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In this experiment, the rare earth Gd element was added to Finemet alloy to observe the microstructure and soft magnetic properties. The experimental results showed that the samples with the addition of 0.5% Gd and 1.0% Gd can be quenched and cast normally, and the MS of Fe73Cu1Nb3Si13.5B9Gd0.5 alloy was 10.41% higher than that of Finemet. After annealing, crystal grains of about 10 nm were formed. The μi and μm values of Fe73Cu1Nb3Si13.5B9Gd0.5 alloy were 25.51% and 22.23% higher, respectively, and the coercivity HC was reduced by 12.19% compared to Finemet. At 1 kHz, the μe value of Fe73Cu1Nb3Si13.5B9Gd0.5 alloy at room temperature was 14.57% higher than that of Finemet, while the μe reached 162.34 k and 142.42 k at 90 °C and 150 °C (24% and 29.51% higher, respectively). The Fe72.5Cu1Nb3Si13.5B9Gd1.0 alloy had the best performance at 100 kHz, with higher μe values than Finemet across the ambient temperature range of 30 °C to 150 °C. After tension annealing, the μe values of Fe72.5Cu1Nb3Si13.5B9Gd1.0 alloy were 20–30% higher than those of Finemet. [ABSTRACT FROM AUTHOR]

Adjusting fibers shape can further optimize absorbing properties of the FeSiAlp/PP fibers composites. 80 wt% FeSiAlp/PP rhombic cross-sectional fibers were successfully prepared by liquid phase blending and extrusion drawing. The strength of the fibers is about 6 ~ 8 MPa. The effective absorption bandwidth (EAB, RL < −10 dB) of the resin matrix composites modified by rhombic cross-sectional fibers is 3.9 GHz and the optimal RL reaches −18.43 dB at 4.5 GHz. Compared with the resin matrix composites modified by circular cross-sectional fibers, the EAB increases by 1.8 GHz and there is a second absorption peak, which has better broadband absorption characteristics. [ABSTRACT FROM AUTHOR]

FeNi nanopowders are dispersed into the polypropylene to form FeNip/PP nanocomposites by a combination method of high-temperature solution blending process and two-step blending process. The excellent dispersion of FeNi nanoparticles led to significant improvements in mechanical and soft magnetic properties. When the powders content is in the range of 1 ∼ 3 wt.%, the strength of PP resin reached its peak strength which is 20 ∼ 27% higher than that of the pure resin. The composites have wave-absorbing properties in the frequency range of 1 ∼ 2 GHz. It was concluded that the multi-step dispersion process is a simple and versatile way for the fabrication of polyolefin-based nanocomposites with superior functionalities. [ABSTRACT FROM AUTHOR]

• New metamaterial design methods was proposed. • Great performance improvement in bandwidth compared with the initial material. • Lighter weight and more widely used. • Analysis of absorbing principle is comprehensive. The thickness and absorption width of electromagnetic wave-absorbing- materials remain a considerable challenge. This paper proposed a new design method for metamaterial absorbers. The absorber is composed of magnetic composites with a periodic structure. The effective absorption bandwidth (reflection loss <−10 dB) achieves 13.4 GHz, from 4.6 GHz to 18 GHz with 3.5 mm thickness (0.05 λ max ). There are two absorption peaks at 6.1 GHz and 10.8 GHz, the reflection loss reaches −20 dB and −15.6 dB, respectively. The loss mechanism is analyzed by analyzing the electric field distribution and surface current. Actual samples were prepared, their reflection losses were measured, and the test results verified the simulation results. [ABSTRACT FROM AUTHOR]

