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A ceramic core is the key component in the manufacture of the hollow turbine blades of aeroengines. Compared with the traditional injection molding method, 3D printing is more suitable for manufacturing ceramic cores with a complex geometry at high precision. However, the stair-stepping effect is inevitable in the 3D printing process and affects the surface roughness and strength of the ceramic core. In this study, to explore the influence of nano-silica content on the microstructure and properties of the ceramic core, silicon-based ceramic cores were fabricated with the addition of nano-silica powder by digital light processing and subsequent sintering at 1200 °C. The results showed that the apparent porosity and pore size of the ceramic core gradually decreased as both the nano-silica powder content and bulk density increased. Meanwhile, the printing interlayer spacing was significantly reduced, resulting in a low surface roughness, high flexural strength, and creep-resistance. To simulate the entire casting process of a superalloy blade, the thermal deformation behavior of the ceramic core was observed by heating and cooling cycles performed in a thermal dilatometer at 1540 °C. The total linear shrinkage decreased as the nano-silica powder content increased, which was mainly due to the phase transformation of cristobalite and the densification of the ceramic core sintered at 1200 °C. The low surface roughness and linear shrinkage as well as high flexural strength of the ceramic core can contribute to the excellent quality of cast superalloy blades.

With poor mechanical properties and engineering characteristics, loess soils alone cannot meet the requirements of high-speed railway subgrade and large-sized building foundations based on shear strength and bearing capacity. Therefore, it is necessary to improve the mechanical properties of loess. In soil reinforcement, encouraging outcomes have been achieved by using fibers as reinforcement material for its relatively low costs and the low environment impact results from this material. To investigate the mechanical properties and the reinforcement mechanism of fiber-reinforced loess, ring shear tests were performed on loess samples with varying polypropylene fiber contents (0%, 0.25%, 0.50%, 0.75%, and 1%) and moisture contents (12%, 14%, 16%, 18%, and 20%). Furthermore, the macroscopic structure and microscopic images of the shear plane of reinforced specimens were analyzed as well. The test results showed that firstly polypropylene fibers significantly improved the peak strength and the residual strength of loess, and the optimal fiber content and the optimal moisture content were found to be 0.5% and 16%, respectively. The theoretical relationships between the fiber content Fc, the moisture content Mc, the peak strength τ, and the residual strength τr of reinforced loess were quantitatively determined. In addition, the fiber reinforcement mechanism was revealed based on the macroscopic shear plane of fiber-reinforced loess and SEM microscopic images of the shear plane.

Here in, the effects of FeSiAl particle size on the dielectric and microwave absorption properties of FeSiAl/Al2O3 composites were studied. FeSiAl/Al2O3 composites containing 18–25 μm, 25–48 μm, and 48–75 μm FeSiAl particles were prepared by hot-pressed sintering based on uniformly mixed FeSiAl and Al2O3 powders. Results show that the real permittivity and the imaginary permittivity are significantly promoted with increasing FeSiAl particle size, which is ascribed to the enhanced interfacial polarization and conductance loss. In addition, the favorable matching impedance and suitable attenuation coefficient enabled the composite containing 25–48 μm FeSiAl powder to show a minimum reflection loss of −34.4 dB at 11.7 GHz and an effective absorption bandwidth (

Large quasi-elastic deformation with high degree of rebound resilience was reported in dense, monolithic ceramics for the first time, which was achieved in the cyclic compression-resilience tests on bulk amorphous Al2O3–ZrO2–Y2O3 at 600 °C. As the compression strain was 4%, the resilience ratios in the three cycles were 89.5%, 100% and 100%, respectively; for compression strain of 8%, the resilience ratios were 74.5%, 90.6% and 92.0%. The superior elastic deformation in amorphous Al2O3–ZrO2–Y2O3 was due to the round trip migration of atoms through free volume in amorphous phase, and the residual strain after deformation of 4% and 8% are resulted from structural densification and shear band formation, respectively. This work could inspire new guidance on elastic deformation in ceramics, and provide new guidance to ceramic materials with high elastic deformation and rebound resilience in engineering applications.

Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of naturally drained ring shear tests were carried out on loess from three landslides at two shear rates (0.1 and 1 mm min−1). Experimental results showed that the shear displacement to achieve the residual stage for specimens with higher shear rate was greater than that of the lower rate; both the peak and residual friction coefficient became smaller with increase in shear rate for each sample; at two shear rates, the residual friction coefficients for all specimens under the lower normal stress were greater than those under the higher normal stress. Moreover, specimens with almost the same low fraction of clay (CF) showed a similar shear rate effect on the residual friction coefficient, with normal stress increasing, whereas specimens with high CF (24 %) showed a contrasting tendency, indicating that such an effect is closely associated with CF. The test results revealed that the difference in the residual friction angle ϕr at the two shear rates, ϕr(1)−ϕr(0.1) under each normal stress level are either positive or negative values, of which the maximum magnitude is about 0.8∘. However, the difference ϕr(1)−ϕr(0.1) determined under all normal stress levels was negative, which indicates that the residual shear parameters reduced with the increasing of the shear rate in the loess area. Such a negative shear rate effect on loess could be attributed to a greater ability of clay particles in specimens to restore broken bonds at low shear rates.

Reduced graphene oxide (rGO) nanosheets/alumina (Al2O3) composite ceramics were fabricated by hot-pressing sintering. The density, porosity, microhardness, flexural strength and complex permittivity were investigated to study their mechanical and dielectric properties. The results revealed that the rGO nanosheets were uniformly distributed in the Al2O3 matrix and that the composite ceramics were highly dense at 3.67–3.99 g/cm3. Due to low rGO hardness and elevated porosity, the microhardness exhibits a decreasing trend as the rGO content increases. The flexural strength first increased and then decreased with the escalation of rGO content, and the highest strength of 313.75 MPa was obtained at 3 wt%, increasing by 37.61% relative to that of the hot-pressing sintered Al2O3 ceramic. Owing to the enhanced interfacial polarization, dipole polarization, polarization relaxation loss and conductance loss, the real part and imaginary part of complex permittivity increase from 10.40 to 52.73 and from 0.08 to 28.86 as the rGO content rose from 0 wt% to 4 wt%, respectively.

