Lightweight, high-performance, thermally insulating, and antifrosting porous materials are in increasing demand to improve energy efficiency in many fields, such as aerospace and wearable devices. However, traditional thermally insulating materials (porous ceramics, polymer-based sponges) could not simultaneously meet these demands. Here, we propose a hierarchical assembly strategy for producing nanocomposite foams with lightweight, mechanically flexible, superinsulating, and antifrosting properties. The nanocomposite foams consist of a highly anisotropic reduced graphene oxide/polyimide (abbreviated as rGO/PI) network and hollow graphene oxide microspheres. The hierarchical nanocomposite foams are ultralight (density of 9.2 mg·cm–3) and exhibit ultralow thermal conductivity of 9 mW·m–1·K–1, which is about a third that of traditional polymer-based insulating materials. Meanwhile, the nanocomposite foams show excellent icephobic performance. Our results show that hierarchical nanocomposite foams have promising applications in aerospace, wearable devices, refrigerators, and liquid nitrogen/oxygen transportation.Keywords: antifrosting; graphene oxide; hierarchical; lightweight; thermally insulating;

•Elastic-plastic behavior in electrospun silica-based fiber•Point contact between the randomly oriented fibers before the tensile test•Side contact between the aligned fibers after the tensile testTo understand the relationship between mechanical behavior and fiber assembly in electrospun ceramic-based fibrous mats, the tensile performance of silica, silica/polydimethylsiloxane and silica/polymethyl methacrylate hybrid fibrous mats was investigated. Elastic-plastic behavior as a whole was confirmed in the silica-based fibrous mats. The initial isotropy and disordered networks with point contact between the randomly oriented fibers before the tensile test and the highly oriented fibrous bundles with side contact between the aligned fibers after the tensile test were observed using scanning electron microscopy.

Imparting elasticity and functionality to materials is one of the key objects of materials science research. Here, inspired by the art of kirigami, mechanical metamaterials comprising carbon nanotubes (CNTs) are hypothetically constructed. Using classical molecular dynamics (MD) simulations, a systematic study of the elastic limit, extensibility and yield stress of as-generated CNTs kirigami (CNT-k) is performed. Three designated kirigami patterns are employed to achieve high stretchability of CNTs. It is shown that CNT-k typically exhibits three distinct deformation stages, of which the first stage, which is referred to as geometric deformation, contributes quite a high proportion of the ductility. Various geometric parameters of CNT-k that influence the key mechanical properties of interest are respectively discussed. Three types of CNT-k with specifically identical geometric parameters exhibit distinct mechanical characteristics. This study provides an interesting example of interplay between the geometry, ductility, and mechanical characteristics of tubular materials.

Molecular dynamics (MD) is appearing in increasing applications in materials science, nanotechnologies, condensed matter physics, computational physics, biochemistry, and biophysics. Finding mechanically static equilibrium configurations of molecular systems is one of the most practical tasks in MD. Most existing potential energy optimization algorithms do not permit searching equilibrium configurations through longer MD trajectories. We introduce a simple method of utilizing a microcanonical (NVE) ensemble to obtain static equilibriums of molecular systems, that is significantly faster than the standard implementations of quick-min (QM) and fast inertial relaxation engine (FIRE) optimization algorithms. The new method is based on the capability of NVE to convert potential energy to kinetic energy. The surprising efficiency of the method is illustrated using an indentation test on monolayer graphene and, in particular, the versatility of the method is illustrated using relaxation of a polystyrene chain through longer MD trajectories and large deformation. The capability of the new method in finding more stable equilibrium configurations than common optimization algorithms is demonstrated in relaxation of a pressured lubricating oil layer and a warped monolayer graphene cantilever.