High entropy alloy nanopowders were successfully prepared by liquid-phase reduction methods and their applications were preliminarily discussed. The prepared high entropy alloy nanopowders consisted of FeNi alloy spherical powders and NiFeCoCrY alloy spherical powders with a particle size of about 100 nm. The powders have soft magnetic properties, the saturation magnetization field strength were up to 5000 Qe and the saturation magnetization strength Ms was about 17.3 emu/g. The powders have the excellent property of low high-frequency loss in the frequency range of 0.3–8.5 GHz. When the thickness of the powders coating was 5 mm, the powders showed excellent absorption performance in the Ku band; and when the thickness of the powders coating was 10 mm; the powders showed good wave-absorbing performance in the X band. The powders have good moulding, and the powders have large specific surface area, so that the magnetic powder core composites could be prepared under low pressure and without coating insulators, and the magnetic powder cores showed excellent frequency-constant magnetization and magnetic field-constant magnetization characteristics. In the frequency range of 1~100 KHz; the μm of the magnetic powder core heat-treated at 800 °C reached 359, the μe was about 4.6 and the change rate of μe with frequency was less than 1%, meanwhile; the magnetic powder core still maintains constant μe value under the action of the external magnetic field from 0 to 12,000 A/m. The high entropy alloy nanopowders have a broad application prospect in soft magnetic composites. [ABSTRACT FROM AUTHOR]

Titanium alloys have become indispensable materials for lightweight and high-thrust-to-weight-ratio aeroengines owing to their low densities and high specific strengths. However, as the thrust-to-weight ratio increases, the temperature in an aeroengine increases to values considerably above the service temperature of the titanium alloy. Effective design and preparation of the interface structure are a potential approach to enhance the service life and dependability of thermal barrier coatings (TBCs). In this study, TBCs were prepared by spark plasma sintering (SPS) on Ti-6Al-4V, and a texture was engraved at the bond coating (BC)/top coating (TC) interface by a fibre laser. The laser texturing induced segmentation cracks. High-density segmentation cracks (dense vertical cracks (DVCs)) could be formed at densely spaced areas of the texturing. Based on the bimodal structure characteristic obtained by SPS, bimodal-structured DVC TBCs were realised, which provided the coating with higher strain tolerance and thermal insulation performance. After 138 cycles of thermal shock at 800 °C, the spallation area of a 2-mm square coating was only 34.55 % of that of unengraved TBCs. In addition, the laser-textured coating had a better thermal insulation performance. The thermal insulation temperature of a hexagonal 2-mm coating reached 215 °C. [Display omitted] • Induced segmentation cracks in thermal barrier coatings by laser texturing • Thermal barrier coatings with density segmentation cracks and bimodal structures were realised • Laser texturing at the interface gave the better thermal insulation performance [ABSTRACT FROM AUTHOR]

The Fe50Ni50 alloy powders were successfully synthesized with the liquid phase reduction method and then treated with the transverse magnetic field of 200 kA/m. The influences of transverse magnetic field treatment on microstructures and radar absorbing properties of the powders were mainly investigated. Whether the powders were treated with the transverse magnetic field or not, the main phases of Fe50Ni50 alloy powders were FeNi 3 and a small amount of Fe 2 O 3 . Results showed that the real part of complex permeability μʹ; of the Fe50Ni50 alloy powders in 1–5 GHz increased significantly, especially at the frequency of 1 GHz, the μʹ; increased from 2.2 to 2.8 after transverse magnetic field treatment. The magnetic loss tanδm of the Fe50Ni50 alloy powders after transverse magnetic field treatment was ≥0.3 in the frequency range of 1–13 GHz and 0.7–1.05 in the frequency range of 3.5–9.0 GHz. Compared with those of the untreated powders, the wave-absorbing properties of the powders after transverse magnetic field treatment were significantly improved. The Fe50Ni50 alloy powders coatings with thickness of 1.5 mm exhibited excellent wave-absorbing properties after transverse magnetic field treatment, and the qualified absorption band width reached nearly 3 GHz when the reflectivity |R| was ≥10 dB. [ABSTRACT FROM AUTHOR]

