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The current study investigates the process of preparing and analysing porous-structured ceramics made from zirconium, aluminium, and magnesium ceramic oxides. The starch consolidation casting (SCC) technique, with different types of starches (potato and tapioca), was used for this purpose. Our objective was to methodically examine the impact of different processing factors, such as the temperature at which pre-sintering and sintering occur, and the proportions of ceramic powders, on the microstructure, mechanical characteristics, and porosity of the resultant composites. Pre-sintering effectively reduced the rate of shrinkage during the final sintering stage; this resulted in more controlled and predictable shrinkage, leading to better dimensional stability and reduced risk of defects in the final product. A higher alumina content was associated with an increase in apparent porosity and a reduction in volume shrinkage and apparent densities. The mercury intrusion porosimetry (MIP) findings concluded that the prepared porous ceramics have a multi-modal pore structure. The highest calculated compressive strength was 76.89 MPa for a sample with a porous structure, which was manufactured using 20 wt.% tapioca starch and 30 wt.% alumina content. The main advantage of alumina is its ability to improve compressive strength by refining the grain structure and serving as a barrier against fracture development. [ABSTRACT FROM AUTHOR]

Manufacturing ceramic green structures using starch consolidation casting is an established process that is simple, non-hazard, and low-cost. In this study, starch consolidation casting is used to prepare ceramics based on submicron monoclinic zirconia with additions of alumina and magnesia. Scanning electron microscopy results indicate that the size of pores decreased and the morphological irregularity increased when the tapioca starch content increased. The sample with 30 wt.% tapioca starch in a 55 wt.% slurry concentration had the highest estimated apparent porosity (around 56%), whereas the sample with 10 wt.% in a 68 wt.% suspension concentration had the lowest (about 35%). [ABSTRACT FROM AUTHOR]

Gas injection for enhancing gas recovery (GI–EGR) is a multifaceted process that requires a solid theoretical foundation to be implemented orderly. However, there are limited reports on the micro-mechanisms of GI–EGR technology applied to coalbed methane reservoirs, especially for deep strata. To address this gap, this study utilized molecular simulation techniques to construct the organic pore models of anthracite with varying sizes and morphologies, and explored the micro-dynamic behaviors of CH4 and various gas injected components including N2, CO2 and flue gas confined in nanopores. The aim was to reveal the competitive adsorption mechanisms of gases in multi-component systems under shallow and deep geological conditions. The results demonstrated that the isosteric heats of CH4, N2 and CO2 all increased after the transition from shallow to deep, with rising amplitudes of 18.8%, 22.8% and 17.8%, respectively, in the respective single-component systems. In multi-component adsorption models, the isosteric heats remained higher than those under shallow conditions, but there were some small fluctuations due to the interference between various gases. On the other hand, the self-diffusion coefficients of single CH4, N2 and CO2 in the deep condition decreased by 37.6%, 27.2% and 23.1%, respectively, compared to those in conventional shallow conditions. As a consequence, the difference in diffusivity among various gases would get narrowed. The molecular-level observations herein have the potential to improve the understanding of gas occurrence and lay a solid foundation for the GI–EGR technology. [ABSTRACT FROM AUTHOR]

To essentially explore and quantitatively clarify the mesoscopic failure mechanism of deep weak interlayer zone (WIZ) induced by complex stress levels and stress paths (i.e., particle breakage and orientation, pore morphology, etc.), a semi-quantitative mesoscopic structural damage analysis methodology has been proposed, by involving SEM-MATLAB image processing technique with representative meso-structural parameters after sufficient analysis of basic geotechnical properties of WIZ. Results show that the natural WIZ exhibiting a flocculated structure could be characterized as a well-graded geotechnical material forming main clay minerals, in which most pores are intergranular, with the pore size distribution concentrated in 0.007–200 μm. Higher initial confining pressure and axial loading tend to intensify the particle breakage degree and particle size distribution characteristics of WIZ more than that of axial and circumferential unloading, in which the stress path II of axial pressure loading and confining pressure unloading under the initial confining pressure of 25 MPa is the most severe with average particle area reduced by 56% and particle Korcak fractal dimension increased by 36%. The broken particles undergoing a series of irreversible dislocation, tumbling and rotation under the action of shear and tensile stress, tend to orient in the direction of 0°–15°, in which particles in stress path IV aggregate in two directions of 0–15° and 60–90° due to the bidirectional unloading. The unloading stress path IV shows the most distinct directional orientation and orderliness, with particle anisotropy increased by 267% and directional probability entropy reduced by 13%. Particle breakage and orientation in WIZ are accompanied by obvious filling, expansion and propagation of the meso-pores and meso-cracks, in which stress path IV under lower confining pressure most affects the morphological complexity of pore and crack boundaries with the pore morphology fraction dimension increased by 13.5%. The quantitative theoretical correlation of macro-meso parameters has been established by the stepwise regression analysis of two most relevant and representative correlation indexes (i.e., Korcak fractal dimension and pore morphology fractal dimension) with the ultimate bearing strength of WIZ, which has been proved to have high fitting accuracy by comparing the regression results with the test measured values. The meso-structural damage mechanism of WIZ under stress paths II and IV could, respectively, match the failure law of structural stress-induced collapse in the spandrel and the plastic squeezing-out failure of WIZ on the high sidewall of underground excavations. Research could provide feasible ideas for the relationship between macroscopic failure and mesoscopic damage of WIZ, as well as the effective basis for the further discussion of macro-meso constitutive model establishment. Highlights: A semi-quantitative method by SEM-MATLAB image processing technique was proposed to explore the mesoscopic failure mechanism of weak interlayer zone. The particle breakage, particle orientation, pore morphology and crack evolution induced by complex stress paths were quantitatively explored. The quantitative theoretical correlation of macro-meso parameters was established by stepwise regression analysis. The correlation between meso-structural variation and engineering failure mechanism of weak interlayer zone was discussed. [ABSTRACT FROM AUTHOR]

Copyright of Iron Steel Vanadium Titanium is the property of Iron Steel Vanadium Titanium Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Manufacturing defects, such as porosity and inclusions, can significantly compromise the structural integrity and performance of additively manufactured parts by acting as stress concentrators and potential initiation sites for failure. This paper investigates the effects of pore system morphology (number of pores, total volume, volume fraction, and standard deviation of size of pores) on the material response of additively manufactured Ti6Al4V specimens under a shear–compression stress state. An automatic approach for finite element simulations, using the J2 plasticity model, was utilized on a shear–compression specimen with artificial pores of varying characteristics to generate the dataset. An artificial neural network (ANN) surrogate model was developed to predict peak force and failure displacement of specimens with different pore attributes. The ANN demonstrated effective prediction capabilities, offering insights into the importance of individual input variables on mechanical performance of additively manufactured parts. Additionally, a sensitivity analysis using the Garson equation was performed to identify the most influential parameters affecting the material's behaviour. It was observed that materials with more uniform pore sizes exhibit better mechanical properties than those with a wider size distribution. Overall, the study contributes to a better understanding of the interplay between pore characteristics and material response, providing better defect-aware design and property–porosity linkage in additive manufacturing processes. [ABSTRACT FROM AUTHOR]

Manufacturing defects, such as porosity and inclusions, can significantly compromise the structural integrity and performance of additively manufactured parts by acting as stress concentrators and potential initiation sites for failure. This paper investigates the effects of pore system morphology (number of pores, total volume, volume fraction, and standard deviation of size of pores) on the material response of additively manufactured Ti6Al4V specimens under a shear–compression stress state. An automatic approach for finite element simulations, using the J2 plasticity model, was utilized on a shear–compression specimen with artificial pores of varying characteristics to generate the dataset. An artificial neural network (ANN) surrogate model was developed to predict peak force and failure displacement of specimens with different pore attributes. The ANN demonstrated effective prediction capabilities, offering insights into the importance of individual input variables on mechanical performance of additively manufactured parts. Additionally, a sensitivity analysis using the Garson equation was performed to identify the most influential parameters affecting the material’s behaviour. It was observed that materials with more uniform pore sizes exhibit better mechanical properties than those with a wider size distribution. Overall, the study contributes to a better understanding of the interplay between pore characteristics and material response, providing better defect-aware design and property–porosity linkage in additive manufacturing processes.

