design and manufacturing solutions to build structurally strong and electrochemically effective electrodes that can also lead to scalable MEC. Two designs based on the interdigitated and spiral electrode architectures are proposed and evaluated. The added design freedom with additive manufacturing by selective laser melting of specific alloys of choice is effectively utilised in physically prototyping the interdigitated and spiral electrode forms designed with controlled porosity constraints. Microstructural, electrochemical, and cell performance characterisations led to the understanding that the spiral electrode configuration with polypyrrole-coated stainless steel 316L anode is a promising design option for both longitudinal and lateral scale-up of the MEC.

In this study, the effect of build orientation (0 degrees, 45 degrees and 90 degrees from a build platform) on microstructural response as well as mechanical and corrosion properties was investigated by comparing laser powder bed fusion-produced samples in the as-built and solution-annealed states. By increasing build orientation, Widmanst & auml;tten gamma-austenite formation was lowered because of faster cooling and shorter melt tracts, whilst retaining similar delta-ferrite/gamma-austenite phase fractions. This is correlated with improved corrosion performance in the 90 degrees orientation from chemically homogeneous grain boundary gamma-austenite. The prevailing delta-ferrite as-built samples exhibit a strong < 001 > delta-ferrite crystallographic texture in the normal direction across all orientations together with greater hardness and mechanical strength in comparison to solution-annealed samples by virtue of less slip systems in the BCC delta-ferrite structure and fine cellular solidification structure. The 45 degrees build orientation exhibits a greater Widmanst & auml;tten gamma-austenite content and periodic recrystallisation between scan checkers, contributing to improved mechanical strength and ductility. Solution annealing softened structures, from an increase in the gamma-austenite content, via intergranular nucleation or through prior grain boundaries and Widmanst & auml;tten needles. The underlying delta-ferrite grain structure and crystallographic texture relationship is retained, although weakened from the recrystallisation process. Tensile strength is reduced compared to the as-built structures and worsened in the 90 degrees orientation due to few Widmanst & auml;tten needles, although elongation is significantly increased, and pitting corrosion performance is improved by the removal of stresses and the equilibrium microstructure.

Flexible dye-sensitized solar cells (DSSCs) offer several benefits in terms of cheap fabrication, mass production, lightweight, and, finally, conforming to uneven surfaces. However, these cells are mainly fabricated using commercially polymer substrates with limited functional properties. DSSCs performance is highly influenced by the dye adsorbent capability of nano-crystalline oxide semiconductors (TiO2), which require a large surface area, and this can be achieved by developing texture or microstructures on substrates. Further, texture-based substrates reduced the optical reflection, increased the optical path of light, and trapped large amounts of light. Different transparent filaments are used to print flexible substrates that possess high transparency using a versatile fused filament fabrication. Facile laser-engraved fractal textures are developed on printed polymer substrates, which act as photoanodes and counter electrodes. The maximum attained power conversion efficiency and short-circuit current density (Jsc) are 3.90% and 9.34 mA/cm2, respectively, for fractal anode-fractal cathode based DSSCs, which are 82.2% and 47.7%, respectively, higher than as-printed anode- as-printed cathode-based DSSCs.

Microfluidic fuel cells (MFFCs) have been attracting significant research attention in recent years, considering the wider application potential. The application of additive manufacturing to facilitate the fabrication of customized flow channel structures and achieving controlled fluid flow attributes has been demonstrated. The next step is to exploit the wider possibilities with the use of additive technologies and explore the possible implementation of carefully crafted flow pathways to achieve better flow patterns as well as closely controlled reaction sites for better ion exchange. The design, analysis, and experimental validation of three flow channel forms are presented in this article, aiming at the effective use of additive technologies and achieving MFFCs with enhanced efficiencies. The planar, interdigitated, and corrugated honeycomb structures evaluated the target utilization of the infill patterns, elongated reaction sites, and the scaling-up of the cells into multilayer variants, respectively. Numerical simulation, experimental dye-flow, and electrical characterization results indicate that all three forms perform better than the variants reported in the current literature, while the scaled-up level 2 honeycomb structure appears to be the most promising one with the maximum current and power densities at 2.17 mA/cm2 and 812.8 mu W/cm2, respectively.

Manufacturing industries have taken a leap with the coming of polymer composites and have been much broadly explored in this era. Composites with ceramic reinforcements to polymer matrices have proven potentially efficient in improving mechanical properties. This work explores the idea in implementing PLA-silicon nitride composites in manufacturing through conventional injection molding and modern 3D printing techniques. The study points to the better strength enhancement of tensile, flexural and impact test results in composites in the lower additive weight ratio of 95:05, substantiated by a detailed mechanical and morphological analysis of specimens in three different weight ratios. The specimens printed by 3D printing show a negligible variation in the strength parameters when compared to the injection-molded counterparts, which in effect extends the scope of further research in the area.

