Double-layer Composites Research Articles

Spring stiffness and heterointerface effects on GaN/AlN double-layer composites polishing

Spring stiffness and heterointerface effects on GaN/AlN double-layer composites polishing

Optimizing double-layer rubber composites for eco-friendly laminates: A thermal-mechanical characterization

Optimizing double-layer rubber composites for eco-friendly laminates: A thermal-mechanical characterization

One‐Step Electrodeposition of Iron Oxyhydroxide Onto 3D Porous Graphene Substrates for on Chip Asymmetric Micro‐Supercapacitors

AbstractElectrochemical capacitors based on redox active materials can achieve greater capacitance values than traditional electric double layer composites. Herein, electrodeposition of iron oxyhydroxide from a mildly acidic acetate precursor is reported. The one‐step deposition resulted in a submicron film composed of FeOOH phase, which was confirmed via Raman and x‐ray photoelectron spectroscopy. The capacitance increased linearly with loading amount and achieved a maximum at 1600 mC deposition with 120 mF cm−2 at 25 mV s−1 after which the film became more resistive, limiting electrolyte access to the porous graphene substrate. The deposited FeOOH demonstrated promising rate capability and good cycling stability, without phase changes, retaining 82 % of the initial capacitance after 5000 consecutive charge/discharge cycles. The charge storage mechanism of FeOOH was determined via in situ Raman spectroscopy, which followed reversible iron oxygen vibration changes upon cycling which become more intense upon reduction as a result of sodium ion intercalation. Furthermore, an asymmetric configuration full cell combining FeOOH/MnO2 allowed the working voltage to be extended to 2 V, maintaining an ideal capacitor behaviour, and achieving a maximum energy and power density of 21 μWh cm−2 and 2.5 mW cm−2 respectively.

Engineering battery corrosion films by tuning electrical double layer composition

Engineering battery corrosion films by tuning electrical double layer composition

Construction of boron-based double-layer core-shell structure composites and their combustion energy release characteristics

Although boron (B) powder has a high energy density, the high boiling point oxide layer (B2O3) on the surface seriously hinders the combustion of internal B particles, which further limits the use of B powder. In order to solve this issue, polydopamine (PDA) was used as a sandwich layer (sandwich layer used to connect solid-liquid interface) between the original B powder and liquid perfluoropolyether (PFPE), and then a double-layer core-shell structure B@PDA@PFPE was prepared through the electrostatic self-assembly method. Herein, PDA not only helps remove naturally occurring B2O3, but also provides more active sites and improves the reactivity of B and PFPE. The results indicate that the B@PDA@PFPE has excellent combustion flame and energy release characteristics due to the superior dispersion and reactivity of PFPE. Compared to that of the original B powder, the results of thermal decomposition and combustion heat of B@PDA@PFPE with 30%PFPE discloses that the oxidation temperature drops by about 19.5 ℃, the combustion efficiency rises by about 22.3 %, and the flame expansion rate and flame temperature rise by approximately 40 times and 95.6 ℃, respectively. Therefore, the construction of double-layer core-shell structure effectively promotes the combustion of B powder. This work provides a new strategy for the application of B powder.

Preparation of integrated carbon fiber stitched fabric reinforced (SiBCN) ceramic/resin double-layered composites for ablation resistance, thermal insulation and compression resistance performance

This paper reports a novel integrated carbon fiber fabric reinforced ceramic/resin double-layered composite. The composites were prepared by a low energy consumption process of stratified impregnate pyrolysis. The double-layered composites consist of an amorphous SiBCN ceramic upper layer and a SiBCN resin bottom layer. In the ablation experiment, the temperature of the composite material's ablated surface exceeded 1850 °C, while the temperature of the backside remained below 70 °C within 60 s of ablation. Even after 90 s of ablation, the backside temperature was still significantly lower than the theoretical application temperature of SiBCN resin. The ablated surface has no visible pits or cracks. The maximum mass ablation rate and line ablation rate were −0.01259 mg/s and 0.000933 mm/s, respectively. High-density amorphous SiBCN ceramic layer effectively play the role of high temperature and ablation resistance. In addition, the compressive strengths of the composites before and after ablation were above 340 MPa. Integrated composites that combine anti-ablation, insulation, and compression resistance have potential in aerospace applications.