The mechanical characteristics of nano-scale interface between by carbon nanotubes (CNTs) play critical roles in macro-mechanical properties of CNT-based hierarchical composites. In this study, an in-situ peeling experiment for a sidewall-contacted junction assembled by two individual CNTs was achieved by using a force measurement system in the scanning electron microscope. The whole peeling mechanical behaviors were investigated by a typical peeling force-displacement curve combining with corresponding experiment video, and an interesting double peaks phenomenon about peeling force was observed. In order to further reveal this peeling process, a model of two-dimensional finite element analysis was developed, where an equivalence of rectangular sections to cylindrical sections of CNTs and a bilinear cohesive law were employed. The theoretical prediction of peeling behaviors was agreed with the experimental one. More importantly, by this model it is found that the double peaks of peeling force result from shape transition of CNTs from concave to arc, with an abruptly interface crack. This work could provide an in-depth understanding on mechanical behaviors of CNT-based hierarchical composites.

Assembling graphene nanosheets into three dimensional aerogels has attracted considerable interest due to their unique properties and potential applications in many fields. Here, graphene aerogels constructed from interconnected graphene nanosheet-coated carbon fibers are fabricated by using cigarette filters as templates via a simple dip-coating method. The composite aerogels are ultralight (ρ = 7.6 mg cm−3) yet have high mechanical strength (0.07 MPa); when used as electromagnetic wave absorbers, they showed a minimum reflection loss value of −30.53 dB at 14.6 GHz and the bandwidth of reflection loss less than −10 dB (90% absorption) was 4.1 GHz. Furthermore, coating polypyrrole onto the composite aerogels can increase the minimum reflection loss value to −45.12 dB. Our results provide a promising approach to fabricate graphene-based composite aerogels with a strong electromagnetic wave absorption ability.

In this paper, the structural and phase change characteristics of Al–Si/Al2O3 core/shell structure were investigated during thermal cycling from room temperature to 1000 °C by means of scanning electron microscopy (SEM), thermogravimetry (TG) and differential scanning calorimeter (DSC). The smooth and dense shells can maintain the integrity of core/shell structures during thermal cycling. The latent heat of the encapsulated Al–Si alloy reduces to 271.90 kJ/kg after 20 times thermal cycling. The experimental and calculative results between latent heat and mass increase were compared. The consumption of Al element in core/shell structures results in the latent heat reducing. The cracked ratio of the shells at different times of thermal cycling was estimated, the result of which is that the accumulative cracked ratio exceeds 20% after 20 times thermal cycling. The rupture of the shell is attributed to the thermal mis-match stress between the core and the shell. The crack at the interface can release serious thermal stress in thermal cycling.

The creation of superelastic, flexible three-dimensional (3D) graphene-based architectures is still a great challenge due to structure collapse or significant plastic deformation. Herein, we report a facile approach of transforming the mechanically fragile reduced graphene oxide (rGO) aerogel into superflexible 3D architectures by introducing water-soluble polyimide (PI). The rGO/PI nanocomposites are fabricated using strategies of freeze casting and thermal annealing. The resulting monoliths exhibit low density, excellent flexibility, superelasticity with high recovery rate, and extraordinary reversible compressibility. The synergistic effect between rGO and PI endows the elastomer with desirable electrical conductivity, remarkable compression sensitivity, and excellent durable stability. The rGO/PI nanocomposites show potential applications in multifunctional strain sensors under the deformations of compression, bending, stretching, and torsion.Keywords: graphene; mechanically flexible; polyimide; strain sensor; superelastic;

Al–Si eutectic alloy is a kind of ideal high temperature phase change materials (PCMs) because of its high latent heat and good heat transfer performance. However, it is difficult for Al–Si alloy to be safely applied because of its causticity and incompatibility. In this paper, an inorganic Al–Si/Al2O3 micro-particles core/shell structure was prepared by the sol–gel process with the modification of silane coupling agent. The direct evidence for the forming of the dense and stable α-Al2O3 shell layer, whose thickness is about 3–5 μm, is presented by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). In terms of the analyses of Fourier transform infrared (FT-IR) and thermogravimetry (TG), it is apparent that the silane coupling agent is successfully grafted on the surface of Al–Si alloy micro-particles, which promotes the condensation between boehmite sols and silanol groups. The latent heat of the encapsulated Al–Si alloy was 307.21 kJ/kg and decreased during the process of microencapsulation. The reasons for the reduction of the latent heat are the excess alumina sols and the depletion of Al–Si alloy.

