Shrinkage Rate Research Articles

Performance evaluation of bamboo species for structural applications using TOPSIS and VIKOR: A comparative study

This study focuses on and investigates bamboo as a workable building material for civil engineering projects. The various bamboo species suitable for the building are identified and their intrinsic mechanical and physical properties are investigated to get a thorough understanding. A detailed methodology is proposed that presents all the steps performed from sample size collection to investigating the characteristics of the bamboo species and demonstrating bamboo's structural capabilities. The study provides insightful and technical knowledge that will be extremely helpful in advancing the sustainable incorporation of bamboo into civil engineering construction methods. The findings have proven that varieties of bamboo with higher density and lower shrinkage rates, such as Thyrsostachys Oliveri (Oliveri), perform superior in structural applications. Multi-criteria decision-making techniques (TOPSIS and VIKOR) revealed Dendrocalamus strictus (Manvel) and Thyrsostachys Oliveri (Oliveri) as top-performing species, making them suitable for structural applications.

3D Micro-CT and O-PTIR Spectroscopy Bring New Understanding of the Influence of Filler Content in Dental Resin Composites

BackgroundDental resin composites' performance is intricately linked to their polymerisation shrinkage characteristics. This study compares polymerisation shrinkage using advanced 3D micro-computed tomography (micro-CT) and traditional 2D linear assessments. It delves into the crucial role of filler content on shrinkage and the degree of conversion in dental resin composites, providing valuable insights for the field. MethodsFive experimental dental composite materials were prepared with increasing filler contents (55-75wt%) and analysed using either 3D micro-CT for volumetric shrinkage or a custom-designed linometer for 2D linear shrinkage. The degree of conversion was assessed using Optical Photothermal Infrared (O-PTIR) and Fourier-Transform Infrared (FTIR) spectroscopy. Light transmittance through a 2-mm layer was evaluated using a NIST-calibrated spectrometer. Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDX) examined surface morphology and elemental distribution. Correlation between the investigated parameters was determined using Spearman correlation analyses. ResultsThe study found significant differences in polymerisation-related properties among different filler content categories, with volumetric shrinkage consistently demonstrating higher mean values than linear shrinkage across most groups. Volumetric shrinkage decreased with increasing curing depth, showing no direct correlation between filler content and shrinkage levels at different curing depths. The results highlighted a strong negative correlation between filler content and degree of conversion, volumetric and linear shrinkage, as well as maximum shrinkage rate. Light transmittance showed a moderate correlation with the filler content and a weak correlation with other tested parameters. ConclusionsThis study underscores the importance of considering both volumetric and linear shrinkage in the design and analysis of dental composite materials. The findings advocate optimising filler content to minimise shrinkage and enhance material performance. Integrating micro-CT and O-PTIR techniques offers novel insights into dental composites' polymerisation behaviour, providing a foundation for future research to develop materials with improved clinical outcomes.

Spatiotemporal evolution and driving mechanism of Dongting Lake based on 2005–2020 multi-source remote sensing data

As one of the largest inland lakes in China, Dongting Lake has attracted widespread attention owing to its rich natural resources, unique geographical landscape, and important ecological functions. Recently, Dongting Lake has experienced phenomena such as an early dry season and backflow during the flood season. Multi-source remote sensing data and the normalised difference water index (NDWI) threshold method were used to systematically analyse the water area of the lake from 2005 to 2020. Additionally, it employed a centre of gravity migration model and a geographic detector model to investigate the lake's evolution patterns and driving mechanisms. The research identified notable fluctuations in Dongting Lake's water area during this period, with a particularly sharp decline in 2006—from 1509.74 km2 to 815 km2, marking a decrease of 694.74 km2 and a shrinkage rate of 46.01 %. Spatial analysis indicated that the centre of gravity of these water areas changed primarily between Nandashan Town, the Dongting Lake Management Committee, Wanzihu Township, and Qingtan Township, underscoring their significant influence on lake dynamics, including runoff, surface water availability, sediment deposition, and precipitation, all of which displayed strong positive correlations (Pearson coefficients of 0.57, 0.68, and 0.63, respectively), whereas population density showed a negative correlation (Pearson coefficient of −0.56). Furthermore, the study highlighted the substantial impact of the Digital Elevation Model (DEM) and its interaction with slope and aspect on Dongting Lake's evolution, with Q values of 0.537 and 0.543, respectively, emphasising their critical roles in shaping lake area changes and providing a crucial scientific basis for enhancing the understanding and effective management of water resources in the Dongting Lake Basin through comprehensive analysis of its spatiotemporal evolution and driving mechanisms.

