Search Results (221)

Porous ceramics have garnered widespread attention in high-temperature insulation, aerospace, and other fields due to their excellent thermal stability, low density, and superior thermal insulation performance. However, traditional preparation technologies suffer from limitations such as poor pore structure controllability, unstable mechanical properties, and long production cycles. In recent years, 3D printing (additive manufacturing) technology has emerged as a disruptive approach to address these challenges, enabling precise fabrication of porous ceramics with complex structures and tailored properties. This review comprehensively summarizes the research progress on 3D-printed porous ceramics, focusing on preparation technologies, structure optimization, and performance regulation. First, the principles and drawbacks of traditional preparation methods are analyzed. Then, four mainstream 3D printing technologies (Binder Jetting, Material Extrusion, Vat Photopolymerization, and Material Jetting) for porous ceramics are elaborated on in terms of forming mechanisms, process characteristics, typical cases, and performance advantages/disadvantages. Additionally, the structure–property optimization strategies, including the design of Triply Periodic Minimal Surface structures and the application of computational modeling and simulation, are discussed to achieve the balance between thermal insulation and mechanical properties. Finally, current challenges and future development trends of 3D-printed porous ceramics are prospected. This review provides a systematic reference for the rational selection of preparation technologies, structural design, and performance optimization of porous ceramics, promoting their engineering applications in high-value fields. Full article

The manuscript deals with the bending behavior of beams with relatively less investigated cellular topologies based on triply periodic minimal surfaces (TPMSs). Three types of sandwich-type specimens (namely Schoen IWP, Fischer–Koch S, and Schoen F-RD) with five different volume fractions of 10, 15, 20, 25, and 35% (±1%) made of aluminum alloy AlSi10Mg by selective laser melting (SLM) technology were investigated. Three-point bending tests were performed at room temperature on a Zwick/Roell 1456 universal testing machine. The force–deflection dependences were plotted, while in addition to nominal stresses, the effective flexural stiffness and energy absorption to failure were evaluated to compare the properties of the investigated cellular beams. In the preparatory phase, critical aspects of possible premature failure of the samples with the smallest and highest selected volume fractions were addressed, while the manufacturability and fracture surfaces of the samples were assessed in order to improve the input conditions of the setup. By comparing the results obtained in the experimental testing in the second phase, it was found that the highest nominal bending stresses were achieved by the Schoen F-RD structure (although not significantly higher than Fischer–Koch S), but in terms of stiffness and amount of absorbed energy, the Fischer–Koch S structure showed the highest values. The improvement of input parameters led to an increase in the achieved nominal bending stresses by at least 100 MPa for all types of investigated structures compared to the first phase. The combined use of preliminary SLM process optimization, bending tests, and fracture surface/EDX analysis made it possible to relate the flexural response of the investigated TPMS topologies to manufacturing-related defects and premature-failure mechanisms in thin-walled AlSi10Mg cellular structures. The presented specimen configuration is intended as a comparative experimental benchmark for flexural performance of sandwich-type TPMS beams under quasi-static loading. Full article

Aiming at the technical bottleneck that traditional porous structures can hardly achieve mechanical load-bearing and acoustic regulation simultaneously, this study designs and fabricates three implicit surface porous structures (Gyroid, Diamond, Lidinoid) based on the bionic principle of trabecular bone. Experimental characterization and numerical analysis of their mechano-acoustic coupling performance are systematically carried out. Selective Laser Melting (SLM) technology is employed to realize the integrated forming of 316L bionic structures. Quasi-static compression experiments and finite element simulations are conducted to reveal the progressive deformation mechanism and energy absorption characteristics of different topological configurations. The results indicate that the Diamond structure exhibits the optimal comprehensive performance in terms of load-bearing capacity, specific energy absorption and isotropy. On this basis, the sound absorption and sound insulation performances of the structures are evaluated via an acoustic impedance tube test. The results show that the Diamond structure possesses a remarkably higher sound absorption coefficient and sound insulation value in the high-frequency range than other configurations, demonstrating excellent acoustic energy dissipation and sound wave isolation capability. The research indicates that the synergistic optimization of mechanical and acoustic performances can be achieved by regulating the Triply Periodic Minimal Surface (TPMS) topological configuration. Benefiting from its efficient stress transfer paths and intricate sound wave propagation channels, the Diamond structure realizes the coupling of high load-bearing capacity, superior energy absorption and favorable acoustic performance. This work provides a theoretical basis and technical support for the design of bionic porous structures in multifunctional scenarios such as bone implants and protective noise reduction. Full article