•The computed lattice parameters increase with increasing the A atomic radii.•The cohesive energies and Debye temperatures decrease accordingly.•The band structure shows Zr2AN is conductive.The structural, electronic and elastic properties of ternary Zr2AN (A = Ga, In and Tl) ceramics have been studied by first-principles calculations. The obtained lattice parameters are in agreement with available data. The computed lattice parameters increase with increasing the atomic radii for A elements, whereas the cohesive energies and Debye temperatures decrease accordingly. The band structure shows that these three ceramics are all conductive. The density of states at the Fermi level (Ef) mainly originates from Zr d state with a minor contribution of A p states. Below Ef, the hybridization peak of Zr d–N p lies in lower energy range which indicates that Zr–N bond is stronger than Zr–A bond. The charge density distribution shows that Zr and N atoms form a strong Zr–N–Zr covalently bonded chain.

In this paper, Ti–Cr–Al–C materials were investigated by self-propagating high-temperature synthesis (SHS) according to the experimental study and numerical simulation results. The highest adiabatic combustion temperature Tad of 2,467.45 K indicates that the 2Ti–0Cr–Al–C is the highest exothermic reaction system in the Ti–Cr–Al–C system. The adiabatic combustion temperature decreases with the increase of the Cr content. And a higher exothermal reaction would result in higher porosity which is induced by the high temperature and pressure of C reducing atmosphere and Al vapor. Combustion characterization of the products shows that the geometrical alternating layers result in the high exothermal reaction and flame-front propagating velocity. The higher the Tad is, the thinner the layer is. To demonstrate the process of the microscopic characterization and show the detailed combustion process closed to the experimental observations, the flame-front propagating velocity and temperature distribution were simulated numerically.

In this paper, phase composition of the Mn+1AXn phases by self-propagating high-temperature synthesis (SHS) was determined using Ti, Cr, Al, and carbon black as raw materials. And, phase composition and microstructures of the Mn+1AXn phases-contained bulk by SHS with the pseudo-hot isostatic pressing (SHS/PHIP) were investigated in Ti–Cr–Al–C systems raw materials. Rietveld XRD refinement was introduced to study the lattice parameters and phase composition of the resultant phases from the SHSed and SHS/PHIPed samples. Ti2AlCx, Ti3AlC2x, and Cr2AlCx by SHS were detected in the Ti–Cr–Al–C systems, as well as the binary carbide of TiC and intermetallics. The mechanical properties of the synthesized bulk samples were determined, exhibiting a high strength and toughness compared with the typical monolithic Mn+1AXn phase ceramics. It is indicated that the samples prepared by SHS/PHIP are identified to be a strategy for improving the mechanical properties of monolithic Mn+1AXn phase.

•Of most importance, the SHS/PHIP process has a significant effect on the microstructures of Ti2AlC.•There are high-density lattice defects in Ti2AlC bulk synthesized by SHS/PHIP.•The high-density vacancies and stacking faults are both contributed to its nonstoichiometry, with many nano pores.•The large-scale Ti2AlC bulk with Φ150 × 25 mm2 was fabricated successfully, and the relative density was raised.Ti2AlC bulk pellets, Φ150 × 25 mm2 in size, were fabricated by self-propagating high temperature combustion synthesis with pseudo hot isostatic pressing (SHS/PHIP). The growth morphology and microstructures were investigated in detail by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The used SHS/PHIP process results in some unusual microstructures. The relative density increases to over 98% when increasing the size of the used pellet. The as-fabricated Ti2AlC has many lattice defects, contributing to its low phonon thermal conductivity. Interestingly, many nanopores were present in Ti2AlC grains. Of much importance, a high density of vacancies contributes to the nonstoichiometry of Ti2AlC synthesized by the SHS/PHIP process. Ti2AlC synthesized by the SHS/PHIP process is deformed with high residual stress, due to fast cooling and grain growth.