Bulk amorphous Al2O3–ZrO2–Y2O3 samples are fabricated by hot pressing and heat treated at 750–950 °C to adjust the free volume and crystallinity degrees, and the cooperative effects of free volume and nanocrystallite on plasticity are explored. With increasing heat treatment temperature, the free volume decreases monotonically, and the nanocrystallization initiates above 800 °C. Under compression at 500 °C, the plastic strain is in linear correlation to the free volume for fully amorphous samples or amorphous/nanocrystalline composites, respectively. The larger free volume concentration is beneficial to the formation and propagation of shear bands, and achieves to larger plasticity. Although the amorphous/nanocrystalline composites have lower free volume, they display better plasticity than the fully amorphous samples, attributed to the microstress concentration at the interfaces between nanocrystalline and amorphous matrix. Due to the coexistence of tiny nanocrystallite and sufficient free volume, the sample heat treated at 850 °C exhibits the best plasticity with strain of 9.9%.

Two-dimensional (2D) materials have been attracted highly interest in recent years due to their low structural symmetry, excellent photoresponse and high air stability. However, most 2D materials can only response to specific light, which limits the development of wide spectrum photodetectors. Proper band gap and the regulation of Fermi level are foundations for realizing electronic multi-channel transitions, which is an effective method to achieve wide spectral response. Herein, a noble 2D material, Palladium phosphide sulfide (PdPS), is designed and synthesized. The band gap of PdPS is around 2.1 eV and the formation of S vacancies, interstitial Pd and P atoms promote the Fermi level very close to the conduction band. Therefore, PdPS-based photodetector shows impressive wide spectral response from solar blind ultraviolet (SBUV) to near infrared (NIR) based on the multi-channel tranisiton. It also exhibits superior optoelectrical properties with photoresponsivity (R) of 1×103 A/W and detectivity (D*) of 4×1011 Jones at 532 nm. Moreover, PdPS exhibits good performance of polarization detection with dichroic ratio of ∼3.7 at 808 nm. Significantly, it achieves polarimetric imaging and hidden target detection in complex environments through active detection. This article is protected by copyright. All rights reserved.

It is generally assumed that the measured strength of brittle ceramics follows a Weibull distribution. However, there seems to be few sound and direct evidences to support this assumption. Several previous studies have shown that other distributions, such as normal distribution and log-normal distribution may describe more appropriately the strength data than Weibull distribution. In this paper, the efficiency of using a normal distribution to describe the strength which follows a Weibull distribution is examined based on Monte-Carlo simulations. It was shown that there exist strong correlations between the parameters of normal distribution and those of Weibull distribution. For the designed fracture probability not lower than 0.01, analyses based on both normal distribution and Weibull distribution may give nearly identical predictions for the applicable stress levels. For lower fracture probabilities, the differences between the predictions of both distributions are not significant. It was suggested that, if there is no evidence to confirm that the measured strength follows a certain distribution, normal distribution and Weibull distribution seem to have the same efficiency in analysing the statistical variations in the measured strength of ceramics.

An CoCrFeMnNi high-entropy alloy (HEA) particles reinforced 2024Al alloy composite was prepared by spark plasma sintering (SPS). There is an interdiffusion (ID) layer between the HEA particle and the matrix. The composition and micromechanical properties of the diffusion layer were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), electron probe and nanoindentation. The unique element distribution in the diffusion layer and the obvious creep phenomenon are related to the sintering mode. The hardness of the composite is increased 63.7%, which was attributed to particle reinforcement and the relative low content of sintering defects in the matrix.

Silica-based composite ceramic cores doped with silica nanopowders were fabricated, and effects of nanopowder content on the properties of ceramic cores were investigated. With increasing content of nano-silica powders, the fraction of cristobalite crystallite showed monotonic increase in the sintered ceramic cores due to the high surface energy of nanopowders. The linear shrinkage, bulk density and chemical leachability initially decreased to a minimum value and then increased, and the flexural strength displayed an opposite tendency. When the fraction of silica nanopowders was 0.6 wt%, the ceramic cores exhibited superior properties, including linear shrinkage of 0.6%, apparent porosity of 27.5%, leachability of 0.28 g/min, creep deformation of 0.2 mm, and flexural strength of 30.5 MPa at room temperature and 28.9 MPa at 1540 °C. In casting simulation at 1540 °C, large quantities of cristobalite were crystallized, which might provide enhanced mechanical property in the casting, and the phase transition from α to β-cristobalite during cooling would introduce microcracks and lead to better leaching of ceramic cores after casting, which well meet the need of ceramic cores for hollow turbine blades.

This study investigated a magnetically recycled modified polishing powder (CMIO@PP) as an adsorbent of phosphate; the CMIO@PP was synthesized by combining the modified La/Ce-containing waste polishing powder with CaO2-modified Fe3O4 (CMIO). Results indicate that the CMIO@PP nanocomposite presents a crystal structure comprising La (OH)3, Ce (OH)3, and Fe3O4, and that CMIO is uniformly dispersed in the modified polishing powder. The CMIO@PP (1:3) is a suitable choice considering its magnetism and adsorption capacity. The magnetic adsorbent exhibits a high adsorption capacity of 53.72 mg/g, a short equilibrium time of 60 min, and superior selectivity for phosphate. Moreover, the adsorbent strongly depends on the pH during the adsorption process and maintains a large adsorption capacity when the pH level is between 2 and 6. The adsorption of phosphate by the CMIO@PP (1:3) accords with the Langmuir isotherm model, and the adsorption process follows the pseudo-second order model. Meanwhile, adsorption–desorption experiments show that the adsorbent could be recycled a few times and that a high removal efficiency of phosphate from civil wastewater was achieved. Finally, mechanisms show that the adsorption of phosphate by the CMIO@PP (1:3) is mainly caused by electrostatic attraction and ligand exchange.