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bone bionics and structural engineering have sparked a broad interest in optimizing artificial scaffolds for better bone regeneration. However, the mechanism behind scaffold pore morphology-regulated bone regeneration remains unclear, making the structure design of scaffolds for bone repair challenging. To address this issue, we have carefully assessed diverse cell behaviors of bone mesenchymal stem cells (BMSCs) on the β-tricalcium phosphate (β-TCP) scaffolds with three representative pore morphologies (i.e., cross column, diamond, and gyroid pore unit, respectively). Among the scaffolds, BMSCs on the β-TCP scaffold with diamond pore unit (designated as D-scaffold) demonstrated enhanced cytoskeletal forces, elongated nucleus, faster cell mobility, and better osteogenic differentiation potential (for example, the alkaline phosphatase expression level in D-scaffold were 1.5–2 times higher than other groups). RNA-sequencing analysis and signaling pathway intervention revealed that Ras homolog gene family A (RhoA)/Rho-associated kinase-2 (ROCK2) has in-depth participated in the pore morphology-mediated BMSCs behaviors, indicating an important role of mechanical signaling transduction in scaffold-cell interactions. Finally, femoral condyle defect repair results showed that D-scaffold could effectively promote endogenous bone regeneration, of which the osteogenesis rate was 1.2–1.8 times higher than the other groups. Overall, this work provides insights into pore morphology-mediated bone regeneration mechanisms for developing novel bioadaptive scaffold designs.

The excavation and unloading of silty mudstone slopes often precipitate slope instability and collapse. While abundant research addresses the macro deterioration of rock strength, the micro-damage mechanism of silty mudstone remains largely uncharted. To bridge this gap, our study innovatively utilized nano-materials to prepare silt-like mudstone subjected to the triaxial unloading test considering multiple paths. Then we delved into the variation in microstructure using Scanning Electron Microscopy (SEM), binarization, and fractal dimensions. Our findings reveal that: (1) The peak stress, residual stress, and residual strain of silt-like mudstone display a decreasing trend with an increase in initial deviatoric stress while the peak strain initially increases and subsequently decreases; (2) Following unloading, the crack propagation on fracture surface is dictated by both confining pressure and initial deviatoric stress, which profoundly impact porosity, particle fragmentation, and pore expansion; (3) As confining pressure and initial deviatoric stress elevate, the average morphology coefficient rises with a reduction in rate of change. The impact of unloading confining pressure on pore morphology diminishes; (4) The fractal dimension increases with increased confining pressure and initial deviatoric stress, with a transition in the pore surface from smooth to rough.

The accurate calculation of the contribution which provided by clay minerals in coal on methane adsorption not only bares a significant importance for evaluating the effectiveness of acid stimulation in improving permeability and estimating the coalbed methane reserves but also serves a guide for the governance and utilization of methane resources. In this study, hydrochloric acid (HCl) and hydrofluoric acid (HF) were used to remove specific minerals in Qingdong coal samples. We firstly analyzed the mineral compositions of coal samples with different acidification treatments based on the X-ray diffraction (XRD) experiments, together with analysis of the changes in pore morphology and adsorption capacity. The results showed that acidification did not significantly change the shape of the pores, which remained slit-/plate-like pore. However, the altered adsorption capacity of the coal samples was attributed to changes in pore structure and mineral distribution. Acid erosion of mesopores promoted the transition from mesopores to macropores, contributing to an increase of 8.4% and 24.36% in the percentage of macropores in coal samples treated with HCl and HF, respectively. Fractal dimension D1 grew from 2.2193 to 2.3888 and 2.2572, respectively, but D2 decreased from 2.6146 to 2.5814 and 2.5433, indicating an increment in pore surface roughness and a simplification of the pore structure. The mineral richness of the coal seams should be taken into consideration when applying acid stimulation to increase permeability due to that the acidification products may block the passage of gas migration when the mineral content is slight, which can hinder gas extraction. The aim of this study is to quantitatively determine the contribution rate of clay minerals in coal to methane adsorption with a calculation method is provided by combining pore parameters and limit adsorption capacity, resulting in a contribution rate of 15%. [ABSTRACT FROM AUTHOR]

A semi-solid route is expected to be a fabrication method that can fabricate aluminum alloy foams with a variety of mechanical properties, but the allowance fluctuation of the fabrication conditions of aluminum alloy foams with high reproducibility is not clear. The objective of this study was to reveal the allowance fluctuation between the setting temperature and the actual temperature of the melt to fabricate stable foams, having pores with small pores and high circularity, and the influence of the increasing volume fraction of the solid on the pore morphology. Al-Si alloy foams were fabricated five times by adding a blowing agent into a semi-solid slurry under the same setting fabrication conditions, such as the temperature and concentration of oxygen in the atmosphere. The results of small relative standard deviations of pore diameter and circularity indicated that the conducted fabrication process had high reproducibility, even if the volume fraction of the solid changed in a range of 5%. When the volume fraction of the solid exceeds the minimal fraction of primary crystals for prevention of drainage, the clogging effect works more efficiently because the ratio of clogged cell walls increases. Additionally, the preferred range of the volume fraction of the solid for the fabrication of stable foam was revealed to be around 15% to 35%. [ABSTRACT FROM AUTHOR]

Utilization of wastes for the preparation of ceramic foams has gradually become a major direction in the development of new building materials. In this paper, all wastes-based ceramic foams based on electrical insulators waste (EIW) and red mud (RM) were prepared through the high-temperature foaming method. The factors affecting the increase in pore size under different preparation conditions (RM content, temperature and time) were investigated separately by studying the changes in pore size. With the increase of RM content, sintering temperature and sintering time, the pore morphology gradually evolved from a regular spherical shape to a polygonal or irregular shape with a corresponding increase in pore size, albeit at different rates. The pore size enhancement ascribed to changes in RM content was primarily attributed to the synergistic influences of a plurality of factors including glass phase content, viscosity, and gas phase content. Sintering temperature mainly affected the balance between the forces acting inside and outside the pores and the gas phase solubility in the liquid phase to adjust the size of pores. The influence of sintering time on pore size and morphology emanated from the glass phase viscosity and the resulting changes in the release rate of gas phase. In summary, the study will help to investigate the actual controlling factors of composition and process on the pore structure, and provides significant insights into the optimization and adjustment of pore structure for samples obtained by high-temperature sintering. [ABSTRACT FROM AUTHOR]

