Ultrastrong nanotwinned (NT) metals hold promise for mitigating friction and wear—essential for enhancing the energy efficiency and longevity of all moving systems. However, optimizing their tribological performance ...
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Ultrastrong nanotwinned (NT) metals hold promise for mitigating friction and wear—essential for enhancing the energy efficiency and longevity of all moving systems. However, optimizing their tribological performance has long suffered from the absence of friction and wear laws across varying tribological loading scales. Here, we have discovered full-scaling twin lamella spacing (λ)-dependent friction and wear laws in NT pure nickel and identified critical deformation mechanisms for reducing friction and wear. Nanoscale friction initially increases with decreasing λ, peaking at 20 nm, and then decreases due to a transition from dislocation-twin boundary interactions to detwinning. Under microscale loading, friction and wear reduce linearly with decreasing λ, attributed to an unforeseen phase transition from face-centered cubic to hexagonal close-packed structures. Furthermore, under macroscale loading, the formation of a durable oxide layer and a stable gradient nanostructure in nanotwinned nickel with λ exceeding 20 nm aids in mitigating wear loss.
We proposed a new method, electroplating followed by spark plasma sintering(SPS), to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu laye...
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We proposed a new method, electroplating followed by spark plasma sintering(SPS), to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu layer can effectively enhance the strength of the interface between the ceramics and the metals, resulting in a high flexural strength and toughness of the laminated TiB2-B4 C composites simultaneously. A flexural strength and fracture toughness of 651 MPa and 11.6 MPam^(1/2) respectively,are achieved, an approximately 90% improvement over TiB2-B4 C bulk.
作者:
CAO MingHe TIAN Wei LI MingFa SUN WenHua HU MingJi LIU HanXingState Key Laboratory of Advanced Technology for Materials Synthesis and Processing
Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 China
The NaNbO3 powders were synthesized and their crystal structure changes were analyzed by ultrahigh pressure up to 6 *** results indicate that the pure NaNbO3 powders can be synthesized at 300℃ under a pressure of 4 G...
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The NaNbO3 powders were synthesized and their crystal structure changes were analyzed by ultrahigh pressure up to 6 *** results indicate that the pure NaNbO3 powders can be synthesized at 300℃ under a pressure of 4 GPa, to sig- nificantly restrain the Na element volatilization compared with the traditional syn- thesis method. It is found that the crystal structure of synthesized NaNbO3 changes from low symmetry to high symmetry with the increase of the pressure.
Addressing the corrosion issues arising from incorporating highly conductive fillers into the rubber matrix remains a significant challenge, particularly in the harsh marine corrosion environment and under the threat ...
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Pure K2Ti4O9 whiskers were prepared by KDC(Kneading-Drying-Calcination) method with TiO2 and K2CO3 as raw materials. The influences of TiO2/K2CO3 molar ratio(RT/K), calcination temperature(TC) and cooling proces...
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Pure K2Ti4O9 whiskers were prepared by KDC(Kneading-Drying-Calcination) method with TiO2 and K2CO3 as raw materials. The influences of TiO2/K2CO3 molar ratio(RT/K), calcination temperature(TC) and cooling process on phase composition and morphology of the whiskers were investigated by TG-DSC(thermo gravimetric-differential scanning calorimeter), XRD(X-ray diffraction), and SEM(scanning electron microscope). Pure K2Ti4O9 potassium titanate whiskers with large length-diameter ratio(r)(over 250) can be obtained at RT/K = 2.9 and TC = 950 ℃.
To satisfy the demand of zinc oxide(ZnO) with advanced muti-functional properties, significant efforts have been made in synthesizing ZnO with various structure and morphology. In particular, hydrothermal method has...
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To satisfy the demand of zinc oxide(ZnO) with advanced muti-functional properties, significant efforts have been made in synthesizing ZnO with various structure and morphology. In particular, hydrothermal method has attracted considerable attentions, in which Zn4CO3(OH)6·H2O(ZCHH) is commonly found as a metastable precursor. However, the formation and crystallization mechanisms of ZCHH are still lacking and urgently needed. In the present study, the crystallization pathway of ZCHH was systematically investigated, and the results demonstrate that the amorphous zinc carbonate(AZC) was an even more unstable precursor. AZC nanoparticles typically aggregated to form one-dimensional(1D) ZCHH nanorods, however, two-dimensional(2D) ZCHH nanofilms were obtained in the presence of a certain concentration of calcium ion. The results suggest that calcium ions could promote the partial dissolution of AZC and facilitate the aggregation of AZC nanoparticles to form crystalline nanofilm. Moreover, 2D ZnO nanofilms could be obtained by heat treatment of the ZCHH nanofilms. The calcium ion mediated nonclassical crystallization pathway provides inspiration for fabrication of ZnO with controlled morphology and offers new opportunities for inorganic regulated materialsynthesis.
