Cs₄PbBr₆ Combined with Graphite as Anode for High-Performance Lithium Batteries

Cs4PbBr6 quantum dots are glass-based materials. The perovskite structural material of Cs4PbBr6 quantum dots has shown an unexpected electronic performance. However, the glass-based Cs4PbBr6 quantum dots’ capacity becomes weaker when running in charge/discharge. Here, graphite was introduced to Cs4PbBr6 quantum dots using the grinding method to enhance the cycling stability of Cs4PbBr6 quantum dots. The 10%, 25%, 35%, 40%, 75% content Cs4PbBr6 quantum dots were added to graphite (CQDs/G) and CQDs/G as an active material for lithium anode in electronic testing. The test results displayed 35% Cs4PbBr6 quantum dots content in CQDs/G, showing an excellent cycle performance (136.5 mAh g−1 after 1000 cycles at 0.5 A g−1 current density) and good rate ability. Graphite protected the CQDs in the long term, and has high potential economic value

Numerical Simulation of Ti/Al Bimetal Composite Fabricated by Explosive Welding

In this paper, a 2D numerical model that is more physically realistic was established to simulate the complete process of Ti/Al explosive welding. Basing on the ANSYS/AUTODYN software package, the smoothed particle hydrodynamics (SPH) and arbitrary Lagrangian-Eulerian (ALE) were used for running this simulation. The numerical model can capture the typical physics in the explosive welding process, including the expansion of explosives, flyer plate bending, the impact of metal plates, jetting, and the wavy interface. The variable physical parameters during the explosive welding process were discussed. Most parts of the jet originated from the aluminum plate. According to the model, the jet velocity reached 7402 m/s. The pressure at the detonation point was too small to make the two plates to bond. The pressure could reach an order of magnitude of 107 kPa when the detonation energy tended to be stable and was far more than the yield strength of both materials, which resulted in an obvious narrow region of plastic strain emerging close to the collision zone. The signs of shear stresses between the two plates were the opposite. The interface morphology changed from straight to wave along the propagation of the detonation wave in the simulation, which was consistent with the experimental results

Study on Mechanism and Influencing Factors of Wheel Strengthening and Toughening of High-Speed and Heavy-Load Train

When maximum speed of 160 km/h is reached and the axle load reaches 25–30 tons, the train wheels need to have high strength and toughness. The main chemical elements affecting the strength and toughness of the wheel were determined by the mechanical features of the samples with different chemical compositions. Through analysis of the impact fracture of typical specimens, the difference of wheel toughness was mainly reflected in the dimple band, crack source, and cleavage pattern. By SEM analysis of fracture cracks, the critical size difference was found to exist between the grains during brittle fracture, where the intergranular fracture between grains of different sizes is mainly due to the different interfacial stresses between grains of different sizes

Study on Microstructure and Properties of NM500/Q345 Clad Plates at Different Austenitization Temperatures

In this paper, the change in the mechanical properties of a composite plate was studied using the heat treatment method, and it was found that the performance of the composite plate was greatly improved under the process of quenching at 900 °C and tempering at 200 °C. The hot-rolled NM500/Q345 clad plates were subjected to heat treatment tests of 860 °C, 900 °C, and 940 °C austenitization + 200 tempering. With the help of an optical microscope, scanning electron microscope, EBSD, and transmission electron microscope, the microstructure, interface element distribution, and defect composition at the composite bonding interface of hot rolling and heat treatment were analyzed. An analysis and friction and wear tests were carried out on the wear resistance of the clad NM500. It was found that the microstructure of the NM500/Q345 clad plate before austenitization was mainly pearlite and ferrite, and both were transformed into lath martensite after austenitization. As the austenitization temperature increased, the size of the martensitic lath bundle also became coarse. After austenitization at 900 °C and tempering at 200 °C, the lath-like martensite structure of NM500 contained high-density dislocations between the laths. With the increase in the austenitization temperature, the surface Rockwell hardness showed a trend of first increasing and then decreasing. The wear was the worst when the material was not quenched. When the clad plate was quenched at 900 °C and tempered at 200 °C, the wear of NM500 was the lightest; the maximum depth of the wear scar was 14 μm; the width was the narrowest, 0.73 mm; and the wear volume was the smallest, 0.0305 mm3

Study on Microstructure and Properties of NM500/Q345 Clad Plates at Different Austenitization Temperatures

In this paper, the change in the mechanical properties of a composite plate was studied using the heat treatment method, and it was found that the performance of the composite plate was greatly improved under the process of quenching at 900 °C and tempering at 200 °C. The hot-rolled NM500/Q345 clad plates were subjected to heat treatment tests of 860 °C, 900 °C, and 940 °C austenitization + 200 tempering. With the help of an optical microscope, scanning electron microscope, EBSD, and transmission electron microscope, the microstructure, interface element distribution, and defect composition at the composite bonding interface of hot rolling and heat treatment were analyzed. An analysis and friction and wear tests were carried out on the wear resistance of the clad NM500. It was found that the microstructure of the NM500/Q345 clad plate before austenitization was mainly pearlite and ferrite, and both were transformed into lath martensite after austenitization. As the austenitization temperature increased, the size of the martensitic lath bundle also became coarse. After austenitization at 900 °C and tempering at 200 °C, the lath-like martensite structure of NM500 contained high-density dislocations between the laths. With the increase in the austenitization temperature, the surface Rockwell hardness showed a trend of first increasing and then decreasing. The wear was the worst when the material was not quenched. When the clad plate was quenched at 900 °C and tempered at 200 °C, the wear of NM500 was the lightest; the maximum depth of the wear scar was 14 μm; the width was the narrowest, 0.73 mm; and the wear volume was the smallest, 0.0305 mm3