Enantiomeric analysis of chiral phenyl aromatic compounds by coated capillary electrochromatography based on aMOF-on-MOF stationary phase.

Chiral phenyl aromatic compounds (CPACs) are widely used in drug development, food/cosmetic production, and other organic synthesis processes, and their different enantiomers have distinct physiological activities and application differences. A double-layer metal-organic framework composite (MOF-on-MOF) was obtained by in situ synthesis of chiral metal-organic framework (CMOM-3S) on the surface of an iron-based metal-organic framework (NH2-MIL-101(Fe)). According to ourinvestigation, MOF-on-MOF composite was for the first time applied tothe stationary phase of capillary electrochromatography (CEC), and enantioseparations of eight CPACs were accomplished. Compared with single CMOM-3S, the enantioseparation performance of the coated capillary columns based on NH2-MIL-101(Fe)@CMOM-3S was improved by 34.07 ~ 720.0%. The R-/S-mandelic acid in actual sample (apricot leaves) was detected by the newly CEC system to be 0.0118mgmL-1 and 0.0523mgmL-1, respectively. The spike recoveries were 96.60 ~ 104.7%, indicating its good stability and accuracy. In addition, the selective adsorption capacity of MOF-on-MOF composites was verified by adsorption experiments.

Physical origin of enhanced electrical conduction in aluminum-graphene composites

The electronic and transport properties of aluminum-graphene composite materials were investigated using the ab initio plane wave density functional theory. The interfacial structure is reported for several configurations. In some cases, the face-centered aluminum (111) surface relaxes in a nearly ideal registry with graphene, resulting in a remarkably continuous interface structure. The Kubo–Greenwood formula and space-projected conductivity were employed to study electronic conduction in aluminum single- and double-layer graphene-aluminum composite models. The electronic density of states at the Fermi level is enhanced by the graphene for certain aluminum–graphene interfaces, thus improving electronic conductivity. In double-layer graphene composites, conductivity varies non-monotonically with temperature, showing an increase between 300 and 400 K at short aluminum-graphene distances, unlike the consistent decrease in single-layer composites.

Poly(arylene ether nitrile) composite foams with magnetically and electrically separated structures for frequency-selective electromagnetic interference shielding

With the rapid development of communication technology and modern intelligent electronic systems, the demand for frequency-selective electromagnetic interference (EMI) shielding materials has grown. In this work, poly(arylene ether nitrile) (PEN) composite foams with separated magnetic and conductive layers were prepared via delayed non-solvent induced phase separation, where the distribution of magnetic and conductive layers was designed to construct double-layer asymmetric structures and sandwich structures. Benefiting from destructive interference between electromagnetic waves (EMWs) in the magnetically and electrically separated porous structures, the double-layer asymmetric composites (M−C) exhibited outstanding absorption-dominated EMI shielding performance with favorable frequency selectivity, which did not occur in conventional double-layer composites. Specifically, M−C achieved a maximum shielding efficiency (SE) of 49.3 dB and a maximum average absorption ratio (Ar) of 93.9 %. Meanwhile, increasing the thickness of the magnetic layer of M−C can lower the characteristic frequency (fc) of the shielding peak and enhance average SE and average Ar. Moreover, M−C could show higher fc, average Ar, and average adsorption coefficient in the X-band when the incident EMWs first met with the magnetic layer, which was unavailable in frequency-selective PEN-based sandwich-structured composites. This effort offers a novel, flexible design to fabricate absorption-dominated EMI shielding materials with frequency selectivity.

Manufacturing and flexural testing of woven lattice sandwich-ply laminate composites

In this research, single-layered, double-layered and three-layered woven lattice sandwich-ply (WLS) composites were designed and manufactured. Bending experiments were performed on the clamped and simply-supported WLS panels. The effects of multi-layered construction and boundary constraints on flexural behaviors were investigated. Typical damage modes of core fracture, face shear fracture and bending fracture of the panels with four constrained ends, and those of core shear, compression, fracture and face fracture of the panels with two constrained ends were revealed. It is clear that the multi-layered construction can significantly improve the strength, stiffness, and energy absorption. Boundary constraint affects the deformation characteristics, but it will be suppressed as core shear stiffness increases.

"Enamel layering" using double-layered enamel-shade resin composites: The strategy to simulate the optical characteristics of human enamel.