Since its first appearance almost a couple of decades ago, microfluidic fuel cells (MFFCs) have gained considerable research momentum due to their potential applications in portable devices. The main focus has been on the effective fabrication of microfluidic channels with different materials, where the manufacturing limitations proved to be the main stumbling blocks. Paper-based MFFCs have been reported with some success, where the porosity of the flow channel medium drives the reactants, greatly reducing the need for elaborate external devices and complex manufacturing obstacles, although the longevity of these cells remains questionable. The current article addresses this issue by replacing the paper-based flow channels with 3D-printed substrates of different structural forms to serve as pathways for controlled flow and mixing responses of the reactant liquids without the use of other devices, such as micro pumps and valves. The line-by-line material consolidation mechanics of fused filament fabrication and the porous mesostructural responses of a commercial polymer filament are combined to build the microfluidic fuel channels of varying configurations. Numerical and experimental characterizations proved the cells to perform better than the current paper-based counterparts, apart from better longevity and possible new opportunities for future improvements based on more complex micro-, meso-, and macrostructural advances.

This study addresses the challenge of breaking the trade-off dilemma between strength and ductility in additively manufactured Titanium (Ti) products. By leveraging concentration non-uniformity and controlled diffusion during in-situ alloying of unalloyed titanium (CP-Ti) and 316L stainless steel (SS316) powders via laser powder bed fusion (LPBF), we formulated a novel Fe-containing alloy with improved printability and enhanced mechanical performance. The microstructure of the as-built Ti alloy comprises a heterostructure of nano-scaled martensitic alpha ' within the micro-scaled equiaxed prior-beta grains, resulting from rapid solidification inherent in LPBF. Since the modified laser-powder bed fusion in this work lacks a pre-heating function, a stress-relief annealing process was conducted to enhance the mechanical properties of the as-built parts. The annealed in-situ alloyed Ti-Fe achieves a superb balance between strength and ductility, with an ultimate tensile strength (UTS) of approximately 1118.0 MPa and an elongation of similar to 9.0 %. This study provides insights for designing high-performance Ti alloys with heterostructures using a mixture of elemental powder and alloyed powders via LPBF. The significance of concentration non-uniformity and diffusion during solidification is highlighted, demonstrating how these factors contribute to the formation of superior heterostructures through additive manufacturing.

GaN HEMTs on circuit boards used for power electronics applications suffer from the generation of excessive heat that may eventually destroy them. Both immersion and conduction (using a cold plate) methods for cooling have been evaluated in the past. The objective of this work is to design and build a cold plate solution to this thermal problem by means of forced convection through optimised cooling channels integrated into a cold plate. Considering the complex and convoluted shapes these fluid-flow channels take within enclosures that rest on the heat dissipating surface of the GaN chip, additive manufacturing based on powder bed fusion processing of a thermally conductive metal is a part of the solution. Finite volume (FV) simulations based on ANSYS Fluent module are used for evaluating thermal fields within the heat exchanger block resting on the GaN HEMTs, taken as the plate heat source. Initial impressions from the FV results indicate the design alterations evaluated to be suitable for better thermal management of GaN HEMTs. Physical prototyping of the cooling block was also successful based on additive consolidation of metallic powders by selective laser melting.

3D printing, or additive manufacturing, allows for static, three-dimensional components to be produced through a point-by-point material consolidation method. 4D printing is an emerging technique in the field of AM which allows for static structures to become dynamic with the use of smart materials and the later exposure to changing stimuli such as temperature, light, and electricity. The fourth dimension in 4D printing refers to the transformation over time experienced by the component. The concept of self-assembly and programmable materials was initially introduced in 2012 by scientist Skylar Tibbits from the Massachusetts Institute of Technology (MIT) in order to fulfil applications where a dynamic function was needed. Over the past ten years, the number of publications on the field has grown exponentially and gained increased popularity around researchers and engineers of various disciplines. 4D printing structures are mainly produced using fused deposition modelling (FDM) and stereolithography (SLA) processes, however, different techniques are implemented depending on the class of materials being used and the complexity of the shape being produced. As 4D printing began to allow for active structures to autonomously transform over time without adding time, cost or extra components to the previous static components, several potential applications were raised. Among these applications are smart biomedical devices, soft robotics, smart packaging solutions, self-healing devices, among others. This paper will review the status of the 4D printing technology by sorting relevant publications based on the different techniques utilised by researchers to achieve autonomous transformation of components post-printing.

Superconducting electric motors require many small, geometrically complex parts, and manufacturing these can be difficult. Additive manufacturing has various advantages that are beneficial to producing small and intricate structures. However, superconducting electric motors operate under cryogenic conditions, and there is limited information to how laser melted metals, in particular, cobalt chromium, perform under these conditions. This paper explores the change in the mechanical properties of laser melted cobalt chromium under cryogenic conditions. An experimental analysis was conducted at two conditions: room temperature (295 K) and cryogenic temperatures (77 K). The results from these experiments show that at cryogenic conditions, the ultimate tensile strength (UTS) increases to 1201.77 MPa from 780.57 MPa at room temperature. In addition, a study on the effects of heat treatment (HT) to the cobalt chromium specimens after manufacturing was conducted and found to be indeterminably effective. At room temperature, the UTS of cobalt chromium increased by 13% after heat treatment, however, at cryogenic conditions, the UTS decreased by 8% after heat treatment.