Spatiotemporal Changes of Glaciers in the Yigong Zangbo River Basin over the Period of the 1970s to 2023 and Their Driving Factors

The glaciers in southeastern Tibet Plateau (SETP) influenced by oceanic climate are sensitive to global warming, and there remains a notable deficiency in accurate multitemporal change analyses of these glaciers. We conduct glacier inventories in the Yigong Zangbo River Basin (YZRB) in SETP for the years 1988, 2015, and 2023 utilizing Landsat and Sentinel-2 imagery, and analyze the glacier spatiotemporal variation incorporating the existing glacier inventory data. Since the 1970s until 2023, the glaciers significantly retreated at a rate of 0.76 ± 0.11%·a−1, with the area decreasing from 2583.09 ± 88.80 km2 to 1635.89 ± 71.74 km2, and the ice volume reducing from 221.7017 ± 7.9618 km3 to 152.7429 ± 6.1747 km3. The most significant retreat occurred in glaciers smaller than 1 km2. Additionally, glaciers on southern aspects retreated slower than the northern counterparts. The glaciers in the western YZRB witnessed a significantly greater shrinkage rate than those in the eastern section, with the most pronounced changes occurring in Aso Longbu River Basin. Furthermore, severe glacier mass deficits were observed from 2000 to 2019, averaging a loss rate of 0.57 ± 0.06 m w.e. a−1. The continuous rise in air temperature has primarily induced a general widespread glacier change in the YZRB. However, diverse topography led to spatial variability in glacier changes with discrepancies as large as several times. The features of individual glaciers, such as glacier size, debris cover, and the development of ice-contact glacial lakes enhanced the local complexity of glacier change and elusive response behaviors to climate warming led by the different topographic conditions.

Chemotherapy combined with lenvatinib and PD-1 may be a potential better alternative option for advanced unresectable intrahepatic cholangiocarcinoma: a retrospective real-world study.

Currently, the prognosis of advanced intrahepatic cholangiocarcinoma (ICC) is poor, and the current treatment methods are not effective. The aim of this study was to evaluate the anticancer efficacy of chemotherapy combined with PD-1 inhibitors and tyrosine kinase inhibitors (TKIs) in patients with ICC. We retrospectively screened patients with advanced intrahepatic cholangiocarcinoma (ICC) who received chemotherapy combined with lenvatinib and PD-1. We evaluated overall survival (OS), progression-free survival (PFS), the objective response rate (ORR), the disease control rate (DCR), the tumor shrinkage rate, and safety. We enrolled 95 patients with ICC and divided them into three groups with a median follow-up duration of 15.1 months. The chemotherapy group (chemo-regimen group), chemotherapy combined with immune checkpoint inhibitors (dual-regimen group), and chemotherapy combined with lenvatinib (triple-regimen group) had median OS times of 13.1 months, 20.8 months, and 39.6 months, respectively. Notably, the triple-regimen group had a significantly longer OS than did the chemo-regimen and dual-regimen groups. The chemo-regimen group, dual-regimen group, and triple-regimen group reported median PFS durations of 4.8 months, 11.9 months, and 23.4 months, respectively. Both combination groups exhibited significantly longer PFS than the chemotherapy-only group (P<0.05). The ORRs of the chemo-regimen, dual-regimen, and triple-regimen groups were 18.2%, 55.5%, and 54.7%, respectively. The DCRs were 72.7%, 90%, and 96.2%, respectively, indicating significantly better outcomes in the combination therapy groups. The combination of chemotherapy with PD-1 inhibitors and lenvatinib demonstrates considerable efficacy and tolerability as a treatment strategy for patients with advanced ICC.