• A composite structured metamaterial absorber with good wave absorption performance was prepared to cover X-band and Ku-band perfectly at low thickness (2.2 mm). • Investigated the influence of different structural parameters and polarization angles on wave absorption and energy absorption. • The open-hole effect was discovered and proposed, and the study of the corresponding mechanism and influence law can provide technical and theoretical guidance for the design of metamaterial structures of other materials. • The bandwidth of the designed metamaterials is increased by 1.34 times compared with that of pure composite materials. • The combination of numerical simulations and experiments provides a good match between experiments and simulations. In this paper, propose the open-hole effect, which can improve the absorption effect of electromagnetic absorbers in the X- and Ku-band by regularly opening certain shaped through-holes in the dielectric material. Based on this effect, an ultra-wideband metamaterial absorber with a special open-hole structure is designed and successfully prepared by numerical simulation, and the effective wavelength bandwidth (absorption > 90 %) covers X- and Ku-band. By optimizing the dielectric material and structural parameters of the absorber, an ultra-broadband metamaterial absorber with a thickness of 2.2 mm, a maximum absorption rate of 99.35 % and an effective absorption bandwidth of 11.6 GHz was obtained. Simulations of TE and TM waves at different angles show that the absorber has excellent electromagnetic wave absorption at different angles of incidence (θ < 30°). [ABSTRACT FROM AUTHOR]

In this paper, a type of smooth even endogeny conversion coat composed of Cu 0.86 Fe 2.14 O 4 and (Cu 0.18 Fe 0.82 )Cu 0.82 Fe 1.18 O 4 phases was successfully obtained by a conversion reaction on the surfaces of Fe 71.5 Cu 1 Nb 3 Si 13.5 B 9 V 2 amorphous alloy ribbons. In this way, its ribbon thickness was decreased about 6–8 µm equivalently. The phase composition and microstructure of the conversion coat were investigated by XRD and SEM. In addition, the adhesion test of epoxy resin and amorphous alloy ribbon was verified by dipping experiments. It is found that the interface bonding strength between the conversion coat and ribbons is strong comparatively. On one hand, the proper interface between conversion coat and epoxy resin make it easy for ribbons to be encapsulated; on the other hand, the ribbons perform better significant piezomagnetic effect than the untreated ones due to a thinner thickness. This work may be a good basic for the applications of Fe 71.5 Cu 1 Nb 3 Si 13.5 B 9 V 2 amorphous alloy ribbons in piezomagnetic sensor and other devices based on the piezomagnetism effect. [ABSTRACT FROM AUTHOR]

• The addition of magnetic materials broadens the effective absorption bandwidth. • Synergy between dielectric and magnetic losses strengthens microwave absorption. • The composite structure design improves the wave absorption performance. • 3 mm CSMMA has an effective absorption bandwidth of 11.53 GHz. The requirements for electromagnetic wave absorbing materials are increasing as modern technology advances. However, traditional absorbing materials have limitations due to their thickness and incompatibility with high and low frequencies, and metamaterial absorbers have limitations due to their narrow effective absorption bandwidth. This paper overcomes these problems and designs and prepares a broadband, thin and light metamaterial absorber. The effective absorption bandwidth of the composite structure metamaterial absorber (CSMMA) with a thickness d 1 of 3 mm reaches 11.55 GHz with the addition of FeSiBPCuY 5 p/paraffin magnetic composite into the metamaterial absorber and the optimization of the structural parameters. The composite structure design greatly improves the absorption performance of the metamaterial absorber. The advantages of the tunable frequency absorption characteristics of the metamaterial absorber and the high-frequency broadband absorption performance of the magnetic wave absorbing materials are fully exploited in the design of the absorber. Which is of great significance for the development of broadband and thin-absorbing materials. This absorber can be adapted to meet the needs of practical applications by adjusting its structural design, expanding its range of applications and having a substantial influence on the use of wave absorbing materials. [ABSTRACT FROM AUTHOR]

