Multilayer Nanocomposites Research Articles

Microstructure, Mechanical and Tribological Properties of Advanced Layered WN/MeN (Me = Zr, Cr, Mo, Nb) Nanocomposite Coatings.

Due to the increased demands for drilling and cutting tools working at extreme machining conditions, protective coatings are extensively utilized to prolong the tool life and eliminate the need for lubricants. The present work reports on the effect of a second MeN (Me = Zr, Cr, Mo, Nb) layer in WN-based nanocomposite multilayers on microstructure, phase composition, and mechanical and tribological properties. The WN/MoN multilayers have not been studied yet, and cathodic-arc physical vapor deposition (CA-PVD) has been used to fabricate studied coating systems for the first time. Moreover, first-principles calculations were performed to gain more insight into the properties of deposited multilayers. Two types of coating microstructure with different kinds of lattices were observed: (i) face-centered cubic (fcc) on fcc-W2N (WN/CrN and WN/ZrN) and (ii) a combination of hexagonal and fcc on fcc-W2N (WN/MoN and WN/NbN). Among the four studied systems, the WN/NbN had superior properties: the lowest specific wear rate (1.7 × 10−6 mm3/Nm) and high hardness (36 GPa) and plasticity index H/E (0.93). Low surface roughness, high elastic strain to failure, Nb2O5 and WO3 tribofilms forming during sliding, ductile behavior of NbN, and nanocomposite structure contributed to high tribological performance. The results indicated the suitability of WN/NbN as a protective coating operating in challenging conditions.

Synthesis of hierarchical multilayer N-doped Mo2C@MoO3 nanostructure for high-performance supercapacitor application

Hybrid multilayered nanocomposites have been extensively produced and used as electrode in electrochemical energy storage devices. The electrochemical performances of electrodes are dependent on the electrodes composition, which in turn,mainly depends on the various methods of fabrication.. Herewith, multilayer N-doped Mo2C@MoO3 (N-MoC) nanocomposites were synthesized using an in situ method by pyrolysis of a mixture containing ammonium molybdate tetrahydrate and amino triazole under a N2 atmosphere. The electrodes were systematically produced via insertion of N-MoC at different weight percentages (N-MoC X, X:1, 5, 10 and 15) prepared with carbon composite host material. Among all prepared electrodes, N-MoC10 shows a high specific capacitance of 322 F g−1 at 0.5 A g−1 in 3 M Glycerol/KOH with a wide operation window from 0 to 2 V. In addition, the assembled symmetrical device conveys an energy density of 37.5 Wh kg−1 at a power density of 2.495 W kg−1. The present findings suggest that the application of N-MoC nanocomposites improves both physical and electrochemical performance of materials used for electrodes preparationand the corresponding assembled devices.

다층 적층 나노복합체의 마찰학적 특성 비교 연구

Wear resistance studies for the multilayer laminate nanocomposite experimentally need a lot of time and money to investigate the effects of different parameters over it. Furthermore, the impact of these parameters on the surface occurs within a microsecond making the investigation very difficult. Statistical methods such as response surface methodology can be an effective technique in this matter. In the current work, the response surface methodology and the artificial neural network were used to design and analyze the weight loss at different temperatures, sliding speeds, applied loads, and weight percentages of graphene nanoplatelet (GNP) for multilayers laminate composite consists of polyurethane resin and anhydride hardener reinforced with 30 volume fraction of random fiber-glass. It was found that increasing GNP content could effectively increase friction coefficient and reduce the wear rate of multilayer laminate nanocomposite. The predicted values from artificial neural networks and experimental methods are found very close to each other.

The Simulation Design of Microwave Absorption Performance for the Multi-Layered Carbon-Based Nanocomposites Using Intelligent Optimization Algorithm.

The optimal design objectives of the microwave absorbing (MA) materials are high absorption, wide bandwidth, light weight and thin thickness. However, it is difficult for single-layer MA materials to meet all of these requirements. Constructing multi-layer structure absorbing coating is an important means to improve performance of MA materials. The carbon-based nanocomposites are excellent MA materials. In this paper, genetic algorithm (GA) and artificial bee colony algorithm (ABC) are used to optimize the design of multi-layer materials. We selected ten kinds of materials to construct the multi-layer absorbing material and optimize the performance. Two algorithms were applied to optimize the two-layer MA material with a total thickness of 3 mm, and it was found that the optimal bandwidth was 8.12 GHz and reflectivity was −53.4 dB. When three layers of MA material with the same thickness are optimized, the ultra-wide bandwidth was 10.6 GHz and ultra-high reflectivity was −84.86 dB. The bandwidth and reflectivity of the optimized material are better than the single-layer material without optimization. Comparing the GA and the ABC algorithm, the ABC algorithm can obtain the optimal solution in the shortest time and highest efficiency. At present, no such results have been reported.