Ice‐templating, also known as directional freezing or freeze‐casting, features the tunability of microstructure, the wide applicability of functional nanomaterials, and the fabrication of multiscale well‐controlled biomimetic materials. Recently, integrating ice‐templating with other materials' processing technologies (such as, spraying, spinning, filtration, and hydrothermal), it has been investigated to tailor pore morphology of scaffolds for emerging applications. Such integration endows materials with various structures (cellular, dendritic, and lamellar) and dimensions (0D, 1D, 2D, and 3D), which opens up a new avenue for improving material properties and developing new materials. Herein, this review probes into the relationship of integrative ice frozen assembly with structure and describes the fundamental principles and synthesis strategies for preparing multi‐scale materials with complex biomimetic structures via ice‐templating. Focusing on ice crystal nucleation and growth, it summarizes the performance of ice‐templating in constructing pore geometries. Additionally, the review analyzes in depth the correlation between microstructure and macromorphology of final scaffolds, highlighting the application of integrative ice frozen assembly in electrochemical energy storage and conversion, and prospects for future research directions for this field. [ABSTRACT FROM AUTHOR]

The effect of pore morphology and regional distribution on liquid diffusion directionality in nonwoven fabrics was investigated in this study. Pore orientation angle (POA) and pore aspect ratio ( PAR) were proposed to characterize the pore morphology, and α-region, β-region, and αβ-region were used to describe the characteristics of the pore regional distribution. The directional characteristics of macroscopic diffusion of liquid in nonwoven fabrics were characterized by the indicator of primary diffusion orientation angle (PDOA). Ten kinds of spunlaced nonwoven fabrics were selected. Firstly, the data of pore characteristic indices of each sample were obtained through scanning electron microscope (SEM) and the image processing technology as well, and the pore regional distribution map of each sample was further acquired. Then, the PDOA of each sample was obtained through the droplet method and image processing technology. Based on the data and statistical analysis, it was found that the PDOA of a certain volume of liquid in the nonwoven fabrics presented a significant linear relationship with the average POA of the nonwoven fabrics. And the characteristics of pore distribution affected the directionality of liquid diffusion in the nonwoven fabrics. The samples with a large proportion of α-region and good distribution had prominent liquid diffusion along the direction of laying-up, and the difference in liquid diffusion of the samples was more obvious between the directions of laying-up and vertical laying-up. [ABSTRACT FROM AUTHOR]

The pore characteristics of saline soil greatly influence its engineering properties, such as deformation, strength, and permeability. To explore the microscopic pore characteristics of the saline soil profile in Qian’an country, Northeastern China, a study based on the mercury injection test (MIP) and the scanning electron microscope (SEM) test combined with fractal theory was carried out. The results reveal that the pore size of undisturbed saline soil at the sampling point presents the characteristic of trimodal distribution and shows different microscopic characteristics with a depth of 60 cm as the boundary. The shallow soil (surface—40 cm) has poor compactness, high porosity, and macropores (4–40 μm) dominate, while the deep soil (60–100 cm) has higher compactness, smaller porosity, and more uniform pore size distribution. In addition, the pore morphology of the saline soil profile is closer to the sub-long strip or oblate, which indicates the pore has a poor roundness, and the pore edge lines are relatively smooth. The geostatic stress, freeze–thaw cycle, clay content, and soluble salt affect the pore microstructure together. Furthermore, the pore characteristics were evaluated based on the fractal dimension (D ) and surface fractal dimension (Dr ). D has the strongest correlation with the content of small pores (0.04–0.4 μm), and Dr has the strongest correlation with the shape coefficient. D and Dr can jointly reflect the microscopic pore structure characteristics with a good corresponding relationship. [ABSTRACT FROM AUTHOR]

Melt electrowriting (MEW) enables the electric field‐assisted digital fabrication of precisely defined scaffold architectures of micron‐sized fibers. However, charge accumulation and consequent disruption of the precoded pattern by fiber bridging prevents controlled printing at small interfiber distances. This, together with the periodical layer stacking characteristic for additive manufacturing, typically results in scaffolds with channel‐like macroporosity, which need to be combined with other biofabrication techniques to achieve the desired microporosity for cellular infiltration. Therefore, a design strategy is devised to introduce controlled interconnected microporosity directly in MEW scaffolds by an algorithm that creates arrays of bridging‐free parallel fibers, angularly shifted from layer to layer and starting at a random point to avoid periodical fiber stacking, and hence channel‐like pores while defining micropores. This work hypothesizes that pore size can be controlled, decoupled from fiber diameter, and the mechanical properties, including anisotropy ratio, can be tuned. The authors demonstrate this while leveraging the platform for both flat and seamless tubular scaffolds and characterize them via micro‐computed tomography and tensile loading. Lastly, successful cell ingrowth into the micropores and extracellular matrix formation are shown. This platform enables microporous scaffolds entirely via MEW that can be tailored to the architectural and mechanical requirements of the target tissues. [ABSTRACT FROM AUTHOR]

The adsorption, diffusion, and aggregation of methane from coal are often studied based on slit or carbon nanotube models and isothermal adsorption and thermodynamics theories. However, the pore morphology of the slit model involves a single slit, and the carbon nanotube model does not consider the molecular structure of coal. The difference of the adsorption capacity of coal to methane was determined without considering the external environmental conditions by the molecular structure and pore morphology of coal. The study of methane adsorption by coal under single condition cannot reveal its mechanism. In view of this, elemental analysis, FTIR spectrum, XPS electron energy spectrum, 13C NMR, and isothermal adsorption tests were conducted on the semi-anthracite of Changping mine and the anthracite of Sihe Mine in Shanxi Province, China. The grand canonical Monte Carlo (GCMC) and molecular dynamics simulation method was used to establish the coal molecular structure model. By comparing the results with the experimental test results, the accuracy and practicability of the molecular structure model are confirmed. Based on the adsorption potential energy theory and aggregation model, the adsorption force of methane on aromatic ring structure, pyrrole nitrogen structure, aliphatic structure, and oxygen-containing functional group was calculated. The relationship between pore morphology, methane aggregation morphology, and coal molecular structure was revealed. The results show that the adsorption force of coal molecular structure on methane is as follows: aromatic ring structure (1.96 kcal/mol) > pyridine nitrogen (1.41 kcal/mol) > pyrrorole nitrogen (1.05 kcal/mol) > aliphatic structure (0.29 kcal/mol) > oxygen-containing functional group (0.20 kcal/mol). In the long and narrow regular pores of semi-anthracite and anthracite, methane aggregates in clusters at turns and aperture changes, and the adsorption and aggregation positions are mainly determined by the aromatic ring structure, the positions of pyrrole nitrogen and pyridine nitrogen. The degree of aggregation is controlled by the interaction energy and pore morphology. The results pertaining to coal molecular structure and pore morphology on methane adsorption and aggregation location and degree are conducive to the evaluation of the adsorption mechanism of methane in coal. [ABSTRACT FROM AUTHOR]

Cu-1.3Cr alloys with directional pore structure were fabricated under hydrogen atmosphere. The pore morphology during the solidification is investigated. It is found that the porosity is increased from 18% to 44% and the average pore diameter was decreased from 3.24 mm to 0.44 mm when the hydrogen pressure varies from 0.1 MPa to 0.6 MPa. Theoretical analysis shows the gas pore pressure drops significantly during the growth of pore. For a coarse pore, the drops of pore pressure will result in a backflow of the melt from solidification interface into gas pore, and this will result in a “bamboo” like structure. For small gas pores, the pressure difference between two neighboring gas pores drives the hydrogen gas from the short one to the long one. This is the reason that a short pore more easily coalesce with a long pore.