Effect of Radio Frequency Vacuum Drying on Drying Characteristics and Physicochemical Quality of Codonopsis pilosula Slices

In this study, the radio frequency vacuum drying (RFVD) technique was used to dry Codonopsis pilosula slices. The effects of the drying temperature, slice thickness, plate spacing, and vacuum degree on the drying characteristics and physicochemical properties of the slices were investigated. The results showed that as the drying temperature and vacuum degree increased and the slice thickness and plate distance decreased, the drying rate and effective moisture diffusion coefficient of the Codonopsis pilosula slices improved, and the required drying time was shortened by 11.11% to 29.41% compared to that after hot air drying (HAD). Through comparison, it was found that the Midilli and Weibull models could better describe the moisture variation trend during the RFVD of Codonopsis pilosula. After RFVD, the retention of lobetyolin and syringin in Codonopsis pilosula significantly increased, with maximum contents of 135.74 mg/100 g and 19.16 mg/100 g respectively, which were 75.2% and 124.28% higher than those obtained by HAD. The contents of polysaccharides, total phenolics, and total flavonoids and antioxidant performance were also enhanced. The color, shrinkage rate, and internal tissue structure were significantly improved. In conclusion, RFVD not only increases the drying speed of Codonopsis pilosula slices but also ensures the good quality of the dried products.

Recycle of steel slag as cementitious material and fine aggregate in concrete: mechanical, durability property and environmental impact.

Using steel slag (SS) as cementitious material and fine aggregate in concrete is an effective and environmental method for SS consumption and cost reduction. In this paper, SS was recycled in large volumes in concrete as partial cementitious material and fine aggregate. The compressive strength and reaction mechanism of cementitious material with different SS powder contents including 20%, 25%, 30%, and 35% were presented. The results indicated that 20% of SS powder improved the compressive strength by 34.57% and the hydration products were ettringite (AFt) and calcium silica hydrate(C-(A)-S-H). Furthermore, the mechanical and durability performance of concrete with SS as fine aggregate were investigated. When the SS substitution rate was 75%, the compressive strength was increased by 37.83%. The volume shrinkage rate and 28d-carbonation depth were reduced nearly by 64% for 90days and 2.33mm, respectively. The chloride ion penetration resistance reached the optimal grade Q-V and abrasion resistance was improved by nearly 24%. Along with the reduced CO2 by 210-294kg/m3 and the decreased cost by 12.61 USD/m3, it is regarded as an effective method to consume steel slag. As such, this research provided a scientific and systematic basis for the large-scale disposal and utilization of industrial waste residues as well as recycled materials preparation.

Preparation of high-strength and low-shrinkage composite salt cores by binder jetting and vacuum impregnation

ABSTRACT Binder jetting (BJ) technology was employed combined with vacuum impregnation to fabricate alumina-reinforced Na2SO4-NaCl water soluble composite salt cores (WSCSC), intended for manufacturing aluminum alloy castings featuring intricate cavity structures. The bending strength and sintering shrinkage rate of WSCSC were investigated to discern the influences of alumina content, vacuum impregnation pressure and time, accompanied by a detailed analysis of the microstructure and reinforcement mechanism. The findings reveal that WSCSC containing 40 wt.% alumina exhibits exceptional mechanical properties, demonstrating a bending strength of 29.13 MPa, which is 197% higher than that of WSCSC without alumina. Furthermore, when the vacuum impregnation of saturated brine is conducted at a pressure of 30 KPa for 90 s, the resulting WSCSC possesses a sintering shrinkage rate of 4.94%, reflecting a significant reduction of 73.5% compared to that of WSCSC without vacuum impregnation treatment. Microstructural analyses show that alumina, as a stable secondary phase, can refine the NaCl grains within WSCSC, deflecting cracks and elongating their propagation paths, thereby remarkably enhancing the bending strength. Moreover, the fine inorganic salt particles crystallized and precipitated from saturated brine during the drying process are filled in the internal pores of WSCSC through vacuum impregnation, dramatically reducing the sintering shrinkage rate. Ultimately, the high-strength and low-shrinkage WSCSC parts were successfully manufactured.