Hot compression behavior of Mg–Zn–Y–Mn–Ti magnesium alloy enhanced by lamellar LPSO phase and spherical W phase

The hot compression experiments of the solution-treated Mg93.5Zn2.5Y2.5Mn1Ti0.5 alloy were carried out using a Gleeble-1500D thermal simulator under the conditions of a temperature of 350∼500 °C, a strain rate of 0.001–1 s−1 and a strain of 0.9. According to the stress-strain curve, the characteristics of flow stress were analyzed. Moreover, the constitutive equation of flow stress, the kinetic model of dynamic recrystallization, and the processing map were established. The results show that the flow stress of the alloy decreases as the deformation temperature increases or the strain rate decreases. The constitutive equation of flow stress can be expressed as a hyperbolic sine function: ε˙=4.27115×1019[sinh(0.01153σ)]8.493×exp(2.856×105/RT). With the increase of the deformation temperature or the decrease of the strain rate, the volume fraction and grain size of dynamic recrystallization of the alloy increase continuously. Its dynamic recrystallization volume fraction can be expressed by the Avrami equation as: XDRX=1−exp[−2.05((ε−εc)/ε∗)1.42]. The instability region of the alloy increases with the increase of strain. The first instability region is (350–410 °C, 0.12–1 s−1), the second one is (450–500 °C, 0.001–1 s−1), and the optimum domain for the hot processing of this alloy is (380–450 °C, 0.001–0.01 s−1)

Effects of B4C on the formation of LPSO phase and mechanical properties of Mg–Zn–Y–Mn alloy

Effects of B4C on the microstructure and properties of Mg94Zn2.5Y2.5Mn1 alloy were investigated by means of optical microscope, scanning electron microscope, X-ray diffraction, transmission electron microscope, nano indentation tester and electronic universal testing machine. The results indicated that the as-cast Mg94Zn2.5Y2.5Mn1 alloy was mainly composed of α-Mg, fishbone-like W phase, and block 18 R long period stacking ordered (LPSO) phase. The addition of an appropriate amount of B4C could effectively refine grains, promote the formation of the LPSO phase and inhibit the generation of the W phase. The microstructure and mechanical properties of the alloy were both optimal at the addition of 0.5 at.% B4C. The microstructure exhibited a refined grain size from 41.2 μm to 20.7 μm, and the volume fraction of the LPSO phase increased from 8.1 % to 22.5 %. The yield strength increases from 112 MPa to 145 MPa, the tensile strength of the alloy was enhanced from 192 MPa to 256 MPa, and the elongation increased from 4.8 % to 8.6 %

Hospital of Shandong Academy of

rheumatoid arthritis developmen

Riding practices of e-bike riders after the implementation of electric bike management regulations: An observational study in Hangzhou, China

Objective: This study aimed to understand the riding behaviors of electric bike (e-bike) users in Hangzhou after the “Regulations of Zhejiang Province on the Administration of Electric Bicycles”. Methods: The study consisted of two parts, including a questionnaire survey of local e-bike users in Shangcheng District and Jiande County in Hangzhou City, and a cross-sectional observational study of 16 intersections. Results: A total of 789 e-bike riders participated in the questionnaire survey, and the riding behavior of 99,407 e-bike users was observed. The main purpose of using e-bike was work and daily life, 46.0% of them used e-bikes more than 5 days a week, and 58.5% used e-bikes for less than 30 min each time. A vast majority (81.7%) of e-bike riders believe that the implementation of Zhejiang Regulations has significantly improved the safety level of e-bike riding in the region. The field survey found that the correct rates of helmet wearing by e-bike riders and passengers were 78.83% and 42.27%. The main violations were invalid/non-helmet wearing (21.17%), followed by carrying passengers and running red lights (7.94% and 4.26%). The rates of invalid/non-helmet wearing and running red lights were significantly higher during non-morning rush hour, weekends, and roads without separate non-motorized vehicle lanes than in other conditions (all P < 0.05). Additionally, sunny days and crossroads were risk factors for passenger-carrying and invalid/non-helmet wearing compared to rainy/cloudy days and T-intersections. Conclusions: The phenomenon that e-bike users' correct practice lags far behind the awareness of various violations has shown some improvement. To further enhance safety measures for e-bike riders, it is necessary to promote education, improve infrastructure, and strengthen law enforcement, in support of the “Zhejiang Regulations” and behavioral interventions