Large Fracture Strain Research Articles

Rapid-annealed FeSiBPCu nanocrystalline alloy with high Bs approaching 1.9 T and good bendability

To promote energy savings, high efficiency and miniaturization of power electronic devices, Fe–Si–B–P–Cu nanocrystalline soft magnetic materials with high saturation magnetization (Bs) parallel to that of the 6.5 wt% Si steel and low coercivity (Hc) are desired. In this work, 30 μm-thick Fe84Si3B10P2Cu1 and Fe84.5Si3B9.5P2Cu1 (at.%) amorphous/nanocrystalline precursor ribbons were melt-spun, which has high Fe contents comparable to that of the 6.5 wt% Si steel. These ribbons consist of an amorphous matrix and pre-existing α-Fe of approximately 28–30 nm in size possessed relatively low and similar-value activation energy of nucleation and growth in the range of 224–249 kJ/mol. Which could induce strong crystallization competition and effectively suppress coarsening of the pre-existing α-Fe. The Fe84Si3B10P2Cu1 nanocrystalline alloy obtained by rapid-annealing (∼100 °C/s) the amorphous/nanocrystalline precursor at 480 °C for 30 s (Fe84-480) exhibited a fine and uniform nanostructure containing α-Fe with small average grain size of approximately 23.1 nm and high volume fraction. The Fe84-480 alloy possessed a high Bs of approximately 1.88 T, a low Hc of 8.6 A/m, and good bendability revealed by relatively large bending fracture strain of ∼1.65%, making it a promising soft magnetic material for power electronic devices.

Nanoporous amorphous carbon nanopillars with lightweight, ultrahigh strength, large fracture strain, and high damping capability

Simultaneous achievement of lightweight, ultrahigh strength, large fracture strain, and high damping capability is challenging because some of these mechanical properties are mutually exclusive. Here, we utilize self-assembled polymeric carbon precursor materials in combination with scalable nano-imprinting lithography to produce nanoporous carbon nanopillars. Remarkably, nanoporosity induced via sacrificial template significantly reduces the mass density of amorphous carbon to 0.66 ~ 0.82 g cm−3 while the yield and fracture strengths of nanoporous carbon nanopillars are higher than those of most engineering materials with the similar mass density. Moreover, these nanopillars display both elastic and plastic behavior with large fracture strain. A reversible part of the sp2-to-sp3 transition produces large elastic strain and a high loss factor (up to 0.033) comparable to Ni-Ti shape memory alloys. The irreversible part of the sp2-to-sp3 transition enables plastic deformation, leading to a large fracture strain of up to 35%. These findings are substantiated using simulation studies. None of the existing structural materials exhibit a comparable combination of mass density, strength, deformability, and damping capability. Hence, the results of this study illustrate the potential of both dense and nanoporous amorphous carbon materials as superior structural nanomaterials.

Excellent dynamic shear resistance and high dynamic plasticity in TiZrVNbAl multicomponent alloy via high content orthorhombic phase

Premature adiabatic shear localization caused by strain softening is a roadblock for the application of body-centered cubic (BCC) structured high-entropy alloy (HEAs) in the impact field. A micron-scale orthorhombic-phase (O-phase) strengthened TiZrVNbAl alloy was developed to delay adiabatic shear failure and enhance dynamic ductility. The O-phase can not only reduce the slip length, but also promote the pinning and tangling of the dislocations near the phase boundaries. The introduction of the O-phase transformed the strain hardening rate from negative to positive, resulting in a significantly improved dynamic shear resistance. Meanwhile, slip transfer across the O-phase via dislocation cutting mechanisms and a reduction of slip band spacing guaranteed dynamic deformation uniformity. Benefiting from the introduction of the O-phase, the alloy exhibits an excellent stored energy density (∼446 J/cm3, surpass the reported BCC-HEAs and typical titanium alloys), a large dynamic fracture strain (∼42 %) and a considerable dynamic specific yield strength (∼241 MPa cm3 g–1). The present study presents an effective approach for developing BCC-HEAs with excellent dynamic shear resistance and plasticity.