• The absorber with special structure design not only overcomes the problem of narrow absorption band of metamaterials, but also solves the shortcoming of weak C-band absorption effect of magnetic material absorber. • The wave-absorbing properties of the FeSiAl p /epoxy resin composite is greatly improved compared with the simple FR4 matrix material, the effective bandwidth (bandwidth with reflectance less than −10 dB) increased by 11.4 times from 0.32 GHz to 4.29 GHz, and the absorber has obvious C-band absorption effect. • After optimizing the dimensions of absorber, the FeSiAlp/epoxy resin composite absorber with a thickness of 2.2 mm reached peak simultaneously at 7.20 GHz and 15.40 GHz, and peak reflectivity reached −11.51 dB and −13.01 dB, respectively, and corresponding absorption reached 92.93% and 95.00%, respectively. The effective bandwidth reached 4.29 GHz, and the absorber had obvious absorption effect in C-band. A novel broadband incident angle independent magnetic composite metamaterial absorber with C-band absorbing effect is proposed. The wave-absorbing properties of the FeSiAl p /epoxy resin composite is greatly improved compared with the simple FR4 matrix material, the effective bandwidth (bandwidth with reflectance less than −10 dB) increased by 11.4 times from 0.32 GHz to 4.29 GHz, and the absorber has obvious C-band absorption effect. After optimizing the dimensions of absorber, the FeSiAlp/epoxy resin composite absorber with a thickness of 2.2 mm reached peak simultaneously at 7.20 GHz and 15.40 GHz, and peak reflectivity reached −11.51 dB and −13.01 dB, respectively, and corresponding absorption reached 92.93% and 95.00%, respectively. The effective bandwidth reached 4.29 GHz. The experiment basically verified the simulation results. Therefore, the absorber with special structure design not only overcomes the problem of narrow absorption band of metamaterials, but also solves the shortcoming of weak C-band absorption effect of magnetic material absorber. [ABSTRACT FROM AUTHOR]

Firstly, the spherical Fe50Ni50 powders, particle size about 100 nm, were prepared by liquid phase reduction method, and then were mixed with butyl rubber (IIR) dispersed in liquid. Fe50Ni50 powders/IIR nanocomposite films, powder mass fraction was 65 wt%, were harvested through being mixed and milled lastly. The force sensitive properties of the films were studied under the condition of that the loading/unloading speed of the stress was 0.10 mm/min controlled by the LYYL-500N high-grade microcomputer controlling compression-testing machine, and the test frequency of impedance (Z) was 1 kHz tested with the TH2816B LCR digital electric bridge. Results show that Fe50Ni50 powders can be dispersed uniformly as nanometer scale in this nanocomposite by liquid phase mixing method. And the Fe50Ni50 powders/IIR nanocomposite film, thickness 185 μm, has excellent force–sensitive properties when the stress is between 0.20Mpa and 0.90Mpa. The impedance ∼ stress curve appears approximately linear decline, and stress sensitivity |k| value is stable in 40–60, stability S value is about 1∼ 2 kΩ, and the film enters into a steadily sensitive stage responding to stress. [ABSTRACT FROM AUTHOR]