The electrical, thermal, and mechanical properties as well as the effect of the temperature of large-scale Ti2AlC bulk synthesized by self-propagating high temperature combustion synthesis with pseudo hot isostatic pressing were investigated in detail. With increasing temperature, the lattice defects contribute to the decreasing phonon thermal conductivity, and the electrical resistivity increases linearly from room temperature (RT) to 900 °C. The RT flexural strength, compressive strength, fracture toughness, work of fracture, and Vickers hardness were measured to be 606 ± 20 MPa, 1057 ± 84 MPa, 6.9 ± 0.2 MPa m1/2, 158 ± 12 J/m2, and 4.7 ± 0.2 GPa, respectively. With increasing temperature, the flexural and compressive strengths both keep almost unchanged in the zone of brittle failure, but decrease sharply as the plastic deformation occurs. The brittle-plastic transition temperature under flexure (900–950 °C) is higher than compression (700–800 °C). Interestingly, a non-catastrophic failure is observed in the SENB test, with the high work of fracture (158 ± 12 J/m2).

Silica aerogels were successfully synthesized by tetraethoxysilane (TEOS) and trimethylchlorosilane (TMCS) co-precursor method. Silica gels were prepared in two steps. For the introduction of the hydrophobic group Si(CH3)3 and its presence at the growth front, the degrees of the condensation and the crosslinking of the samples should be affected. Depending on the NH4OH-catalyzed reactions at different temperatures in the second step, ‘seeded’ growth and direct growth with different mechanisms were observed and investigated. For the sample obtained from ‘seeded’ growth, first gelation results in the dense gel with good hydrophobic behavior, relative low specific surface area. After the second gelation, the final aerogel was found to have the increased specific surface area and the decrease in the hydrophobicity. The experimental results show little difference between the final aerogel product from seeded growth and the sample from direct growth, but different growth mechanisms were revealed.Highlights► TEOS and TMCS as co-precursors for the preparation of silica aerogel ► Hydrophobic group Si(CH3)3 was attached on the backbone directly. ► Seeded growth and direct growth with different mechanisms were confirmed.

Using tetraethoxysilane (TEOS) and trimethylchlorosilane (TMCS) as co-precursors, we explore the one-step synthesis of hydrophobic silica aerogel via in situ surface modification at ambient pressure. Compared with hydrophilic feature of the products prepared by TEOS single precursor (without TMCS surface modification procedure), hydrophobic behavior of the aerogel obtained from TEOS and TMCS co-precursors was observed. Fourier Transform Infrared spectra (FTIR), Thermogravimetric analysis (TGA) and 29Si NMR spectra were conducted to confirm the successful introduction of the hydrophobic group on the silica surface. In contrast to the multiple chemical modification approach, the procedure for one-step synthesis was simplified and the processing time was shortened from 2 weeks to 2 days.Highlights► Using tetraethoxysilane (TEOS) and trimethylchlorosilane (TMCS) as co-precursors. ► One-step synthesis of hydrophobic silica aerogel by in situ surface modification at ambient pressure. ► The simplified procedure for synthesis and relative short processing time.

The cyclic-oxidation behavior of Ti3AlC2 was investigated at 1000–1300 °C in air for up 40 cycles. It was revealed that Ti3AlC2 had excellent resistance to thermal cycling. The cyclic oxidation of Ti3AlC2 basically obeyed a parabolic law. In all cases, the scales were dense, resistant to spalling and highly stratified. The inner continuous α-Al2O3 layer was well adhesive, while the outermost layer changed from rutile TiO2 at temperatures below 1100 °C to Al2TiO5 at 1200 and 1300 °C, respectively. At 1300 °C, a mechanical-keying structure of inner Al2O3 to the Ti3AlC2 substrate formed, which improved the resistance to scale-spallation.Research highlights► In this manuscript, the cyclic-oxidation behavior of Ti3AlC2 was systematically studied at 1000–1300 °C in air for up 40 cycles for the first time. ► The results revealed that Ti3AlC2 had excellent resistance to thermal cycling. The cyclic oxidation of Ti3AlC2 mostly obeyed a parabolic law from 1000 to 1300 °C. In all cases, the scales were dense, crack-free, resistance to spalling and highly demixed. The inner continuous α-Al2O3 layer was well adhesive to Ti3AlC2. The outermost layer was changed from rutile TiO2 at temperatures below 1100 °C to Al2TiO5 at 1200 and 1300 °C, respectively. ► At 1300 °C, a mechanical-keying structure of inner Al2O3 to the Ti3AlC2 substrate, which improved the resistance to scale-spalling, was discovered for MAX phase materials for the first time.

