Co-Fe-Pd nanoparticles fabricated by ultrasonic irradiation and their ORR activities in alkaline solution
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•Co5Fe2Pd1 nanoparticles were synthesized by using ultrasonic ...irradiation.•Co, Fe and Pd in Co5Fe2Pd1 nanoparticles are most in the metallic state.•Co5Fe2Pd1 nanoparticles exhibit superior ORR properties due to trimetallic microalloying effect (lattice strain).•The yield of H2O2 produced in the ORR process is 9–11% for the Co5Fe2Pd1 nanoparticles.•Co5Fe2Pd1 nanoparticles are expected as a promising ORR catalyst in the fuel cell.
Metal nanoparticles, namely Co, Co5Fe2, Co5Pd1 and Co5Fe2Pd1, were successfully synthesized by applying an ultrasonic irradiation method, and their electro-catalytic activities toward ORR were also evaluated in 0.1 M KOH solution. Co5Fe2Pd1 nanoparticles with an average diameter of 3 to 5 nm were found mostly in the metallic state. Due to the trimetallic microalloying effect, Co5Fe2Pd1 nanoparticles exhibited higher ORR activity than those of Co, Co5Fe2 and Co5Pd1 nanoparticles, even higher than that of commercial Pt/C catalyst. Also, Co5Fe2Pd1 nanoparticles were more tolerant than commercial Pt/C catalyst to the poisoning effect of methanol, whereas on them the ORR proceeded predominately via the four-electron pathway. The concentration of citric acid was also found to affect the size distribution of the Co5Fe2Pd1 nanoparticles, and thus influenced their electro-catalytic activities for ORR.
Increasingly advanced applications of polymer fibers are driving the demand for new, high-performance fiber types. One way to produce polymer fibers is by electrospinning from polymer solutions and ...melts. Polymer melt electrospinning produces fibers with small diameters through solvent-free processing and has applications within different fields, ranging from textile and construction, to the biotech and pharmaceutical industries. Modeling of the electrospinning process has been mainly limited to simulations of geometry-dependent electric field distributions. The associated large change in viscosity upon fiber formation and elongation is a key issue governing the electrospinning process, apart from other environmental factors. This paper investigates the melt electrospinning of aerogel-containing fibers and proposes a logistic viscosity model approach with parametric ramping in a finite element method (FEM) simulation. The formation of melt electrospun fibers is studied with regard to the spinning temperature and the distance to the collector. The formation of PET-Aerogel composite fibers by pneumatic transport is demonstrated, and the critical parameter is found to be the temperature of the gas phase. The experimental results form the basis for the electrospinning model, which is shown to reproduce the trend for the fiber diameter, both for polymer as well as polymer-aerogel composites.
Artificial Intelligence (AI) is driving advancements across various fields by simulating and enhancing human intelligence. In Natural Language Processing (NLP), transformer models like the Kerformer, ...a linear transformer based on a kernel approach, have garnered success. However, traditional attention mechanisms in these models have quadratic calculation costs linked to input sequence lengths, hampering efficiency in tasks with extended orders. To tackle this, Kerformer introduces a nonlinear reweighting mechanism, transforming maximum attention into feature-based dot product attention. By exploiting the non-negativity and non-linear weighting traits of softmax computation, separate non-negativity operations for
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Secondary aluminum dross is a byproduct of the electrolytic aluminum industry, whose main components are Al2O3, AlN and Na3AlF6. Secondary aluminum dross is a type of hazardous waste, with a ...tremendous yield every year. Realizing the harmless treatment or resource utilization of secondary aluminum dross has important economic and social benefits. In the present research, the process of preparing premelted calcium aluminate slag used for molten steel refining from secondary aluminum dross was studied in detail. Firstly, the chemical composition and phase component of secondary aluminum dross were analyzed systematically. Then, according to phase diagram analysis and melting point measurement, the appropriate mixing ratio of CaO and secondary aluminum dross and the appropriate calcination temperature were determined. On this basis, an experiment of premelted calcium aluminate slag preparation was carried out in a tubular resistance furnace. The phase component and micromorphology of the premelted slag were analyzed by XRD and SEM. The results show that the main component of the premelted calcium aluminate slag is 11CaO·7Al2O3·CaF2 phase with a low melting point. The original Na3AlF6 phase, which is the cause of leachable fluoride in secondary aluminum dross, disappears totally, and there is no water-soluble fluoride detected in the leaching toxicity detection. The research indicates that the process of preparing premelted calcium slag from secondary aluminum dross is feasible, which provides a helpful reference for the resource utilization of secondary aluminum dross.
