Porous Metal Research Articles

Sustainable recycling of aluminum scraps to recycled aerospace-grade 7075 aluminum alloy sheets

The production of aerospace-grade aluminum alloy sheet is characterized by stringent demands, resulting in a low yield rate. The processing of this material generates considerable amounts of highly alloyed scrap, complicating its recycling due to the challenge of maintaining melt cleanliness. This study employed an aerospace-grade melt refining system to purify the recycled 7075 alloy melt obtained from comprehensive scrap remelting. The melt's cleanliness was assessed using Porous Disc Filtration Analysis (PoDFA) and Liquid Metal Cleanliness Analyzer (LiMCA) and Alscan. The microstructure of the ingots and sheets was examined through Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD), whereas the mechanical properties of recycled sheets were evaluated and benchmarked against those of primary sheet at an aerospace-certified testing facility. The findings indicate that the recycled 7075 sheet meets aviation standards, with no significant differences in microstructure or performance when compared to primary sheet. Furthermore, the study highlights the economic benefits of recycling scrap, revealing a potential cost saving of $4210.8 per ton of recycled sheet. The findings presented herein offer a theoretical framework and empirical evidence supporting the development of a recycling system for aerospace scraps and the certification of airworthiness for recycled aerospace aluminum alloy.

Prediction of quasi-static mechanical properties of flexible porous metal rubber structures in ultra-wide temperature range

Metal rubber, which has the advantages of low density, strong environmental adaptability, and excellent design flexibility, is widely applied in manufacturing industries such as the aerospace, shipping, and automotive industries. Based on the research object of flexible porous metal rubber (FPMR) structures made of high-temperature elastic alloys, this study established a constitutive model for the quasi-static mechanical properties of FPMR structure under ultra-wide temperature range conditions. Firstly, the forming mechanism and the influencing factors of the static stiffness properties of the FPMR micro-structure were analyzed. Then, the theoretical model of the FPMR micro-element spring was established by applying the cylindrical spiral compression spring stiffness theory, and the theoretical model was corrected based on the large deformation theory and numerical analysis methods. A comparative analysis was carried out through the corrected theoretical model and the test results of different test samples. And the results show that the corrected theoretical model can comprehensively reflect the nonlinear quasi-static stiffness characteristics of the FPMR structure in an ultra-wide temperature range. More importantly, by comparison with the prediction models proposed by other scholars, it is proved that the model proposed in this paper has higher prediction accuracy and the goodness of fit R2 is closer to 1, which provides a theoretical basis for the application of metal rubber in flexible support structures under ultra-high temperature environments.

A One-Nano MOF-Two-Functions Strategy Toward Self-healing, Anti-inflammatory, and Antibacterial Hydrogels for Infected Wound Repair

Porous metal–organic frameworks (MOF)-based hydrogels have recently attracted wide attention in sensing, catalysis, water treatment, and biomedicine. Yet, limited by challenges of insufficient stability, inordinate metal-ion leakage, and weak wound healing efficacy, the design of MOF-based hydrogel dressings for infected wounds has been rarely explored. Here, we propose a “one-nano MOF-two-functions” strategy to demonstrate the molecular engineering of a chemically stable nano MOF, which acts as both a carrier and a dynamic cross-linker, to fabricate functional composite hydrogels. The active amino groups of the MOF are employed to create dynamic networks with aldehyde-bearing alginate, ensuring excellent compatibility of the MOF with the polymer matrix and imparting effective self-healing properties to the resulting hydrogels. Simultaneously, two active ingredients, Cu nanoparticles (NPs) and curcumin, can be loaded into the nano MOF, achieving synergistic anti-inflammatory and antibacterial effects. Assisted by the mechanical stability and drug co-delivery in an infected full-thickness skin model, the MOF-based hydrogel can reduce the bacterial load on the wound by ∼103 times, and promote collagen deposition and angiogenesis by ∼1.5 and ∼3 times, compared with the control group. The “one-nano MOF-two-functions” design exhibits significant potential for high-performance infected wound dressings.