To evaluate the optical match between enamel and resin composites fabricated using mono-layered and double-layered techniques. Enamel slabs were prepared from human upper incisors and canines. Mono-layered composite replicas were prepared from seven Filtek Z350XT and Estelite Sigma shades using silicone molds prepared from the respective enamel surfaces. Translucent and enamel shades (A2 or A3) of the two materials were produced from incisor molds for double-layered replicas, and the groups with the best results underwent accelerated aging. Spectrophotometric evaluation was performed using CIE color system. The differences in translucency (ΔTP) and color (ΔE00 ) between the enamel and paired composite replicas were calculated and analyzed using parametric statistics (α = 0.05). For the mono-layered composites, white enamel and translucent shades of Filtek yielded the lowest ΔTP for canines (4.6) and incisors (8.9), respectively. The ΔE00 of mono-layered replicas ranged from 5.1 to 11.8. Double-layered Filtek replicas displayed a better 1-day optical match with the lowest ΔTP (3.4-4.0) and ΔE00 (4.2-4.6), irrespective of each layer's thickness. For canines, the lowest ΔTP of Filtek white enamel was close to the acceptable threshold (4.43). For incisors, the thicker translucent double-layered Filtek composites demonstrated the greatest optical match before and after aging. Upper incisors and canines have distinct enamel optical properties. Enamel layering using specific double-layered resin composites could achieve a better optical match with upper incisor enamel.

Integrated Design of a Functional Composite Electrolyte and Cathode for All-Solid-State Li Metal Batteries

Solid composite electrolytes exhibit tremendous potential for practical all-solid-state lithium metal batteries (ASSLMBs), whereas the interfacial contact between cathode and electrolyte remains a long-standing problem. Herein, we demonstrate an integrated design of a double-layer functional composite electrolyte and cathode (ID-FCC), which effectively improves interfacial contact and increases cycle stability. One composite electrolyte layer, PVDFLiFSI@LLZNTO (PL1@L), comes into contact with the LLZNTO (Li6.5La3Zr1.5Nb0.4Ta0.1O12)-containing cathode, while the other layer, PEOLiTFSI@LLZNTO (PL2@L) with a Li anode, is introduced in each. Such a design establishes a continuous network for the transport of Li+ on the interface, and includes the advantages of both PEO and PVDF for improving stability with the electrodes. The Li symmetric cells Li/PL2@L-PL1@L-PL2@L/Li steadily cycled for more than 3800 h under the current density of 0.05 mA cm−2 at 60 °C. Outstandingly, the all-solid-state batteries of LiFePO4-ID-FCC/Li showed an initial specific capacity of 161.5 mA h g−1 at 60 °C, demonstrating a remaining capacity ratio of 56.1% after 1000 cycles at 0.1 C and 74.5% after 400 cycles at 0.5 C, respectively. This work provides an effective strategy for solid-state electrolyte and interface design towards ASSLMBs with high electrochemical performance.

Microwave absorption properties of double-layer structured basalt fiber/resin composites containing carbon black and nano-Fe3O4

ABSTRACT Basalt fibers (BF)-reinforced double-layered resin composite with excellent absorption performance in X band (8.2–12.4 GHz) has been designed, choosing carbon black (CB) and nano-Fe3O4 as absorbent for absorbing layer and matching layer, respectively. The electromagnetic parameters of the composites were measured by vector network analyzer using waveguide method. The calculated result suggests that an increased amount of absorbent could significantly improve the microwave absorbability of the single-layered composites in the measured frequency. For double-layered composites, the optimum microwave absorption performance can be obtained by tailoring the electromagnetic parameters and thicknesses of each layer. The minimum reflection loss of −43.97 dB and full X band effective absorption can be achieved when the thickness of the matching layer (BF/Fe3O410) and absorbing layer (BF/CB7.5) were 0.3 mm and 2.7 mm, respectively. Therefore, utilization of dielectric loss, magnetic loss absorbent and BF/resin double-layered structure has designed flexibility, and contributes to promote the development of high-performance microwave absorbing composites.