Contact angles of five common grades of molten steel on Al2O3, MgO and MgO·Al2O3 inclusion substrates have been measured precisely by a sessile drop technique at 1823/1873 K, and the wettability of ...each type of inclusions is discussed. Interfacial tension between the steels and the inclusions is calculated through the Young equation. Thus, coagulation coefficient, which is used to evaluate agglomeration tendency of inclusions, has been calculated based on the collision-coagulation theory combined with the interfacial tension data. The results of the coagulation coefficient show that the agglomeration tendency of the three typical oxide inclusions in molten steel is Al2O3 > MgO > MgO·Al2O3, and the relationship between coagulation coefficient αt of inclusions and contact angle θ between inclusions and molten steels can be expressed as αt = 4.923 × 10−5μrI3(ρMε / μ)1/2 / (σI – σMcosθ)−0.242. Furthermore, in order to verify the validity of the results obtained, three deoxidation experiments in resistance furnace were carried out. The resulting samples were quenched and then analyzed by SEM-EDS and ASPEX. The results of inclusions observed in the quenched samples show good agreement with the results of inclusion agglomeration tendency. Overall, the effects of wettability and interfacial tension on inclusion agglomeration behaviors are proved to be remarkable.
Due to the advantages of Mg on inclusions and carbides in H13 steel, Mg wire was added into industrial ladle after VD process to replace traditional Ca treatment in this paper, which is of great ...significance for industrial production of H13 steel. This paper focuses on the effects of Mg treatment and traditional Ca treatment on the inclusions, carbides, microstructure and mechanical properties in H13 steel. The results show that feeding Mg wire during EAF→ LF→ VD → CC steelmaking process can ensure the submerged nozzle not being blocked under the condition of continuous casting 15 heats of steel ladle, which means feeding Ca wire can be replaced with Mg wire from the aspect of steelmaking production. The primary carbides in Mg treatment steel are mainly precipitated with MgO or MgAl2O4 as the cores and small in size, while the primary carbides in Ca treatment steel are almost large-size carbides without core. The samples taken from the intermediate ladle show that the primary carbide types are all V-rich, Mo-rich and V–Mo-rich composite, and the size of primary carbides in Mg treatment steel is much smaller than that in Ca treatment steel. Adding Mg is helpful to improve the equiaxed crystal rate of continuous casting ingot. The annealed hot rolling samples show that Mg treatment could interrupt the M23C6 (M = Cr, Fe) chain carbides distributed along the grain boundary. The impact test shows that the dimple fracture surface become small and deep after adding Mg, which improves impact toughness significantly.
During the process of electroslag remelting (ESR) of steel containing titanium and aluminum, the activity ratio between titania and alumina in CaF2-CaO-MgO-Al2O3-TiO2 slag must be fixed in order to ...guarantee the titanium and aluminum contents in the ESR ingots. Under the condition of fixed activity ratio between titania and alumina in the slag, the melting temperature of slag should be investigated to improve the surface quality of ESR ingots. Therefore, this paper focuses on finding a kind of slag with low melting temperature that can be used for producing steel containing titanium. In the current study, the thermodynamic equilibrium of 3Ti + 2(Al2O3) = 4Al + 3(TiO2) between SUS321 steel and the two slag systems (CaF2:MgO:CaO:Al2O3:TiO2 = 46:4:25:(25 − x):x and CaF2:MgO:CaO:Al2O3:TiO2 = 46:4:(25 − 0.5 x):(25 − 0.5 x):x) are studied in an electrical resistance furnace based on Factsage software. After obtaining the equilibrium slag with fixed activity ratio between titania and alumina, the melting temperatures of the two slag systems are studied using slag melting experimental measurements and phase diagrams. The results show that the slag systems CaF2:MgO:CaO:Al2O3:TiO2 = 46:4:25:(25 − x):x, which consists of pre-melted slag S0 (CaF2:MgO:CaO:Al2O3 = 46:4:25:25) and pre-melted slag F1 (CaF2:MgO:CaO:TiO2 = 46:4:25:25), can not only control the aluminum and titanium contents in steel, but also have the desired low melting temperature property.
