Passive heat management technology holds significant promise in mitigating the fossil energy crisis. However, most current passive radiative cooling textiles merely reflect sunlight, causing ...unnecessary cooling in cold regions during winter and lacking dynamic control. Herein, we were inspired by chameleons to develop a temperature-sensitive passive heat management nanocomposite using a multi-layered assembly strategy. This nanocomposite consisted of the core layer of metal-coated fabric and the surface layer composed of polydimethylsiloxane (PDMS), hexagonal boron nitride (h-BN), and organic temperature-variable material (OTM). When the nanocomposite contained 15 wt% OTM, the average reflectance in the cold (15 °C) and hot (30 °C) modes was 47.66% and 80.92%, respectively. Additionally, the average emissivity was found to be 91.64% and 91.31% in the cold and hot modes, respectively. Significantly, the nanocomposite demonstrated cyclic stability in multiple temperature response tests. In practical experiments, it effectively reduced the temperature within a car and a small wooden house model by 14.0 and 7.1 °C, respectively. Moreover, the nanocomposite facilitated the accelerated ice melting at a rate of 10.85 ± 0.3 g within 1 h. Additionally, the presence of a copper metal layer in the 15 wt% OTM nanocomposite was found to contribute to antimicrobial efficiencies of 56% and 38% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. This nanocomposite possesses the potential to stimulate inventive designs in the forthcoming era of functional nanocomposites, owing to its dynamic radiative cooling, solar heating capabilities, and scalability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Defect-free functionally graded material of HSLA steel to Cu-based alloy was successfully produced.•By synchrotron X-ray diffraction the interface revealed a mixture of Cu (FCC), Fe ...(BCC), and Fe(FCC) in the interface region.•Microhardness ranged from 260 HV1 to 120 HV1.
In this work, a functionally graded material (FGM) part was fabricated by depositing a Cu-based alloy on top of a high strength low alloy (HSLA) steel by twin-wire and arc additive manufacturing (T-WAAM). Copper and steel parts are of interest in many industries since they can combine high thermal/electrical conductivity, wear resistance with excellent mechanical properties. However, mixing copper with steel is difficult due to mismatches in the coefficient of thermal expansion, in the melting temperature, and crystal structure. Moreover, the existence of a miscibility gap during solidification, when the melt is undercooled, causes serious phase separation and segregation during solidification which greatly affects the mechanical properties. Copper and steel control samples and the functionally graded material specimen were fabricated and investigated using optical microscopy, scanning electron microscopy, and high energy synchrotron X-ray diffraction. Retained δ-ferrite was found in a Cu matrix at the interface region due to regions with mixed composition. A smooth gradient of hardness and electric conductivity along the FGM sample height was obtained. An ultimate tensile strength of 690 MPa and an elongation at fracture of 16.6% were measured in the FGM part.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this systemic review, conducted in accordance with the PRISMA statement, was to investigate the impact of surface pretreatments on the bonding strength of high performance polymers (HPPs).
...Eight databases were searched through March 2019. Risk of bias was assessed and random effects meta-analyses were applied to analyze mean differences in shear bond strength (SBS) and tensile bond strength (TBS), considering surface pretreatments and bonding agents after 24h and thermocycling.
A total of 235 relevant titles and abstracts were found, yielding 11 final selections. Low risk of bias was observed in most studies. For polyetheretherketone (PEEK) specimens, random-effect models showed that, compared to non-treated controls, pretreatments associated with Visio.link® (Bredent, Senden, GE) increased TBS by 26.72MPa (95% confidence interval (CI), 19.69–33.76; p<0.00001) and increased SBS by 4.86MPa (95% CI, 2.61–7.10; p<0.00001). Air abrasion improved SBS by 4.90MPa (95% CI, 3.90–5.90; p<0.00001) (50μm alumina) and 4.51MPa (95% CI, 1.85–7.18; p=0.0009) (silica-coated CoJet). In comparison to non-treated controls, Visio.link® and Signum PEEK Bond® (Heraeus Kulzer, Hanau, GE) increased SBS by 33.76MPa (95% CI, 18.72–48.81; p<0.00001) and 33.28MPa (95% CI, 17.48–49.07; p<0.00001), respectively. No differences were found between Visio.link® and Signum PEEK Bond® or Monobond Plus/Heliobond® (Ivoclar Vivadent, Schaan, LH) (p>0.05). Similar results were observed for polyetherketoneketone (PEKK) specimens.