Lewis acidic molten salts etching route driven construction of double-layered MXene-Fe/carbon nanotube/silicone rubber composites for high-performance microwave absorption

Transition metal carbide/nitride (MXene) materials have triggered intensive research interest in the field of microwave absorption (MA). However, the complicated fabrication process and monotonous loss mechanism of MXene materials seriously hinder their practical applications. Here, we first developed a green and facile synthesis of dielectric-magnetic MXene-Fe nanocomposites via one-step Lewis acidic molten salts etching, which were combined with carbon nanotube (CNT) filler and silicone rubber (SR) matrix to fabricate double-layered MXene-Fe/CNT/SR composites by casting and curing. The in-situ growth magnetic Fe nanoparticles on MXene and unique double-layered structure composed of MXene-Fe/SR as the upper absorption layer and CNT/SR as the bottom reflection layer imparted the composites with excellent MA properties by offering appropriate impedance matching, strengthened internal reflection, polarization, magnetic loss, and conductive loss. Accordingly, the proposed double-layered composites showed superior MA properties compared with other MXene-based composites. The MXene-Fe-45%/CNT-5%/SR sample showed a reflection loss value of −65.9 dB at 12 GHz and an effective absorption bandwidth up to 8.24 GHz at 2.86 mm thickness. The double-layered composites exhibited tunable absorption frequency between the whole Ku-band and X-band by simply regulating the sample thicknesses and filler contents. These features indicate that the developed double-layered MXene-Fe/CNT/SR composites have great potential for high-performance MA applications. This study offers a novel and simple strategy to develop high-efficiency and broadband MA materials.

Mid-Infrared Continuous Varifocal Metalens with Adjustable Intensity Based on Phase Change Materials

Metalenses can greatly reduce the complexity of imaging systems due to their small size and light weight and also provide a platform for the realization of multifunctional imaging devices. Achieving dynamic focus length tunability is highly important for metalens research. In this paper, based on single-crystal Ge and a new low-loss phase change material Ge2Sb2Se5 (GSSe), a tunable metalens formed by a double-layer metasurface composite was realized in the mid-infrared band. The first-layer metasurface formed by Ge nanopillars combines propagation and the geometric phase (equivalent to a half-wave plate function) to produce single- or multiple-polarization-dependent foci. The second-layer metasurface formed by GSSe nanopillars provides a tunable propagation phase, and the double-layer metalens can achieve the tunability of the focus length depending on the different crystalline fractions of GSSe. The focal length varies from 62.91 to 67.13 μm under right circularly polarized light incidence and from 33.84 to 36.66 μm under left circularly polarized light incidence. Despite the difference in the crystallographic fraction, the metalens’s focusing efficiency is maintained basically around 59% and 48% when zooming under RCP and LCP wave excitation. Meanwhile, the incident wave’s ellipticity can be changed to alter the relative intensity ratios of the bifocals from 0.03 to 4.26. This continuous varifocal metalens with adjustable intensity may have potential in practical applications such as optical tomography, multiple imaging, and systems of optical communication.

Colorimetric active carboxymethyl chitosan/oxidized sodium alginate-Oxalis triangularis ssp. papilionacea anthocyanins film@gelatin/zein-linalool membrane for milk freshness monitoring and preservation

Colorimetric active double-layer composites of film@membrane were developed via direct electrospinning functional nanofibers on colorimetric film. In the structure, oxidized sodium alginate cross-linked carboxymethyl chitosan (CO) was used as colorimetric film matrix to incorporate the anthocyanins extract from Oxalis triangularis ssp. papilionacea (OTA); while the blend of gelatin/zein (GZ) was used as fibrous matrix for linalool (L) encapsulation. Besides good barrier and water resistance, the outer-layer of CO-OTA showed colorimetric sensitivity towards pH-stimuli with reversible color changes. The inner-layer of GZ-L exhibited good antibacterial activities against Staphylococcus aureus and Escherichia coli. The volatile release of L from fibrous matrix was well controlled and mainly followed Fickian diffusion. Moreover, the antioxidant activity of the composites is source from the released linalool. The high reliability on milk freshness monitoring and double shelf-life extending at 25 °C suggest the potential of CO-OTA@GZ-L in colorimetric active food packaging.