Autogenous shrinkage of high-performance concrete subjected to different curing temperatures

High-performance concrete (HPC) shows obvious autogenous shrinkage in the early stage. In actual engineering, the interior of HPC undergoes a variable temperature evolution, and the impact of variable temperature conditions on the autogenous shrinkage of HPC is unclear. This paper examines the impact of different curing temperatures on the material properties of HPC, as well as the evolution of HPC autogenous shrinkage. Three measured temperature histories and four constant temperatures were used as curing conditions. Additionally, an HPC autogenous shrinkage prediction model was established considering the impact of curing temperature. The test results indicate that the compressive strength and elastic modulus of HPC increase with increasing curing temperature. Furthermore, there is a significant increase in the autogenous shrinkage rate of HPC as the curing temperature increases. Existing maturity methods overestimate the impact of temperature on the autogenous shrinkage process of HPC. The proposed autogenous shrinkage prediction model enhances the accuracy in predicting the autogenous shrinkage of HPC under constant and variable curing temperature conditions.

Strategies for reusing multiple recycled powders: Evaluating the mechanical performance and sustainability of Engineered Cementitious Composites (ECC)

Engineering Cementitious Composites (ECC) are fibre-reinforced cementitious materials with excellent tensile strain capacity. Recycling powder from building and demolition waste can improve the ecological efficiency of concrete and reduce the cost of raw materials. In this study, recycled glass powder (RGP) was used to partially replace traditional cement. Based on using a 1:1 replacement of recycled brick powder (RBP) and recycled concrete powder (RCP) for fine aggregates, two sets of variables were set: the RGP substitution rate (10 %, 15 %, 20 %, and 25 %) and RGP particle-size range (38–75 μm, 75–150 μm, and 150–300 μm). Comprehensive material testing and mechanical experiments were conducted, including X-ray diffraction analysis, thermogravimetric analysis, shrinkage tests, uniaxial compressive tests, uniaxial tensile tests, and scanning electron microscopy. The results indicated that fully substituting quartz sand with RBP and RCP enhanced the ECC performance. Incorporating RGP significantly improved the ultimate tensile strain and crack-propagation ability of the ECC while reducing the 90-d shrinkage rate. The 28-d compressive strength and tensile strength have some loss, but can meet the strength requirements. SEM showed that incorporating RGP weakened the bonding strength of the fibre matrix, making it easier for the fibres to be pulled out. By evaluating the experimental results, the mix ratio of a 20 % substitution rate and 75–150-μm size was selected. A material-sustainability indicator (MSI) analysis of the raw materials and production process of RGP-ECC was performed. The embodied energy, carbon emissions, and economic indices were reduced to a certain extent, thereby improving the ecological efficiency of concrete.

Enhancing the mechanical and thermal properties of foam concrete by incorporating glass lightweight microspheres

The inferior mechanical strength and thermal resistance of foam concrete limited its application in thermal insulation engineering. This study focused on enhancing the mechanical strength and thermal resistance of foam concrete by incorporating glass lightweight microspheres (GLM) to partially replace foam. The roles of GLM in foam concrete were investigated through physical, mechanical, and thermal properties tests. The improvement mechanism behind the mechanical strength and thermal resistance was further revealed. Results indicated that the addition of GLM enhanced mechanical strength of foam concrete by promoting hydration reaction, optimizing pore structure, and improving GLM-paste interfaces. The mechanical strength of foam concrete with 20 % GLM increased by about 40 %. Moreover, GLM improved the residual compressive strength after exposure to 800°C, with an enhancement of 39.8 %. The inclusion of GLM reduced the risks of crack formation, densified the paste, and strengthened the foam wall due to its hollow structure, pozzolanic reactivity, melting and filling effects, and the phase transformation of additional C-S-H into well-packed wollastonite. Additionally, GLM with closed and isolated pores reduced the drying shrinkage and water absorption rate of foam concrete. The finding suggests that incorporating an appropriate amount of GLM can produce high-strength, low-density, and thermal-resistant foam concrete.