Failure analysis of CFRP/Al single lap adhesive joint with enhancing porous metal foam insert

Cohesive failure is one of the main causes of adhesive bonding failure. The enhanced method and mechanism for adhesive signify a critical research issue for better adhesive joint design. This study proposes using a porous metal foam insert adhesive to enhance the carbon fiber reinforced polymer/aluminum single lap joint. In particular, stress distribution and failure locations of joints with and without insert were compared by simulation modeling. The insert of the Cu-foam, Fe-foam, and Ni-foam, compared to no insert, increased the shear strength of the bonded joint by 32.23 %, 36.66 %, and 66.82 %, respectively. Compared to no insert, the crack propagation of the joint with a metal foam insert was changed from the cross-section of the adhesive layer to the plane of the foam insert. The highest strength of the adhesive joint with the Ni-foam insert was further analyzed to determine fatigue behavior compared with pure adhesive joint under different stress levels. Compared to no insert, the fatigue life increased highly, and the crack path was prolonged.

Development of Novel Surface-Enhanced Raman Spectroscopy-Based Biosensors by Controlling the Roughness of Gold/Alumina Platforms for Highly Sensitive Detection of Pyocyanin Secreted from Pseudomonas aeruginosa.

Pyocyanin is considered a maker of Pseudomonas aeruginosa (P. aeruginosa) infection. Pyocyanin is among the toxins released by the P. aeruginosa bacteria. Therefore, the development of a direct detection of PYO is crucial due to its importance. Among the different optical techniques, the Raman technique showed unique advantages because of its fingerprint data, no sample preparation, and high sensitivity besides its ease of use. Noble metal nanostructures were used to improve the Raman response based on the surface-enhanced Raman scattering (SERS) technique. Anodic metal oxide attracts much interest due to its unique morphology and applications. The porous metal structure provides a large surface area that could be used as a hard template for periodic nanostructure array fabrication. Porous shapes and sizes could be controlled by controlling the anodization parameters, including the anodization voltage, current, temperature, and time, besides the metal purity and the electrolyte type/concentration. The anodization of aluminum foil results in anodic aluminum oxide (AAO) formation with different roughness. Here, we will use the roughness as hotspot centers to enhance the Raman signals. Firstly, a thin film of gold was deposited to develop gold/alumina (Au/AAO) platforms and then applied as SERS-active surfaces. The morphology and roughness of the developed substrates were investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The Au/AAO substrates were used for monitoring pyocyanin secreted from Pseudomonas aeruginosa microorganisms based on the SERS technique. The results showed that the roughness degree affects the enhancement efficiency of this sensor. The high enhancement was obtained in the case of depositing a 30 nm layer of gold onto the second anodized substrates. The developed sensor showed high sensitivity toward pyocyanin with a limit of detection of 96 nM with a linear response over a dynamic range from 1 µM to 9 µM.

Thermal conductivity enhancement of polyethylene glycol/NF composite as stabilized phase change materials for thermal energy storage

Polyethylene glycol (PEG) has the advantages of large latent heat of phase transition, a wide range of phase transition, and cheap price, but the application of PEG in the latent thermal energy storage (TES) systems is hindered due to its lower heat transfer rate and leakage. Porous metal foam has excellent thermal conductivity and high strength, which can effectively improve the problems of PEG. In this study, PEG/nickel foam (NF) composite phase change materials (PCM) were prepared by vacuum molten impregnation method using NF as substrate. It was found that PEG had good compatibility with NF, and the highest impregnation rate of PEG6000/NF reached 85.73 %. The thermal conductivity of PEG2000/NF can be increased to 1.58 1.58 W·m−1 K−1, nearly 4 times larger than that of pure PEG. The phase change temperature range of the composite PCM is 51–63 °C, and the phase change enthalpy is 67.8–126.3 J·g−1. Furthermore, the PEG/NF composite demonstrated outstanding photothermal conversion properties and high thermal stability, which can be widely used in the field of building temperature control and device heat dissipation.