To improve the efficiency of energy, phase change microcapsules with capric acid as core material and urea–formaldehyde resin modified by graphene oxide (GO) as shell material were synthesized by in situ polymerization. The particle characteristics, chemical structure, thermal conductivity and thermal stability of capric acid phase change microcapsules were studied by environmental scanning electron microscopy, laser particle size analyzer, Fourier transform infrared spectroscopy, thermal conductivity meter and differential scanning calorimeter. The results showed that the surfaces of MEPCMs–0.3%GO, MEPCMs–0.6%GO and MEPCMs–0.9%GO are relatively smooth compared with MEPCMs, but the surface smoothness of capric acid phase change microcapsules will decrease with the increase in graphene oxide dosage. The inflection point of encapsulation ratio of capric acid phase change microcapsules occurs in the 0.6% dosage of graphene oxide. Compared with MEPCMs, thermal conductivity of MEPCMs–0.9%GO increased by 75.1%, 64.2% and 73.6% at 20 °C, 30 °C and 40 °C, respectively. In the thermal cycle experiment, capric acid phase change microcapsules possess the better heat stability. Because graphene oxide can be stably buried or embedded in the shell material of urea–formaldehyde resin and forms heat transfer channels on the surface and inside of urea–formaldehyde resin, the thermal properties of capric acid phase change microcapsules can be improved.

The residual strength of slip zone loess is strongly affected by the moisture content. To explore such an effect, slip zone loess obtained from Baqiao landslide was used in ring shear tests under moisture content ranging from 6% to 29%. Laboratory tests were utilized for the determination of the stress–displacement relationship and residual strength parameters for the effect of moisture content in loess. The experimental results showed that the residual strength generally decreases with increasing moisture content. In addition, for a given shearing rate, the residual strength at any moisture content is approximately proportional to the normal stress. The stress fluctuation of shear stress was found to be greater with high shearing rates. Furthermore, the effect of moisture content on the residual strength parameters (cohesion and friction angle) was presented: the residual cohesion of slip zone loess was observed to increase with moisture content to a certain limit that approaches the plastic limit, above which it decreases. Also, the friction angle of slip zone loess was found to decrease with increasing moisture content. Additionally, due to the increase of the moisture content, the scratch color on the shear surface changed from the original color yellow to brown and the thickness of the shearing band of samples reduced. Finally, the mechanism of the influence of moisture content on the macroscopic morphology of the shear surface was also analyzed and illustrated. The study may provide a basis for understanding the shear behavior of slip zone loess under different moisture contents, as well as guidelines for loess landslide stability prevention and prediction.

In this work, compressive deformation is performed on bulk amorphous Al2O3-ZrO2-Y2O3 at moderate temperatures. The amorphous samples display brittle fracture without any noticeable permanent strain at 500 °C. However, a large plastic strain of up to 15.1% is achieved at 600 °C. During the entire compressive deformation process, the samples remain amorphous, and shear bands start to form, accompanied by a stress drop. The amorphous AZY shows low Vickers hardness value of 2.8 GPa at 500 °C, and 2.2 GPa at 600 °C, due to the disordering microstructure. In the optical microscope images, local plastic deformation are detected around the indention without large cracks. Transmission electron microscopic observations and selected area electron diffraction analysis suggest that the shear band formation originates from the presence of free volume. Furthermore, the nucleation and propogation of shear bands lead to the large macroscopic plastic strain in the bulk amorphous Al2O3-ZrO2-Y2O3.

In order to improve the electrochemical properties of MoS2, an important method of reflecting synergy between different components has been proposed. And this article describes that four kinds of electrode materials were prepared using a simple hydrothermal method. Herein, a composite doping a small amount of carbon quantum dots (CQDs) can be used as an excellent electrode material. It can be found that carbon quantum dots/MoS2@ZnS composite (CQDs/MoS2@ZnS composite) possesses a higher specific capacitance of 2899.5 F g−1 than MoS2@ZnS composite (2176.1 F g−1), single MoS2 (1067.6 F g−1) and single ZnS (423.4 F g−1). Moreover, CQDs/MoS2@ZnS has excellent cycling stability, maintaining 76.1% of original capacitance after 3500 cycles. The results indicate that the CQDs/MoS2@ZnS composite electrode has potential application in supercapacitors, and the investigation also provides an important idea to improve electrochemical performance of other electrode materials through doping a small amount of CQDs.

This article shows that carbon dots (CQDs), polystyrene sphere (PS) or silica sphere (SiO2) assembled on MoS2 have been successfully synthesized as electrode materials (CQDs/MoS2, PS/MoS2 and SiO2/MoS2) for supercapacitors by a simple hydrothermal process. It can be observed that SiO2 is distributed in the periphery of the flower-like MoS2, and the special morphology has a positive effect on electrochemical performance. As expected, SiO2/MoS2 as a promising electrode material for supercapacitor, exhibiting a higher specific capacitance of 1448.53 F g−1 at a current density of 5 A g−1 and good cycle stability of 70.10% retention after 2000 cycles. This method also provides a reference for the electrode material of supercapacitors with better performance in the future.