The objective of this study is to mitigate the bottom-out failure and improve the energy absorption of conventional helmet liners during high-energy impacts, thereby reducing the risk of head injuries. To this end, a locally reinforced Primitive-type triply periodic minimal surface (P-TPMS) energy-absorbing liner is proposed for the helmet forehead region, which facilitates progressive energy dissipation through layer-by-layer buckling deformation. A finite element model of a helmet–head coupling was created based on a previously verified high-fidelity head model and subsequently validated against the ECE 22.06 standard drop-test methodology. Three critical design parameters—outer protective layer thickness, triply periodic minimal surface (TPMS) unit cell size, and wall thickness—were optimized employing the Box–Behnken Design (BBD) response surface methodology, resulting in quadratic regression models for the head injury criteria (HIC) and peak linear acceleration (PLA) with good fit ($R^2$ > 0.97). Optimal parameter combinations were established using multi-objective optimization, with protective efficacy carefully assessed from both head dynamic response and biomechanical response perspectives. The ideal P-TPMS liner possesses an outer protective layer thickness of 14.95 mm, a TPMS unit cell size of 12.23 mm, and a wall thickness of 3.93 mm. Compared to the traditional expanded polystyrene (EPS) liner, the optimized P-TPMS liner significantly reduces HIC (by ∼16%) and PLA (by ∼14%) while extending the impact duration. More critically, it transitions both intracranial pressure and brain tissue strain below their respective clinical injury thresholds, substantially lowering the risks of skull fracture and mild traumatic brain injury (mTBI). The P-TPMS construction facilitates continuous energy dissipation during impacts via incremental layer-by-layer buckling deformation, hence extending impact duration and markedly improving helmet protective efficacy. These findings offer theoretical foundations and technical direction for the creation of localized heterogeneous liner designs in advanced high-performance helmets, although the results are limited to frontal flat-anvil impact conditions. Full article

The present study addresses the fabrication of porous gyroid architectures by additive manufacturing from preceramic polymer feedstocks. Photocurable emulsions were engineered by combining a silicone powder with acrylate monomers and dispersing an emulsified secondary phase of calcium nitrate. The formulations showed light-curing behaviour compatible with digital light processing vat photopolymerization (DLP-VPP), enabling high-fidelity replication of triply periodic minimal surface (TPMS) gyroids (designed porosity: 85 vol.%). After pyrolysis in nitrogen at 700 °C, the lattices converted into CaO–SiO₂-derived amorphous matrices embedding an in situ turbostratic/pyrolytic carbon fraction, as suggested by the photothermal response and preliminary impedance behaviour, although the latter was measured in liquid electrolyte and therefore does not isolate electronic transport. To improve robustness during polymer-to-ceramic conversion, pharmaceutical borosilicate waste glass (BASG) was added as a passive filler (30–70 wt.%). The waste-glass phase acts as a passive filler that improves processing robustness and can mitigate shrinkage-induced damage during pyrolysis, while remaining electrically insulating (dielectric) and therefore not directly contributing to electronic conduction. The resulting structures combine high surface-to-volume ratio, controlled open porosity, and structural integrity with electrochemical responsiveness under the adopted test conditions, making them promising architected platforms for electrochemical components where interconnected porosity is advantageous. Full article

Three-dimensional scaffolds based on triply periodic minimal surfaces (TPMSs) have attracted growing interest in bone tissue engineering because of their high interconnectivity and ability to combine high porosity with mechanical integrity. However, in fused deposition modeling (FDM), printed architecture may systematically deviate from the nominal design, thereby affecting structural fidelity and mechanical performance. This study investigated the influence of FDM processing parameters and nozzle diameter on the effective microarchitecture and compressive elastic modulus of polycaprolactone (PCL) gyroid scaffolds. First, a Taguchi L18 design was used to evaluate the effects of extrusion temperature, printing speed, and flow rate on pore size for two nozzle diameters (0.4 and 0.3 mm). In a second experimental stage, prismatic specimens fabricated at three nominal porosity levels were compression-tested to determine the elastic modulus (E), and measured porosity (ϕ) was quantified by densimetric measurements. A systematic mismatch was observed between the nominal design and the printed scaffold architecture, with both pore size and measured porosity consistently lower than their intended values. The dominant process parameter associated with pore-size variability was nozzle-specific: extrusion temperature contributed most for the 0.4 mm nozzle, whereas printing speed contributed most for the 0.3 mm nozzle. In compression, E decreased with increasing measured porosity, and statistical analysis showed that the E–ϕ relationship was nozzle-dependent. Overall, these findings support a process–structure–property interpretation based on the effective printed microarchitecture rather than on nominal design parameters alone. The experimental stiffness ranges obtained here also provide an exploratory mechanical contextualization relative to reported trabecular bone domains, without implying site-specific scaffold selection. Full article