Mo3P/Mo heterojunction for efficient conversion of lithium polysulfides in high-performance lithium-sulfur batteries.

Realizing efficient immobilization of lithium polysulfides (LiPSs) as well as reversible catalytic conversion between LiPSs and the insoluble Li2S is vital to restrain the shuttle effect, which requires highly reactive catalysts for high-performance Li-S batteries. Here, three-dimensional ordered porous Mo-based metal phosphides (3DOP Mo3P/Mo) with heterogeneous structures were fabricated and utilized as separator-modified coatings for Li-S batteries to catalyze the conversion of LiPSs. The adsorption, catalytic and electrochemical performance of the corresponding cells were compared among 3DOP Mo3P/Mo and 3DOP Mo, by kinetic and electrochemical performance measurements. It was found that the cell with 3DOP Mo3P/Mo modified separator deliver better electrochemical performance, with a high specific capacity of 469.66mAh g-1 after 500 cycles at a high current density of 1°C. This work provides an idea and a guideline for the design of the separator modification for high-performance Li-S batteries.

The Evaluation of the Cytotoxicity and Corrosion Processes of Porous Structures Manufactured Using Binder Jetting Technology from Stainless Steel 316L with Diamond-like Carbon Coating

With the growing interest in additive manufacturing technology, assessing the biocompatibility of manufactured elements for medical and veterinary applications has become crucial. This study aimed to investigate the corrosion properties and cytotoxicity of porous structures designed to enhance the osseointegration potential of implant surfaces. The structures were fabricated using BJ technology from 316L stainless steel powder, and their surfaces were modified with a DLC coating. The studies carried out on porous metal samples with and without DLC coatings demonstrated low cytotoxicity. However, no significant differences were found between the uncoated and DLC-coated samples, likely due to variations in the thickness of the coating on the porous samples and the occurrence of mechanical damage.

ТЕХНОЛОГИЧЕСКИЕ МЕТОДЫ ФОРМООБРАЗОВАНИЯ КАЧЕСТВЕННОЙ ПОВЕРХНОСТИ ДЕТАЛЕЙ ИЗ АЛЮМИНИЕВЫХ И МЕДНЫХ СПЛАВОВ

The surface quality of aluminum and copper alloy parts is studied when they are formed, which is important for transport engineering. The main task is to determine the conditions conducive to the formation of specified criteria for surface quality and to find out the dependencies of various factors when applying edge cutting machining and electrochemical processes. The research includes experimental and analytical parts, which are presented as conclusions, including the most optimal modes and conditions in terms of quality formation. The research methods are of an experimental and practical nature with the comparison and evaluation of the results obtained, in which the features of porous metal ceramics machining and methods for improving the efficiency of surface forming while maintaining the functional physical parameters of the part surfaces are considered. The novelty of the study is in finding dependencies of the obtained quality on the machining conditions and the comparative characteristics of the obtained surfaces not only in terms of changes in roughness, but also in surface porosity. As a result, recommendations are made for machining such materials, which minimize the effect of pore tightening and reduce deformation phenomena in the material.

Electrodeposited Porous Ni-Fe-Co Thin Films By Hydrogen Templating Onto an Inverted Recessed Disk Electrode