Study on notch tensile properties of Fe-Mn-Si shape memory alloy

In order to investigate the effect of stress concentration on the mechanical properties of Fe-Mn-Si shape memory alloy, Fe17Mn5Si10Cr5Ni shape memory alloy was selected as the research object in this study. Specimens with different notch types and sizes were designed, and uniaxial tensile tests were conducted on the notched specimens at room temperature. The effects of notch parameters on stress–strain curve, the notch tensile strength, notch sensitivity, and fracture mode were studied. The results indicate that Fe-Mn-Si shape memory alloy is sensitive to notches. V-shaped notch specimens with the same notch radius exhibit stronger ductility and larger fracture strain than U-shaped notch specimens. The tensile strength of the notch increases with the decrease of the notch radius. The stress concentration caused by the notch limits the plastic deformation ability of the material, resulting in significantly lower ductility of the notched specimen compared to the smooth specimen. The presence of notches does not change the tensile fracture type of the alloy, which is ductile fracture. Compared with Q235 steel, Fe-Mn-Si shape memory alloy has better ductility. The stress–strain curve of Q235 steel shows a clear yield plateau and slight hardening behavior, while the yield plateau of Fe-Mn-Si shape memory alloy is not obvious.

Effect of cooling rate and Nb addition on the strengthening in eutectic CoCr1.3FeMnNi0.7Nbx (0 ≤ x ≤ 0.45) high entropy alloys comprising of low stacking fault energy FCC phase

The CoCr1.3FeNi0.7MnNbx (0.3 ≤ x ≤ 0.45) eutectic high entropy alloy (EHEA) comprising of ultrafine lamellae of low stacking fault energy (SFE = 11 mJ/m2) face centered cubic (FCC) and Laves phase are synthesized at cooling rates of 2.5–10 K/s (arc melted ingots, AMIs) and 4.2 × 102 K/s (suction cast bars, SCBs). The microstructural investigation suggests that secondary dendritic arm spacing (SDAS) and interlamellar spacing are refined in SCBs due to a higher cooling rate than the AMIs. Whereas, deformation twins evolve in FCC phase due to its low SFE. The EHEAs exhibit a high yield strength of 1327 MPa for x = 0.367 SCB and a large fracture strain of 20% for x = 0.3 AMI under compression. Systematic investigation on the influence of Nb addition, microstructure refinement, and evolution of deformation twins during straining on the strengthening mechanisms reveals that the phase interface strengthening, solid solution strengthening, and twin boundary strengthening play critical roles in providing the high flow stress. The post-deformation analysis and the presence of multiple positive slopes in work hardening curves confirms that the concurrent effect of the evolution of dislocations, deformation twins, and their mutual interactions are solely responsible for the severe strain hardening at multiple stages during plastic deformation. The low values of strain rate sensitivity (0.0106–0.0111) and the activation volume (28b3-41b3) suggest that the deformation kinetics is governed by the dislocation interactions with the ultrafine lamellae interface and twin boundaries.

TiO2/SiO2 spiral crimped Janus fibers engineered for stretchable ceramic membranes with high-temperature resistance.