Enhancement of Magnetoelectric Effect in Compositionally Graded Ferroelectric/Ferromagnetic Pb(1−x)SrxTiO3/CoFe2O4 Nanocomposites

In this study, phase-field model is developed for ferroelectric/ferromagnetic nanocomposites, in which ferroelectric composition is spatially varied along the thickness of ferroelectric layers. The developed phase field model is applied to investigate the effect of composition gradient on magnetoelectric response of the multilayer nanocomposite. Stripe domain structures are observed in both ferroelectric and ferromagnetic layers, however the sizes of magnetic domains are larger than that of polarization ones. Particularly, the size of polarization domains and geometry of domain walls are altered according to the gradient of ferroelectric composition. The obtained results suggest that the larger the composition gradient is, the higher the magnetoelectric effect becomes. The enhancement of magnetoelectric effect is attributed to the concentration of energy in ferroelectric layer, which originates from the spatial variation of ferroelectric composition.

Magnetic amino-functionalized metal-organic frameworks as a novel solid support in ionic liquids-based effervescent tablets for efficient extraction of polycyclic aromatic hydrocarbons in milks

Herein, a kind of novel multi-layer core-shell nanocomposites (NSPN) was prepared by employing SiO2 and polyvinylpyrrolidone (PVP) polymers as modifiers and amino-functionalized metal-organic frameworks (NH2-MIL101(Fe)) as coating. It was referred to as the NSPN and ILs-based effervescence-assisted dispersive solid-phase microextraction, hereafter abbreviated as NIE-DSM. In terms of extraction efficiency, SiO2 and PVP as modifiers and NH2-MIL(Fe) as coating onto the surface of NiFe2O4 cores played a synergistically enhancing effect on adsorption/extraction. Effervescent tablets were prepared by integrating the NSPN magnetic nanoparticles as adsorbents with imidazolium-based ionic liquids (ILs) as extractants as well as acidic and alkaline sources. Under vigorous dispersion of CO2 bubbles, the NIE-DSM method realized the goal of rapidly diffusing and separating the adsorbent/extractant (~3 min) without needing conventional vortexing or centrifugation step. Consequently, the NIE-DSM approach combined dispersion and adsorption/extractant in a synchronous way. Under optimized conditions, the NIE-DSM/HPLC-FLD method gave low limits of detection (0.008–0.034 μg kg−1) and satisfactory extraction recoveries (74.1–101.6%) for five polycyclic aromatic hydrocarbons (PAHs; fluorene, anthracene, pyrene, chrysene and benzo(a)pyrene) in milk samples. The intra-day and inter-day precision, expressed as relative standard deviations, was < 5.9% and 6.5%, respectively, demonstrating a high precision. Owing to no requirement for electrical power, this method shows great potential for outdoor monitoring of trace-level PAHs in food matrices.

Gaussian thermal shock-induced thermoelastic wave propagation in an FG multilayer hybrid nanocomposite cylinder reinforced by GPLs and CNTs

In this paper, a new modified micromechanical model is proposed to obtain the mechanical and thermal properties of a reinforced functionally graded (FG) multilayer hybrid nanocomposite cylinder for thermoelastic wave propagation analysis with energy dissipation using Green–Naghdi theory. The FG multilayer hybrid nanocomposite cylinder is assumed to be under Gaussian thermal shock loading and also it is reinforced by graphene platelets (GPLs) and carbon nanotubes (CNTs). The cylinder is assumed to be made of multi-layers (sub-cylinders), and each layer is reinforced by a uniform distribution of GPLs and CNTs. A modified micromechanical model is proposed to calculate the thermo-mechanical properties with nonlinear grading patterns of the GPLs and CNTs along the radial direction of the cylinder. The nonlinear grading patterns of the GPLs and CNTs distributions along the radial direction of the whole cylinder can be created using a suitable arrangement of the layers (sub-cylinders). An effective meshless collocation method based on the generalized finite difference (GFD) method and the Newmark method are employed to solve the coupled governing equations of the GN-based coupled thermoelasticity analysis. The effects of the key parameters such as the weight fraction of the GPLs and CNTs and volume fraction index on the thermoelastic wave propagations and dynamic behaviors of the field variables are studied in detail. Also, the effects of the reinforcement by GPLs and/or CNTs in a hybrid nanocomposite on the transient behaviors of cylinder in both temperature and displacement fields are compared. The accuracy and stability of the presented meshless method and also the proposed new modified micromechanical model is verified by the published reference data.