Porous electrodes are advantageous for a variety of applications to enhance surface area per volume. Hydrogen templating is one well-known method to generate a porous metal, where metal deposits around generated gas bubbles from the same electrode surface. The technique has been demonstrated with noble (e.g., Au, Ag, Cu) and less noble (e.g., Ni) elemental deposits, but few alloy system.1 Ni-Fe-Co is of interest due to its electrocatalytic ability towards the oxygen evolution reaction for alkaline water splitting. Rafailović et al.2 galvanostatically electrodeposited an alloy at very high current density at pH 2 having 20 micron pore size with nano scale dendritic features, and Li and Podlaha3 potentiostatically electrodeposited Ni-Fe-Co alloys at pH < 0.5 into polycarbonate templates along with hydrogen templating to create pores in nanowires. There was a large distribution of pore size between 10 and 100 nm with the largest percentage between 20 and 40 nm. To better understand the control of pore size in the Ni-Fe-Co alloy system an inverted rotating disk electrode was used to control the limiting current of the proton reduction reaction during alloy electrodeposition. A boric acid, simple salt electrolyte was used with a three-electrode system to generate polarization curves and electrodeposits at different electrode rotation rates. The influence of mass transport and hydrogen bubble formation at different rotation rates were examined and affected porosity. Porosity was characterized by scanning electron microscopy (SEM) and the inspection of current during ferri/ferrocyanide polarization. Porous films were observed for deposits galvanostatically fabricated at current densities above the proton reduction limiting current density, but before water reduction, producing pore sizes on the order of 10s to 100s of nm, but below a micron. The ratio of the applied current density to proton reduction limiting current density was an important factor. J. Plowman, L. A. Jones, and S. K. Bhargava, Chemical Communications, 51, 4331-4346 (2015).D. Rafailović, C. Gammer, C. Rentenberger, T. Trišović, C. Kleber, and H. P. Karnthaler, Nano Energy, 2, 523-529 (2013).D. Li and E. J. Podlaha, Nano Letters, 19, 3569-3574 (2019).

Reduction of Air Pollution from IC Engine Exhausts Through Condensation with Novel Porous Copper Metal Foams

Reduction of Air Pollution from IC Engine Exhausts Through Condensation with Novel Porous Copper Metal Foams

Hydrogenation of inert aromatic compounds under mild conditions catalyzed by confined trimetal sites in porous metal silicate materials

Complete hydrogenation of aromatic compounds is an important subject in various industry fields. However, due to the high stabilization energy of aromatic compounds resulting from their high aromaticity and non-polarity, the hydrogenation reaction is usually performed under harsh reaction conditions in the presence of noble metal-based catalysts. We report herein a porous metal silicate (PMS) material PMS-58, which consists of Cu, Ce and Co trimetal active sites, demonstrating high catalytic activity and selectivity in hydrogenating of a series of aromatic compounds under mild conditions (60 °C and 0.5 MPa H2). PMS-58 is superior to the previously reported non-noble metal-based catalysts and could be favorably compared to noble metal-based catalysts. The unique catalytic properties of PMS-58 are derived from the synergistic work of trimetal sites with Ce species serving as strong Lewis acid sites for dissociation of dihydrogen, Co species stabilizing Cu(I) species, and Cu(I) species playing a crucial role in activating aromatic rings. Therefore, this work provides a new approach in developing highly efficient non-noble metal catalysts for complete hydrogenation of arenes under mild conditions, which could be applied in removal of aromatic compounds in petroleum products.

Prediction of Macroscopic Deformation Bands in Porous Metals with Unidirectional Through‐Pores

Prediction of Macroscopic Deformation Bands in Porous Metals with Unidirectional Through‐Pores

Metal-Organic Framework Functionalized Chitosan/Pectin Membranes for Solar-Driven Photo-Oxidation and Adsorption of Arsenic