Synthetic dyes in the aquatic environment caused various ecological and health problems that are detrimental to sustainable development. To solve these problems, we designed a dense Fe 3 Ni 2 phase alloy film (FeNi-M) on copper substrate by the directional magnetic field-assisted wet chemical film formation method. The degradation and adsorption of Congo red (CR) in water were achieved by using the surface activity of the film. The degradation rate of FeNi-M alloy film reached 99.5% at 48 h and the k obs is 0.10982 h−1, which is 2.1 and 7.5 times of FeNi alloy film (0.05147 h−1) and Ni film （0.01465 h−1）, respectively. The degradation processes of all three films were in accordance with the pseudo-first-order kinetic model. In addition, FeNi-M alloy films have excellent cycling performance with more than 90% removal rate after 5 cycles. We also discussed the possible degradation mechanism and pathway of CR. We speculated that the main part of alloy responsible for providing electrons were iron atoms and very few electrons were produced by nickel. However, nickel was beneficial to increase the activity of iron atoms and played a catalytic role, thereby greatly enhancing the efficiency of iron atoms on the reaction. Synthetic dyes in the aquatic environment caused various ecological and health problems that are detrimental to sustainable development. To solve these problems, we designed a dense Fe 3 Ni 2 phase alloy film (FeNi-M) on copper substrate by the directional magnetic field-assisted wet chemical film formation method. The degradation and adsorption of Congo red (CR) in water were achieved by using the surface activity of the film. The degradation rate of FeNi-M alloy film reached 99.5% at 48 h and the k obs is 0.10982 h−1, which is 2.1 and 7.5 times of FeNi alloy film (0.05147 h−1) and Ni film （0.01465 h−1）, respectively. The degradation processes of all three films were in accordance with the pseudo-first-order kinetic model. In addition, FeNi-M alloy films have excellent cycling performance with more than 90% removal rate after 5 cycles. [Display omitted] The data that support the findings of this study are available from the corresponding author upon reasonable request. [ABSTRACT FROM AUTHOR]

• A new type of FeSiBY amorphous alloy flexible force-sensitive film have been developed in this paper. By increasing the number of film layers, the linear range of the piezomagnetic curve of the film can be effectively broadened. • The piezomagnetic sensor composed of FeSiBY film has the advantages of high sensitivity, wide sensing range, fast response speed, strong anti-interference ability and good repetitiveness, it can be used to test both static compressive stress and dynamic compressive stress and can meet the requirements of subtle stress detection and complex surface test. • We provided a simple, low-cost, and strong anti-interference solution for making flexible film sensors. This sensor is applied to a variety of human physiological activities (such as pulse, pronunciation, joint bending, etc.) with good results. It has broad application prospects in wearable electronic devices and health monitoring. Flexible force-sensitive sensors are widely used in wearable devices, electronic skins, human-computer interaction and other fields due to their simple manufacturing process, low cost, strong flexibility and great integration potential. A new type of FeSiBY amorphous alloy flexible force-sensitive film and its sensor has been developed in this paper. The film had high elastic modulus, microhardness and higher phase transition temperature. The piezomagnetic effect of this new type of film was significantly better than the Fe 78 Si 13 B 9 amorphous alloy film currently used. The single-layer FeSiBY film exhibits a linear change in the micro-stress range of 0–1.2KPa, and the sensitivity was as high as 88.87μH/KPa, which was far better than Fe 78 Si 13 B 9 amorphous alloy film's (the highest was only 0.52μH/KPa). By increasing the number of film layers, the linear range of the piezomagnetic curve of the film can be effectively broadened. The upper limit of the linear range of the piezomagnetic curve of the sensor after 4 layers of films was superimposed reaches 16KPa, and the sensitivity still reached 6.84 μH/KPa. In the area of linear change of the piezomagnetic curve, the loading piezomagnetic curve of FeSiBY film was highly consistent with the unloading piezomagnetic curve, and there was no elastic hysteresis. Meanwhile, the environmental temperature had little effect on the piezomagnetic curve. The piezomagnetic sensor composed of FeSiBY film had the advantages of high sensitivity, wide sensing range, fast response speed, strong anti-interference ability and good repetitiveness, it can be used to test both static compressive stress and dynamic compressive stress and can meet the requirements of subtle stress detection and complex surface test. The sensor was applied to a variety of human physiological activities (such as pulse, pronunciation, joint bending, etc.) with good results. This flexible force-sensitive film sensor has broad application prospects in wearable electronic devices and health monitoring. This article provides a simple, low-cost, and strong anti-interference solution for making flexible film sensors with good force-sensitive properties. [ABSTRACT FROM AUTHOR]