Size shrinkage and compressive behaviour of Al2O3 honeycomb structures fabricated via Digital Light Processing technology

Al2O3 ceramic have excellent chemical inertness, superior heat resistance, and excellent corrosion resistance, so they are considered ideal materials for manufacturing high-performance components such as thermal end devices in aerospace, heat dissipation panels in electronic communication, and exhaust filters in the automotive industry. Digital Light Processing (DLP) is a useful technology to fabricate complex Al2O3 ceramic components. However, the size shrinkage effect of DLP-fabricated components need to be investigated deeply before its further application. In this work, we utilized DLP technology to fabricate Al2O3 ceramic honeycomb structures and systematically investigated their microstructure, size shrinkage, and mechanical properties. Our findings revealed that the Al2O3 ceramic grains exhibit flake-like structures with an average diameter of 1–2 μm, and the ceramic particles are tightly bonded. The shrinkage rates in the X and Y axes were 7.54 % and 7.42 %, respectively, while the Z-axis exhibited a more significant shrinkage of 13.04 %. This anisotropic shrinkage in different direction was attributed to accumulation of the interlayer bonding under gravity action during debinding and sintering process. The compressive stress-strain curve of the honeycomb structures demonstrated a typical brittle compressive behavior, including elastic, stress plateau, and brittle fracture stages. The honeycomb structures exhibited an elastic modulus of 54.49 ± 1.22 MPa and a compressive strength of 10.22 ± 0.42 MPa. The fracture analysis indicated that the fractures region of honeycomb structures initiated at the corners of the honeycomb structures, indicating their easy-broken compared to the walls. These findings provide valuable guidance for the high-precision and high-performance manufacturing of complex Al2O3 ceramic components.

An Injectable Thermosensitive Hydrogel with Antibacterial and Antioxidation Properties for Accelerating Wound Healing.

As a new type of wound dressing, hydrogels have attracted more and more attention. However, traditional hydrogel wound dressings lack inherent antibacterial properties and are difficult to match irregular wounds, which leads to an easy wound bacterial infection. To solve the problems associated with traditional hydrogels, in this research, a thermosensitive hydrogel (PFLD) for wound dressings was developed based on Poloxamer 407 (PF127), lysine (Lys), and 3,4-dihydroxyphenylacetic acid (DOPAC). Rheological tests indicated that the PFLD hydrogel possesses injectability, adaptability to deformation, and sufficient mechanical strength for wound dressing applications. In addition, it could in situ gel at 33 °C, which indicated that the hydrogel could undergo sol-to-gel transition under body temperature. Upon using it in wound treatment, it could adapt to irregular wounds to achieve full coverage of the wound and promote the rapid hemostasis of wound bleeding. Due to the presence of DOPAC in the hydrogel, it exhibited excellent antibacterial and antioxidant properties on the wounds. The skin defect model showed that the wound shrinkage was the fastest after PFLD hydrogel treatment. On day 14, the wound shrinkage rates were 81.68 and 99.77% for the control and PFLD hydrogel groups, respectively. Therefore, the PFLD hydrogel has a broad application prospect as a dressing for the treatment of irregular wounds.

Food-based biomaterials: pH-responsive alginate/gellan gum/carboxymethyl cellulose hydrogel beads for lactoferrin delivery