In this work, phase pure Cr2AlC and impure Cr2AlC with Cr7C3 have been fabricated to investigate the mechanical, thermal, and electrical properties. The thermal expansion coefficient is determined as 1.25 × 10−5 K−1 in the temperature range of 25–1200 °C. The thermal conductivity of the Cr2AlC is 15.73 W/m K when it is measured at 200 °C. With increasing temperature from 25 °C to 900 °C, the electrical conductivity of Cr2AlC decreases from 1.8 × 106 Ω−1 m−1 to 5.6 × 105 Ω−1 m−1. For the impure phase of Cr7C3, it has a strengthening and embrittlement effect on the bulk Cr2AlC. And the Cr2AlC with Cr7C3 would result in a lower high-temperature thermal expansion coefficient, thermal conductivity, specific heat capacity and electrical conductivity.Highlights► Effect of the synthesized coexistent Cr7C3 on the mechanical properties of Cr2AlC is shown. ► Thermal and electric properties of high-purity and dense Cr2AlC are firstly determined. ► Effect of the Cr7C3 on the thermal and electric properties of Cr2AlC is firstly shown.

Carbon nanotubes (CNTs) doped SiO2/SiO2–PbO double layer coating is prepared on Ni alloy plate by hybrid SiO2 sol-gel method and SiO2–PbO powders with certain heat treatment. The SiO2–PbO top layer is observed to possess a kind of porous and skeleton-like structure. The emissivity enhancement mechanisms of the coating's structure and doping carbon nanotubes are investigated in this study. Spectral emissivity measurements from 1.28 to 25 μm at 570 and 820 K show that the carbon nanotubes doped SiO2/SiO2–PbO double layer coating possesses strong blackbody character and the coating's emissivity can reach as high as 0.94 at 820 K.Research highlights► CNTs doped SiO2/SiO2-PbO double layer high emissivity coating is first prepared. ► SiO2-PbO top layer possess a porous and skeleton-like structure. ► Coating's surface is modified by doping carbon nanotubes. ► The emissivity enhancement mechanism of porous structure and CNTs is investigated. ► Coating's emissivity can reach as high as 0.94 at 820 K.

This study first prepared B-doped SiO2 coating by hybrid sol–gel method. SiO2 coatings had been successfully used for thermal protection, but its toughness, oxidation resistance and cost are weak points. Hybrid sol–gel method could prepare ultra thin and low cost SiO2 coatings on nickel alloys. And doping B could improve the coatings’ toughness and oxidation resistance. Thermogravimetry, differential thermal analysis and Fourier transform infrared spectroscopy were used to investigate the additives’ effect on coatings’ formations at different temperatures. X-ray photoelectron spectroscopy and X-ray diffraction were used to investigate the coatings’ element distribution and phase. The results showed that B-doped SiO2 thermal protective coatings could withstand 1050 °C, and Si–O–B bond was generated to improve the coatings’ toughness. A crystal mullite phase formed on the coatings’ surface at high temperature by thermal diffusion of Al, which significantly improved B-doped SiO2 thermal protective coatings’ oxidation resistance.