The presence of arsenic as neutral arsenite and oxoanionic arsenate species are a worldwide issue that requires an effective remediation technology capable to remove both AsIII and AsV from water. In this research we propose the assembly of a membrane build up from chitosan/pectin (CHIPEC) composite biopolymer and the UiO-66-NH2 porous and photo-active metal–organic framework. CHIPEC@UiO-66-NH2 membrane integrates porosity, adsorptive capacity, and activity to photo-oxidize and adsorb AsIII and AsV species. Nanometric-sized UiO-66-NH2 was synthetized and homogeneously distributed within the CHIPEC matrix, achieving a composite membrane with optical physico-chemical and optical properties (band gap of 2.91 eV) suitable to be applied on photooxidation of AsIII and adsorption of AsV. Under optimal conditions, maximum adsorption capacities (Qmax) values of 254 and 168 mg g−1 were reached for AsIII adsorption by MOF and membrane, respectively. Notably, for AsV adsorption, Qmax values of 268 and 335 mg g−1 were reached for powdered and immobilized MOF, respectively. Moreover, the membrane keeps most of its activity for AsV adsorption when employed in surface and groundwater matrixes. Further, the efficiently of UiO-66-NH2 to photo-oxidize AsIII to AsV, subsequently adsorbing the arsenate oxyanions, is improved by a factor of five when is integrated into the polymer. A detailed multi-step mechanism for the arsenic transformation and adsorption in CHIPEC@UiO-66-NH2 has been proposed on the basis of the anionic exchange at Zr hexa-nuclear clusters and amino groups in the MOF. Overall, MOF-biopolymeric composite has been proved as a straightforward, efficient, low-cost, and environmentally friendly solution for detoxifying arsenic in surface and underground water.

Calcination process of porous metal–organic frameworks derived from nickel sulfide composites for supercapacitor and computer vision for investigating the porosity-electrochemical correlation

The utilization of metal–organic framework nanostructured electrode materials in supercapacitors and sensor applications is achieved by various chemical methods. In this study, we create NiS and NiS@MOF-BDC by employing nickel precursors and benzene dicarboxylic acid (BDC) as chelating organic linkers through a thermal reduction procedure at a temperature of 400 °C to produce the composite. The composite heterostructure enhanced the conductivity, porous characteristics, and diverse potential morphological qualities. The production of composite electrodes demonstrates a specific capacity of 260F/g (104C/g) when subjected to a current density of 1A/g. Additionally, these electrodes exhibit exceptional cyclic stability, enduring 5000 cycles, when used with a 2 M KOH electrolyte. Moreover, the synthesized composite HR-TEM images were analyzed using computer vision and AI techniques for estimating the porosity and investigating the enhanced electrochemical correlation.

High energy absorption design of porous metals using deep learning

Due to its remarkable energy absorption properties, porous metals have widespread applications in engineering. However, the high randomness of pore morphology greatly hinders the effective design and analysis of high energy absorption structures. To address this challenge, this paper first introduces a deep learning-based framework for high energy absorption-oriented design of random porous metals structures. The framework comprises two steps: (i) a generator powered by Wasserstein deep convolutional generative adversarial network is developed to swiftly generate a vast design space (∼one million samples) of porous metals with real random pore morphology. (ii) an inverse search strategy based on convolutional neural network is applied to quickly pick out the optimal structure with the best energy absorption from the design space. Results show that the optimal energy absorption is about 17.71 % higher than the maximum value of initial structures from CT scan. Additionally, a 575-fold increase in computational efficiency is achieved compared to the traversal search using finite element method. Subsequently, the deformation process of the optimal structure is analyzed focusing on the pore morphology and compression performance, showing that random porous metals with uniformly sized pores are capable of withstanding higher stress under the same strain and exhibit no yield band during compression. Inspired by this, a structural homogenization method is introduced and validated to create porous metal structure with stable microstructure evolution, extended plateau stress and high energy absorption.

Metal–organic frameworks and their composites: Design, synthesis, properties, and energy storage applications

Porous crystalline metal–organic frameworks (MOFs) are promising materials for supercapacitors (SCs) owing to their excellent pore structures, large surface areas, adjustable topological types, and multivalent active metal nodes, which endow them with ideal energy-storage performance. However, despite their successful application in many fields such as catalysis, gas adsorption and separation, and sensors, various intrinsic defects have hindered their practical application in SCs. In recent years, MOFs have demonstrated significant advancements in their electrochemical performance, and their applications in SCs have been gaining momentum. This review summarizes the design, classification, synthesis strategies, and properties of MOFs. The formation conditions and mechanisms of MOFs are discussed and the effects of the different types and synthesis strategies of MOFs on their properties are compared to improve their design and preparation. The research progress on pristine MOFs and their composites in SCs is reviewed, highlighting the solutions for the intrinsic defects in pristine MOFs in SC applications. The challenges of utilizing MOF-based materials in SC applications are summarized and potential solutions for their future development are suggested.