The tensile brittleness of ceramic nanofibrous materials makes them unable to withstand the relatively large fracture strain, greatly limiting their applications in extreme environments such as high or ultra-low temperatures. Herein, highly stretchable and elastic ceramic nanofibrous membranes composed of titanium dioxide/silicon dioxide (TiO2/SiO2) bicomponent spiral crimped Janus fibers were designed and synthesized via conjugate electrospinning combined with calcination treatment. Owing to the opposite charges attached, the two fibers assembled side by side to form a Janus structure. Interestingly, radial shrinkage differences existed on the two sides of the TiO2/SiO2 composite nanofibers, constructing a helical crimp structure along the fiber axis. The special configuration effectively improves the stretchability of TiO2/SiO2 ceramic nanofibrous membranes, with up to 70.59% elongation at break, excellent resilience at 20% tensile strain and plastic deformation of only 3.48% after 100 cycles. Additionally, the relatively fluffy ceramic membranes constructed from spiral crimped Janus fibers delivered a lower thermal conductivity of 0.0317 W m-1 K-1, attributed to the increased internal still air content. This work not only reveals the attractive tensile mechanism of ceramic membranes arising from the highly curly nanofibers, but also proposes an effective strategy to make the ceramic materials withstand the complex dynamic strain in extreme temperature environments (from -196 °C to 1300 °C).

Influence of interstitial carbon content on the microstructure, mechanical and electrochemical corrosion properties of CoFeNiMn multi-principal component alloys

In this study, the effects of carbon content on the microstructural evolution as well as compression and electrochemical corrosion properties of CoFeNiMn multi-principal component alloys (MPCAs) were investigated. A series of (Co25Fe25Ni25Mn25)100−xCx (x = 4, 5, 6, 7, 8) alloys were prepared by vacuum arc melting. Increasing carbon content, the structure transits from a single face-centered-cubic (FCC) phase into a mixed structure containing FCC phase and M23C6 carbides. The yield strength and hardness of the (Co25Fe25Ni25Mn25)100−xCx alloys were enhanced by increasing carbon content, which in turn decreases the ductility. The alloys containing eutectic carbides had a good combination of high yield strength (880 MPa), high fracture strength (2773 MPa), and large fracture strain (47%). Electrochemical measurements indicated that carbon content evidently affects the corrosion resistance of (Co25Fe25Ni25Mn25)100−xCx alloys in 3.5 wt% NaCl solution. Their corrosion resistance initially increases and then decreases with increasing carbon content. The increase in M23C6 carbides can accelerate pitting corrosion and degenerate their corrosion resistance. These findings not only provide comprehensive understanding of the carbon-alloyed behavior in FCC-type MPCAs but also show their potential engineering application as high-performance structural materials.

Towards the understanding of fracture resistance of an ultrahigh-strength martensitic press-hardened steel

Identifying the fracture resistance capabilities and gaining a deeper understanding of the controlling damage mechanisms are important to the development of press-hardened steels (PHS) for automotive applications. In this study, the fracture properties of a novel PHS alloyed with Cr and Si (CrSi-PHS) were assessed by using uniaxial tensile and double-edge notched tensile (DENT) tests. Under uniaxial tension, the fracture resistance is characterized by the fracture strain and work of fracture, and the CrSi-PHS presents a desirable compromise with strength when comparing with other grades of advance high-strength steels (AHSS). The large fracture strain is attributed to the high resistance to damage nucleation even with a high density of grain boundaries. Fracture toughness is characterized by the DENT tests. The fracture toughness parameters of CrSi-PHS are lower than that of the commercial PHS 22MnB5 but comparable to the multiphase AHSSs with lower strength levels. The stress triaxiality near the fatigue pre-crack in DENT tests leads to a change of damage mechanism in CrSi-PHS. The crack propagates discontinuously by joining the micro-cracks and subsequently by the ductile fracture of micro-ligaments. The local plasticity at the crack tip region is suggested to contribute significantly to the energy dissipation. The observations demonstrate a strong dependence of the fracture mode and fracture resistance on the loading condition in the ultrahigh-strength martensitic steels.