In recent years, the development of lightweight broadband absorbers has always been pursued by researchers. In this paper, a low-frequency, broadband and lightweight absorber is designed and prepared by combining the metamaterial structure with the magnetic composite material. First of all, the quality of the absorber was low, which was 40% lower than that of traditional absorber composite materials. Secondly, the absorber had excellent absorbing effect, and its absorbing bandwidth (bandwidth with reflectivity less than −10 dB) reached 6.72 GHz, and its RL min (minimum reflection loss) value had dropped to − 23.94 dB. Finally, the absorber also had obvious effects at low frequencies, the absorber's RL min value reached − 10.10 dB at 7.36GH. Simultaneously, the experimental results also verify the above results very well. Therefore, this kind of absorber gives full play to the advantages of magnetic composite material and metamaterial structure. This design concept provides a new development path for the design of absorber materials, and will also play a huge role in promoting the application of absorbing materials in military and civilian fields, such as the research and development of a new generation of stealth fighters. [ABSTRACT FROM AUTHOR]

Titanium alloys play an important role in lightweight aircraft engines owing to their low densities and high specific strengths. However, an increase in the thrust-to-weight ratio causes the engine operating temperature to be much higher than the service temperature, which deteriorates the oxidation resistance and mechanical properties. In this study, yttria-partially stabilised zirconia (8YSZ)/NiCrAlY thermal barrier coatings (TBCs) with a bimodal structure were prepared on Ti–6Al–4V by using spark plasma sintering (SPS) to improve the service temperature. The distinctive bimodal structure possessed dense particle contacts and a uniform distribution of porous nanoparticles, resulting in higher strain tolerance, sintering resistance, and lower thermal conductivity. Therefore, the bimodal structure prepared by lowering the SPS preparation temperature increased the high-temperature service time of TBCs on titanium alloy. The ceramic top coating (TC) and bond coating (BC) were well connected after isothermal oxidation at 800 °C for 100 h. The TBCs only shed 6% of their surface area at high temperature and large-angle bending. In addition, the bimodal-structured TBCs effectively improved the oxidation resistance of the Ti–6Al–4V substrate. The Ti–6Al–4V substrate with bimodal-structured TBCs only gained 0.51 times the mass gained by the bare Ti–6Al–4V after 100 h of isothermal oxidation. [ABSTRACT FROM AUTHOR]

• The composite film with two layers can correct the fluctuations in the initial stage of the force-sensitive curve and improve the stability of the force sensitivity at the initial stage. • The composite film has high force-sensitive properties in the compressive stress interval of 0–0.1 MPa, when the thickness of the film is 200–230 μm, the film has the highest sensitivity. • The force-sensitive film is the most stable and sensitive one among the current piezomagnetic force-sensitive films. Piezomagnetic sensor is a subject undergoing intense study. In this paper, a force-sensitive composite film with two layers was designed, and the force-sensitive properties of the film at σ ≤ 0.2 MPa was studied by inductance measurement. The composite film with a complex force-sensing mechanism can correct the fluctuations in the initial stage of the force-sensitive curve and improve the stability of the force sensitivity at the initial stage. Compared to the force-sensitive properties of Fe 78 Si 13 B 9 amorphous alloy film, the composite film's is significantly higher. When the thickness of the composite film is 180–250 μm, the film has high force-sensitive properties in the compressive stress interval of 0–0.1 MPa, the force-sensitive curve in the sensitive interval is linear approximation. When the thickness of the composite film is 200 μm and the test frequency f = 1 KHz, the sensitivity of the pressure sensor is as high as 0.27 μH/KPa in a wide pressure interval (0 ~ 0.06 MPa). When the thickness of the composite film is 230 μm and the test frequency is 1 KHz, the sensitivity of the pressure sensor is as high as 0.59 μH/KPa in a wide pressure interval (0 ~ 0.02 MPa). The force-sensitive film is the most stable and sensitive one among the current piezomagnetic force-sensitive films. In addition, it has broad application prospects. [ABSTRACT FROM AUTHOR]