In this work, cristobalite seeds were doped in silica-based ceramic cores, and the effect of particle size on the properties of ceramic cores was investigated. With decreasing particle size...

It is well known that the hydromechanical behavior of both saturated and unsaturated loess soils is significantly influenced by the soil fabric. However, there is limited understanding of how the soil fabric or structure evolves due to mechanical, hydraulic and chemical changes on loess soils. Information of the microstructural evolution or change in pore-size distribution (i.e., PSD) of loess soils along different stress paths is valuable for proposing an advanced constitutive model that considers the microstructure and can better model the hydromechanical behavior of loess soils. For this reason, in the present study, the microstructure is characterized on intact and saturated loess specimens before and after oedometer consolidation tests, using scanning electron microscopy and mercury intrusion porosimetry methods. The results suggest that the loading-induced change in PSD varies with stress level and saturation state of the loess soil. A reduction arises in the cumulative intrusion void ratio due to an increase in vertical stress, which accounts for compression of inter-aggregate pores greater than 6 μm. However, loading saturated loess leads to transformation from a bimodal PSD into a trimodal one that defines three major pore series, namely large-pore series (i.e., more than 6 μm), medium-pore series (i.e., between 0.1 and 6 μm) and small-pore series (i.e., less than 0.1 μm). The trimodal nature of PSD is, however, destructed under higher vertical stresses. Both large pores and medium pores are compressed under higher vertical stresses (i.e., > 600 kPa). The inundating-induced change in PSD is dependent on loading condition and can be discerned to take place in the same three pore series. Not only large pores but also medium pores collapse upon inundating under higher vertical stresses (i.e., > 600 kPa). The microstructural evolution is consistent with the mechanical responses of both intact and saturated loess.

In present work, Al2O3 nanoceramics toughened with 5 mol% ZrO2 and 10 mol% ZrO2 were prepared by pressureless sintering; polycrystalline ZrO2 powders and Al2O3-ZrO2 amorphous powders were used as dopants in conventional sintering and amorphous-phase-assisted sintering, respectively. In amorphous-phase-assisted sintering, the densification of Al2O3-ZrO2 nanoceramics was highly promoted, and nanoceramics with composition of Al2O3-5 mol% ZrO2 and Al2O3-10 mol% ZrO2 were almost fully densified at temperature as low as 1350 °C. The easy densification was attributed to the metastable state and phase transition of amorphous powders, which acted as sintering aids. The nanoceramics exhibited dense and homogenous mixture of Al2O3 and ZrO2 particles with fine grain size, and the microstructure refinement further contributed to superior mechanical properties with high Vickers hardness, bending strength and Weibull modulus values. This work may provide new guidance for low temperature fabrication of nanoceramics by employing amorphous powders as sintering aids.

Based on a new elastic clump model, a flexible membrane is proposed for the discrete element numerical simulations of triaxial tests. Conversional triaxial tests of sandstone under the confining pressures of 2 MPa and 8 MPa were carried out, in order to validate the effectiveness of the proposed numerical simulation method. The numerical model is validated by comparing the numerical results with the test results. The deformation and failure process of numerical model is analyzed by stress–strain curves, micro fractures, displacement fields, stress fields and energy fields. The model shows an X-shape shear failure zone, of which the angle is very close to that of the test; the dip angle of most shear fractures is close to the angle of the internal friction; and there is a large amount of slipping frictional heat generated on the failure surface. During the loading process, the stress chain and stress concentration appear in the middle of the model, which lead to displacement zoning in the model. The failure of the model is associated with the growth of the micro tensile- and shear fractures. This study provides an effective tool for the macro–micro investigation of rock failure processes.

The triggering mechanism and movement evolution of loess-red clay landslides, which occurred frequently along the contact between the loess and red clay on the Loess Plateau, are closely related to the mechanical properties of the contact surface. This work presents an experimental investigation on loess, clay and loess-red clay interlaminar (LRCI) samples obtained from a typical loess-red clay landslide in northern part of Shaanxi province of China, using a series of ring shear tests, microscopic observation and scanning electron microscopy tests, in an attempt to explore the mechanical behavior of loess, clay and LRCI samples with variation in moisture content, normal stress and shear rate. The results revealed that for all specimens, both the peak shear strength $$\tau_{p}$$ τ p and the residual shear strength $$\tau_{r}$$ τ r decreased with increasing moisture content, among which, moisture content has the greatest influence on the $$\tau_{p}$$ τ p and $$\tau_{r}$$ τ r of red clay, followed by the LRCI specimen, and the loess specimen is least affected by moisture content. Meanwhile, exponential functions describing the correlations between shear strength and moisture content of LRCI, red clay and loess specimens were proposed. Furthermore, the macroscopic morphological characteristics and the microstructure of shear surface obtained from the LRCI specimens showed that a localized water accumulation was built up within the shear surface as the water content increases to some extent, and a high degree of liquefaction developed within shear surface when the moisture content reached to the saturate degree. The microstructural observation on LRCI specimen suggested that the shear surface became smoother and the larger percentage of small-sized pores was observed with moisture content. Accordingly, the built-up excess pore water pressure during shearing is difficult to be dissipated due to a close structure of small-sized pores. Due to the low permeability, high pore-water pressure built up within the shear zone and the increase in the fine particle content, the LRCI soils with a high saturation degree shows the potential for the localized liquefaction within shear zone, which further provides a scientific explanation for the triggering mechanism of loess-red clay landslides with high-speed and long- run out.

