Institutional Repository of Ningbo Institute of Material Technology & Engineering, CAS
Not a member yet
14529 research outputs found
Sort by
Enhanced Magnetic Properties of FeSiAl Soft Magnetic Composites Prepared by Utilizing PSA as Resin Insulating Layer
No full textThermosetting organic resins are widely applied as insulating coatings for soft magnetic powder cores (SMPCs) because of their high electrical resistivity. However, their poor thermal stability and thermal decomposition lead to a decrease in electrical resistivity, thus limiting the annealing temperature of SMPCs. The large amount of internal stress generated by soft magnetic composites during pressing must be mitigated at high temperatures; therefore, it is especially important to find organic resins with excellent thermal stabilities. In this study, we prepared SMPCs using poly-silicon-containing arylacetylene resin, an organic resin resistant to high temperatures, as an insulating layer. With 2 wt % PSA as an insulating layer and annealed at 700 degrees C for 1 h, the FeSiAl SMPCs achieved the best magnetic properties, including the lowest core loss of 184 mW/cm(3) (measured at 0.1 T and 50 kHz) and highest permeability of 96
In-situ synthesis of graphene-like carbon encapsulated copper particles for reinforcing copper matrix composites
No full textOwing to the unfavorable wetting and density difference between graphene and copper, it remains challenging to achieve homogeneous dispersion of graphene for utilizing the unique nature of graphene in copper matrix composites. Here, we design an in-situ process to fabricate graphene-like carbon (GLC) reinforcing copper-matrix composites: GLC can be directly fabricated on commercial copper particles using modified PECVD method followed by vacuum hot pressing, which is high-efficiency and can be massively produced for graphene reinforced metal matrix composites in industrial level. After hot pressing, the GLC with ultralow content (170 to 350 ppm) can be uniformly dispersed and tightly embedded within the copper matrix. A remarkable thermal conductivity enhancement efficiency of 85% and enhanced thermal conductivity (439W m(-1) K-1), accompanied by the higher wear resistance, can be obtained in our GLC reinforced coppermatrix composites. In actual arc ablation performance measurement, the breakdown strength and relative arc ablation resistance of GLC/Cu composites can be significantly improved by 106.5% and 33.3% than pure copper, respectively, demonstrating GLC/Cu composites a promising candidate for application as high voltage electrical contacts. (c) 2021 The Author(s). Published by Elsevier Ltd
An enhanced flexible room temperature ammonia gas sensor based on GP-PANI/PVDF multi-hierarchical nanocomposite film
No full textResistive-type polyaniline (PANI) based sensing film was fabricated by a simple in-situ polymerization method with graphene (GP) as additives on flexible porous polyvinylidene fluoride (PVDF) substrate. The fabricated flexible GP-PANI/PVDF membrane demonstrates a multi-hierarchical porous microstructure, enhancing its sensing performance towards ammonia (NH3). The optimized GP-PANI/PVDF sensor shows 60% response towards 1 ppm NH3 with a response time of 46 s, and 10% response towards 0.1 ppm NH3 at 24 degrees C, respectively. Moreover, the GP-PANI/PVDF sensor presents excellent flexibility, exhibiting only small response values' difference upon several bending angles and after 1500 bending/extending cycles. Besides, the GP-PANI/PVDF sensor exhibits a strong linear relationship between the NH3 response values and working temperatures with a range of 24 degrees C similar to 50 degrees C. The results demonstrate that the flexible GP-PANI/PVDF film sensor holds great promise for the application of portable, lightweight, and room temperature sub-ppm level NH3 detection devices
Enhanced tribological properties of aligned graphene-epoxy composites