Layer-by-Layer Assembled Nano-Composite Multilayer Gas Barrier Film Manufactured with Stretchable Substrate

Most gas barrier films produce cracks that lead to a significant loss of gas barrier integrity when strain is applied. In order to fabricate stretchable gas barrier films with low water permeability and high endurance after stretching, we used polydiallydimethylammonium (PDDA) mixed with graphene oxide (GO) and poly (vinyl alcohol) (PVA) mixed with montmorillonite (MMT). These films were manufactured by layer-by-layer assembly on an Ecoflex/polydimethylsiloxane (PDMS) substrate with pre-strain applied. A total of 30 layers of PDDA (GO)/PVA (MMT) coated on the substrate exhibited a low water vapor transmission rate of 2.5 × 10−2 g/m2 day after 100 cycles of stretching (30% strain). In addition, they exhibited a high light transmittance of 86.54%. Thus, the prepared stretchable gas barrier film has potential applications as a barrier film in transparent and stretchable electronic devices.

Free vibration and dynamic transient response of functionally graded composite beams reinforced with graphene nanoplatelets (GPLs) resting on elastic foundation in thermal environment

In this article, free vibration and dynamic transient response of a multilayer polymer nanocomposite beam resting on elastic foundation reinforced by graphene platelets (GPLs) non-uniformly distributed through the thickness direction in thermal environment is investigated. Theoretical formulations are derived based on Hamilton’s principle, Timoshenko beam theory relationships. The effective Young’s modulus of the GPL/polymer composite is estimated by Halpin–Tsai micromechanics model to account for the effects of GPL geometry and dimensions. The vibration frequencies of the beam are obtained numerically by generalized differential quadrature method (GDQM). The influences of the distribution pattern, weight fraction, the number of layers, thermal environment, slenderness ratio of the beam, boundary conditions, and types of elastic foundations on the free vibration behavior and transient response are presented. The results show that adding a very small amount of GPLs into polymer matrix as reinforcements together with the elastic foundation, significantly increases the natural frequencies of the beam. Placing more GPLs near the top and bottom surfaces of the beam are the most effective ways to strengthen the beam stiffness and increase the natural frequencies. Besides, with the increasing of foundation’s stiffness, the displacement amplitude of the functionally graded composite beam reinforced by GPLs subjected to impulsive load decreases.

Strength prediction of multi-layered copper-based composites fabricated by accumulative roll bonding

This work aims to evaluate the feasibility of the fabrication of nanostructured Cu/Al/Ag multi-layered composites by accumulative roll bonding (ARB), and to analyze the tensile properties and electrical conductivity of the produced composites. A theoretical model using strengthening mechanisms and some structural parameters extracted from X-ray diffraction is also developed to predict the tensile strength of the composites. It was found that by progression of ARB, the experimental and calculated tensile strengths are enhanced, reach a maximum of about 450 and 510 MPa at the fifth cycle of ARB, respectively and then are reduced. The electrical conductivity decreased slightly by increasing the number of ARB cycles at initial ARB cycles, but the decrease was intensified at the final ARB cycles. In conclusion, the merit of ARB to fabricate this type of multi-layered nanocomposites and the accuracy of the developed model to predict tensile strength were realized.

Efficient Heat Shielding of Steel with Multilayer Nanocomposite Thin Film.

In an effort to protect metal substrates from extreme heat, polymer-clay multilayer thin films are studied as expendable thermal barrier coatings. Nanocomposite films with a thickness ranging from 2 to 35 μm were deposited on steel plates and exposed to the flame from a butane torch. The 35 μm coating, composed of 14 deposited bilayers of tris(hydroxymethyl)aminomethane (THAM)-buffered polyethylenimine (PEI) and vermiculite clay (VMT), decreased the maximum temperature observed on the back side of a 0.32 cm thick steel plate by over 100 °C when heated with a butane torch. Upon exposure to high temperature, the polymer and amine salt undergo pyrolysis and intumesce, subsequently forming a char and blowing gas. The char encases the nanoclay platelets, and a ceramic bubble is formed. The macro-scale bubble, in tandem with the nanocomposite coating properties, increases resistance to heat transfer into the underlying metal substrate. This heat shielding behavior occurs through radiative effects and low aggregate through-plane conductivity resulting from multilayer nanodomains and intumesced porosity (i.e., conduction through the gas as the film expands to form a ceramic bubble). These relatively thin and lightweight films could be used to protect important metal parts (in automobiles, aircraft, etc.) from fire-related damage or other types of transient high-temperature situations.