The behavior of soils at small strains (< 10−5) is of significant interest for geotechnical engineers. Compared with the small-strain properties of sand or clay, those of saline soil have been investigated less extensively and therefore remain poorly understood. Accordingly, this study investigates the influence of microstructure on the small-strain shear modulus (G0) of saline soil. A series of specifically designed experiments was conducted on saline soil specimens under unsaturated conditions via the resonant column technique and scanning electron microscopy. The results showed that the G0 of saline soil increases with the dry density. The obtained values of the fitting parameter, A, are between 52.06 and 63.42, with an average value of 58.82, while those of the fitting parameter, n, are between 0.284 and 0.363, with an average value of 0.322. The Na2SO4 content was employed as a state variable, using which Hardin’s equation was modified for proper consideration of the influence of the Na2SO4 content on the prediction of G0. The results show that G0 increases with the Na2SO4 content. The inflection point of the Na2SO4 content with a significant change in G0 is 20%. The main contact forms of soil particles are edge–edge, edge–surface, and surface–surface contacts. With increasing Na2SO4 content, the cementation of soil particles by salt crystals gradually replaces the inter-particle contact, and sulfate crystal cementation becomes the dominant factor affecting G0.

The structural deformation caused by temperature change is the main reason for cracking of mass concrete. In order to avoid or reduce the crack of the side wall of cast-in-place mass concrete in tunnel, the effects of different dosage of hydration heat inhibitor on the internal temperature rise curve of concrete, strength and the properties of the mixture are analyzed through experimental research, and the optimal dosage of 1% of cementing material is finally determined. The engineering application results show that after adding hydration heat inhibitor to the tunnel side wall concrete, the maximum temperature rise in the tunnel side wall is obviously reduced, and the arrival time of the temperature peak is delayed. No cracks appear in the tunnel side wall, and the crack control effect is good.

A composite material with temperature-humidity control functions was prepared by using sepiolite-zeolite powder as humidity control matrix and capric acid phase change microcapsules as temperature control material. The micromorphology, thermal conductivity, compressive strength, hygrothermal effect were studied by environmental scanning electron microscope (ESEM), thermal conductivity test, strength test and hygrothermal effect test, respectively. The results showed that the phase change temperature of capric acid phase change microcapsule is between 31 °C ~ 32 °C, the phase change enthalpy is 123.91 J/g, and it has good thermal stability. The humidity control performance is the best and the maximum humidity absorption rate is 6.28% when sepiolite-zeolite powder ratio is 9:1. The humidity control matrix@CAM (Capric acid microcapsules) can control the relative humidity of the environment at 51.74 ~ 58.54% and reduce the temperature fluctuation range by 2 °C ~ 3 °C. Capric acid phase change microcapsules are embedded in the interlaced sepiolite and zeolite powder to form a frame space body which produce capillary condensation adsorption and surface adsorption, absorb and desorb heat through phase changes, thus giving humidity control matrix@CAM a good temperature-humidity control performance.

Loess landslides are closely related to the variation in mechanical properties of soils due to the leaching of irrigation water in the irrigation area which causes the loss of soluble salt in the loess stratum. To investigate the effect of leaching on the mechanical characteristics of loess, ring shear tests were conducted on the slip zone soil samples obtained from a typical loess landslide under different soaking time and salt concentration. Furthermore, the microstructural observations were made on shear planes by using SEM (scanning electron microscopy) tests. The experiment revealed that: firstly, the shear strength of loess decreases with the increase of soaking time before reaching the minimum value at the soaking time of 1 d, and then increases with the soaking time until reaching a relatively stable value. Secondly, the shear strength of loess has an increasing tendency with the salt concentration before reaching a maximum value at the salt concentration of 8%, and then shear strength decreases. In addition, a &ldquo, stress-softening&rdquo, was found for the loess samples with the soaking time of 1 d and salt concentration of 8%. It is found that the total number of micropores and small-pores in loess samples decreases with increasing salt concentration up to 8%, but increases rapidly between salt contents of 8% and 20%. The SEM tests showed that the increase in salt concentration (0% to 8%) facilities the formation of small aggregates within loess soils, which in turn promotes the increasing of shear strength. However, further increase in salt concentration (8% to 20%) helps the development of relatively large aggregates in loess samples, resulting in the reduction in shear strength.

The microcapsule containing phase change materials(microPCMs) with high efficiency of photothermal conversion was prepared by in-situ polymerization via ultrasonic dispersion which used capric acid(CA) as core material and nano silicon carbide(nano-SiC) modified melamine-urea-formaldehyde(MUF) resin as wall material. The nano-SiC has good cross-linking with MUF shell. When the nano-SiC was added in microPCMs, it behaves superior thermal conductivity and thermal storage properties. When the content of nano-SiC arrives 6 wt%, the performance of the microPCMs whose encapsulation efficiency is 65.7% is the best, and thermal conductivity increase by 59.2%. Due to the proper amount of nano-SiC added into the MUF shell, it can effectively fill the tiny holes on the MUF shell. Therefore, the microPCMs with appropriate nano-SiC have better leakage prevention. It is worth noting that MicroPCMs-6% and MicroPCMs-8% show excellent photothermal conversion property, and the photothermal conversion rate is 74.4% and 71.1% respectively in the photothermal conversion experiment. Because nano-SiC can effectively capture and absorb photons under light irradiation and convert light into heat through internal molecular vibration, the microPCMs with appropriate nano-SiC behaves well in photothermal conversion. In other words, microPCMs have potential in solar energy utilization and thermal energy storage.