The present study utilizes a combination of sodium alginate (Alg), gellan gum (GG), and sodium carboxymethyl cellulose (CMC) to fabricate a ternary composite hydrogel system to encapsulate and release lactoferrin (LF). Rheological properties as well as extensive microscopy and spectroscopy characterization are performed on these materials demonstrating that the physical properties of the resultant hydrogels, such as particle size, water content, gray value, and shrinkage rate were related to the concentration of Alg. In addition, most of these hydrogels were found to have reticulated shells and inner laminar structures assembled based on hydrogen bonding and electrostatic forces. Furthermore, the encapsulation efficiency of LF in hydrogels ranged from 78.3 ± 0.3 to 83.5 ± 0.2 %. Notably, a small amount of encapsulated LF was released from the hydrogel beads in an acid environment (up to 2.2 ± 0.3 % in 2 h), while a controlled release manner was found to take place in an alkaline environment. This phenomenon indicated the potential of these hydrogels as promising matrices for bioactive compound loading and adsorption. The release mechanism varied from Alg concentration suggesting the tunable and versatile properties of this ternary composite hydrogel system. Our findings identify the potential of Alg-GG-CMC hydrogel as a delivery system suitable for various applications in the food industry.

Performance and Microstructure of Grouting Materials Made from Shield Muck.

In response to the environmental pollution caused by transportation and accumulation of large-scale shield muck, the on-site reutilization of shield muck is an effective approach. This study explored the feasibility of silty clay muck to prepare muck grout. Through orthogonal experiments, the effects of cement, fly ash, shield muck, admixture, and the water-solid ratio on the fresh properties and mechanical properties of muck grout were studied. The performance prediction model was established Additionally, the intrinsic relationships between the compressive strength and microstructure of shield muck grouting materials were explored through multi-technology microstructural characterization. The results indicate that the content of muck and the water-solid ratio have a greater significant influence on the bleeding ratio, flowability, setting time, and volume shrinkage rate of muck grout compared to other factors. Cement has a greater significant influence on the compressive strength of muck grout than other factors. An optimal mix proportion (12% for cement, 18% for fly ash, 50% for muck, 0.465 for water-solid ratio, 19.5% for river sand, and 0.5% for bentonite) can produce grouting materials that meet performance requirements. The filling effect of cementitious substances and the particle agglomeration effect reduce the internal pores of grouting materials, improving their internal structure and significantly enhancing their compressive strength. Utilizing shield muck as a raw material for shield synchronous grouting is feasible.

Effect of heat treatment on microstructure and mechanical properties of oscillating laser-arc hybrid welded 12Cr13 thick plate

Heat treatment of oscillating laser-arc hybrid welded 12Cr13 martensitic stainless steel was carried out, the microstructure and mechanical properties were studied. The results showed that sound formation was obtained without crack, pores and lack of fusion. The microstructure of the weld was mainly columnar austenite with strong texture. After heat treatment, the microstructure was coarsened but the homogeneity was improved with the grain sizes in the weld center of about 250 μm. The fractions of the high angle grain boundaries decreased while the fractions of CSL boundaries increased. After heat treatment, the strength and hardness of the weld decreased. However, the elongation and section shrinkage rate are increased by 25 % and 20 %, respectively, and the impact energy of the heat affected zone is increased from 62 J to 88 J. Finally, the effect of the oscillating laser beam on the energy distribution and molten pool flow was discussed, the effect mechanism of heat treatment on microstructure and properties of weld was illustrated, and the relationship between the microstructure and properties of the weld was established.

Effects of superplasticizer on properties of calcined ginger nuts-based grouting material for earthen site cracks