Double-layered laser induced graphene (LIG) porous composites with interlocked wave-shaped array for large linearity range and highly pressure-resolution sensor

There is an urgent need for developing flexible pressure sensors with ultra-high pressure-resolution and wide linear range to expand the application of wearable electronic devices. Here, a strategy was proposed for fabricating a LIG composite with wave-shaped array and multi-scale porous structure for wide-range and high-precision pressure detection. The synergism of the internal three-dimension porous structure and the inter-layer interlocked wave-shaped array endows the assembled double-layer LIG composite with numerous variable electrical conductive paths and easy deformation. Therefore, great improvements have been achieved in detection broad range and accuracy, exhibiting a large linearity range (0–100 kPa) and high pressure-resolution (millipascal-scale) over the full linearity range. These sensing properties make the double-layer LIG composites feasible for detecting subtle physiological signals and monitoring large human motions. Meanwhile, integrating the synthesis of graphene as active material and the design of flexible sensing structure by laser direct writing (LDW) technique provides an effective strategy for manufacturing high performance sensors with simple and low cost.

Interfacial microstructure and resistance-temperature characteristics of Ti(C, N)-based cermet/LaCrO3–Y2O3 laminated composite

A laminated Ti(C, N)-based cermet/LaCrO3–Y2O3 composite which is used for making smart temperature measuring cutting tool was prepared by spark plasma sintering. In this work, the interfacial microstructure and resistance-temperature (R-T) characteristics of double-layer and triple-layer structures with different layer thicknesses of LaCrO3–Y2O3 were investigated, the mechanism of interfacial evolution and changes in R-T characteristics of double-layer composites prepared at different sintering temperatures were studied, and the temperature measuring performance of the smart tool was tested. The results indicated as the thermosensitive ceramic layer thickness was 1.5 mm, the laminated composites showed the best performance. For the double-layer structure, its starting measuring temperature was 457K, and the thermal constant B reached 14194K. Cutting tests showed the resistance of the smart tool fluctuated sharply with cutting time, and the resistance variation reached up to 2 × 108Ω within 1 s, which indicated that the smart cutting tool had a short response time and high temperature measuring sensitivity.

Fabrication and comparison of mechanical and EMI shielding properties of various fibre reinforced multi-layered epoxy composites

The present work deals with the comparison of the various Fibre Reinforced Epoxy Composites (FRECs) for EMI shielding applications. The fabrication of the FRECs was done by simple hand-lay-up method. The composites consisting of silk fibre, glass fibre, carbon fibre with single and double layer and the hybrid of these three fibres. The collation of different FRECs revealed that the properties of the neat epoxy could be improved by the reinforcement of fibres. The double layered composites showed high tensile strength and flexural strength than the single layered composites whereas the EMI shielding property of the both single and double layered composites remain unchanged. Among FRECs, the CFRP-2 composite showed excellent mechanical properties with 24.9 N/mm2 tensile strength and 140.5 N/mm2 flexural strength. Also, the CFRP and hybrid composites exhibited nearly same EMI shielding Effectiveness (SE) value of around −27dB to −29.7 dB in the X-band frequency range. The work imparted the dominance of absorption phenomenon over the reflection in the prepared FRECs. Being insulators, Glass fibre, silk fibre and epoxy, GFRP and SFRP composites showed low EMI SE value. However, the EMI shielding property of these composites can be increased by incorporating conducting and magnetic fillers to the composites. Hence, the FRECs due to its light weight, corrosion resistance and high mechanical properties became the potential candidate for developing EMI shielding material over conventional metals.

Finite element modelling of carbon fiber reinforced with vespel and honey-comb structure

Carbon fiber is considered as a material of future. It has better mechanical properties when compared to metals like steel and aluminium. And its high strength to weight ratio makes it a promising component for modern buildings, spacecrafts etc. Carbon fiber has a low compressive to tensile strength ratio. Carbon fiber can't operate under high temperature conditions. Current work proposes a composite design which will help in shielding carbon fiber from high temperature. For this sole purpose we are using high temperature polyimide plastic, vespel SP-21 and high temperature epoxy resin eccobond 104. The manufacturing of the composite is done by vacuum bagging process. The manufactured composite is future heat treated to obtain high tensile strength. Using rules of mixture equations approximate equivalent properties of the composite is found and is used for finite element modelling of the composite. This model is used for the analysis of a single layer and double layer of the composite sheet. The stresses and elongation at the layers are analyzed. The optimum loads for single and double layer composite was found by trial and error method.