Developing precious metal-free electrocatalysts with both high and stable oxygen reduction reaction (ORR) electrochemical activity is still the key challenge in the wide application of clean energy, e.g. fuel cells or metal air batteries. Here, TiC based precious metal-free ORR catalyst has been studied by doping heterogeneous atoms. N-doping results in enhanced ORR performance of N/TiC, which was further elevated by introducing metal (e.g. Fe, Co) into TiC powders. Especially, the resultant Fe-N/TiC demonstrates the highest ORR activity among the prepared samples, which exhibits approximate 4e− pathway with a comparable electron-transfer number to the benchmark 20 wt%Pt/C, and much higher methanol tolerance than the latter in alkaline media. The high ORR performance of Fe-N/TiC composite could be ascribed to the cooperative effects of both N and metal doping, in which the N doping would lead to the change of electronic structure near the TiC surface and the formation of C-N active sites, and the metal species addition leads to the formation of a certain amount of Me-Nx active sites resulting in the further ORR activity enhancement. The reasonably high and stable electrochemical catalytic activity and the excellent methanol tolerance make the precious-metal free Fe-N/TiC composite a promising candidate cathode catalyst in ORR.

FeSiAl/Al2O3 composites were fabricated by hot-pressed sintering to evaluate the mechanical, dielectric and microwave absorption properties. The results show that the flexural strength of the composites increases with the increase of FeSiAl content, while the density and micro-hardness exhibit a downward tendency. The complex permittivity increases with increasing FeSiAl content in the X-band, which is resulted from the enhanced interfacial polarization, relaxation loss and conductance loss. Meanwhile, a rapid enhancement of complex permittivity for the composite with 10 wt.% FeSiAl is achieved due to the formation of conductive clusters and enhanced conductance loss. By calculating the reflection loss, the composite with 5 wt.% FeSiAl possesses the effective absorption bandwidth (

To mitigate autogenous shrinkage that may cause early-age cracking of alkali-activated fly ash-slag (AAFS) concrete, internal curing using superabsorbent polymers (SAP) is employed in this study. AAFS pastes with different SAP dosages (0–0.5%) and slag replacement ratios to fly ash (15–30%) are investigated. Experimental results indicate that with the addition of SAP workability of fresh paste is improved while compressive strength is comparatively reduced. As SAP dosage increases from 0.2% to 0.5%, chemical shrinkage and autogenous shrinkage of AAFS pastes are reduced by around 18% to 45% and 76% to 85%, respectively. Internal curing of SAP is found to lower the heat peak and shift the peak to the right. This indicates the slower hydration rate corresponding to the lower chemo-mechanical deformation (chemical shrinkage), which contributes to the mitigation of autogenous shrinkage. Therefore, internal curing by means of SAP is an efficient method for mitigating autogenous shrinkage in AAFS pastes.

Binary transition metal oxides (BTMO) (Co-Zn, Co-Cu) on Ni foam are fabricated through a facile and cost efficient hydrothermal method. In the three-electrode system testing, CoO@ZnO shows the highest specific capacitance of 2.394 F/cm2 at a current density of 5 mA/cm2 as well as excellent cycling stability which remains 76.5% of initial capacitance after 1000 cycles. This study provides an important method for the synthesis of high performance BTMO for supercapacitors.

Diseases, trauma, and injuries are highly prevalent conditions that lead to many critical tissue defects. Tissue engineering has great potentials to develop functional scaffolds that mimic natural tissue structures to improve or replace biological functions. In many kinds of technologies, electrospinning has received widespread attention for its outstanding functions, which is capable of producing nanofibre structures similar to the natural extracellular matrix. Amongst the available biopolymers for electrospinning, poly (caprolactone) (PCL) has shown favorable outcomes for tissue regeneration applications. According to the characteristics of different tissues, PCL can be modified by altering the functional groups or combining with other materials, such as synthetic polymers, natural polymers, and metal materials, to improve its physicochemical, mechanical, and biological properties, making the electrospun scaffolds meet the requirements of different tissue engineering and regenerative medicine. Moreover, efforts have been made to modify nanofibres with several bioactive substances to provide cells with the necessary chemical cues and a more in vivo like environment. In this review, some recent developments in both the design and utility of electrospun PCL-based scaffolds in the fields of bone, cartilage, skin, tendon, ligament, and nerve are highlighted, along with their potential impact on future research and clinical applications.

A facile and cost effective way has been developed to fabricate a unique structure of Ni3S2 and CoS (CNS) composite. CNS composite are synthesized on the surface of nickel foam (NF) using a hydrothermal process. NF acts as both a substrate and Ni source for composite. CNS are directly applied as the electrode for supercapacitors. XRD results indicate the presence of Ni3S2, CoS, and Ni phases in the sample. SEM results show that the CNS consist of interweaved nanoplates with average diameter of 15 μm and a thickness of 250 nm. Electrochemical measurements indicate the CNS have the specific capacitance of 4.73 F cm−2 at a current density of 1 mA cm−2. When the current density increases from 1 mA cm−2 to 20 mA cm−2, 63.4% capacitance is retained. Thus, the facile, low-cost and novel synthesis method and outstanding performance make the CNS an ideal electrode material for the electrochemical energy storage devices.

Two kinds of electrode materials Ni(OH)2 and Ni(OH)2@Zn(OH)2 composite are fabricated on nickel foam. Electrochemical experiments indicate Ni(OH)2@Zn(OH)2 composite deserves further study due to high specific capacitance and good cycle stability, so that it can achieve energy storage and conversion as much as possible. When the hydrothermal time is different, the electrochemical performance of the sample is also different. Accurately, samples can obtain better electrochemical performance at 15 h, and the maximum specific capacitance of Ni(OH)2@Zn(OH)2 is 7.87 F cm−2 compared to Ni(OH)2 (0.61 F cm−2) at 5 mA cm−2. Even at 50 mA cm−2, specific capacitance is 5.24 F cm−2 and rate capability is 66.6%. Furthermore, Ni(OH)2@Zn(OH)2-15 h loses 19.8% after 1000 cycles, revealing the composite has an outstanding stable cycle. These properties also indicate Ni(OH)2@Zn(OH)2-15 h is a promising electrode material.