• Fe 78-x Si 13 B 9 Y x alloy powders with excellent absorbing properties were prepared. • The mechanism of yttrium's influence on absorbing performance was explored. • The minimum interference thickness at 0.3 GHz decreased by 56.5%. • The performances were due to synergistic effects of components and structure. In this study, the effect of rare earth Y on the microwave absorbing properties of the powders was studied, directing against low electromagnetic loss (tanδ) and low dielectric constant of Fe 78 Si 13 B 9 alloy powders in the frequency band of 0.3–3 GHz. The results showed that when Y content is less than 2 at%, Y solid dissolves in dendrite gap of α-Fe, forming interstitial solid solution. With the increase of Y content, the permeability and dielectric constant of Fe 78-x Si 13 B 9 Y x alloy powders increase, especially the dielectric loss and magnetic loss increase significantly. Fe 76 Si 13 B 9 Y 2 alloy powders have excellent absorbing properties. When the frequency is 0.3 GHz and 1 GHz, the loss tangent value of that is as high as 5.22 and 2.42 respectively, and the minimum interference thickness is reduced to 11.81 mm and 5.20 mm, which is 45% of that of Fe 78 Si 13 B 9 alloy powders. Fe 76 Si 13 B 9 Y 2 alloy powders has excellent electromagnetic loss absorption and interference absorption properties at the same time. [ABSTRACT FROM AUTHOR]

In this paper, a single phase ε-Fe(Si)3N powder was successfully synthesized through the salt bath nitriding reaction method. The flaky FeSi alloy powder was used as the iron source, and non-toxic CO(NH2)2 was used as the nitrogen source. The nitridation mechanism, the preparation technology, the soft magnetic properties, and the magnetization temperature dependence of the powder were studied. The research result showed that ε-Fe(Si)3N alloy powders were synthesized in a high temperature nitrification system after the surface of flaky FeSi alloy powders were activated by a high-energy ball mill. The optimum nitriding process was nitridation for 1 h at 550 °C. The ε-Fe(Si)3N powder had good thermal stability at less than 478.8 °C. It was shown that ε-Fe(Si)3N powder has good soft magnetic properties, and the saturation magnetization of the powder was up to 139 emu/g. The saturation magnetization of ε-Fe(Si)3N powder remains basically constant in the temperature range of 300–400 K. In the temperature range of 400–600 K, the saturation magnetization decreases slightly with the increase of temperature, indicating that the magnetic ε-Fe(Si)3N powder has good magnetization temperature dependence. [ABSTRACT FROM AUTHOR]

Abstract In this study, flaky Fe 95 Si 1 B 2 P 0.5 Cu 1.5 powders with a particle size of 48–75 μm were compounded with graphene (GR) by high-energy ball milling to prepare GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders. The electromagnetic parameters of GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders in the frequency band of 0.3–8.5 GHz were determined by a vector network analyser. The influence of milling time and graphene content on the electromagnetic parameters of GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders was studied. The results showed that with the increase of graphene content, magnetic permeability and dielectric constant increase simultaneously. The 1.0 wt% GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite powders prepared by milling for 24 h exhibited the best absorbing property. In the frequency band of 0.3–8.5 GHz, for 1.0 wt% GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite, the dielectric constant was 182.4–18.2, and the magnetic permeability was 7.3–1.0. The dielectric loss tangent was 3.40–6.60, the magnetic loss tangent was 0.48–3.46, and their sum was 5.28–8.60; therefore, 1.0 wt% GR/Fe 95 Si 1 B 2 P 0.5 Cu 1.5 composite exhibited excellent absorbing properties. [ABSTRACT FROM AUTHOR]