Fabrication of three-dimensional bicontinuous porous aluminum by vapor phase dealloying

The development of lightweight, high-specific-surface-area, and exceptionally tough porous aluminum (Al) through dealloying has been consistently captured the attention of the porous metal field. However, widely employed dealloying approaches such as electrochemical dealloying (ECD) and liquid metal dealloying (LMD) face limitations in constructing porous metals with high chemical reactivities. In this study, we employed an emerging vapor phase dealloying (VPD) method, utilizing the differences in saturated vapor pressures among alloy constituents to selectively remove elements with high vapor pressures under optimized temperature and vacuum conditions. The VPD process, characterized by its chemical-free nature and the application of high temperatures, rapidly produces porous Al with varying ligament sizes from the MgZnAl system. The resulting porous Al, distinguished by its crack-free structure and substantial ligament size, exhibits remarkable toughness. The successful fabrication of porous Al using the VPD method effectively bridges the existing gap in generating porous metals with low melting points and high chemical reactivity through ECD and LMD methods. This advancement holds significance for broadening the range of systems and application fields for porous metals.

Simulation and Experimental Investigation of the Effect of Pore Shape on Heat Transfer Behavior of Phase Change Materials in Porous Metal Structures.

With the gradual increase in energy demand in global industrialization, the energy crisis has become an urgent problem. Due to high heat storage density, small volume change, and nearly constant transition temperature, phase change materials (PCMs) provide a promising method to store thermal energy. In this work, we designed and fabricated three kinds of porous metal structures with hexagonal, rectangular, and circular pores and explored the phase change process of PCMs within them. A two-dimensional numerical model was established to investigate the heat transfer process of PCMs within different shapes of porous metal structures and analyze the influence of heat source location on the thermal performance of the thermal storage units. Visualization experiments were also carried out to reveal the melting process of PCMs within different porous metal structures by a digital camera. The results show that paraffin in a porous metal structure with hexagonal pores has the fastest melting rate, while that in a porous metal structure with circular pores has the slowest melting rate. Under the bottom heating mode, the melting time of the paraffin in porous metal structures with hexagonal pores is shortened by 18.6% compared to that in porous metal structures with circular pores. Under the left heating mode, the corresponding melting time is shortened by 16.7%. These findings in this work will offer an effective method to design and optimize the structure of porous metal and improve the thermal properties of PCMs.

Scalable Production of 2D Non‐Layered Metal Oxides through Metal–Organic Gel Rapid Redox Transformation

Two‐dimensional (2D) nonlayered metal compounds with porous structure show broad application prospects in electrochemistry‐related fields due to their abundant active sites, open ions/electrons diffusion channels, and faradaic reactions. However, scalable and universal synthesis of 2D porous compounds still remains challenging. Here, inspired by blowing gum, a metal‐organic gel (MOG) rapid redox transformation (MRRT) strategy is proposed for the mass production of a wide variety of 2D porous metal oxides. Adequate crosslinking degree of MOG precursor and its rapid redox with NO3‐ are critical for generating gas pressure from interior to exterior, thus blowing the MOG into 2D carbon nanosheets, which further act as self‐sacrifice template for formation of oxides with porous and ultrathin structure. The versatility of this strategy is demonstrated by the fabrication of 39 metal oxides, including 10 transition metal oxides, one II‐main group oxide, two III‐main group oxides, 22 perovskite oxides, four high‐entropy oxides. As an illustrative verification, the 2D transition metal oxides exhibit excellent capacitive deionization (CDI) performance. Moreover, the assembled CDI cell could act as desalting battery to supply electrical energy during electrode regeneration. This MRRT strategy offers opportunities for achieving universal synthesis of 2D porous oxides with nonlayered structures and studying their electrochemistry‐related applications.