In this study, the ratio f of the plastic zone radius, , to the contact radius, , for different material properties and at various indentation depths was investigated using a three-dimensio...

Impurity control remains to be a challenge to titanium metal injection moulding (Ti-MIM). Much attention has been paid to polyethylene glycol (PEG) based binder systems due to the eco-friendly and water-soluble feature of PEG. In this study, a new easy-to-debind PEG/polypropylene carbonate (PPC)-based binder system (76% PEG+17% PPC+3% polymethyl methacrylate (PMMA)+2% stearic acid (SA)+2% polyvinyl acetate (PVAc)) was developed. The rheological properties of the feedstocks prepared with the binder system in different proportions were assessed. Debinding behaviours of the moulded samples and impurity contents of oxygen (O), carbon (C), and nitrogen (N) of the thermal debound specimens were investigated as well.

Metal matrix composites (MMCs) are the new generation materials that combine both the metallic properties (ductility and toughness) and ceramic characteristics (high strength and modulus), leading to higher strength in shear and compression, at higher service temperatures. Titanium matrix composites possess light weight, high strength and good corrosion resistance and are used as structural materials in automobiles and aerospace industries. In the present study, in situ Ti-TiB composites were fabricated by reinforcing (2, 5, 10 and 20 wt. %) TiB2 powder (mean size

This work investigated the effects of current density and deposition time on the properties of electrodeposited PbO2. The PbO2 preparation was conducted on Ti/SnO2–Sb substrates by galvanostatic anodic deposition in a newly proposed methanesulfonate electrolytic solution. Phase constituents and microstructures of the deposited PbO2 coatings were characterized. Increasing current density in the range ≤ 100 mA cm− 2 leads to the formation of highly textured coatings with an increased content of α-PbO2 phase. Concurrently, a high current density favors a compact and flat surface morphology. The study of deposition time indicates a change of crystallite growth manner from an initially random growth to a later-stage preferred growth along distinct orientations. The change of crystallite growth is corroborated by the cross-sectional microstructures of the PbO2 deposits. The microstructural transition occurs only in the initial deposition stage. After a brief period, prolonged electrodeposition barely changes the surface morphology of PbO2 coatings.

Fluorescence-labeled self-healing microcapsules demonstrate the excellent ability to heal microcracks, and can also visualize the healing process of microcracks. The healing process of internal and external microcracks was visualized and quantified with laser scanning confocal microscope (LSCM) and step profiler. When 3.0 wt% microcapsules were incorporated into cement-based materials, the strength recovery rate was the highest, reaching 35.8%, and the healing effect of external microcracks reached 19.2%. When microcracks appear inside the resin matrix, fluorescence-labeled self-healing microcapsules can not only detect the specific location of the microcracks but also repair them, and quantify the width of microcracks. The change in the pore structure of cement-based self-healing materials is mainly due to the release of core materials into the microcracks and pores, thereby achieving the healing effect. It provides a unique insight into the visualization and quantification of self-healing behaviors of microcracks.

Twist-angle two-dimensional systems, such as twisted bilayer graphene, twisted bilayer transition metal dichalcogenides, twisted bilayer phosphorene and their multilayer van der Waals heterostructures, exhibit novel and tunable properties due to the formation of Moiré superlattice and modulated Moiré bands. The review presents a brief venation on the development of “twistronics” and subsequent applications based on band engineering by twisting. Theoretical predictions followed by experimental realization of magic-angle bilayer graphene ignited the flame of investigation on the new freedom degree, twist-angle, to adjust (opto)electrical behaviors. Then, the merging of Dirac cones and the presence of flat bands gave rise to enhanced light-matter interaction and gate-dependent electrical phases, respectively, leading to applications in photodetectors and superconductor electronic devices. At the same time, the increasing amount of theoretical simulation on extended twisted 2D materials like TMDs and BPs called for further experimental verification. Finally, recently discovered properties in twisted bilayer h-BN evidenced h-BN could be an ideal candidate for dielectric and ferroelectric devices. Hence, both the predictions and confirmed properties imply twist-angle two-dimensional superlattice is a group of promising candidates for next-generation (opto)electronics.

This study reports on a novel encapsulation rolling process for producing thin crack-free W-18.5 wt%Cu composite sheets. An increased rolling reduction ratio leads to the majority of the tungsten (W) particles being deformed and elongated along the rolling direction. Some W particles break into small particles under the large rolling force, resulting in a significant reduction in particle size. The rolling reduction ratio significantly affects the mechanical and electrical properties. It is observed that the highest values of relative density and hardness are 99.8% and 457 HV, after a total thickness reduction of 75%. The electrical conductivity, thermal conductivity and coefficient of thermal expansion (CTE) decreases significantly with the rolling reduction ratio. At the rolling reduction ratio of 75%, the W-Cu composite achieves a low CTE of 7.19 × 10−6/K but with a low thermal conductivity of 129.18 W/(m K). Furthermore, annealing at 1000 °C shows a negligible effect on the electrical and thermal conductivities of the W-Cu composite sheet when the annealing time is less than 3 h. Instead of the matrix phases, the W-Cu interfaces are deemed to play a significant role in determining the electrical and thermal conductivities. Therefore, improving the W-Cu interfacial bond is crucial to achieving high electrical and thermal conductivity while maintaining a low CTE.

