Advanced Powder Technology最新文献

This study presents an innovative approach for synthesizing hierarchical porous carbon materials (HPCMs) tailored for high-performance supercapacitors. The proposed method combines oxidative foaming with self-activation, in-situ template, in-situ activation and template synthesis, respectively, utilizing glucose reactions with oxidizing agents like ammonium persulfate (APS), magnesium nitrate hexahydrate (MNH), and potassium persulfate (KPS). The process involves two stages: low-temperature foaming to initiate macropore formation and high-temperature annealing to create meso/micropores through in-situ template and activation. Generally, increasing the ratio of oxidant to glucose in the synthesis process can notably enhance the high specific surface area and pore volume of the HPCMs with a combination of micro/meso/macropores, exhibiting maximum values of 821 m²/g and 0.61 cm³/g (APS), 2077 m²/g and 3.05 cm³/g (MNH), 1845 m²/g and 1.29 cm³/g (KPS), respectively. Furthermore, the O and N, or S elements, can also be in-situ doped in the carbon framework. The hierarchical porous structure and the doping elements enhance the electrochemical performance of supercapacitors. The APS@4, with a high mass loading of 3.2 mg/cm², exhibits a superior specific capacitance of 144 F/g and an areal capacitance of 456 mF/cm² at a current density of 1 A/g. It demonstrates excellent cycling stability based on a capacitance retention of 100 % after 10,000 cycles.

In this study, an eco-friendly compound, carrageenan, was employed as a depressant for the selective separation of chalcopyrite and pyrite. The depressant performance and mechanism were comprehensively investigated. The results of the flotation experiments demonstrated that carrageenan exhibited selective depression towards pyrite as opposed to chalcopyrite, achieving flotation recoveries of 88.57 % for chalcopyrite and 9.57 % for pyrite with the combination of 2 × 10^-5 mol/L SIBX and 20 mg/L carrageenan. The results of AFM and contact angle measurements revealed that carrageenan exhibited selective adsorption on pyrite surface, resulting in an enhancement in surface hydrophilicity. In contrast, the adsorption of carrageenan on chalcopyrite surface was found to be negligible. Zeta potential and XPS analyses further confirmed the chemisorption of carrageenan on the pyrite surface, indicating the reaction involving sulfuric acid and hydroxyl groups on carrageenan and Fe sites on pyrite. Therefore, carrageenan holds potential as a promising depressant for the selective separation of chalcopyrite from pyrite.

In this study, modified low rank coal water slurry (M-LRCWS) was prepared by using diesel modified low rank coal (LRC) and compared with low LRC water slurry (LRCWS) to investigate the slurry formation mechanism and combustion characteristics of coal water slurry. Meanwhile, the combustion kinetics of coal-water slurry was investigated using kinetic methods to probe the combustion reaction mechanism. The results showed that the slurry formation concentration of LRC was 70 %, while the slurry formation concentration of M-LRCWS was 72 %, which was an increase of 2 %. The diesel modification positively affected the stability of CWS. The comprehensive combustion characteristics index of the same slurry deteriorated with increasing heating rate. At the same heating rate, M-LRCWS has better combined combustion performance, higher flammability and more stable ignition performance. Combustion kinetics calculations showed that the reaction activation energies were 105.50 kJ/mol for M-LRCWS and 99.59 kJ/mol for LRCWS using the FWO method, and 93.48 kJ/mol for M-LRCWS and 92.68 kJ/mol for LRCWS using the Starink method. The activation energy of M-LRCWS is slightly higher than that of LRCWS, which indicates that the diesel fuel is encapsulated in the coal particles and it is difficult to activate the substance. As a result, the dispersion system is more stable and favorable for storage and transportation. The physical functions of LRCWS and M-LRCWS were calculated using the Achar differential equation and the Coats-Redfern integral equation, and the results showed that both LRCWS and M-LRCWS followed the tertiary reaction (F3) mechanism.