The morphology and surface chemistry of the sulfur host within lithium-sulfur (Li-S) batteries significantly influence the overall battery performance. To investigate this relationship, we employed a non-toxic heat treatment to produce reduced graphene oxide (rGO) with varying degrees of reduction, resulting in distinct surface chemistries. The physicochemical characteristics and electrochemical properties of four differently reduced GO samples and rGO/sulfur composite cathodes developed with supercritical CO 2 technology were examined. Our study established a clear correlation between the specific surface area and porosity of rGO and the electrochemical performance of the corresponding rGO/sulfur composite cathodes. Notably, rGO samples reduced at 350°C (rGO350) exhibited superior discharge capacity and long-term cycling stability compared to those reduced at higher temperatures. This performance enhancement can be attributed to the combination of high surface area, porosity, and an open morphology in rGO350. These findings underscore the importance of optimizing carbon chemistry, microstructure, and cathode synthesis strategies in Li-S batteries. By effectively controlling sulfur loading and distribution within the rGO network, we can enhance active material utilization, boost electronic conductivity, and ensure the long-term stability of rGO/sulfur composite cathodes. Our research suggests that SC-CO 2 -assisted synthesis offers a promising approach for designing high-performance carbon/sulfur composite cathodes for Li-S batteries. This method provides a versatile platform for tailoring the rGO morphology and surface chemistry, optimizing battery performance. By carefully considering the interplay between these factors, we can unlock the full potential of Li-S batteries for various applications. [Display omitted] • SC-CO2: an excellent hydrophobic solvent that boosts sulfur dissolution and penetration into carbon, improving utilization. • Rapid, green, facile, and highly efficient room temperature synthesis route for high-performance Li-S battery cathodes. • Investigating how adjusting carbon surface chemistry, microstructure, and synthesis method affects cathode performance. • Promising future technology for large-scale electrode synthesis with the least toxicity and energy demands. [ABSTRACT FROM AUTHOR]

Utilization of solid waste can be a preferable waste management solution. In this study, a type of self-foamed glass ceramic material was prepared using lead zinc mine tailings, red mud, and silica sand tailings through in-situ decomposition foaming. The effect of silica sand tailings content on the pore morphology, microstructure, and basic performances of the prepared specimen was analyzed. Meanwhile, the differences in the pore morphology and self-foaming behavior of the foamed glass ceramics were discussed. The obtained results indicated that the addition of silica sand tailings facilitated the formation of the glass phase in samples, and the composition, content, and viscosity of the glass phase could be changed by adjusting the content of silica sand tailings, resulting in a uniform distribution of the formed pores. Owing to their well-distributed pore structure, foamed glass ceramics exhibit excellent comprehensive properties (light weight and high strength), making them a potential non-load-bearing material. In this study, the comprehensive properties of the sample prepared with 40 wt% silica sand tailings were determined to be the best: exhibiting the lowest bulk density (0.63 g/cm3), highest porosity (72.6%), and an applicable mechanical strength (9.7 MPa). This study utilized three solid wastes through a reasonable combination based on their chemical composition, and proposed a novel technique for the preparation of self-foaming glass ceramics via the cooperative treatment of various wastes. [ABSTRACT FROM AUTHOR]

Closed-cell aluminum foam has a porous structure and metal properties due to its unique composition. As a structural material, it has the advantages of being lightweight, having a large specific surface area, and having high specific strength and stiffness. As a functional material, it can be used for sound and noise reduction, heat insulation, electromagnetic shielding, damping, and energy absorption, but it also has poor mechanical properties and poor surface flatness, and can be easily corroded. Considering the abovementioned problems, researchers have gradually extended their research on foam materials. Under the research of many international scholars, studies have shifted from simple aluminum foam preparation to improving and optimizing aluminum foam composite structures (AFCSs). From the perspective of development prospects, AFCSs have better application prospects than single aluminum foam. In this paper, the research progress on the preparation technology of AFCSs in recent years was reviewed based on the performance enhancement mechanism of aluminum matrix composites and the structural characteristics of aluminum foam. The morphology and pore structures of closed-cell AFCSs under different preparation methods were summarized. However, due to the limitations of existing experimental conditions, this paper only considered the advantages and disadvantages of AFCS preparation methods. The improvement of AFCS preparation technology, the development of the potential properties of AFCSs, and the promotion of AFCS industrial applications were also considered. [ABSTRACT FROM AUTHOR]

A semi-solid route is expected to be a fabrication method that can fabricate aluminum alloy foams with a variety of mechanical properties, but the allowance fluctuation of the fabrication conditions of aluminum alloy foams with high reproducibility is not clear. The objective of this study was to reveal the allowance fluctuation between the setting temperature and the actual temperature of the melt to fabricate stable foams, having pores with small pores and high circularity, and the influence of the increasing volume fraction of the solid on the pore morphology. Al-Si alloy foams were fabricated five times by adding a blowing agent into a semi-solid slurry under the same setting fabrication conditions, such as the temperature and concentration of oxygen in the atmosphere. The results of small relative standard deviations of pore diameter and circularity indicated that the conducted fabrication process had high reproducibility, even if the volume fraction of the solid changed in a range of 5%. When the volume fraction of the solid exceeds the minimal fraction of primary crystals for prevention of drainage, the clogging effect works more efficiently because the ratio of clogged cell walls increases. Additionally, the preferred range of the volume fraction of the solid for the fabrication of stable foam was revealed to be around 15% to 35%.

Featured Application: Ceramic pore network characterization, ceramic firing temperature studies. Understanding the firing regimes of archaeological ceramics reveals clues about the history of technological developments, but current methods for determining firing history have limitations. We experimented with non-destructive micro-CT combined with 3D image analysis to collect data on 42 pore variables, hypothesizing that pore systems are affected by ceramic firing temperatures. Analysis of variance showed that 26 of the variables are significantly related to firing temperature. Total volume porosity (open and closed pores) goes down with increased firing temperature, as does the fraction of pores accessible to a surface. Maximum pore volume, maximum and standard deviation of pore surface area, and pore elongation measures all decrease with higher firing temperatures while shape factors indicating greater sphericity increase. Pore connectivity measures decrease with higher firing temperatures, and variation in pore and connection lengths increases. The highest fired ceramics have low connection tortuosity. Three-dimensional image analysis of micro-CT data can augment existing methods of archaeothermometry, and since many pore characteristics impact the functional properties of ceramics (density, durability, mechanical strength, thermal conductivity, permeability, and diffusion), firing temperature studies of pore systems can inform wider archaeological ceramics research. [ABSTRACT FROM AUTHOR]