This review shows improved HPP bonding following the application of various surface pretreatments, including air abrasion and bonding agents.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A crystal viscoplasticity (CVP) model for the creep-fatigue interactions of nickel-base superalloy CMSX-8 is proposed. At the microstructure scale of relevance, the superalloys are a composite ...material comprised of a γ phase and a γ′ strengthening phase with unique deformation mechanisms that are highly dependent on temperature. Considering the differences in the deformation of the individual material phases is paramount to predicting the deformation behavior of superalloys at a wide range of temperatures. In this work, we account for the relevant deformation mechanisms that take place in both material phases by utilizing two additive strain rates to model the deformation on each material phase. The model is capable of representing the creep-fatigue interactions in single-crystal superalloys for realistic 3-dimensional components in an Abaqus User Material Subroutine (UMAT). Using a set of material parameters calibrated to superalloy CMSX-8, the model predicts creep-fatigue, fatigue and thermomechanical fatigue behavior of this single-crystal superalloy. Finally, a sensitivity study of the material parameters is done to explore the effect on the deformation due to changes in the material parameters relevant to the microstructure.
•The crystal viscoplasticity model explicitly models the deformation in the gamma and gamma' phases.•The model predicts creep-fatigue and thermomechanical fatigue responses.•The full 3D model is implemented as a user subroutine for ABAQUS.•Parameters are established for a reduced Re single-crystal Ni-base superalloy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Biological organisms produce high-performance composite materials, such as bone, wood and insect cuticle, which provide inspiration for the design of novel materials. Ascidians (sea squirts) produce ...an organic exoskeleton, known as a tunic, which has been studied quite extensively in several species. However, currently, there are still gaps in our knowledge about the detailed structure and composition of this cellulosic biocomposite. Here, we investigate the composition and hierarchical structure of the tough tunic from the species Halocynthia roretzi, through a cross-disciplinary approach combining traditional histology, immunohistochemistry, vibrational spectroscopy, X-ray diffraction, and atomic force and electron microscopies. The picture emerging is that the tunic of H. roretzi is a hierarchically-structured composite of cellulose and proteins with several compositionally and structurally distinct zones. At the surface is a thin sclerotized cuticular layer with elevated composition of protein containing halogenated amino acids and cross-linked via dityrosine linkages. The fibrous layer makes up the bulk of the tunic and is comprised primarily of helicoidally-ordered crystalline cellulose fibres with a lower protein content. The subcuticular zone directly beneath the surface contains much less organized cellulose fibres. Given current efforts to utilize biorenewable cellulose sources for the sustainable production of bio-inspired composites, these insights establish the tunic of H. roretzi as an exciting new archetype for extracting relevant design principles.
Tunicates are the only animals able to produce cellulose. They use this structural polysaccharide to build an exoskeleton called a tunic. Here, we investigate the composition and hierarchical structure of the tough tunic from the sea pineapple Halocynthia roretzi through a multiscale cross-disciplinary approach. The tunic of this species is a composite of cellulose and proteins with two distinct layers. At the surface is a thin sclerotized cuticular layer with a higher protein content containing halogenated amino acids and cross-linked via dityrosine linkages. The fibrous layer makes up the bulk of the tunic and is comprised of well-ordered cellulose fibres with a lower protein content. Given current efforts to utilize cellulose to produce advanced materials, the tunic of the sea pineapple provides a striking model for the design of bio-inspired cellulosic composites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Particularly in plastically anisotropic crystals, such as hexagonal close packed (HCP) materials, plastic deformation is realized by slip acting in the small volumes within individual crystals. Here ...we extend a full field fast Fourier transform (FFT)-based elasto-viscoplastic formulation to simulate the development of a single slip band on either prismatic or basal planes spanning a crystal. Calculations of the strain and stress fields induced locally within the band and parent crystal, and ahead of the band/grain boundary junction in the neighboring crystal are analyzed as the slip band intensifies under increasing applied strain. We report a substantial influence of the crystallographic orientation of the nearest neighboring grain on the rate of slip band localization. Performing the analysis on two materials, CP-Ti and Mg, indicates that the strength of the material affects the rate of localization, with stronger materials tending to localize more easily. A slip band tip stress-based criterion is proposed for identifying the nearest neighbor orientations in which slip band transmission is possible and the likely slip system for which it occurs. This indicator is validated against experimental studies on commercially pure Ti, an Mg–Y alloy, and Ti–6Al–4V. We show that for low GB misorientations, the slip band is likely to transmit into another slip band of the same type in the neighbor grain, while for high GB misorientations, it is likely to transmit into one of a different type or to not transmit at all.