Dynamic tensile deformation of Al0.1Ti0.1CoCrFeNi high entropy alloy with heterogeneous grain structure

The single-phase Al0.1Ti0.1CoCrFeNi high-entropy alloy (HEA) with heterogeneous grain structure was processed through cold rolling followed by annealing at 1073 K. The mechanical behaviors of this HEA under quasi-static (10−3 ∼ 10−1 s−1) and dynamic (1200 ∼ 3000 s−1) uniaxial tension were investigated. A combination of high tensile strength and large fracture strain was achieved. Specifically, the yield strength and ultimate tensile strength were increased from 381 MPa and 1000 MPa at 10−3 s−1 to 590 MPa and over 1200 MPa at a strain rate of 3000 s−1, respectively. Meanwhile, the engineering fracture strain of the HEA increased from 43 % to 62 % with increasing strain rate. Under dynamic tension, a high density of dislocations, together with numerous deformation twins and stacking faults, inside the fine grains contributed to the simultaneous improvement of the tensile strength and ductility.

Designing hierarchical eutectic high-entropy alloys via partial similar substitution in the Ni-Fe-Ti-Hf-Nb alloys

Hierarchical eutectic high entropy alloys show distinguished mobility and castability, the fine lamella structure, and the excellent compression property, but their development still faces challenges. Here, the partial similar substitution method is to design hierarchical eutectic high-entropy alloys. This concept successfully developed a hierarchical eutectic Ni3FeTi3HfNb2 high-entropy alloy composed of B2 intermetallic compounds and disordered body-centered cubic (BCC) phases. It displays an outstanding compression property, with the yield strength (σs) as high as 1407 MPa, the large fracture strain of 22.1% and the large elastic strain of 3.0%. The combination of high strength and good ductility exhibits a promising application in industry. Moreover, the anisotropy and the relationships among microstructure evolution, mechanical property and Nb concentration are systematically discussed.

Process-microstructure-properties of CuAlNi shape memory alloys fabricated by laser powder bed fusion

Cu -based shape memory alloys (SMAs) show great potential in the application of high temperature, but their performance improvement combining with additive manufacturing is still challenging. In this paper, nearly defect-free (99.7% relative density) CuAlNi SMAs with two types of thermal-induced martensites, 18R and 2H, were successfully fabricated by laser powder bed fusion (LPBF). The remelting printing strategy with systematic optimization framework including densification and printability analysis was used to get optimal process window. The twin-related self-accommodation structure with long period stacking order substructure was formed during additive manufacturing process. The as-build samples show excellent mechanical properties (ultimate compressive strength of 1593 ± 10 MPa and large fracture strain of 23.0% ± 0.1%) with double-yielding, and outstanding shape memory effect, with maximum recoverable strain of 3.39% and nearly 100% recovery rate under compressive strain not exceeding 6%. Furthermore, the microstructural evolution in LPBF involving remelting, martensitic transformation, and 2H martensite was discussed. This result not only builds the microstructure framework involving high reflectivity alloys and martensitic transformation but also provides insight into the applicability of LPBF process in producing Cu-based SMAs.

Tough, Healable, and Sensitive Strain Sensor Based on Multiphysically Cross-Linked Hydrogel for Ionic Skin.

Ion conductive hydrogels (ICHs) have attracted great interest in the application of ionic skin because of their superior characteristics. However, it remains a challenge for ICHs to achieve balanced properties of high strength, large fracture strain, self-healing and freezing tolerance. In this study, a strong, stretchable, self-healing and antifreezing ICH was demonstrated by rationally designing a multiphysically cross-linked network structure consisting of the hydrophobic association, metal-ion coordination and chain entanglement among poly(acrylic acid) (PAA) polymer chains. The deliberately designed Brij S 100 acrylate (Brij-100A) micelle cross-linker can effectively dissipate energy and endow hydrogels with desirable stretchability. The self-healing ability of hydrogels originates from the reversible hydrophobic association in micelles and Fe3+-COO- coordination. After the addition of NaCl, the chain-entangled physical network caused by the salting-out effect can both enhance mechanical strength and promote electron transport. With the synergy of hydrophobic association, mental-ligand coordination and chain entanglement, the PAA/Brij-100A/Fe3+/NaCl (PAA/BA/Fe3+/NaCl) hydrogels exhibited a high tensile strain of 1140%, a tensile strength of 0.93 MPa and a toughness of 3.48 MJ m-3. Besides, the PAA/BA/Fe3+/NaCl hydrogels exhibited a high conductivity of 0.43 S m-1 and good freezing resistance. The ionic skin based on the PAA/BA/Fe3+/NaCl hydrogels showed high sensitivity (GF = 5.29), wide strain range (0-950%), fast response time (220 ms) and good stability. Also, the self-healing ability of the ionic skin can significantly prolong its service time, and the antifreezing property can broaden its applicable temperature. This study offers new insight into the design of multifunctional ionic skin for wearable electronics.