Polylactic acid (PLA) scaffolds with triply periodic minimal surface (TPMS) structures have become ideal scaffolds in the field of bone defect repair due to their good designability, connectivity, biocompatibility, and degradability. However, it is currently difficult to obtain the scaffold degradation rate and osteogenic efficacy from in vivo experiments, making it challenging to provide recommendations for scaffold design. In this study, an algorithm to construct a TPMS scaffold–interfacial layer–tissue three-phase composite model was developed using polylactic acid hydrolysis and bone remodeling as the governing equations to simulate scaffold degradation and tissue osteogenesis behavior under an external mechanical stimulus. This method is based on a numerical calculation framework that can more closely simulate the in vivo environment, characterizing the changes in the overall macroscopic mechanical properties of tissue under the influence of scaffold degradation and tissue osteogenesis. The results confirmed the accelerating effect of mechanical stimulation on scaffold degradation and its promoting effect on new bone formation. Under 10% compressive loading, the Schwarz P representative volume element (RVE) lost 33% of its apparent modulus within initial days, while the lidinoid RVE, despite showing a much higher initial modulus, dropped to only 20% of its initial value over the same period. In addition, the mechanical performance of the fused TPMS RVE was not simply linear, even though the surface equations are combined linearly. These results provide a new method for pre-designing scaffold structures based on numerical simulation results using the finite element simulation. Full article

6063 aluminum alloy has broad application prospects in aerospace and microelectronic thermal management systems due to its good thermal conductivity and moderate strength. However, its extremely high hot cracking susceptibility during the laser powder bed fusion (LPBF) process limits the direct manufacturing of complex components. This study proposes a strategy combining material composition modification with advanced structural design. By introducing TiH₂ nanoparticles (1.0~4.5 wt.%) to modify the 6063 aluminum alloy powder, Diamond-type porous structures based on triply periodic minimal surfaces (TPMS) were successfully fabricated using LPBF technology. The results show that the introduction of TiH₂ significantly suppresses the solidification cracking of the aluminum alloy. The underlying mechanism is that the L1₂-structured Al₃Ti particles, generated by the in situ decomposition of TiH₂ in the melt pool, provide high-density heterogeneous nucleation sites. This leads to a drastic decrease in the average grain size from 30.46 μm to 0.75 μm (a reduction of 97.5%), achieving a remarkable columnar-to-equiaxed transition (CET). In terms of mechanical properties, the 3.0 wt.% TiH₂ addition group exhibits excellent plateau stress (28.5 MPa) and energy absorption capacity, which is mainly attributed to the synergistic effect of fine-grain strengthening and Orowan dispersion strengthening. Thermal tests reveal that the thermal conductivity of the 3.0 wt.% group reaches 123 W/(m·K) at 100 °C. The healing of cracks reconstructs the macroscopic heat conduction paths, resulting in a significant improvement in thermal conductivity compared with the unmodified group. This work provides a theoretical reference for the development of high-performance, crack-free, and multi-functional integrated aluminum alloy components via additive manufacturing. Full article

This work examines the simulation-based torsion properties of TPMS structures. Although TPMS structures are gaining more interest in research and potential practical applications, their torsion properties are not widely studied. In this work, sheet-based Diamond, Gyroid, and Primitive TPMS structures are analyzed numerically using the finite element method. The samples have a diameter of 20 mm and a length of 40 mm. Relative densities are 30%, 50%, and 70%, while unit cell sizes are 10 mm, 15 mm, and 20 mm. Cell geometry did not significantly affect the properties for samples with a 10 mm unit cell size. For other unit cell sizes, the shear modulus and shear yield stress were 1.5–4 times higher for the Primitive structure than for other geometries. With increasing relative density, the shear modulus and shear yield stress increased by 1.5–2 times for the Diamond and Gyroid structures, as well as for the Primitive structure with a 10 mm unit cell size. The Primitive structure with 15 mm and 20 mm unit cell sizes showed a decrease in properties with increasing relative density. Regarding the effect of unit cell size, the shear modulus and shear yield stress showed insignificant differences for the Diamond and Gyroid structures, while the Primitive structure showed dependence on unit cell size. Samples with a 15 mm unit cell size had 1.5–2 times higher shear modulus and 1.5–3 times higher shear yield stress than samples with a 10 mm unit cell size. Samples with a 20 mm unit cell size exhibited slightly lower shear modulus and shear yield stress than those with 15 mm unit cells. Full article

