An understanding of dendrite growth is required in order to improve the properties of castings. For this reason, cellular automaton-finite difference(CA-FD) method was used to investigate the dendrite growth during di...
详细信息
An understanding of dendrite growth is required in order to improve the properties of castings. For this reason, cellular automaton-finite difference(CA-FD) method was used to investigate the dendrite growth during directional solidification(DS)process. The solute diffusion model combined with macro temperature field model was established for predicting the dendrite growth behavior. Model validation was performed by the DS experiment, and the cooling curves and grain structures obtained by the experiment presented a reasonable agreement with the simulation results. The competitive growth of dendrites was also simulated by the proposed model, and the competitive behavior of dendrites with different misalignment angles was also discussed in ***, 3D dendrites growth was also investigated by experiment and simulation, and both were in good accordance. The influence on dendrites growth of initial nucleus was investigated by three simulation cases, and the results showed that the initial nuclei just had an effect on the initial growth stage of columnar dendrites, but had little influence on the final dendritic morphology and the primary dendrite arm spacing.
The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure an...
详细信息
The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure and solid particle erosion resistance for CF/PC composites after ultraviolet irradiation were studied. It was shown that ultraviolet irradiation causes photo-oxygen aging and photo-fries re-arrangement of the composite, and the result was confirmed by FTIR. We correlated the solid particle erosion resistance with aging time, and found that the solid particle erosion resistance of CF/PC composites greatly decreased by UVB irradiation during 15 hours. Furthermore, the eroded material surface was analyzed using scanning electron microscope (SEM). It suggests that ultraviolet aging leads to plasticization and degradation, resulting in reduction of erosion resistance of the composite.
In this paper, AZ91D magnesium alloy with weak basal texture, fine grains, high-density dislocations and nano-precipitates had been fabricated via laser powder-bed-fusion (L-PBF). Due to these special microscopic char...
详细信息
Ethylamine has been widely used in production and life, but it needs to be monitored in real-time because of its important harm to human health. In this study, an SnO2/rGO nanocomposite gas sensitive material was synt...
详细信息
Understanding the core-shell structure of carbon-encapsulated alloys aids in enhancing catalyst stability. DFT simulations reveal that the intrinsic electric field of the alloy modulates carbon atom behavior, effectiv...
Understanding the core-shell structure of carbon-encapsulated alloys aids in enhancing catalyst stability. DFT simulations reveal that the intrinsic electric field of the alloy modulates carbon atom behavior, effectively lowering the Gibbs free energy required for water dissociation and hydrogen adsorption on the carbon surface. Carbon-encapsulated RuMn alloy nanoparticles supported on carbon nanofibers (RuMn/CNFs) was fabricated as self-supporting electrode materials to validate this conclusion via a synergistic electrospinning‑carbonization protocol. The rational design of Ru/Mn stoichiometric modulation synergized with carbon nanofiber's superior electrical conductivity and RuMn/CNFs' hydrophilic-hydrophobic dual functionality endows the catalyst with exceptional alkaline hydrogen evolution performance. Specifically, the optimized RuMn/CNFs achieves a remarkably low overpotential of 80 mV at 100 mA cm −2 coupled with an Tafel slope of 46.3 mV dec −1 . Analysis of surface morphology, internal structure, and changes in metal ion concentration in the electrolyte over various hydrogen production times revealed that Mn atoms, with lower electronegativity, leach from the graphite carbon-encapsulated alloy core-shell structure, creating defects on the surface of the RuMn alloy core. Atomic-scale interfacial interactions between RuMn lattice defects and the carbon shell orchestrate two synergistic effects: (1) enhance the adsorption of water onto the carbon shell, and (2) a 47 % reduction in water dissociation energy barriers (DFT-calculated). This dual modulation drives ultrafast Volmer step kinetics, endowing RuMn/CNFs with a good activity enhancement over pristine counterparts at industrial current densities (2.3 V at 500 mA cm −2 ). This work establishes a mechanistic framework for understanding dynamic interface reconstruction in carbon-encapsulated electrocatalysts, offering critical insights into operando structural evolution patterns and active site generation me
Balancing electrochemical activity and structural reversibility of fibrous electrodes with accelerated Faradaic charge transfer kinetics and pseudocapacitive storage are highly crucial for fiber-shaped supercapacitors...