Stress-state-dependency of post-necking hardening rule and its influence on ductile fracture prediction

This paper presents the investigation of the stress-state-dependency of the post-necking hardening rule of the Q355B structural steel and its influence on fracture prediction. The comparisons of the testing result and the simulation based on the Mises model with the stress-state-independent hardening rule indicate that triaxiality dependency under axisymmetric tension is negligible, while the reduced yield stress increases with the rising triaxiality under plane strain. In addition, the overestimated predicted force based on the Mises model is continuously ramping up along with the plastic deformation under the shear-dominant condition. It can be considered by the reduced post-necking hardening rate under the requirement of convexity of the yield surface. The stress-state-dependent hardening model (SDH model) is herein proposed including the modified triaxiality-dependent Hosford yield criterion and state-dependent post-necking hardening rule. The comparative studies of the proposed and conventional models show similar calculated fracture strains under high triaxiality, but considerably larger fracture strain under low triaxiality from the proposed SDH model, since the reduced post-necking hardening rate intensifies the localization of plastic deformation. Using the proposed pressure-dependent maximum shear stress (PMSS) fracture model, the calibrated fracture parameters based on the data from SDH the model produce better fracture simulations under various stress states, especially the complex condition in multi-hole plate (MHP) specimen. It emphasizes the necessity of the consideration of stress-state-dependency in the post-necking hardening rule for accurate fracture prediction.

Actuation of shape memory poly(vinyl alcohol) and graphene oxide film in water

The PVA/GO film prepared by vacuum-assisted self-assembly exhibits quick thermo-/water- responsive shape memory effect. The anisotropic lamellar structure of GO sheets and plenty of chemical groups containing oxygen in the PVA/GO film facilitate rapid recovery in water. The lamellar structure of GO sheets improves the recovery stress of composite and results in a 16-fold increase in Young’s modulus. PVA molecular chain slides along the direction of the laminated GO sheets, consistent with the extension direction, ensuring that the composite film maintains a large fracture strain. The straight film is programmed into a spiral shape by the plasticization of water on PVA instead of ordinary heating and the spiral film can drive a weight 160 times its own weight to rotate in water at room temperature (about 25[Formula: see text]C).

Study on the Impact Resistance of FRP Pasted onto a Blastproof Partition Wall under Out-of-Plane Repeated Impact Load

A blastproof partition wall in civil air defense engineering is easily subjected to out-of-plane impact loads, such as object impacts, and structural collapse in peacetime. In this study, the pendulum impact test was carried out for the first time on six blastproof partition walls pasted with fiber-reinforced polymer (FRP). Using a method combining finite element simulation and experimental research, the influence of parameters such as the FRP type, layer number and width, and pendulum impact number on the impact resistance of the wall was systematically studied. The test results show that pasting FRP on the back of the blastproof partition wall can significantly improve the impact resistance and reduce the damage degree of the concrete. The impact recovery coefficient increased from 0.33 to 0.57, but with the increase in the number of impacts, large-rupture-strain FRP (LRS-FRP) can give full play to the advantages of a large tensile fracture strain and cooperate with the wall to deform, and the selection of FRP with a large tensile fracture strain is the key to resisting multiple impact loads. Finally, the experimental basis and an economical and reliable protection method are provided for the study of improving the impact resistance of the blastproof partition wall.