Concentrating the chromium in chromium slag and improving the chromium–iron ratio is beneficial for the further utilization of chromium slag. In this paper, chromium slag obtained from a chromite ...lime-free roasting plant was used as the raw material. Pellets made of the chromium slag and pulverized coal were reduced at different pre-reduction temperatures and then separated by a melting separation process or magnetic separation process, respectively. The mass and composition of the metallized pellets before separation, along with the alloy and tail slag after separation, were comprehensively analyzed. The experimental results showed that the output yield of alloy, iron recovery rate, and chromium content in the alloy were all higher when using melting separation than when using magnetic separation, because of the further reduction during the melting stage. More importantly, a relatively low pre-reduction temperature and selection of magnetic separation process were found to be more beneficial for chromium enrichment in slag; the highest chromium–iron ratio in tail slag can reach 2.88.
Siamese networks have found applications in various fields, notably object tracking, due to their remarkable speed and accuracy. Siamese tracking networks rely on cross-correlation to obtain the ...similarity score between the target template and the search region. However, since cross-correlation is a local matching operation, it cannot effectively capture the global context information. While the Transformer for feature fusion can better capture long-range dependencies and obtain more semantic information, more localized edge information is needed to distinguish the target from the background. Cross-correlation fusion and Transformer fusion have their advantages. They can complement each other, so we combine them and propose a dual feature fusion tracker (SiamCT) to obtain the local correlations and global dependencies between the target and the search region. Specifically, we construct two parallel feature fusion paths based on cross-correlation and Transformer. Among them, for cross-correlation fusion, we adopt the more efficient two-dimension pixel-wise cross-correlation (TDPC), which performs correlation operations from both spatial and channel dimensions, and the interaction of multidimensional information helps to realize more accurate feature fusion. Subsequently, the fused features are augmented by coordinate attention (CA) for orientation-dependent positional information. For Transformer fusion, we introduce cos-based linear attention(ClA) to improve Transformer's ability to acquire global context information. Our SiamCT outperforms existing leading methods in GOT-10k, LaSOT, TrackingNet, and OTB100 benchmarks based on extensive experiments.
Oxygen–lime powder bottom blowing converters have significant advantages in metallurgical performance, and have drawn more attention in recent studies. The key for oxygen–lime powder bottom blowing ...converter applications is to solve the problem of the furnace life. Erosion wear of the bottom injecting lance induced by a high velocity gas–solid jet inside the lance is an important factor for the furnace life but has rarely been studied. To reveal the gas–solid jet flow and erosion wear characteristics in the bottom injecting lance, a computational fluid dynamic model coupled with a discrete phase erosion model was established in the present work. The geometric dimension and boundary conditions of the lance were consistent with a commercial bottom injecting lance applied on a 120 ton converter. The simulated results were validated via a jet measurement experiment and an industrial experiment. The results show that the pressure loss in the lance of the gas–solid jet is much higher than that of pure gas jet, and the gas velocity at the lance outlet decreases after powder addition. Mixing powder into the gas has an obvious influence on the pressure variation curve and the velocity variation curve of the gas in the lance. The effect of the lance structure on jet flow and erosion wear was discussed in detail. On the premise that the total length of the lance remains constant, prolonging the shrink pipe length is helpful for reducing the pressure loss in lance. Simultaneously, the value of the maximum erosion wear and the area of the high wear rate region can be significantly reduced by prolonging the shrink pipe, which is vitally important for protecting the lance from being worn out by powder particles. The results of this work provide meaningful explorations and references for the design of converter bottom injecting lance.
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