Bulk TiC/Ti3AlC2 composites containing 5 vol% TiC were fabricated by pressure-assisted self-propagating high-temperature synthesis, and their cyclic oxidation behavior was investigated at 550–950 °C in air for up to 40 cycles. The results demonstrated that at temperatures of 750–950 °C TiC/Ti3AlC2 composites displayed excellent cyclic oxidation resistance. The oxidation kinetics basically followed a parabolic rate law. As revealed by XRD and SEM/EDS, the scales consisted of an outer discontinuous layer of rutile TiO2 and an inner continuous layer of α-Al2O3. The scales were dense, adhesive to the substrate and resistant to thermal cycling. However, at lower temperatures of 550 and 650 °C, the oxidation kinetics followed a linear rate law with larger oxidation rates. The cyclic oxidation resistance was deteriorated owing to the formation of microcracks and voids in the scales.

In this paper, the bulk nano-layered composite, which contains Ti3AlC2, Cr2AlC and TiC, has been synthesized by self-propagating high-temperature synthesis with the pseudo-hot isostatic pressing process (SHS/PHIP). The density, hardness, flexural strength and fracture toughness of the fully dense composite are 4.55 ± 0.02 g/cm3, 10.53 ± 0.48 GPa, 592 ± 25 MPa and 6.23 ± 0.35 MPa m1/2, respectively. The nano-layered composite exhibits a high hardness, flexural strength, and fracture toughness due to the toughening of the overlap joint lamellas of the Ti3AlC2–Cr2AlC phases and the strengthening of the homogeneously dispersed fine TiC particles.Research highlights1. The most possible phases of 1.5Ti–0.5Cr–Al–C prepared by self-propagating high-temperature synthesis (SHS) were determined as Ti3AlC2, Cr2AlC and TiC. 2. The fully dense bulk nano-layered composite was firstly prepared by low-cost SHS/PHIP. 3. The considerable efforts to strengthening of Mn+1AXn phases were developed by incorporating for forming a composite. And the nano-layered composite exhibits high mechanical properties, which could expand the Mn+1AXn widespread applications. 4. The high mechanical properties mainly ascribe to the contribution of homogeneously dispersed fine TiC particles (1 μm) and special ‘Y’ and ‘H’ overlap joint lamellas of the nano-layered (50 nm) Ti3AlC2–Cr2AlC phases.

In this paper, the first-principles pseudopotential total energy method is used to predict the structural, electronic and elastic properties of the M3AlC2 (MAX) phases, where M = 3d, 4d, and 5d early transition metals. Specifically, the effects of the valence electron concentrations (VEC) of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W were examined. The lattice constants are a linear function of the atomic diameter of the M element. In general, M d–Al p hybridizations locate just below the Fermi level and are weaker than the M d–C p bonds, which are deeper in energy. The bulk moduli of the ternary carbides are found to be proportional to the bulk moduli of the corresponding binary carbides. Because the M–Al bonds are less stiff than the M–C bonds, the latter are mainly responsible for the high bulk moduli of the M3AlC2 phases. The M–Al bonds, on the other hand, play a critical role in decreasing the bulk moduli compared to the binary carbides.

The chemical bonding and elastic properties as well as the effect of atomic radii for A element in the Ti3AC2 phases (A = Si, Ge, and Sn) were studied by ab initio total energy calculations using plane-wave pseudopotential method based on DFT. The atomic radii of A element has a weak effect on the electronic structure. However, the bond stiffness was quantitatively examined, which shows that the bond stiffness is affected by the atomic radii of A element. The calculated results including lattice constants, internal coordinate, elastic modulus, sound velocity, and Debye temperature agree with experimental values very well. With the increase of atomic radii of A element from Si, Ge to Sn, the cohesive energy and elastic moduli as well as Debye temperature decrease, but the elastic anisotropy increases. This is related to the change of bond stiffness. It can be predicted that the fracture toughness of Ti3SnC2 would be comparable with that of Ti3SiC2 and Ti3GeC2.

High emissivity coatings are widely used in many cases where heat transfers through electromagnetic radiation that arises due to the temperature of a body. Extensive theoretical and experimental efforts have been made to synthesize and investigate high emissivity coatings. The emissivity can be improved through various or combined mechanisms. The characterization of the emissivity is still a fully open problem. In this paper, we review the various mechanisms associated with the emissivity enhancement and emissivity characterization techniques. Based on these literature reviews, the prospect will be presented in the concluding remarks.

