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Exploring a synergistic-type magnetostructural transformation in Ni-Mn-Ga-X (X = Sn, Sb) Heusler alloys
No full textIn this paper, the magnetostructural transformation from paramagnetic austenite to ferromagnetic martensite is described as a synergistic-type phase transformation because the structural and magnetic subsystems exhibit two unique synergistic effects: (1) lattice vibration and magnetic entropy changes synergistically contribute to the total entropy change; (2) the structure and magnetism synergistically response to external cross-fields. Such synergistic-type phase transformation has been explored in Ni-Mn-Ga-X (X = Sn, Sb) Heusler alloys. By the substitution of Sn/Sb for Ga, a temperature window of 50 K for the synergistic-type phase transformation has been established in the phase diagram of Ni-Mn-Ga-X (X = Sn, Sb). Associated with the synergistic contribution of lattice vibration and magnetic entropy changes, the samples exhibit high phase transformation entropy changes (>= 1.2 J/molK) within the temperature window. The synergistic effects of the magnetostructural transformation make the Ni-Mn-Ga-X (X = Sn, Sb) alloys to be potential multicaloric materials
A damage-effect-involved phenomenological crystal plasticity model and computational methods for mechanical responses of FeCrAl alloys
No full textIn this study, a new damage-effect-involved phenomenological crystal plasticity model is proposed to capture macroscale straining hardening and strain softening behaviors of iron chromium aluminum (FeCrAl) alloys. The constitutive model is described with co-rotational tensors. Damage factor evolves with the effective plastic work calculated by the resolved shear stress and shear strain rate on all slip systems. A stress update algorithm is specially established, and the corresponding self-defined subroutines are incorporated into the finite element analysis via VUMAT in ABAQUS/Explicit. Fast convergence can be achieved with the maximum value of damage factor set very close to 1. The simulated macroscale stress-strain curves can agree well with the experimental ones for various FeCrAl alloys. The yield strengths and ultimate tensile strengths of these alloys can be well captured. The dependence of damage model parameters on the processing conditions, alloy compositions are discussed and analyzed. This work provides a basis for the multiscale simulation research on the mechanical performances of polycrystal alloys
The cutting process and damage mechanism of large thickness CFRP based on water jet guided laser processing
No full textCarbon fiber-reinforced polymer composites (CFRP) is a composite material with resin as matrix and carbon fiber as reinforcement. It has been widely used in aerospace, military products, and automotive industries. However, CFRP is prone to damage because of its complex anisotropy and low interlayer strength, so it is a typical difficultto-process material. Water jet guided laser processing technology is a combination of laser and water jet processing technology, which has the characteristics of no wear, no contact, flexible processing, and potential advantages of reducing HAZ and increasing cutting depth. In this paper, the water jet guided laser processing technology is used to perform cutting experiment for CFRP processing of low damage and large depth. In the experiment, the influencing law of the process parameters such as laser power, CFRP feed speed and water jet speed on the cutting results is obtained; then the cutting thickness of 1 mm, 2 mm, 4 mm and 10 mm CFRP is realized by adopting the parallel path layered scanning method. Moreover, the influences of carbon fiber arrangement direction and laser cutting path on the CFRP cutting damage mechanism are analyzed for the first time, and three damage mechanisms (exposing, falling-off and pulling-out) are summarized, which will provide the reference for the high precision cutting of large thickness CFRP
Enhanced strong metal-support interactions between Pt and WO3-x nanowires for the selective hydrogenation of p-chloronitrobenzene
No full textWO3-x nanowires with oxygen vacancies synthesized by a hydrothermal method were employed as supports to deposit Pt nanoparticles (NPs) via a deposition-reduction method with NaBH4. The Pt/WO3-x nanocomposites exhibit an excellent catalytic hydrogenation performance in the selective hydrogenation of p-chloronitrobenzene due to the interaction between Pt NPs and WO3-x nanowires
Aggregation-Induced Emissive Carbon Dots Gels for Octopus-Inspired Shape/Color Synergistically Adjustable Actuators
No full textSome living organisms such as the octopus have fantastic abilities to simultaneously swim away and alter body color/morphology for disguise and self-protection, especially when there is a threat perception. However, it is still quite challenging to construct artificial soft actuators with octopus-like synergistic shape/color change and directional locomotion behaviors, but such systems could enhance the functions of soft robotics dramatically. Herein, we proposed to utilize unique hydrophobic carbon dots (CDs) with rotatable surficial groups to construct the aggregation-induced emission (AIE) active glycol CDs polymer gel, which could be further employed to be interfacially bonded to an elastomer to produce anisotropic bilayer soft actuator. When putting the actuator on a water surface, glycol spontaneously diffused out from the gel layer to allow water intake, resulting in a color change from a blue dispersion fluorescence to red AIE and a shape deformation, as well as a large surface tension gradient that can promote its autonomous locomotion. Based on these findings, artificial soft swimming robots with octopus-like synergistic shape/color change and directional swimming motion were demonstrated. This study provides an elegant strategy to develop advanced multi-functional bio-inspired intelligent soft robotics