Janus Graphene Oxide Sheets with Fe3O4 Nanoparticles and Polydopamine as Anodes for Lithium-Ion Batteries.

In this study, a one-step process to fabricate "Janus"-structured nanocomposites with iron oxide (Fe3O4) nanoparticles (Fe3O4 NPs) and polydopamine (PDA) on each side of a graphene oxide (GO) nanosheet using the Langmuir-Schaefer technique has been proposed. The Fe3O4 NPs-GO hybrid is used as a high-capacity active material, while PDA is added as a binder due to its unique wet-resistant adhesive property. The transmission electron microscopy image shows a superlattice-like out-of-plane section of the multilayered nanocomposite, which maximizes the density of the composite materials. Grazing-incidence small-angle X-ray scattering results combined with scanning electron microscopy images confirm that the multilayered Janus composite exhibits an in-plane hexagonal array structure of closely packed Fe3O4 NPs. This Janus multilayered structure is expected to maximize the amount of active material in a specific volume and reduce volume changes caused by the conversion reaction of Fe3O4 NPs. According to the electrochemical results, the Janus multilayer electrode delivers an excellent capacity of ∼903 mAh g-1 at a current density of 200 mA g-1 and a reversible capacity of ∼639 mAh g-1 at 1 A g-1 up to the 1800th cycle, indicating that this Janus composite can be a promising anode for Li-ion batteries.

Transferring elastic strain in Mo/Nb/TiNi multilayer nanocomposites by the principle of lattice strain matching

This paper reports a study of multilayer nanolamellar Mo/Nb/TiNi composites designed by the principle of martensitic transformation enabled lattice strain matching. The composite was fabricated by hot packaged accumulative roll bonding (PARB) and wire drawing. The composite showed an apparent yield strength of ~1200 MPa and a recoverable superelastic strain of ~7%, with a mechanical damping of ~62 MJ/m3. Both the Nb and Mo nanolamellae sandwiched between the TiNi layers exhibit large elastic lattice strains of ~2.5% and ~3.0% respectively, benefited from the lattice strain matching and load transfer enabled by the martensitic transformation of the TiNi matrix. The Nb and Mo nanolamellae in the composite exhibited high component stresses of 2.4 GPa and 9.5 GPa, and each carries ~31% of the applied load even though with only 4% and 18% volume fractions, respectively.

Influence of Bias Potential Magnitude on Structural Engineering of ZrN-Based Vacuum-Arc Coatings

The creation of the scientific foundations for the structural engineering of ultrathin nanolayers in multilayer nanocomposites is the basis of modern technologies for the formation of materials with unique functional properties. It is shown that an increase in the negative bias potential (from -70 to -220 V) during the formation of vacuum-arc nanocomposites based on ZrN makes it possible not only to control the preferred orientation of crystallites and substructural characteristics but also changes the conditions for conjugation of crystal lattices in ultrafine (about 8 nm) nanolayers.

Large-Area Nanogap-Controlled 3D Nanoarchitectures Fabricated via Layer-by-Layer Nanoimprint.

The fabrication of large-area and flexible nanostructures currently presents various challenges related to the special requirements for 3D multilayer nanostructures, ultrasmall nanogaps, and size-controlled nanomeshes. To overcome these rigorous challenges, a simple method for fabricating wafer-scale, ultrasmall nanogaps on a flexible substrate using a temperature above the glass transition temperature (Tg) of the substrate and by layer-by-layer nanoimprinting is proposed here. The size of the nanogaps can be easily controlled by adjusting the pressure, heating time, and heating temperature. In addition, 3D multilayer nanostructures and nanocomposites with 2, 3, 5, 7, and 20 layers were fabricated using this method. The fabricated nanogaps with sizes ranging from approximately 1 to 40 nm were observed via high-resolution transmission electron microscopy (HRTEM). The multilayered nanostructures were evaluated using focused ion beam (FIB) technology. Compared with conventional methods, our method could not only easily control the size of the nanogaps on the flexible large-area substrate but could also achieve fast, simple, and cost-effective fabrication of 3D multilayer nanostructures and nanocomposites without any post-treatment. Moreover, a transparent electrode and nanoheater were fabricated and evaluated. Finally, surface-enhanced Raman scattering substrates with different nanogaps were evaluated using rhodamine 6G. In conclusion, it is believed that the proposed method can solve the problems related to the high requirements of nanofabrication and can be applied in the detection of small molecules and for manufacturing flexible electronics and soft actuators.