Poor wettability and weak graphene/Cu interface limit the mechanical properties’ enhancement in graphene/Cu composites. This study devised an interface enhancement approach by Ag decoration of graphene nanoplatelets (Ag-GNPs) and Ag decorated nitrogen doped graphene (Ag-N-GNP) without oxide (during decoration) and carbide (during sintering) formation. Sonication was used to functionalize GNPs for decoration with Ag nanoparticles (NPs) and Cu composites (Ag-GNP/Cu and Ag-N-GNP/Cu) were fabricated using cold pressing (low-pressure) and sintering. 2-Ag-GNP/Cu (2 vol% of Ag-GNPs) and 2-Ag-N-GNP/Cu (2 vol% of Ag-N-GNPs) possessed highest sintered density. In addition, 2-Ag-GNP/Cu and 1-Ag-N-GNP/Cu showed highest microhardness and tensile strength (theoretical), respectively. Higher concentration of Ag NPs on GNPs in Ag-N-GNP (oxygen and nitrogen functionalization) showed lower mechanical properties for Ag-N-GNP/Cu compared to Ag-GNP/Cu with limited Ag NPs on GNPs (oxygen functionalization). Interface modification strategy with noble metal NPs bridging between GNP and Cu suggests controlled functionalization and noble metal NPs’ attachment on GNPs for effective mechanical properties’ enhancement in graphene Cu composites.

La₂FeMnO₆ double perovskites with multifunctional properties have sparked attention in recent years. Nevertheless, there was no direct study elaborating its electrochemical properties for supercapacitor applications. Herein, La₂FeMnO₆ double perovskites were synthesized by the sol–gel method and their structural, morphological, vibrational, optical, magnetic, and electrochemical properties were determined. The X-ray diffraction along with Rietveld refinement showed a cubic structure with Pm-3m space group, and its randomly distributed quasi-spherical morphology was observed from its SEM image. The presence of multiple oxidation states of Mn and Fe in La₂FeMnO₆ was supported by the formation of double exchange interactions between Fe²⁺-O²⁻-Fe³⁺ and Mn³⁺-O²⁻-Mn⁴⁺. The mesoporous structure with 41.79813 m²/g surface area was estimated from the BET analysis. The electrochemical properties of La₂FeMnO₆ were determined using the three electrode setup, and the Cyclic Voltammetric curves possess a quasi-rectangular shape with a specific capacitance of about 10.9 mF g⁻¹ at a current density of 0.5 mA g⁻¹. Dunn’s method illustrate the electrode’s charge storage mechanism and it was determined that the diffusion-controlled process surpasses the capacitive processes at low scan rates. The cyclic stability demonstrated that 96 % of initial specific capacitance was retained even after 5000 cycles which implied the long-term stability and practical use of La₂FeMnO₆ double perovskites. The magnetic analysis showed the presence of ferromagnetic and anti-ferromagnetic interactions both in this system and they are short-range in nature.

In order to elucidate the role of alloying Ni in Ni-advanced weathering steels on the formation of Fe₃O₄ (magnetite) rust particles by atmospheric corrosion in salinity environment, aqueous FeCl₂ solutions containing various amounts of NiCl₂ were aged under bubbling the air at 50 °C for 24 h. The atomic ratio Ni/Fe of the solution was 0 – 0.2 and the solution pH before aging was about 7 over the whole Ni/Fe ratios. Aging for 3 h generated the Green rust(Cl^-) ([Fe₃^IIFe^III(OH)₈]⁺[Cl·nH₂O]^-) as a precursor of Fe₃O₄. Added Ni²⁺ was incorporated into Green rust(Cl^-) to form Ni²⁺-substituted Green rust(Cl^-) ([Fe_3-x^IINi_x^IIFe^III(OH)₈]⁺[Cl·nH₂O]^-]), resulting in enhancement of crystallization of this material. After aging for 24 h, the Ni²⁺-substituted Green rust(Cl^-) formed at Ni/Fe = 0 – 0.08 was mainly transformed into spherical Fe₃O₄ particles. The crystallization and particle growth of Fe₃O₄ were promoted on elevating Ni/Fe ratio. At Ni/Fe ≥ 0.12, Fe₃O₄ formation was suddenly impeded to generate rod-shaped α-FeOOH particles, of which the material possesses more stable crystal structure than Fe₃O₄. These results suggest that alloying Ni in Ni-advanced weathering steels accelerates the formation of stable rust layer composed of Fe₃O₄ and/or α-FeOOH particles by atmospheric corrosion in salinity environment such as coastal and marine zones to contribute to the formation of the protective rust particle layer.