Solid-State Electroanalytical Chemistry and Its Application in Plant Analysis
No full textSolid-state electroanalytical chemistry (SSEAC) is a method to analyze the information of solid materials by electrochemical methods, especially for the analysis of element composition, phase composition and redox state of solid materials. The SSEAC technology has been successfully applied to obtain the electrochemical information of natural pigments, plants, minerals and cultural relics with qualitative and quantitative analysis. SSEAC-based plant analysis is a cross-analysis technique emerging between electroanalytical chemistry and phytochemistry in recent years. SSEAC can provide a new understanding of the interspecific relationship, variation, differentiation and adaptation of species, which has a very intuitive practical value in the identification of medicinal materials, food safety and crop quality control. This article reviews the work of SSEAC technology in plant identification, plant phylogeny and plant physiological monitoring in recent years. This review also summarizes the challenges of SSEAC technology in plant analysis as well as its prospects in future development
Effect of the 345 degrees C and 16.5 MPa autoclave corrosion on the oxidation behavior of Cr-coated zirconium claddings in the high-temperature steam
No full textCr-coated Zirlo tubes were conducted in the autoclave corrosion (345 degrees C and 16.5 MPa), followed by the 1200 degrees C steam oxidation. After the 1-h oxidation, the coated tubes exhibited structural integrity, in contrast to the uncoated ones that had broken into pieces. Moreover, the coated tubes that already underwent the 45-days precorrosion, still remained good oxidation resistance with the weight gain of -4.46 mg/cm2. During the precorrosion, very thin Cr2O3 tissue formed on the outmost surface and along the columnar boundaries, which would suppress the formation of bubbles and cracks in the subsequent oxidation
Recent Progress in Superhydrophilic Carbon-Based Composite Membranes for Oil/Water Emulsion Separation
No full textThe purification of stabilized oil/water emulsions is essential to meet the ever increasing demand for monitoring water in the environment, which has been addressed with superwetting carbon-based separation membranes. These include superhydrophilic carbon-based membranes whose progress in recent years and perspectives are reviewed in this paper. The membrane construction strategy is organized into four parts, vacuum-assisted selfassembly, sol-gel process, electrospinning, and vacuum-assisted filtration. In each section, the design strategies and their responding disadvantages have been comprehensively discussed. The challenges and prospects concerning the superhydrophilic carbon-based separation membranes for oily wastewater purification are also summarized to arouse researchers to carry out more studies
Rational Design of Highly Stable and Active MXene-Based Bifunctional ORR/OER Double-Atom Catalysts
No full textDesigning highly active and bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts has attracted great interest toward metal-air batteries. Herein, an efficient solution to the search for MXene-based bifunctional catalysts is proposed by introducing non-noble metals such as Fe/Co/Ni at the surfaces. These results indicate that the ultrahigh activities in Ni1/Ni2- and Fe1/Ni2-modified MXene-based double-atom catalysts (DACs) for bifunctional ORR/OER are better than those of well-known unifunctional catalysts with low overpotentials, such as Pt(111) for the ORR and IrO2(110) for the OER. Strain can profoundly regulate the catalytic activities of MXene-based DACs, providing a novel pathway for tunable catalytic behavior in flexible MXenes. An electrochemical model, based on density functional theory and theoretical polarization curves, is proposed to reveal the underlying mechanisms, in agreement with experimental results. Electronic structure analyses indicate that the excellent catalytic activities in the MXene-based DACs are attributed to the electron-capturing capability and synergistic interactions between Fe/Co/Ni adsorbents and MXene substrate. These findings not only reveal promising candidates for MXene-based bifunctional ORR/OER catalysts but also provide new theoretical insights into rationally designing noble-metal-free bifunctional DACs
Directing the deposition of lithium metal to the inner concave surface of graphitic carbon tubes to enable lithium-metal batteries
No full textSelective deposition of lithium into a carbonaceous host is considered an effective strategy to prevent the growth of lithium metal dendrities. However, selective deposition of lithium metal into the inner spaces of a hollow carbonaceous host without nucleation seeds remains challenging. Herein, selective deposition of lithium metal is introduced by utilizing the difference in the nucleation barrier of lithium on the inner and outer surface of graphitic tubes. In situ transmission electron microscopy data indicated that uniform deposition of lithium metal into the hollow surface of graphite tubes occurred in the absence of electrolyte, and continued until the tube was fully filled. To increase the amount of lithium that can be accommodated, we contrived a novel method for preparing supersized graphite carbon tubes (S-GCTs) and demonstrated the relationship between morphology and electrochemical performance. Electrochemical study proved that the S-GCTs exhibited high coulombic efficiency (99.3% over 350 cycles) and long-running lifespan (>1200 h) with a low overpotential (<13 mV). The volumetric capacity of S-GCT reached 1.33 A h L-1, which is superior to that obtained in previous work. The fundamental understanding of how to control Li deposition demonstrated in this work will provide new insight for the rational design of lithium metal batteries