This study investigates and compares properties of various P-type Triply Periodic Minimal Surface (TPMS) porous structures for bone scaffold design. At first, six cases of homogeneous single/dual-layer structures, axial single/dual-layer gradient structures and radial single/dual-layer gradient structures with the same average porosity are developed. Dual-layer gradient structures are selected for further design due to more similar pore and stress distributions to human bones, reduced maximum stress, higher yield strength and greater variations in yield strength and elastic modulus (E). The mechanical and permeability properties of ten cases of axial and radial dual-layer gradient structures with the same overall porosity but different inner and outer layer porosities are then further designed and studied. The results show that yield strength is within 112.75–139.97 MPa, E ranges from 11.15 to 13.01 GPa, the permeability (K) falls within 1.51–10.01 × 10⁻⁹ m² and the average wall shear stress (WSS_avg) varies between 6.18 and 9.11 mPa. The yield strength, E and K of radial dual-layer gradient structures are higher and WSS_avg is lower than those of axial dual-layer gradient structures. Moreover, with increase in inner average porosity ($\overline{P}$) and decrease in outer $\overline{P}$, the yield strength, E and K gradually decrease while WSS_avg gradually increases for both types of structures. In particular, the radial dual-layer structure with the lowest porosity of 27.5% in the inner layer and highest porosity of 42.5% in the outer layer has superior mechanical and permeability properties. The findings offer direct guidance for the structural design of bone implants, enabling performance customization for different applications. Full article

Background: Bone tissue engineering has emerged as a promising technique for treating bone defects in large bones. Recent methods have enabled scaffold designs based on predefined microstructures or mechanical behavior patterns, including porosity-graded scaffolds adaptable to heterogeneous load states. However, there is no consensus on the optimal scaffold design strategy, which is sometimes chosen based on the intact bone or results from computational or in vivo experiments. Objective: This work proposes the design of graded-porosity triply periodic minimal surface (TPMS) scaffolds that mimic the mechanical environment within a bone transport callus at the peak of bone tissue production, according to in vivo load measurements. Methods: Finite element models based on computational tomography scans were used to define the strain field of the callus at the peak of bone tissue production. The developed scaffold models were evaluated through finite element simulation. Results: The callus simulations reported that the period in which maximum woven bone tissue production was achieved corresponds to the period of maximum axial strain. The graded-porosity scaffolds simulated demonstrated their ability to replicate this strain field along the callus. The microstructural parameters and strain environment of the proposed graded-porosity scaffolds were consistent with finding from studies assessing the influence of different microstructural parameters or strain conditions on bone ingrown within scaffolds. Conclusions: The proposed approach—designing graded-porosity scaffolds based on the callus strain field at the peak of bone tissue production—proved to be appropriate and may help improve future clinical applications. Full article

Porous scaffolds fabricated via fused deposition modeling (FDM) are promising for bone tissue engineering, but their mechanical performance and geometric fidelity are governed by complex interactions between process parameters and architectural design. This study presents a multi-objective optimization framework for poly (lactic acid) (PLA) scaffolds based on three triply periodic minimal surface (TPMS) topologies—Gyroid, Primitive, and Diamond. A Box–Behnken design combined with response surface methodology was used to model compressive strength, elastic modulus, yield strength, energy absorption density, and discrepancies in volume and porosity as functions of layer thickness (0.05–0.15 mm), extrusion temperature (210–220 °C), and target porosity (50–70%). The resulting quadratic models exhibited strong predictive capability (R² > 77%, with most >90%) and were validated experimentally at extreme parameter combinations, yielding relative errors below 10% for 83% of measurements. Multi-objective optimization using NSGA-II, coupled with principal component analysis and correlation-based objective reduction, revealed that the six original objectives collapse to topology-specific essential pairs: absorbed energy density and porosity discrepancy for Gyroid; Young’s modulus and volume discrepancy for Primitive; and Young’s modulus and porosity discrepancy for Diamond. The generated Pareto fronts quantify the inherent trade-off between mechanical performance and geometric fidelity for each topology, providing designers with explicit decision maps. This framework enables rational, application-driven selection of printing parameters and scaffold architecture, advancing the clinical translation of patient-specific FDM-printed bone scaffolds. Full article