The effects of long-term fertilization on the macropore microstructure of vertisol were studied. In this study, soil pore structure was assessed using intact soil columns (7.4 cm diameter, 20 cm height), which were sampled from five long term fertilization treatments established in 1981, including no fertilizer (CK), inorganic fertilizer (NPK), a single application of organic fertilizer (M), a combination of inorganic fertilizer and organic manure with isonitrogen (MNPK), and a combination of inorganic fertilizer and organic manure with high nitrogen levels (HMNPK). Each column was scanned with X-ray microtomography (μCT) and quantified using image analysis. The results showed that there were macropores in the soil aggregate structure and between the aggregates in each treatment, in particular, the M treatment had the largest number of pores. The order of fractal dimension and anisotropy from large to small was HMNPK>M>MNPK>NPK> CK and MNPK>CK>M>NPK>HMNPK, respectively. Compared with CK, the organic manure treatments (M, MNPK, and HMNPK) increased the number of macropores by 41.5%, 33.3%, and 26.8%, while the porosity increased by seven, six, and ten percentage points, respectively. The fluctuations in the pore size distribution of HMNPK treatment were the most intense, with the first and second peaks appearing at 395~577 μm and 1 545~1 701 μm, respectively. Principal component analysis showed that pores <126 μm in size were mainly affected by particle content, 126~500 μm pores were affected by bulk density, and 500~2 500 μm pores were affected by multiple factors, including sand content, clay content, connectivity, and fractal dimension. Overall, this study demonstrates that long-term application of organic and inorganic fertilizers can significantly improve the morphology and quantity of macropores in vertisol, especially HMNPK treatment, while NPK alone caused no significant improvement. Fractal dimension and connectivity could be used as a quantitative evaluation index for improving the pore structure of vertisol. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present work, the effects on water transport due to the orientation of the layer in the multilayered porous graphene and the different patterns formed when the layer is oriented to some degrees are studied for both circular and non-circular pore configurations. Interestingly, the five-layered graphene membrane with a layer separation of 3.5 Å used in this study shows that the water transport through multilayered porous graphene can be augmented by introducing an angle to certain layers of the multilayered membrane system. [ABSTRACT FROM AUTHOR]

Three‐dimensional biocompatible porous structures can be fabricated using different methods. However, the biological and mechanical behaviors of scaffolds are the center of focus in bone tissue engineering. In this study, tricalcium phosphate scaffolds with similar porosity contents but different pore morphologies were fabricated using two different techniques, namely, the replica method and the pore‐forming agent method. The samples fabricated using the pore‐forming agent showed more than two times higher compressive and bending strengths and more than three times higher compressive moduli. Furthermore, a thin layer of agarose coating improved the compressive and bending strength of both types of ceramic scaffolds. Subsequently, the samples' capability to guide biomineralization was evaluated by immersion into a simulated body fluid that developed Ca‐P nano‐platelets formation and enhanced the compressive strength. Finally, the tetrazolium‐based colorimetric (MTT) assay was used to evaluate L929 cell viability and proliferation on all the samples and confirmed that cell behavior was not affected by pore morphology or agarose coating. In summary, samples produced by the use of the pore‐forming agent showed higher potential to be applied as bone scaffolds in tissue engineering applications. [ABSTRACT FROM AUTHOR]

Lithium‐ion battery separators act as components that have a function of thermal shutdown at a specific temperature for safety issues. Exposing these separators at high temperatures, lower than the shutdown temperature, can affect the performance, structure, and properties of these batteries. In this research, the effect of thermal shrinkage on the structural characterization, thermal and mechanical properties, and ionic conductivity of a polypropylene (PP) lithium‐ion battery separator was studied. The obtained results showed that the PP separator had not any thermal shrinkage along the transverse direction (TD) at different temperatures, but thermal shrinkage along the machine direction (MD) increased from 1.2% at 100°C to 45.9% at 160°C. Heat treatment of the PP separator above 150°C resulted in no air permeability, and the porosities being completely closed. The yield strength along TD was increased due to thermal shrinkage and this behavior enhanced with heat treatment temperature to about 280%. Tensile properties of the separator showed strain‐rate dependency along MD and TD. The puncture failure mode of puncture test was changed from a zigzag surface along TD (failure mode B) at the low heat treatment temperature to cracks along MD at the higher temperature. Finally, the ionic conductivity was decreased from 0.7409 mS.cm−1 for the untreated sample to 0.6881 mS.cm−1 for the heat‐treated PP separator at 130°C. [ABSTRACT FROM AUTHOR]

Ionic conductivity and lithium ion transference number (t L i + ) of electrolytes are essential parameters governing the performances of high energy density lithium metal batteries. Although the importance of t L i + versus ionic conductivity has been theorized by simulation, the systematically experimental study of their respective effects on lithium dendrite suppression and battery performances is rarely carried out. Here, a series of polyvinylidene fluoride and lithated sulfonated poly (ether ether ketone) blend (PVDF/SPEEK-Li) coated polyethylene (PE) separators with exactly the same composition but different pore morphologies are fabricated by vapor and non-solvent induced phase separation. The effects of sulfonate group–ion interaction and pore morphologies on ionic conductivity and t L i + of the electrolytes are studied. The performances of lithium metal batteries can be obviously improved by subtle increase of the t L i + , especially at high charge rates and even with a decrease in conductivity. Even at a high current density of 3 C, the PVDF/SPEEK-Li coated PE separator assembled lithium metal battery using a LiFePO 4 cathode with a mass loading of 10.5 mg cm−2 can run stably for 200 cycles with a capacity retention of 79 %, which is superior to the PE separator assembled battery with a life of only 55 cycles. [Display omitted] PVDF/sulfonated poly(ether ether ketone) coated separators with finely regulated morphologies were fabricated by vapor and non-solvent induced phase separation. The effect of Li + transference number versus ionic conductivity on battery performance was elaborated experimentally. The coating layer enabled effective ion selectivity and suppression of lithium dendrite growth. The assembled Li metal battery with high cathode mass loading showed a capacity retention of 79 % after 200 cycles even if the current density is up to 3 C. • Scalable and controllable VIPS method for the PVDF/SPEEK-Li coated separators. • Selective Li + transport enabled by sulfonate groups on the separators. • Correlations of ionic conductivity and Li + transference number with battery performance. • Stable cycling of Li.||LiFePO 4 batteries with high cathode mass loading and current density. [ABSTRACT FROM AUTHOR]

The LD-X area of the Yinggehai Basin hosts a promising high-temperature and high-pressure tight gas sandstone reservoir with significant resource potential. However, due to the influence of high temperature and carbon dioxide filling, the diagenesis of this reservoir is complex, making the evaluation and characterization of pore structure challenging. Data such as XRD, physical properties, rock slice analysis, electron microscopy, NMR, HPMI, core description, and logging curves were used to systematically analyze the pore type, size, and shape in the LD-X area. The fractal characteristics of small pores, transition pores and large pores are discussed, and the evaluation method of pore structure is established based on the fractal parameters of mercury injection and nuclear magnetic resonance T2 spectrum. The main results are as follows: (1) The pores in LD-X area are mainly intergranular solution pores and feldspar solution pores, with limited retention of primary pores and a considerable reduction in porosity due to calcite cementation; (2) The pore structure within the studied formation is highly complex, resulting in significant variations in mercury influx curves, making the correlation between NMR and mercury injection parameters with porosity and permeability poor; (3) The study area has strong compaction and poor sorting, and due to the existence of multi-stage carbon dioxide filling, calcite cementation is very common and reduces the complexity of pore morphology for small pore. As a result, the larger the fractal dimension of the small pore section, the greater the porosity and permeability; (4) The proposed pore structure evaluation method, integrating the fractal analysis of mercury injection curves and NMR T2 spectrum curves, enables a more precise assessment of pore size, proportion, and shape. It is observed that favorable pore structures frequently correspond to layers with high resistivity and low density in the middle and upper part of the sandstone section on logging profiles. This method provides a new idea for the evaluation of pore structure and favorable reservoir of deep clastic rocks. • The pore structure characteristics and pore size distribution of six typical types in the study area are clarified. • The effect of calcite cement on piecewise fractal is expounded. • The evaluation parameters of pore structure with comprehensive pore size, proportion and shape are constructed. [ABSTRACT FROM AUTHOR]