Indium tin oxide (ITO) thin film as one of promising transparent conducting oxide (TCO) films has attracted ever increasing attention owing to its special optical, photocatalytic and optoelectronic properties. In this research, ITO films were prepared by sol–gel dip-coating method and annealed at different temperatures subsequently. The lateral and surface structures of ITO films as well as the structural evolution have been assessed by grazing incidence small angle X-ray scattering (GISAXS) technique. The films show pore fractal structure when annealed at low temperature (≤ 800 °C) which transforms to a hierarchical fractal structure at high temperature (1000 °C). As the temperature rises, films are densified due to the elimination of small pores on the surface at low temperature and the shrinkage of big pores buried inside at high temperature. However, the surface roughness and porosity near the surface are improved at high annealing temperature.

Incorporation of Ag nanocrystal into indium tin oxide films (Ag–ITO) could enhance the conductivity of transparent oxide thus attracts more and more interest. Ag–ITO films were prepared by a modified sol–gel method. The surface structure was investigated by X-ray diffraction, X-ray diffuse scattering, and X-ray photoelectron spectroscope techniques. The results showed that stannous chloride worked well as the reduction agent of silver and ion donor source, resulting in high quality nanocomposite thin films. The embedment of silver nanoparticles decreased the crystallization temperature and inhibited the growth of indium oxide. Ag–ITO films have a hierarchical structure. Furthermore, the nanocomposite films were densified and homogenized through prolonging the thermal duration time. XPS results confirmed that a small amount of silver oxide appeared.

Radiation heat transfer through fibrous materials is very strong at high temperatures (up to 1000 °C). Indium tin oxide (ITO) thin films were sol–gel deposited onto the surfaces of fibers to reduce the radiation heat transfer as radiation reflective coatings. SEM, XRD and FT-IR techniques were used to characterize the microstructure and performance of films. Results show that ITO thin film is uniformly deposited on fibers with a thickness of about 200 nm and can be used to apply a radiative reflective coating. Moreover, the efficiency of radiation reflective properties of films is improved as the annealing temperature increases. Results prove that ITO film is an excellent candidate to reduce the radiation heat transfer as radiation reflective coatings on fibrous materials.

Imparting elasticity and functionality to materials is one of the key objects of materials science research. Here, inspired by the art of kirigami, mechanical metamaterials comprising carbon nanotubes (CNTs) are hypothetically constructed. Using classical molecular dynamics (MD) simulations, a systematic study of the elastic limit, extensibility and yield stress of as-generated CNTs kirigami (CNT-k) is performed. Three designated kirigami patterns are employed to achieve high stretchability of CNTs. It is shown that CNT-k typically exhibits three distinct deformation stages, of which the first stage, which is referred to as geometric deformation, contributes quite a high proportion of the ductility. Various geometric parameters of CNT-k that influence the key mechanical properties of interest are respectively discussed. Three types of CNT-k with specifically identical geometric parameters exhibit distinct mechanical characteristics. This study provides an interesting example of interplay between the geometry, ductility, and mechanical characteristics of tubular materials.

Assembling graphene nanosheets into three dimensional aerogels has attracted considerable interest due to their unique properties and potential applications in many fields. Here, graphene aerogels constructed from interconnected graphene nanosheet-coated carbon fibers are fabricated by using cigarette filters as templates via a simple dip-coating method. The composite aerogels are ultralight (ρ = 7.6 mg cm−3) yet have high mechanical strength (0.07 MPa); when used as electromagnetic wave absorbers, they showed a minimum reflection loss value of −30.53 dB at 14.6 GHz and the bandwidth of reflection loss less than −10 dB (90% absorption) was 4.1 GHz. Furthermore, coating polypyrrole onto the composite aerogels can increase the minimum reflection loss value to −45.12 dB. Our results provide a promising approach to fabricate graphene-based composite aerogels with a strong electromagnetic wave absorption ability.