详细信息
Balancing electrochemical activity and structural reversibility of fibrous electrodes with accelerated Faradaic charge transfer kinetics and pseudocapacitive storage are highly crucial for fiber-shaped supercapacitors (FSCs). Herein, we report novel core–shell hierarchical fibers for high-performance FSCs, in which the ordered NiCoMoS nanosheets arrays are chemically anchored on Ti 3 C 2 T x fibers. Beneficial from architecting stable polymetallic sulfide arrays and conductive networks, the NiCoMoS−Ti 3 C 2 T x fiber maintains fast charge transfer, low diffusion and OH − adsorption barrier, and stabilized multi-electronic reaction kinetics of polymetallic sulfide. Consequently, the NiCoMoS−Ti 3 C 2 T x fiber exhibits a large volumetric capacitance (2472.3 F cm −3 ) and reversible cycling performance (20,000 cycles). In addition, the solid-state symmetric FSCs deliver a high energy density of 50.6 mWh cm −3 and bending stability, which can significantly power electronic devices and offer sensitive detection for dopamine.
The effects of high pressure rheo-squeeze casting(HPRC) on the Fe-rich phases(FRPs) and mechanical properties of Al-17 Si-(1,1.5)Fe alloys were investigated. The alloy melts were first treated by ultrasonic vibration(...
详细信息
The effects of high pressure rheo-squeeze casting(HPRC) on the Fe-rich phases(FRPs) and mechanical properties of Al-17 Si-(1,1.5)Fe alloys were investigated. The alloy melts were first treated by ultrasonic vibration(UV) and then formed by high-pressure squeeze casting(HPSC). The FRPs in the as-cast HPSC Al-17 Si-1 Fe alloys only contained a long, needle-shaped β-Al5 Fe Si phase at 0 MPa. In addition to the β-Al5 Fe Si phase, the HPSC Al-17 Si-1.5 Fe alloy also contained the plate-shaped δ-Al4 Fe Si2 phase. A fine, block-shaped δ-Al4 Fe Si2 phase was formed in the Al-17 Si-1 Fe alloy treated by UV. The size of FRPs decreased with increasing pressure. After UV treatment, solidification under pressure led to further refinement of the FRPs. Considering alloy samples of the same composition, the ultimate tensile strength(UTS) of the HPRC samples was higher than that of the HPSC samples, and the UTS increased with increasing pressure. The UTS of the Al-17 Si-1 Fe alloy formed by HPSC exceeded that of the Al-17 Si-1.5 Fe alloy formed in the same manner under the same pressure. Conversely, the UTS of the Al-17 Si-1 Fe alloy formed by HPRC decreased to a value lower than that of the Al-17 Si-1.5 Fe alloy formed in the same manner.
Polyethyleneimine (PEI) functionalized Fe3O4 MNPs were synthesized by a modified hypothermal oxidative hydrolysis method. The magnetic nanoparticles showed positively charged surface, strong magnetic responsivity and ...
Polyethyleneimine (PEI) functionalized Fe3O4 MNPs were synthesized by a modified hypothermal oxidative hydrolysis method. The magnetic nanoparticles showed positively charged surface, strong magnetic responsivity and uniform particle size distribution at 56.1±0.6 nm. Aggregation of these magnetic nanoparticles were observed on the surface of different type of bacteria. Magnetic capturing of bacteria were facilitated by these magnetic nanoparticles. The capturing efficiency could reach 90% after two rounds of interactions of 5 minutes. The mechanism and process of interactions between bacteria and polyethyleneimine functionalized Fe3O4 magnetic nanoparticles were explored and discussed. The present study not only provides insight into interactions between Fe3O4@PEI MNPs and bacterial cells, but also opens a new avenue for designing and applying Fe3O4@PEI MNPs as biosensors in microbiology, medicine, and environmental science.
暂无评论