Identification of ductile fracture design curve for hardened quasi-brittle AISI-D2 tool steel to predict shearing tool failure

Tool deformation and fracture during the shearing of ultra-high-strength steel has become a severe problem. Finite element (FE) simulations can help to solve this problem by evaluating improved tool edge designs, but they require the strain/stress range in which no fracture occurs. This study accordingly identified these properties for conventional and improved AISI-D2 tool steels by shearing them in sheet form using harder tools. First, the work-hardening parameters were fitted so that the FE simulation agreed with the measured punching force vs. stroke curves fitted using the Swift and Voce laws for the conventional and improved steels, respectively, at plastic strain levels exceeding 0.1. The plastic strain ε¯p vs. historically averaged stress triaxiality η¯ plots were derived from each element in the FE simulation at the punch stroke corresponding to fracture. The safe zone against ductile fracture was evaluated as a set of ε¯p — η¯ plots, and the exponential curves through the realms of these safe zones were drawn as the ductile fracture design curves. This evaluation suggested a drastically large fracture strain in the negative η¯ region compared with the fracture strain obtained using high-pressure tensile tests also conducted in this study. The effectiveness of the proposed method was confirmed as it clearly indicated the superiority of the improved AISI-D2 steel material.

Laser powder bed fusion of FeCoBSiNb-Cu bulk metallic glass composites: Processing, microstructure and mechanical properties

Fe–Co–B–Si–Nb bulk metallic glasses are prone to the formation of micro-cracks during laser powder bed fusion (LPBF) additive manufacturing. Introducing ductile Cu into Fe–Co–B–Si–Nb bulk metallic glass alloy system rich with Fe and Co could be a promising solution to reduce or even eliminate micro-cracks since there is almost no miscibility of Cu in Fe and Co. In this work, processing, microstructure and mechanical properties of Cu-containing {(Fe0.6Co0.4)0.75B0.2Si0.05}96Nb4 (at.%) bulk metallic glass composites (BMGCs) under different laser power and scanning speed by LPBF are investigated in detail. A moderate area energy density facilitates the fabrication of highly dense (relative density: up to ∼99.5%) and almost crack-free (crack density: ∼0.1 mm−1) FeCoBSiNb–Cu bulk samples. These bulk samples possess an interpenetrating composite microstructure mainly composed of an amorphous Fe(Co)-rich phase and a crystalline Cu-rich phase. A crystalline Cu-rich phase is distributed relatively homogeneously in an amorphous phase and helps to reduce and even eliminate micro-crack formation during LPBF processing. Also, the Cu-rich phase has the effect of a heat sink and thus speeds up heat dissipation, facilitating the formation of an amorphous phase. The microhardness of the ductile Cu-rich phase and the hard amorphous Fe(Co)-rich phase in the interpenetrating composite microstructure was evaluated. Compressive tests at room temperature indicate that the dense bulk samples exhibit a relatively high fracture strength and a large fracture strain. Additionally, bulk samples with lack-of-fusion pores show a larger fracture strain although their fracture strength is lower than that of dense bulk samples. It is concluded that the LPBF-processed FeCoBSiNb–Cu BMGCs constitute a promising wear-resistant material to be used for example as bearing materials.

High-strength, flexible and superhydrophobic graphene/aramid nanofiber nanocomposite films for electromagnetic interference shielding application