Grout injection is an effective technique for repairing cracks in earthen sites. This study aims to address the challenges of Calcined Ginger Nuts (CGN)-based grout and enhance its engineering performance by investigating the compatibility of different superplasticizers. We examined the effects of Polycarboxylate Superplasticizer (PCE) and Naphthalene Superplasticizer (PNS) on the properties of CGN-based grout, focusing on fluidity, rheological properties, mechanical strength, volume stability, color difference, and pore structure. The engineering applicability of the optimized CGN-based grout with superplasticizers was assessed using COMSOL Multiphysics. The results show that fluidity increased with higher dosages of PCE and PNS. The grout containing these superplasticizers behaved as a shear-thinning fluid, following the power law model. Specifically, the consistency coefficient of grout with 0.5 wt% PCE and PNS decreased by 39.73% and 64.83%, respectively. Additionally, 2.9 wt% PCE and PNS reduced volume shrinkage rate by 6.86% and 6.27%, respectively. Initially, increasing the dosage of PCE and PNS improved compressive and flexural strength, but these properties later declined. XRD analysis revealed that PNS above 1.1 wt% and PCE weakened the hydration reaction, while both superplasticizers promoted carbonation. Mercury Intrusion Porosimetry (MIP) showed that 1.1 wt% PCE and PNS reduced the proportion of capillary pores by 13.79% and 10.11%, respectively. Based on these findings, 0.5 wt% PNS demonstrated the best compatibility with CGN-based grout, whereas PCE showed poor compatibility. Numerical simulations using COMSOL Multiphysics confirmed that 0.5 wt% PNS provided superior grouting effectiveness. Therefore, the CGN based grout with 0.5wt% PNS demonstrates excellent engineering performance and applicability. This study offers valuable insights into optimizing CGN-based grout for the preservation of earthen sites.

Hollow Core-Shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with Tiny-Void Space Capable Fast-Charge and Low-Temperature Sodium Storage.

Iron-based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium-ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low-temperature sodium storage. This study pioneers a scalable synthesis of hollow core-shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny-void space (THoCS-0.6Ni) via a one-step spray-drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low-temperature sodium storage. As a result, THoCS-0.6Ni exhibits superior rate capability (86.4 mAh g-1 at 25 C). Notably, THoCS-0.6Ni demonstrates exceptional cycling stability at -20 °C with a capacity of 43.6 mAh g-1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core-shelled structure with tiny-void space cathode materials for reversible batteries with fast-charge and low-temperature Na-storage features.

Hollow Core‐Shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with Tiny‐Void Space Capable Fast‐Charge and Low‐Temperature Sodium Storage

AbstractIron‐based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium‐ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low‐temperature sodium storage. This study pioneers a scalable synthesis of hollow core–shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny‐void space (THoCS‐0.6Ni) via a one‐step spray‐drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low‐temperature sodium storage. As a result, THoCS‐0.6Ni exhibits superior rate capability (86.4 mAh g−1 at 25 C). Notably, THoCS‐0.6Ni demonstrates exceptional cycling stability at −20 °C with a capacity of 43.6 mAh g−1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core–shelled structure with tiny‐void space cathode materials for reversible batteries with fast‐charge and low‐temperature Na‐storage features.

Study on strength and reduction characteristics of iron ore powder-green carbon composite briquettes

The metallurgical industry is a key sector for carbon emissions, and in recent years, there has been widespread attention on the use of biomass resources as a green, renewable, and carbon–neutral energy source material for low carbon ironmaking processes. The waste wood after hydrothermal-pyrolysis carbonization has the characteristics of low content of harmful elements and high content of fixed carbon. In this study, the waste wood after hydrothermal-pyrolysis two-step carbonization treatment was used as a reducing agent for the reduction of iron ore to prepare iron ore powder- green carbon composite briquettes (ICCB) with two carbon–oxygen ratios. The study investigated the effects of reduction behavior and reaction temperature on the reduction performance of the ICCB. The results indicate that with the increase in reaction temperature, the volume of the ICCB gradually contracts, leading to a reduction in mass. The shrinkage rate of the ICCB during self-reduction at 1200℃ is significantly higher than during co-reduction, and the shrinkage effect of the C/O 0.5 ICCB is more pronounced than that of the C/O 0.8 ICCB. Due to the excessive carbon content in the C/O 0.8 ICCB, the carbon cannot be fully consumed during the reaction process, resulting in consistently low compressive strength of the ICCB, with a compressive strength of 12 N after reduction at 1200℃. In contrast, the iron phase in the C/O 0.5 ICCB gradually recrystallizes during the reduction process, ultimately yielding plastic iron briquettes with compressive strengths exceeding 3000 N after different reaction behaviors at 1200℃. In summary, reducing the carbon-to-oxygen ratio and increasing the reaction temperature contribute to the volume contraction and enhanced compressive strength of the ICCB during the reduction process.