•An FFT-based elasto-viscoplastic technique is presented to model discrete slip bands.•The model captures shear localization within slip bands with applied strain.•A slip band tip stress-based criterion is proposed to identify slip transmission paths.•Nearest neighbor grain orientation affects slip band development and its potential transmission.•Type of transmitted slip system is correlated with the misorientation between two grains.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sound absorption mechanism, material modification and structural design of various synthetic fiber materials for industrial noise reduction are reviewed in this paper for the problems of low sound ...absorption coefficient (SAC) and narrow frequency band of porous materials. Delany-Bazley model and Johnson-Champoux-Allard (JCA) model are widely used to predict the SAC, but they are slightly different. The air viscous effect plays an important role in Delany-Bazley model and its modified forms, while JCA model and its modified forms consider the effect of thermal conduction in addition to air viscosity. In addition, synthetic fiber materials such as polymers, metal fibers and inorganic fibers are widely used in noise reduction fields of various industries due to their unique acoustic and mechanical performance. Acoustic properties of polymers are usually improved by adding fillers, using perforated structures, gradient porous structures, and multilayer composite structures. And improving preparation method, increasing thickness of back cavity, combining different pore sizes, developing new composite materials, and adopting perforation technology can greatly promote the engineering application of metal fibers in extreme environments. Common methods to improve the sound absorption performance of inorganic fibers are to modify preparation method, increase thickness of materials and research composite materials.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Thermoelectric (TE) materials and devices are able to convert direct heat to electricity and so have several uses in heat energy harvesting (power generators), wearable electronics, and local ...cooling. Recent advances have led to the emergence of a new class of thermoelectric materials, organic and hybrid (organic/inorganic) materials of the polymer and gel types (aerogels). These nanostructured materials, in addition to being environmentally friendly and abundant, have very low thermal conductivity, low density and specific heat and electricity transport mechanisms. Their fabrication process is less expensive than the synthesis methods of alternative materials and opens the door to previously unattainable thermoelectric module architectures, with modular shapes (surfaces/thicknesses) and sometimes with flexible properties. This study comprehensively summarizes current advancements in organic, inorganic, and composite/hybrid TE aerogels, covering the key ingredients, production technique, TE performance, as well as variables impacting TE performance and the associated mechanisms. Furthermore, the construction techniques and output performance of two typical aerogel-based TE devices/generators (TEG) are compared and examined. This paper also discusses the use of aerogel-based TEG devices in a variety of disciplines described in this review. Finally, the current obstacles and some preliminary proposals for future research potential are offered.
Graphical Abstract
Organic, inorganic, and composite/hybrid TE aerogels are described, as well as the important constituents, manufacturing process, TE performance, and factors influencing TE performance and the related mechanism. In addition, the building methodologies and output performance of two typical aerogel-based TE devices/generators are compared and investigated.
Highlights
TE materials convert heat into electricity and have multiple applications in energy harvesting, wearable electronics, and local cooling.
Organic and hybrid thermoelectric materials, including aerogels, are eco-friendly, have low thermal conductivity and low density, and have unique transport mechanisms.
The less expensive fabrication process for these materials enables modular shapes and flexible properties.
This study summarizes advancements in organic, inorganic, and composite/hybrid TE aerogels, covering ingredients, production techniques, TE performance, variables, and mechanisms.
This review paper compares aerogel-based TEG devices, discusses their potential use in various disciplines, highlights obstacles, and proposes future research directions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Functionally graded porous (FGP) nanocomposites are the most promising materials among the manufacturing and materials sector due to their adjustable physical, mechanical, and operational properties ...for distinctive engineering applications for maximized efficiency. Therefore, investigating the underlying physical and materialistic phenomena of such materials is vital. This research was conducted to analyze the preparation, fabrication, applications, and elastic properties of functionally graded materials (FGMs). The research investigated for both porous and nonporous synthesis, preparation, and manufacturing methods for ceramics, metallic, and polymeric nanocomposites in the first section, which is followed by deep research of the development of elastic properties of the above-mentioned materials. Main nano-reinforcing agents used in FGMs to improve elastic properties were found to be graphene platelets, carbon nanotubes, and carbon nanofibers. In addition, research studied the impact of nano-reinforcing agent on the elastic properties of the FGMs. Shape, size, composition, and distribution of nano-reinforcing agents were analyzed and classified. Furthermore, the research concentrated on modeling of FGP nanocomposites. Extensive mathematical, numerical, and computational modeling were analyzed and classified for different engineering analysis types including buckling, thermal, vibrational, thermoelasticity, static, and dynamic bending. Finally, manufacturing and design methods regarding different materials were summarized. The most common results found in this study are that the addition of reinforcement units to any type of porous and nonporous nanocomposites significantly increases materialistic and material properties. To extend, compressive and tensile stresses, buckling, vibrational, elastic, acoustical, energy absorption, and stress distribution endurance are considerably enhanced when reinforcing is applied to porous and nonporous nanocomposite assemblies. Ultimately, the review concluded that the parameters such as shape, size, composition, and distribution of the reinforcing units are vital in terms of determining the final mechanical and materialistic properties of nanocomposites.
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