Electromagnetic interference (EMI) shielding composite materials exhibit many amazing characteristics, including low density, excellent flexibility and corrosion resistance, compared with metals. However, it is a long-standing challenge for EMI shielding materials to overcome inferior mechanical properties and limited hydrophobic characteristics. In this work, the high-strength, flexible and superhydrophobic graphene nanosheet/aramid nanofiber (GNS/ANF) nanocomposite films with layered microstructure were prepared by the sol-gel transformation and spray coating process. The resultant film exhibits excellent mechanical properties with a high tensile strength (131.17 ± 2.77 MPa), large fracture strain (9.58 ± 0.58%), and favorable toughness (8.84 ± 0.74 MJ m−3), which are 26.2 times, 7.5 times and 221.0 times higher than those of pure GNS films. These results are attributed to synergistic effect between intensive stretching of three dimensional (3D) nanofiber network and extensive sliding of GNS produced effective energy dissipation. Moreover, the film with content of 70 wt% GNS has EMI shielding effectiveness of 31.3 dB, and its reflection coefficient is more than 0.89, revealing a reflection-dominant shielding mechanism. Meanwhile, the film possesses superhydrophobic property (158.7° ± 1.1°) and flame retardancy. The multilayered nanocomposite films have excellent potential for high-performance EMI shielding applications under some outdoor conditions.

Experimental study and finite element analysis on impact resistance of large-rupture-strain FRP reinforced civil air defense wall

In order to study the impact resistance of civil air defense wall strengthened with large-rupture-strain FRP and improve its explosion resistance, the pendulum impact test and ANSYS/LS-DYNA finite element simulation were used to study the influence of the reinforcement area, pendulum impact height and impact times of large-rupture-strain FRP on the impact resistance of civil air defense wall. Large-rupture-strain FRP is a new type of fiber reinforced plastics, which has the advantages of large tensile fracture strain and high strength. It is pasted on the back of the civil air defense wall to improve the overall ductility and flexural stiffness of the civil air defense wall. In this paper, large-rupture-strain FRP is firstly applied to the reinforcement of civil air defense wall resist out-of-plane impact load to improve the impact resistance of civil air defense wall. The advantages of large-rupture- strain FRP reinforcement of civil air defense wall to improve the impact resistance are analyzed from the parameters of civil air defense wall damage degree, mid-span horizontal maximum displacement and residual displacement, concrete cracks and steel strain. The pendulum impact test results show that the civil air defense wall bonded with large-rupture-strain FRP can well coordinate with the wall, restrain the cracking of the back concrete, and avoid the overall collapse of the civil air defense wall due to local damage. The residual displacement is significantly reduced, and the crack width of the concrete is reduced by 25%–76%. Even if the civil air defense wall is subjected to multiple impacts, there is no fracture of large-rupture-strain FRP. The large-rupture-strain FRP can still play a role in strengthening and restrain the stripping of the back concrete fragments. The advantage of large tensile fracture strain of large-rupture-strain FRP makes up for the shortcomings of small tensile fracture strain of FRP commonly used at present, and finally provides a new reinforcement material for improving the explosion resistance of civil air defense wall.

Borax-crosslinked hydrogel electrolyte membranes for quasi-solid state aqueous energy storage devices

A novel borax-crosslinked hydrogel electrolyte membrane is synthesized using radical polymerization to achieve superior electrochemical performances and outstanding mechanical properties. The as-synthesized electrolyte membrane displays high ionic conductivity (1.72 × 10−2 S cm−1), wide electrochemical stable window (∼2.21 V), large fracture stress (42.17 kPa) and fracture strain (205.10%). The membrane enables highly uniform Zn plating/stripping with lower overpotential and longer lifespan from the symmetric Zn cells compared with that using the liquid electrolyte. To demonstrate the applicability of the electrolyte membrane, they are used in quasi-solid state Zn metal batteries (Zn||MnO2) and Zn-ion hybrid supercapacitors (Zn||AC), respectively. The resultant Zn||MnO2 cell delivers a high discharge specific capacity retention of 95% after 1000 cycles at 0.5 A g−1, and the Zn||AC supercapacitor exhibits satisfactory specific capacitance of 290 F g−1 at 1.0 A g−1 and good rate performance. Furthermore, the flexible Zn||MnO2 and Zn||AC devices are also assembled, which can still work even at the bent and compressed states. This work provides a promising route to design the hydrogel electrolytes for the quasi-solid state aqueous energy storage devices.