The mechanical properties of polymeric membranes are very important in water treatment applications. In this study, polysulfone (PSF) membranes with different loadings of cellulose nanofibers (CNFs) were prepared via the phase inversion method. CNF was characterized through transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The pore morphology, mechanical properties, membrane performance and hydrophilicity of pure PSF membranes and PSF/CNF membranes were investigated. The changes in membrane pore structure with the addition of different CNF contents were observed using SEM images. It was shown that the calculated membrane pore sizes correlate with the membrane water fluxes. The pure water flux (PWF) of fabricated membranes increased with the addition of CNFs into the PSF matrix. It was shown that the optimal CNF loading of 0.3 wt.% CNF improved both the elastic modulus and yield stress of the PSF/CNF membranes by 34% and 32%, respectively (corresponds to values of 234.5 MPa and 5.03 MPa, respectively). This result indicates a strong interfacial interaction between the PSF matrix and the reinforced nanofibers. The calculated compaction factor (CF) showed that the membrane resistance to compaction could be improved with CNF reinforcement. Compared to pure PSF membrane, the hydrophilicity was significantly enhanced with the incorporation of 0.1 wt.%, 0.2 wt.% and 0.3 wt.% CNF, as shown by the water contact angle (WCA) results. It can be concluded that CNFs are homogeneously dispersed within the PSF matrix at CNF loading less than 0.5 wt.%. [ABSTRACT FROM AUTHOR]

With the demand for many engineering facilities on coral reefs, it is urgent to study the physical and mechanical properties of reef limestone to meet the needs of coral reef construction. In this paper, real-time high-resolution X-ray micro-CT was used to scan reef limestone sample experimentally under unconfined axial compression for the first time. The rock samples from 286 m below sea level in S Reef were made into cylindrical specimens with diameter of 3.871 mm and height of 8.443 mm to study progressive failure characteristics. Through 2D vertical slices and reconstructed 3D stereograms, the microstructure and pore morphology of the samples were extracted and quantitatively characterized corresponding to each loading stage. These data show that biological components, coral gravel, and algae bonding surface are weak parts in the reef limestone, which reduces its tensile strength and enhances the heterogeneity of the internal structure. In addition, the relationship between the void volume, solid volume, and total volume of reef limestone CT images with the axial stress-strain curve was discussed. [ABSTRACT FROM AUTHOR]

Ultra-rapid microwave sintering of powder metals will provide fine microstructural features that improve mechanical properties. In present study, three grades of stainless steel powder compacts (316L, 430L, 410) were produced using a uniaxial compaction unit. These compacts were sintered by microwave hybrid heating method at 1300°C (super-solidus region). The densification response, microstructural attributes, and mechanical properties were compared at 30, 45 and 60 min holding times. The compositional analysis was performed with the help of optical emission spectroscopy (OES) and scanning electron microscopy equipped with energy dispersed spectroscopy(SEM-EDS). The results obtained from both spectroscopies are compared for the sintered samples. The correlation of mechanical properties is analysed with evolved microstructural attributes (pore volume, pore shape and pore distribution). The excellent strength of 457 ± 16 MPa, 466 ± 6 MPa and 476 ± 26 MPa with 23 ± 1.3%, 14 ± 1.5% and 11 ± 1% of ductility is observed for sintered AISI 316L, 430L and 410, respectively. [ABSTRACT FROM AUTHOR]

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With the increasing usage of porous rocks in engineering construction, their well-performed properties (e.g., permeability and heat insulation) have attracted increasing attention from researchers in engineering geology. In nature, the vesicles in porous rocks always exhibit irregularity in morphology. This article proposes a workflow combining photogrammetry and Fourier transform to accurately acquire, characterize, and regenerate the natural pore morphology of porous rocks, including four steps: 1) initially, several 3D digital models of volcanic porous rock surfaces are reconstructed through a photogrammetry system, and the hollow pores in the surface are split into assemblies; 2) then, the 3D pore assembly is projected to a 2D reference plane with each pore being recognized and extracted; 3) the contours of a single pore are processed based on discrete Fourier transform (DFT), and a series of Fourier descriptors (mainly consist of D2, D3, and D8) are then statistically analyzed; 4) an inverse discrete Fourier transform (IDFT) is then conducted to quantitatively reconstruct the pores. Based on the earlier processes, the pores are distributed in a numerical model (rock failure and process analysis code, RFPA2D), and uniaxial compression simulations are performed to further investigate the influences of porosity and pore morphology on rock strength and stiffness. Herein, we introduce significant Fourier descriptors (i.e., D2, D3, and D8) as representations of three levels of pore morphology. Thus, 12 groups of numerical simulations considering the impact of porosity, pore orientation, D2, D3, and D8 are conducted. Results show that the porosity exerts a first-order control on the mechanical properties of rocks, while the effect of pore orientation is related to D2. All of them closely match those typically observed in previous studies. Furthermore, these simulations also highlight the influence of detailed pore morphology, such as convex hulls and subtle zigzags characterized by D3 and D8, respectively, on the rock failure process, marking that a more complicated morphology (e.g., with more convex hulls) may result in a reduction in rock strength and Young’s modulus. The proposed study provides a novel perspective on natural pore morphology together with its influence on rock strength and stiffness.

Carbon aerogels prepared from resorcinol-formaldehyde aerogels are promising platforms for electrodes, catalysts, adsorbents in environmental chemistry and as electric conductors. For these applications the knowledge of their structure and behavior in aqueous medium is essential. In this work two resorcinol-formaldehyde (RF) carbon aerogels prepared in different ways were characterized with various NMR methods while their pore structure was stepwise saturated with water. The wetting properties were studied by vapor adsorption and low-field NMR relaxometry, while the morphology was followed by NMR cryoporometry during the hydration process. At several water saturation levels the self-diffusion of water was measured. The comprehensive evaluation of the results led to a detailed description of the wetting process of these carbon aerogels beyond the pore size distributions. At low hydration level water clusters formed on and around the hydrophilic functional groups of the surface being able to adsorb water, but no continuous water layer developed on the surface. With increasing water content, spherical water drops formed inside the pore system, and vapor phase diffusion was observed in the partially filled pores. Subsequently the interconnected pore structure was saturated. The determined wet structure was compared to low temperature nitrogen gas adsorption results and scanning electron microscopy images. [Display omitted] • Characterization of porous carbon aerogels synthesized in different ways. • Wetting properties of carbon aerogels, saturation mechanism of the meso- and macropores. • Combined use of NMR cryoporometry, relaxometry and diffusiometry. • Determination of water layer thickness and surface relaxation strength. [ABSTRACT FROM AUTHOR]