Synthesis and characterization of TiO2/ZnO-Ag@TiO2 nanocomposite and their performance as photoanode of organic Dye-Sensitized Solar Cell

DSSC is one of the most promising energy conversion devices. A new scheme of TiO2/[email protected]2 multilayer nanocomposite was introduced as the working layer of organic DSSC. TiO2, as an inert material, was used to encapsulate Ag and applied as the photoanode. ZnO and [email protected]2 nanoparticles were synthesized using co-precipitation and one-pot synthesized method, respectively. The best photovoltaic parameter was performed by the highest fraction of [email protected]2 with the energy gap of 3.14 eV. It was appropriate that the energy gap of the films decreased as [email protected]2 continued to increase, thus it was influenced their photovoltaic performance.

Multilayer polymeric nanocomposites for electromagnetic interference shielding: fabrication, mechanisms, and prospects

Fabrication of multilayer EMI shield opens a creative avenue for designing and constructing flexible nanocomposite films simultaneously featuring excellent EMI shielding performance, fascinating heat removal ability, and robust mechanical properties.

Robust and efficient UV-reflecting one-dimensional photonic crystals enabled by organic/inorganic nanocomposite thin films for photoprotection of transparent polymers

A novel robust and transparent UV-reflecting 1DPhC composed of organic–inorganic nanocomposite multilayers was developed for efficient photoprotection of polymers.

Modeling the processes of atom structure formation of a superconducting spin valve

The paper considers the modeling of a multilayer nanocomposite, the combination of elements of which gives rise to a spin valve effect. The relevance and importance of effects in the field of spintronics and related materials and devices are described. We study the composition and atomic structure of individual layers of a multilayer nanocomposite, as well as the composition and morphology of the interface of nanocomposite layers. We analyzed a sample with a periodic superconductor-ferromagnet structure consisting of more than 20 alternating layers of niobium and cobalt. The deposition process took place in a deep vacuum. The simulation was carried out by the molecular dynamics method using the potential of the modified immersed atom method. The formation of layers was carried out in a stationary mode. The temperature was adjusted using the Nose-Hoover thermostat. The deposition of each nanofilm ended with a relaxation stage for the necessary stabilization and restructuring of the formed nanocomposite. Three deposition temperature regimes were considered: 300 K, 500 K, and 800 K. For these modes, we analysed the atomic structure of nanofilms and transition regions (interface) formed between the layers. A study of the atomic structure of nanofilms showed that niobium is formed by crystalline regions of different orientations. A cobalt nanofilm is characterized by a structure close to amorphous. The structural features of the interface between the superconductor-ferromagnet layers largely depend on a relief of the surface onto which the deposition is made. The smallest variation in atomic composition is observed in the first niobium-cobalt contact zone, since the formation of the first nanofilm occurs on an even plane of the substrate. An analysis of the influence of the temperature regime during the formation of the nanosystem shows the dependence of the processes of formation of multilayer nanofilm formation, the interface of nanolayers, as well as the composition and morphology of heterostructures on the temperature at which a nanocomposite is manufactured. An increased temperature leads to the formation of a more rarefied structure of nanolayers and an increase in the zones of the interface of nanolayers due to the diffusion of atoms of the sprayed materials.

Constructing highly directional multilayer cell structure(HDMCS) towards broadband electromagnetic absorbing performance for CNTs/PMMA nanocomposites foam

The highly directional and multilayer cell structure (HDMCS) was achieved in carbon nanotubes (CNTs)/PMMA nanocomposites via the one-step physical constraint foaming technology. The influence of HDMCS on dielectric properties and electromagnetic absorption performance of CNTs/PMMA foam were investigated, respectively. The results show that when the dielectric constant of CNTs/PMMA foam with HDMCS was reduced, the dielectric loss could be kept stable. The main reason is the HDMCS, which makes the effects of interfacial polarization are mutual restricted and compensated in the direction of parallel and vertical interface. It proposes that the dielectric constant and dielectric loss of multilayer nanocomposites foam could achieve independently regulation. The absorbing bandwidth of the CNTs/PMMA foam with HDMCS was 2.5 GHz (9.1–11.6 GHz), which was wider than 1.7 GHz of the monolayer foam with the thickness of 2 mm. The excellent EMA performance of CNTs/PMMA foam with HDMCS is attributed to the improved impedance match and the multiple reflection mechanisms. This effort demonstrates a feasible and effective approach for the design and fabrication of light weight and good microwave absorption materials.