Advanced Powder Technology最新文献

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.

BaCu_xTi_1-xO_3-x (x = 0, 0.01, 0.02, 0.03, 0.04) nanofibers were synthesized via the hydrothermal method and subsequently subjected to poling. The impact of composition on their tribocatalytic performance and the underlying catalytic mechanism were investigated. After 100 min, all poled BaCu_xTi_1-xO_3-x nanofibers exhibited superior tribocatalytic efficiency compared to pure BaTiO₃, with BaCu_0.02Ti_0.98O_2.98 poled nanofibers achieving a degradation rate of up to 80 % for RhB solution. This is because the increased conductivity and reduced carrier recombination rate which were caused by a 0.02 Cu doping, smaller grain size and poling effect. Control experiments confirmed that both stirring and the presence of a catalyst are essential prerequisites for tribocatalysis. Furthermore, the universality, selectivity, stability, and main active group O₂^– of poled BaCu_xTi_1-xO_3-x (x = 0, 0.01, 0.02, 0.03, 0.04) nanofibers were verified. Lastly, although the tribocatalytic efficiency presented in this paper does not match that of piezoelectric catalysis, the latter requires ultrasonic conditions that are challenging to find naturally. As a result, tribocatalysis offers greater potential for practical applications.

Selective laser melting (SLM) of metal-oxide hybrid powder is currently a cost-effective approach for fabricating oxide-dispersion-strengthened alloys. The distribution behavior of oxide during the SLM process has significant effects on the performance of the final components. In this work, Y₂O₃ strengthened IN625 superalloys were fabricated by selective laser melting using IN625 powder coated by 1 wt% and 3 wt% Y₂O₃. The hybrid powder prepared by the resonant mixing method present the good flowability. Due to the high melting point of Y₂O₃ powder and its harmful effect on the wettability between the melt track and the formed surface, the required laser energy density for successful SLM-fabrication of the hybrid powder should be high. The distribution characteristics of Y₂O₃ during the SLM process and the corresponding evolution mechanism were analyzed. It was found that severe loss of Y₂O₃ occurred during SLM process, resulting from Y₂O₃ slag on the top surface of the built specimen, Y₂O₃ adhered to spatter particles falling into the recycling powder, and Y₂O₃ plume blown into the machine filter by the gas flow. The more Y₂O₃ coated on the metal powder, the more Y₂O₃ lost during SLM. The molten pool with keyhole mode is favorable to reduce Y₂O₃ loss compared to the conduction mode.