The continuous increase in power density of electronic devices imposes stringent requirements on the design of lightweight, high-efficiency heat sinks. To overcome the limitations of conventional single-gradient or monomaterial heat sinks—namely, their suboptimal heat-transfer efficiency and poor structural adaptability—this study proposes a dual-gradient, triply periodic minimal surface (TPMS)-based multimaterial heat sink architecture fabricated from CuCrZr and AlSi₇Mg. Thermal performance was quantified experimentally using infrared thermography, while the underlying flow-field mechanisms were investigated numerically via computational fluid dynamics (CFD) simulations employing the standard k–ε turbulence model. With the TPMS material volume ratio fixed at 3:3 (CuCrZr:AlSi₇Mg), the Z-axis gradient configuration P-Z4-5 delivered the best overall thermal performance, achieving a heat-transfer coefficient (HTC) of 1557.63 W·m⁻²·K⁻¹ and a thermal resistance as low as 1.83 K·W⁻¹ at an inlet velocity of 5 m·s⁻¹. In contrast, the Y-axis gradient configuration P-Y3-6 yielded the most uniform temperature distribution, exhibiting a maximum surface temperature difference of only 21.5 °C under the same inlet condition. Velocity and turbulence distribution analyses reveal that the dual-gradient design enhances both the narrow-tube effect and flow-induced disturbances; furthermore, increasing the inlet velocity from 5 m·s⁻¹ to 21.65 m·s⁻¹ significantly intensifies vorticity-driven fluid mixing. Among all configurations evaluated, P-Z4-5 exhibited the highest j/f factor (i.e., the ratio of Colburn j-factor to Fanning friction factor), followed by P-Z3.5-5.5 and P-Z3-6. These findings establish a promising new pathway for the development of high-performance, lightweight heat sinks tailored for next-generation high-power electronics. Full article

High-entropy alloys (HEAs) exhibit excellent catalytic activity owing to their unique structure and chemical properties. The construction of hierarchical porous HEA catalysts via laser powder bed fusion (LPBF, a typical 3D printing technology) and dealloying techniques opens new avenues for boosting catalytic performance. This study reports the fabrication of a hierarchical porous FeCoNiCuAl HEA catalyst through a two-step strategy: LPBF and subsequent dealloying. The macroscopic triply periodic minimal surface (TPMS) structure of the HEA catalyst was constructed through LPBF, followed by dealloying to create a nanoporous structure on the catalyst surface. The hierarchical porous FeCoNiCuAl HEA catalyst exhibited a catalytic activity 4.33 times higher than that of the pristine, non-porous FeCoNiCuAl HEA (HEA-0). Furthermore, the catalyst maintained nearly 100% degradation efficiency for Acid Red G (ARG) after 20 consecutive catalytic cycles, demonstrating exceptional stability. This stepwise strategy for constructing hierarchical porous structures not only accelerates mass transfer via the macroporous framework but also significantly increases the density of accessible active sites through the nanoporous surface, thereby synergistically enhancing the catalytic activity of HEAs. This work provides a novel and scalable approach for developing high-performance porous HEA catalysts for wastewater treatment. Full article

This study introduces a new synthesis algorithm for triply periodic minimal surfaces based on determining the equilibrium configuration of elastic membranes constrained at their boundaries. Beyond the methodology itself and its computational efficiency, the scientific relevance of this work lies in the 66 surfaces with these characteristics that it enabled to generate. Leveraging their continuous and highly regular geometry, these surfaces were used to define novel shell-based lattices, the mechanical behavior of which was investigated numerically and experimentally through both static and dynamic analyses. The computational models demonstrated high predictive accuracy, with numerical results deviating by less than 10% from the experimental data. Across the new geometries, the surface-area-to-volume ratio ranged from 1.8 to 4.8 cm⁻¹. At infill coefficients of 10%, 20%, and 30%, the structures exhibited a wide range of stiffness and anisotropic behaviors, with equivalent elastic modulus spanning from 0.02% to 25% that of the base material and Zener indices from $4.67\times {10}^{-2}$ to $11.8$. Ultimately, the study revealed a clear influence of cell geometry on stress concentration and modal response. Full article