Photoluminescent lytropic liquid crystals (LLCs) were prepared in aqueous solutions from n-dodecyl tetraethylene monoether (C12E4) and Tyloxapol, which is an oligomer of polyoxyethylene tert-octylphenyl ether (TX-100) with a polymerization degree below 7. The close packing of the seven benzene rings in Tyloxapol induces a strong π–π interaction, which makes Tyloxapol fluorescent. The Tyloxapol/C12E4 mixed system were characterized by polarized optical microscopy (POM) observations, small-angle X-ray scattering (SAXS), rheological and fluorescence measurements with close comparison to the TX-100/C12E4 mixture. It was found that the type of LLCs transfered gradually from lamellar phase to hexagonal phase with increasing mass ratio of Tyloxapol to C12E4, during which an enhanced photoluminescence was observed. Our results showed that encapsulation of fluorescent molecules into the matrix of traditional surfactants could be an effective way for the preparation of photoluminescent LLCs.

Wave absorption, self-healing microcapsules (W/SMCs) were fabricated by solvent evaporation method with epoxy resin (ER) as core material, carbonyl iron powder (CIP) and ethyl cellulose (EC) as hybrid wall. Micromorphology, encapsulated indicator, thermal stability, wave absorption and self-healing properties of microcapsules (MCs) were tested. The results showed that MCs had good appearance when sodium dodecyl sulfate (SDS) concentration was 0.1 %, and MCs doped with CIP had higher thermal decomposition temperature, magnetic loss performance and better low-frequency microwave absorption characteristics. Compressive strength of pure paste increased first and then decreased with the increasing of MCs dosage. The self-healing strength and recovery rate of compressive strength of pure paste with 9 % MCs reached maximum value of 33.8 MPa and 36.01 %, respectively. MCs have both dielectric loss properties of organic materials and magnetic loss properties of CIP.

W-30 wt.% Cu composite powders with homogenous distribution of W and Cu nanoparticles were successfully synthesized by a sol-gel procedure combined with hydrogen reduction. These ultrafine particles smaller than 150 nm exhibited favorable sinterability when densified by field assisted sintering technique (FAST) at the temperatures below the melting point of Cu. Moreover, the as-sintered composites inherited the ultrafine and homogeneous characteristics of the initial particles. The final densities of the sintered samples showed a strong dependence on the sintering temperature and applied pressure. By increasing the sintering temperature or pressure, denser composites with higher thermal conductivity and lower coefficient of thermal expansion (CTE) could be obtained. Specifically, the samples sintered at 950 °C under 120 MPa for 10 min achieved a maximum relative density of 97.3%, exhibiting an excellent thermal conductivity (235.48 W/(m K)) and a relatively low CTE of 9.27 × 10 −6 /K.

Resin light conductive cementitious materials (RLCCM) is a kind of advanced composite materials with good prospects for development, but there is the most vulnerable area on the interface of RLCCM. To find out the effect of coupling agent on interface bonding mechanism of organic-inorganic composite, the micro-hardness, micro-topography, surface morphology structure and chemical reaction of organic transparent resin and inorganic cement matrix interface were evaluated by the micro-hardness tester, environmental scanning electron microscopy (ESEM), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FTIR) tests. The results show that the silane coupling agent A-151 and aluminate coupling agent not only reduced the transparent resin performance weakened region thickness up to 100 μm and the micro-hardness in the transition region was increased by 19.6% and 39.9%, respectively, but also improved the micro-hardness of the surface of the cement matrix in the range of 30 μm, 20 μm to 22.2 and 21.9 MPa, respectively. The interface treated with silane coupling agent A-151, the interfacial micro cracks caused by the sampling process have narrowed and discontinuous in the direction of length. The interface treated with aluminate coupling agent, although the boundary between transparent resin and cement matrix still exists, but the micro cracks caused by the sampling process is almost disappeared, and two substances are closely combined together to present a natural transition state. Silane coupling agent A-151 and cement hydration products formed flat spherical particle diameter of about 78 nm, and these particles mosaiced and fused in the surface of hydrate as a whole, therefore the surface become more denser and smoother. Hydrolyzing silane coupling agent A-151 to produce silanol (–SiOH), which could react with hydroxy (–OH) function groups of CSH to form Si–O–Si bond. Hydrophilic inorganic groups of aluminate coupling agent reacted with hydroxyl (–OH) function groups of CSH to form Al–O–Si bond, and hydrophilic organic groups and resin make crosslinking, twisting reaction happened.

Ratcheting behavior of 90 elbow piping subject to internal pressure 20 MPa and reversed bending 20 kN was investigated using experimental method. The maximum ratcheting strain was found in the circumferential direction of intrados. Ratcheting strain at flanks was also very large. Moreover, the effect of temperature on ratcheting strain of 90 elbow piping was studied through finite element analysis, and the results were compared with room condition (25). The results revealed that ratcheting strain of 90 elbow piping increased with increasing temperature. Ratcheting boundary of 90 elbow piping was determined by Chaboche model combined with C-TDF method. The results revealed that there was no relationship between the dimensionless form of ratcheting boundary and temperature.

The increased public concerns on healthcare, the environment and sustainable development inspired the development of biodegradable and biocompatible electronics that could be used as degradable electronics in implants. In this work, a fully biodegradable and flexible resistance random access memory (RRAM) was developed with low-cost biomaterial gelatin as the dielectric layer and the biodegradable polymer poly(lactide-coglycolide) acid (PLGA) as the substrate. PLGA can be synthesized by a simple solution process, and the PLGA substrate can be peeled off the handling substrate for operation once the devices are fabricated. The fabricated memory devices exhibited reliable nonvolatile resistive switching characteristics with a long retention time over 104 s and a near-constant on/off resistance ratio of 102 even after 200 bending cycles, showing the promising potential for application in flexible electronics. Degradation of the devices in deionized water and in phosphate buffered saline (PBS) solution showed that the whole devices can be completely degraded in water. The dissolution time of the metals and the gelatin layer was a few days, while that for PLGA is about 6 months, and can be modified by changing the synthesis conditions of the film, thus allowing the development of biodegradable electronics with designed dissolution time.