No full textThe random distribution of graphene in epoxy matrix hinders the further applications of graphene-epoxy composites in the field of tribology. Hence, in order to fully utilize the anisotropic properties of graphene, highly aligned graphene-epoxy composites (AGEC) with horizontally oriented structure have been fabricated via an improved vacuum filtration freeze-drying method. The frictional tests results indicated that the wear rate of AGEC slowly increased from 5.19x10(-6) mm(3)/(N center dot m) to 2.87x10(-5) mm(3)/(N center dot m) with the increasing of the normal load from 2 to 10 N, whereas the friction coefficient (COF) remained a constant of 0.109. Compared to the neat epoxy and random graphene-epoxy composites (RGEC), the COF of AGEC was reduced by 87.5% and 71.2%, and the reduction of wear rate was 86.6% and 85.4% at most, respectively. Scanning electron microscope (SEM) observations illustrated that a compact graphene self-lubricant film was formed on the worn surface of AGEC, which enables AGEC to possess excellent tribological performance. Finally, in light of the excellent tribological properties of AGEC, this study highlights a pathway to expand the tribological applications of graphene-epoxy composites
Nanofiltration-like forward osmosis membranes on in-situ mussel-modified polyvinylidene fluoride porous substrate for efficient salt/dye separation
No full textHere, polyvinylidene fluoride (PVDF) membranes were fabricated via non-solvent induced phase separation (NIPS) using dopamine (DA) and polyethyleneimine (PEI) as the hydrophilic additives, which has a loose surface and somewhat improved hydrophilicity. Then nanofiltration (NF)-like thin-film composite forward osmosis (TFC FO) membrane with a loose polyamide (PA) active layer on the blend membrane was synthesized via the interfacial polymerization. The as-prepared NF-like TFC FO membrane exhibited a high water flux (J(w)) of 29.98 L m(-2) h(-1) and a much low specific salt flux (J(s)/J(w)) of 0.018 g/L, when 0.6 M NaCl was used as draw solution (DS). It had a superior rejection of malachite green (99.6% +/- 0.1%) and a low rejection of NaCl (27.4% +/- 4.2%), when filtrated malachite green/NaCl mixture solution in active layer-facing draw solution (AL-FS) mode. The results provide new insights on the design and preparation of FO membranes of selective separation for dyes from salty water
Long-term-stable WO3-PB complementary electrochromic devices
No full textThe complementary electrochromic devices based on WO3 and Prussian blue electrodes (PB) have shown a limited chemical stability and durability because WO3 is degraded in electrochromic performance and PB is gradually dissolved in the Li+-based electrolyte under neutral pH conditions. Herein, the utilization of acetic acid as super-additive solution was proposed to improve WO3 cathodes and stabilize PB anodes, in which the highly nanoporous nanocrystal-in-glass WO3 and hierarchical PB was made by electron beam evaporation and electrochemical deposition method, respectively. Our findings suggest that synergistic effects of Li+ and H+ on WO3 and Prussian blue electrodes contribute to the improvement on electrochemical, electrochromic, and cycling stability performance of the whole device. Impressively, the WO3-PB complementary electrochromic device could experience a superior long-term cycling stability of over 10,000 cycles, with a high coloration efficiency of 137.80 cm(2) C-1 and a maximum transmittance modulation of 66.22%@ 633 nm. All these results open a new way to the construction of high-performance electrochromic devices. (C) 2020 Elsevier B.V. All rights reserved
Exploring U3Si2-based alloys through phase diagram investigations
No full textU3Si2 has been regarded as a promising candidate for the accident tolerant fuel (ATF) in light water reactors (LWRs). To improve the performance of U3Si2, metal M (M=Al, Ti, V, Zr, Nb and Mo) as additions is of great interest. Here we studied the phase diagrams of the U-Si-M systems using the CALPHAD (CALculation of PHAse Diagram) approach aided by the first-principles calculations, to explore the M solubility in U3Si2. The results show that the M solubility is closely related to the electronegativity, the atomic size and the number of mesophases. To be specific, the solubility of M increases with the decreased differences in radius and electronegativity between Si and M, as well as the reduced number of intermediate phases in the binary U-M and Si-M systems. In addition, Al has the largest solubility in U3Si2 among all the elements studied, whereas Zr and Ti have minute solubilities. These findings may facilitate the exploration and development of novel ATF materials. (C) 2021 Elsevier B.V. All rights reserved