The correspondence between the porosity and ultrasonic attenuation coefficient are not unique due to the randomness and complexity of pore morphology in ultrasonic nondestructive testing of composite materials. Thus, the fractal box dimension is used to describe the pore morphology, and the influence of pore morphology on ultrasonic attenuation coefficient is studied in this paper. Firstly, based on the random medium theory, random pore models with different morphologies were constructed. Then the fractal box dimension was used to characterize the pore morphology, and the sensitivity of fractal box dimension to pore morphology such as length, width and distribution was studied. Finally, the relationship between fractal box dimension and ultrasonic attenuation coefficient was established to analyze the influence of fractal box dimension on ultrasonic attenuation. The research shows that the fractal box dimension is sensitive to pore size and pore distribution. The increase of pore length and width size and the aggregation of pore distribution under the same porosity all cause the increase of fractal box dimension. At the same time, the larger the porosity, the larger the fractal box dimension. The influence of pore size change on ultrasonic attenuation coefficient characterized by fractal box dimension under different porosity is more distinguishable than that of pore size change characterized by average length or width. Therefore, fractal box dimension is a parameter that can better characterize the pore morphology of composite materials, which is more conducive to analyzing the influence of pore morphology on ultrasonic testing. [ABSTRACT FROM AUTHOR]

Climate change in Arctic landscapes may increase freeze–thaw frequency within the active layer as well as newly thawed permafrost. Freeze-thaw is a highly disruptive process that can deform soil pores and alter the architecture of the soil pore network with varied impacts to water transport and retention, redox conditions, and microbial activity. Our objective was to investigate how freeze–thaw cycles impacted the pore network of newly thawed permafrost aggregates to improve understanding of what type of transformations can be expected from warming Arctic landscapes. We measured the impact of freeze–thaw on pore morphology, pore throat diameter distribution, and pore connectivity with X-ray computed tomography (XCT) using six permafrost aggregates with sizes of 2.5 cm3 from a mineral soil horizon (Bw; 28–50 cm depths) in Toolik, Alaska. Freeze-thaw cycles were performed using a laboratory incubation consisting of five freeze–thaw cycles (−10 °C to 20 °C) over five weeks. Our findings indicated decreasing spatial connectivity of the pore network across all aggregates with higher frequencies of singly connected pores following freeze–thaw. Water-filled pores that were connected to the pore network decreased in volume while the overall connected pore volumetric fraction was not affected. Shifts in the pore throat diameter distribution were mostly observed in pore throats ranges of 100 µm or less with no corresponding changes to the pore shape factor of pore throats. Responses of the pore network to freeze–thaw varied by aggregate, suggesting that initial pore morphology may play a role in driving freeze–thaw response. Our research suggests that freeze–thaw alters the microenvironment of permafrost aggregates during the incipient stage of deformation following permafrost thaw, impacting soil properties and function in Arctic landscapes undergoing transition.

Piezoelectric energy harvesting has attracted significant attention in recent years due to their high-power density and potential applications for self-powered sensor networks. In comparison to dense piezoelectric ceramics, porous piezoelectric ceramics exhibit superiority due to an enhancement of piezoelectric energy harvesting figure of merit. This paper provides a detailed examination of the effect of pore morphology on the piezoelectric energy harvesting performance of porous barium calcium zirconate titanate 0.5Ba(Zr 0.2 Ti 0.8)O 3 -0.5(Ba 0.7 Ca 0.3)TiO 3 (BCZT) ceramics. Three different pore morphologies of spherical, elliptical, and aligned lamellar pores were created via the burnt-out polymer spheres method and freeze casting. The relative permittivity decreased with increasing porosity volume fraction for all porous BCZT ceramics. Both experimental and simulation results demonstrate that porous BCZT ceramics with aligned lamellar pores exhibit a higher remanent polarization. The longitudinal d 33 piezoelectric charge coefficient decreased with increasing porosity volume fraction for the porous ceramics with three different pore morphologies; however, the rate of decrease in d 33 with porosity is slower for aligned lamellar pores, leading to the highest piezoelectric energy harvesting figure of merit. Moreover, the peak power density of porous BCZT ceramics with aligned lamellar pores is shown to reach up to 38 μW cm-2 when used as an energy harvester, which is significantly higher than that of porous BCZT ceramics with spherical or elliptical pores. This work is beneficial for the design and manufacture of porous ferroelectric materials in devices for piezoelectric energy harvesting applications. [ABSTRACT FROM AUTHOR]

To study the effect of phase–change materials and nanomaterials as new composite materials on the mechanical properties and frost resistance of concrete, it is beneficial for low–carbon and environmentally friendly buildings to be achieved. The effects of freeze–thaw cycles and different preloading strains were considered. ICT scanning was performed, and the compression performance of composite–modified concrete (CMC) were tested. The internal pore structure and strength indicators of the CMC were analyzed during uniaxial compression. Meanwhile, by conducting uniaxial compression tests on CMC at different temperatures, changes in the mechanical properties during real–time freezing and thawing processes were obtained. The results demonstrated that the fractal dimension grows and the compressive performance of the CMC declines as the number of freeze–thaw cycles and preloading strain increases. The proportion of spheroids in the internal pore shape gradually decreases, whereas the proportions of rods, discs, and blades increases. CMC effectively delays the rise or fall of internal temperature during the freeze–thaw process and reduces its internal structural deterioration. Compared with the freeze–thaw effect, an increase in the preloading strain has a more notable impact on the compressive performance of CMC. A stress–strain constitutive model is proposed for a 10 % microencapsulated phase–change materials and a 1.5 % nanoSiO 2 composite–modified concrete (10 mPCMs/1.5 NS CMC), influenced by temperature, through regression analysis. Meanwhile, under low temperatures, the degradation of mechanical properties of 10 mPCMs/1.5 NS CMC and the influence of different preloading strains are considered, leading to the development of stress–strain constitutive models for freeze–thaw cycles and different preloading conditions. • The frost resistance and compressive performance of mPCMs/NanoSiO 2 innovative composite concrete are studied. • The variation patterns of mechanical properties of mPCMs/NanoSiO 2 concrete at different temperatures is obtained. • The impact of preloading strain on mPCMs/NanoSiO 2 concrete is more significant compared to freeze-thaw cycles. • A constitutive model for mPCMs/NanoSiO 2 concrete subjected to low-temperature and preloading strain effects is proposed. [ABSTRACT FROM AUTHOR]

Closed-cell aluminum foam has a porous structure and metal properties due to its unique composition. As a structural material, it has the advantages of being lightweight, having a large specific surface area, and having high specific strength and stiffness. As a functional material, it can be used for sound and noise reduction, heat insulation, electromagnetic shielding, damping, and energy absorption, but it also has poor mechanical properties and poor surface flatness, and can be easily corroded. Considering the abovementioned problems, researchers have gradually extended their research on foam materials. Under the research of many international scholars, studies have shifted from simple aluminum foam preparation to improving and optimizing aluminum foam composite structures (AFCSs). From the perspective of development prospects, AFCSs have better application prospects than single aluminum foam. In this paper, the research progress on the preparation technology of AFCSs in recent years was reviewed based on the performance enhancement mechanism of aluminum matrix composites and the structural characteristics of aluminum foam. The morphology and pore structures of closed-cell AFCSs under different preparation methods were summarized. However, due to the limitations of existing experimental conditions, this paper only considered the advantages and disadvantages of AFCS preparation methods. The improvement of AFCS preparation technology, the development of the potential properties of AFCSs, and the promotion of AFCS industrial applications were also considered.