Understanding the evolution of wear caused by the relative motion between the mantle liner and the concave liner in a cone crusher provides useful insights into the wear and crushing mechanism, which helps industries optimize operating parameters to reduce production costs. This work analyzed wear formation and evolution on the mantle liner using the discrete element method (DEM) with Archard models, in which the effects of operating parameters on wear depth and crushing performance under different wear conditions were investigated. Meanwhile, the response surface method (RSM) was employed to minimize the wear of the mantle liner and improve the crushing characteristics of the cone crusher. Results show that the evolution trend of the wear depth accords with the compressive force, and the extension of the wear area is consistent with the rotating direction of the mantle liner. Changes in the crushing chamber volume caused by operating parameters (except for the eccentric speed) and in the crushing chamber volume ratio caused by different meta-particle sizes can significantly cause different wear depths. And with the increase of the wear depth, the throughput, crushing rate, and power draw all decrease. Additionally, the presence of small-hard meta-particles leads to more severe wear.

Ensuring the stability of cathodes under high voltage (>4.3 V vs. Li/Li + ) necessitates particle-scale surface protection. Research varies on the optimal structure, and systematic studies on the impact of nanoscale coating coverage on cathode particle surfaces and stability are lacking. This study presents a quantitative analysis of coating homogeneity dependency on cathode particles and their stability under high voltage conditions. A metal alkoxide precursor-based coating methodology was used, manipulating the coating structure by understanding the pH dependence of the zeta potential for core particles and altering the precursor evaporation rate. Ta-substituted Li₇La₃Zr₂O₁₂ was chosen as the coating material on Li(Ni_1/3,Co_1/3,Mn_1/3)O₂ cathode particles, varying the coating structure while maintaining the same coating concentration. Coating structure was verified using X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Results showed that cathode particles with more homogeneous coatings exhibited significantly improved cycle stability and lower charge transfer resistance at potentials above 3.9 V. Optimizing coating homogeneity can significantly enhance battery performance, offering insights for more efficient lithium-ion batteries.

Narrow process window of stress relieving annealing limits the development of amorphous soft magnetic composites (SMCs) with excellent combined electromagnetic performance. In addition, flaky amorphous powder is difficult to be uniformly coated by insulation layer due to the edge effect. To address these issues, the FeSiBCCr fine amorphous powder is introduced into the SMC based on flaky FeSiB amorphous powder. On the one hand, the 12 wt% addition of FeSiBCCr powder improves the thermal stability and enhances the annealing temperature by ∼ 20 ℃, broadening the annealing window of SMCs. On the other hand, the fine spherical FeSiBCCr amorphous powder can improve the electrical resistivity of SMC and act as a filler for large-size flaky FeSiB amorphous powder. The improved annealing temperature and the microstructure modification are beneficial to improving the combined electromagnetic properties of amorphous SMCs, including permeability, direct current bias performance and core loss. As a result, the FeSiB SMCs with 12 wt% FeSiBCCr addition possess the high effective permeability μ_e of 46.5 at 100 kHz, high percent effective permeability %μ_e of 74.5 % at 100 kHz and 100 Oe, and low total core loss of 222 kW/m³ at 100 kHz and 50 mT. This work proposes a potential strategy for the industry to fabricate the SMCs with high combined electromagnetic performance.

Under the influence of multiple mining of coal seams, the granules structure formed by the mixing of different grain sizes exists in the collapse zone, and its compaction and re-crushing characteristics become a factor influencing the deformation and movement of the overlying rock layer. Therefore, the characteristics of sandstone granules with different gradations under cyclic loading were investigated in this manuscript. It is shown that the strain of sandstone granules increases with the increase of gradation index n, the dissipation energy of particle movement and crushing shows an increasing trend, and its porosity decreases with the increase of axial stress as a whole. At the early stage of stress loading, the high-gradation sandstone granules have high compression space and crushing potential due to larger size particles, the porosity declines the fastest, the compression modulus increases sharply, and the sandstone granules is compacted rapidly at this stage. When the stress exceeds a certain range, the energy density changes and the porosity reduction of the higher-gradation granules increases, and the larger size particles in the higher-gradations granules samples are broken down into small-size particles. At the same time, the amount of energy density changes and porosity attenuation of the high-gradations sandstone granules increases, the compressive modulus increases again at this stage, the position of the granules particles moves and the distribution is re-distributed, and the granules particles are more compact after the re-distribution, which corresponds to the higher re-distribution of the high-gradations granules samples. Under the external disturbance load, the sandstone granules show the characteristics of “three stages”: pore compression period, elastic deformation period, and crushing and reorganization period. The results of this study can provide theoretical support for revealing the deformation and movement mechanism of the rock mass in the collapse zone under multiple mining.