High-Throughput Screening of Nitrogen-Coordinated Bimetal Catalysts for Multielectron Reduction of CO2 to CH4 with High Selectivity and Low Limiting Potential
No full textSignificant challenges remain for developing efficient catalysts in an electrochemical multielectron CO2 reduction reaction (CO2RR), which usually suffers from poor activity and selectivity. Motivated by the recent experimental progress in fabricating dual-metal atom catalysts (DMACs) in N-doped graphene materials (graphene-N6V4; N: nitrogen and V: vacancy), we sampled eight types of homonuclear (N6V4-M-2, M = Cr, Mn, Fe, Co, Ni, Cu, Pd, and Ag) catalysts and 28 types of heteronuclear (N6V4-M1M2) catalysts to study CO2RR activity via first-principles high-throughput screening. Using stability, activity, and selectivity as indicators along with the broken conventional scaling relationship, N6V4-AgCr was selected as a promising candidate for deep CO2 reduction to methane with a low overpotential of 0.55 V after two screening rounds. Further analysis showed that a frustrated Lewis pair, formed between metal and the para-N, owing to the difference in the electronic arrangement of the d orbitals of various transition metals, caused a difference in the spin polarization of the systems and affected the catalytic performance of each DMAC. Our work not only provides a solid strategy for screening potential catalysts but also demonstrates that their CO2 reduction activities originate from the various atomic and electronic structures of DMACs
Engineering the interface in graphene oxide/epoxy composites using bio-based epoxy-graphene oxide nanomaterial to achieve superior anticorrosion performance
No full textThe protective performance of graphene/polymer composite coatings largely depends on the interface design in resin matrix. Herein, we report the synthesis of bio-based cardanol epoxy modified graphene oxide (GODN) nanomaterial and its application in epoxy coatings for the achievement of fine interface toward high performance anticorrosion composite coatings. The chemical composition of prepared GODN nanomaterial was investigated by FTIR, Raman and XPS spectra, respectively. The presence of cardanol epoxy attached on GO surface promotes the formation of chemical bonds between GO and epoxy resin, providing strong interfacial interaction and enhanced adhesion. Electrochemical results revealed that the GODN1%/EP composite coating exhibits high impedance (4.38 x 10(8) Omega cm(2)) even after 45 days immersion. Compared with pure EP coating, the localized corrosion reaction of GODN1%/EP coating can be inhibited under defected interface. The enhanced protective performance of GODN/EP composite coating was attributed to two aspects: (1) the impermeable GO greatly suppressed the penetration of aggressive ions and (2) the attached cardanol epoxy chains effectively improved the interfacial interaction and thus inhibited the crack propagation. (c) 2020 Elsevier Inc. All rights reserved
Anisotropic transport and de Haas-van Alphen oscillations in quasi-one-dimensional TaPtTe5
No full textBecause of the unique physical properties and potential applications, the exploration of quantum materials with diverse symmetry-protected topological states has attracted considerable interest in the condensed matter community in recent years. Most of the topologically nontirvial materials identified thus far have two-dimensional or three-dimensional structural characteristics, while the quasi-one-dimensional (quasi-1D) analogs are rare. Here, we report on anisotropic magnetoresistance, Hall effect, and quantum de Haas-van Alphen (dHvA) oscillations in TaPtTe5 single crystals, which possess a layered crystal structure with quasi-1D PtTe2 chains. TaPtTe5 manifests an anisotropic magnetoresistance and a nonlinear Hall effect at low temperatures. The analysis of the dHvA oscillations reveals two major oscillation frequencies (63.5 T and 95.2 T). The corresponding light effective masses and the nonzero Berry phases suggest the nontrivial band topology in TaPtTe5, which is further corroborated by the first-principles calculations. Our results suggest that TaPtTe5, in analogy with its sister compounds TaPdTe5 and TaNiTe5, is another quasi-1D material hosting topological Dirac fermions