In polymer electrolyte fuel cells (PEFCs), the gas diffusion layer (GDL) is crucial for managing the flooding tolerance, which is the ability to remove the water produced during power generation from the assembled cell. However, an improved understanding of the properties of GDLs is required to develop effective waterproofing strategies. This study investigated the influence of the polytetrafluoroethylene (PTFE) content on the pore diameter, porosity, wettability, water saturation, and flooding tolerance of waterproofed carbon papers as cathode GDLs in PEFCs. The addition of minimal PTFE (∼6 wt %) to carbon paper provided external waterproofing, whereas internal waterproofing was achieved at a higher PTFE content (∼13 wt %). However, excessive PTFE (∼37 wt %) led to macropore collapse within the carbon paper, reducing fuel cell performance. Although PTFE addition was expected to improve the flooding tolerance, operando synchrotron X-ray radiography revealed that the water saturation level in carbon paper increased with increasing PTFE content. These findings provide a benchmark for assessing whether GDLs meet the flooding tolerance requirements of PEFCs and may be applicable to waterproofed GDLs in electrochemical devices for water and CO 2 electrolysis.

Gas diffusion layers (GDLs) are usually coated with a hydrophobic agent to achieve a delicate balance between liquid and gas phases to maximize mass transport. Yet, most GDL numerical models to date have assumed an average contact angle for all materials, thereby eliminating the possibility of studying the role of the polytetrafluoroethylene (PTFE) content. This study introduces two mixed wettability algorithms to predict the mixed wetting behavior of GDLs composed of multiple materials. The algorithms employ contact angle and distance to solid materials to determine the critical capillary pressure for each pore voxel. The application of the algorithms to the estimation of capillary pressure vs saturation curves for two GDLs, namely, a micro-computed tomography (μ-CT) reconstructed SGL 39BA GDL and a stochastically reconstructed Toray 120C GDL, showed that, in agreement with experimental data, the addition of PTFE resulted in a decrease in saturation at a given capillary pressure. For Toray-120C, the mixed wettability model was capable of reproducing experimentally observed features in the intrusion curve at low saturation that could not be reproduced with a single wettability model, providing a clear link between PTFE coverage and intrusion at low saturation. Numerical results also predicted an increased breakthrough pressure and a decrease in saturation with increasing PTFE, in agreement with experimental observations. The decreased saturation at breakthrough improves gas transport through the layer while maintaining the layer's ability to remove water. Diffusivity simulations confirm the increase in diffusivity at breakthrough with increasing PTFE, thereby providing a rationale for the addition of PTFE, as well as for the optimal amount. This study emphasizes the importance of multimaterial wetting models and calls for more detailed investigations into PTFE and ionomer distributions in GDLs and catalyst layers, respectively.

Nanosized pores were introduced into GaN epitaxial films via electrochemical (EC) etching in strong electrolytes including NaOH, HNO 3 , NaNO 3 , and NaCl. The growth behaviors of GaN nanopores show a strong correlation with the electrolyte types under the same applied bias and electrolyte concentration. Specifically, the resulting morphologies (e.g. pore growth direction and pore size) were mainly pertinent to the anions instead of cations. Pore sizes as small as a few nanometers and pore directions between the horizontal and vertical directions can be adjusted by selecting the electrolytes and etching voltages. The depletion model was employed to interpret the carrier flow pathways, and the pore propagation direction can be regarded as the sum of etch rate vectors of intended etching direction and preferential oxidation direction. Finally, the near-infrared nanoporous (NP) GaN distributed Bragg reflectors (DBRs) were manufactured by the EC etching in different electrolytes. Our study points out that the type of anions in electrolyte greatly impacts pore morphologies of EC etched GaN:Si, thereby affecting the future applications. • For porous GaN prepared by electrochemical etching, there is a strong correlation between pore growth directions and electrolyte types. • The carrier flow pathways and the pore morphologies was interpreted by the depletion model and etch rate vector superposition. • The mechanism and kinetics of electrode reaction in different electrolytes were studied by electrochemical impedance. [ABSTRACT FROM AUTHOR]

CO 2 geosequestration requires coal property examination for long-term storage sustainability. This study explores pore morphologies and water kinetic during wetting under interactions. Results showed that the CO 2 –H 2 O interaction induced intricate modifications in the coal pore architecture over time, causing a decrease in surface roughness and an increase in hydrophobicity of coal after long-term (10 days) and short-term (5 days) treatment. By setting a water intake, capillary force drives the transformation of free water to capillary water and adsorbed water. The adsorption kinetics of coal to water follows the linear driving force (LDF) mass transfer rate law, provided a good agreement with experimental data, validating its applicability to the studied system within the long time limits. As the reaction duration increased, the rate constant increased while the equilibrium adsorption capacity decreased. The modified Wenzel model of hydrophilic surface is proposed to interpret the temporal alterations, showing that untreated coal has substantial contact points on the rough surface, resulting in a smaller apparent contact area than the real contact area, hindering water retention and displaying enhanced wettability. The rule applied hydrophilic surface of both natural wettability adjusted by supercritical carbon dioxide (ScCO 2). • Quantified the alterations of coal pore structure and its fractal dimensions with CO 2 –H 2 O-coal interaction time. • Quantified the migration and distribution of capillary and bulk water by weighted averaged of T 2. • The adsorption kinetics of coal to water follows the linear driving force mass transfer rate law. • Established a modified Wenzel model for evaluating wettability and its relationship with roughness. [ABSTRACT FROM AUTHOR]

To explore the influences of rock water acidity (PH = 4,5,7) over the microstructure and reburning behaviors of oxidized residual coal in the overlying goaf, the pore morphology, coal surface, functional group content and activity of pre-oxidized coal (O 0) and water-immersed oxidized coal (OI) were analyzed by Low-temperature nitrogen adsorption and In-situ diffuse reflection experiments, combining with fractal dimension theory and functional group oxidation kinetics. The oxidation and reburning ability of coal samples has been analyzed by Thermogravimetric-Differential thermal analysis experiment. The results are as follows: Part of the type-III pores of pre-oxidized coal become type-II pores when immersed. The acidic solution has stronger corrosivity to O 0 than distilled water, playing a role in smoothing coal and improving the uniformity of pore structure. The order of reburning ability of samples is OI 7 >OI 4 >O 0 >OI 5 according to the ignition and stage average mass loss rate (R M). The reactivity of –OH may affect the reburning ability of coal more than its initial content. Soaking is beneficial to the decrease of activation energy of aliphatic groups, and the activity of –C=O- and -C-O- in acid-soaked coal molecules is stronger, so that they can take part in coal-oxygen composite reactions at low temperature. • Part of the type-III pores of pre-oxidized coal become type-II pores when immersed. • The reactivity of –OH affects coal reburning ability more than its initial content. • Immersing is beneficial to the decrease of activation energy of aliphatic groups. • The activity of –C=O- and -C-O- in acid-immersed coal molecules is stronger. • Acidic water reduces the heat released in stage II more than distilled water. [ABSTRACT FROM AUTHOR]