Calcite mesocrystals were proposed, and have been widely reported, to form in the presence of polymer additives via oriented assembly of nanoparticles. However, the formation mechanism and the role of polymer additive...
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Calcite mesocrystals were proposed, and have been widely reported, to form in the presence of polymer additives via oriented assembly of nanoparticles. However, the formation mechanism and the role of polymer additives remain elusive. Here, inspired by the biomineralization process of sea urchin spine comprising magnesium calcite mesocrystals, we show that calcite mesocrystals could also be obtained via atachment of amorphous calcium carbonate(ACC) nanoparticles in the presence of inorganic zinc ***, we demonstrate that zinc ions can induce the formation of temporarily stabilized amorphous nanoparticles of less than 20 nm at a significantly lower calcium carbonate concentration as compared to pure solution, which is energetically beneficial for the atachment and occlusion during calcite growth. The cation-mediated particle atachment crystallization significantly improves our understanding of mesocrystal formation mechanisms in biomineralization and offers new opportunities to bioprocess inspired inorganic ions regulated materials fabrication.
In recent years, substantial effort has been dedicated to improving the intrinsic catalytic activity of catalysts through structural modification, component regulation, and chemical state optimization. However, comple...
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In recent years, substantial effort has been dedicated to improving the intrinsic catalytic activity of catalysts through structural modification, component regulation, and chemical state optimization. However, complexity in the design and construction of catalysts, and the possibility of encountering performance ceilings, may constrain their widespread use. Currently, the introduction of in situ external fields, such as force, electric, magnetic, acoustic, light, and thermal fields, is an attractive approach to enhance the catalytic efficiency of catalysts. Such in situ physical fields feature continuity, reversibility, and controllability, and can exert external force or energy on catalysts, thereby affecting their microscopic structures and electron arrangements, accelerating their mass transfer and reaction kinetics. Mutual coupling and conversion among different external fields are also worth exploring. Various in situ external field effects work in multifaceted ways to promote catalysis in energy-environment systems by optimizing mass/energy transfer processes, modifying structures, and accelerating catalytic reaction kinetics, thereby significantly improving the catalytic properties of materials. This review summarizes and analyzes the latest developments in external field-assisted methods for boosting catalyst performance. The external field effect, related catalysis mechanism, and external field-enhanced catalysis are highlighted, and we discuss future challenges, countermeasures, and opportunities for external field-assisted catalysis and beyond.
Chirality is a unique phenomenon in nature. Chiral interactions play an important role in biological and physiological process- es, which provides much inspiration for scientists to develop cbiral materials. As a brea...
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Chirality is a unique phenomenon in nature. Chiral interactions play an important role in biological and physiological process- es, which provides much inspiration for scientists to develop cbiral materials. As a breakthrough from traditional materials, bi- ointerface materials based on chiral polymers have attracted increasing interest over the past few years. Such materials ele- gantly combine the advantages of chiral surfaces and traditional polymers, and provide a novel solution not only for the inves- tigation of chiral interaction mechanisms but also for the design of biomaterials with diverse applications, such as in tissue en- gineering and biocompatible materials, bioregulation, chiral separation and chiral sensors. Herein, we summarize recent ad- vances in the study of chiral effects and applications of chiral polymer-based biointerface materials, and also present some challenges and perspectives.
Calcium fluoride nanoparticles with various amounts of erbium ion dopants were prepared by CTAB/C_4 H_9OH/C_7H_(16)/H_2O reverse micro-emulsion *** nanoparticles were studied by X-ray diffraction(XRD),transmission ele...
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Calcium fluoride nanoparticles with various amounts of erbium ion dopants were prepared by CTAB/C_4 H_9OH/C_7H_(16)/H_2O reverse micro-emulsion *** nanoparticles were studied by X-ray diffraction(XRD),transmission electron microscopy(TEM),fourier transform infrared spectroscopy(FTIR),absorption and fluorescence *** XRD patterns indicate a typical cubic fluorite structure and no other *** results show the synthesized particles having uniform grain size and without *** spectra reveal that there are some amounts of-OH,NO_3^-and other organic functional groups on the particle surfaces before the annealing *** absorption peaks and bands are present in the absorption spectra,corresponding to the rich energy levels of erbium *** Red-Shift of absorption bands and Blue-Shift of fluorescence peaks can be attributed to the weakened energy level split as a result of the decrease in crystal field strength.
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