To meet the current requirements for absorbing materials with broadband, lower thickness, and lower density, the FeNi@C@Fe 3 O 4 magnetic powders with a density of 1.75 g/cm3 are constructed by the hydrothermal method and the liquid phase reduction method. The powders have good matching performance with air impedance in the band of 0.3 GHz ~ 18 GHz, and can consider both dielectric loss and magnetic loss-absorbing mechanisms. The loss tangent, tgδ, of the powders is 0.4–0.5. The powder coat is designed by using the interference absorption mechanism. When the thickness of the coat is 1.8 mm, the absorption peak of the coat is about − 30 dB. The coat has a maximum of effective absorption band for 12.2 GHz ~ 17.3 GHz, and the effective absorption bandwidth is 5.1 GHz. When the glass fiber/epoxy resin composite material of thickness 0.5 mm is coated on the FCFp coat of thickness 1.7 mm, the effective absorption band is further widened to 11.9 GHz ~ 17.6 GHz, and the effective absorption bandwidth reaches 5.7 GHz. The FeNi@C@Fe 3 O 4 powders have the characteristics of dielectric and magnetic loss-absorbing materials, and have the remarkable advantages of the wider effective absorption bandwidth and the lower density, which is a kind of high-efficiency absorbing material with outstanding comprehensive absorption performance. [Display omitted] [ABSTRACT FROM AUTHOR]

• Graphene/Fe 93.5 Si 3.5 Gd 3 composite powders with good wave attenuation performance were prepared. • The mechanism of the effect of graphene and ball milling time on wave attenuation performance was investigated. • Compared with the control group, the real part of dielectric constant rises by up to 472.94% and the real part of permeability increases by up to 23.80%. • The electromagnetic loss reaches 1.20 ∼ 11.78, which is up to 718.06% higher than the control group. In this paper, different graphene (GR)/Fe 93.5 Si 3.5 Gd 3 composite powders were prepared via high-energy ball milling. Through the analysis of the structural morphology and electromagnetic parameters of the composite powder, the effects of ball milling time and graphene on the wave absorption properties of the composite powder were investigated. It is shown that in the ball-milled composite powder, graphene is compounded with the alloy powder in an amorphous state, and the particle size of the composite powder decreases with the increase of ball milling time. Moreover, the addition of graphene and the introduction of high-energy ball milling did improve the electromagnetic parameters of the composite powder. With other conditions guaranteed to be the same, the real part of dielectric constant of the composite powder rises by up to 472.94% and the real part of permeability increases by up to 23.80%. The optimized change of electromagnetic parameters increases the conduction loss of the composite powder, together with the combined effect of spatial polarization and orientation polarization, it increases the dielectric loss of the composite powder. The magnetic loss of the composite powder is also greatly improved by the change of the main mode of magnetic loss to natural resonance. The increase in dielectric loss and magnetic loss has greatly improved the electromagnetic wave absorption performance of the composite powder. Among them, at 0.3 ∼ 8.5 GHz, the electromagnetic loss of 1.0 wt% GR/Fe 93.5 Si 3.5 Gd 3 ball milled for 24 h reaches 1.20 ∼ 11.78. With other conditions being the same, it is respectively 718.06% and 708.22% higher than the composite powder without graphene and the composite powder with the shortest ball milling time, showing excellent microwave attenuating performance. [ABSTRACT FROM AUTHOR]

• Flake FeSiBPCu-N powders were prepared by high temperature nitriding reaction. • FeSiBPCu-N powders show high dielectric loss and thin interference thickness. • Sandwich structure with 1 mm interlayer has excellent absorbing properties in C-band. Firstly, the flake Fe 95 Si 1 B 2 P 0.5 Cu 1.5 alloy powders were prepared by the combined technology of "medium frequency melting + 3D printing + high energy ball milling", and then the flake single phase ε-Fe 3 (SiBPCu)-N powders were prepared by the chemical high temperature nitriding reaction using the flake alloy powders prepared as the precursors. The samples were characterized by Field Emission Scanning Electron Microscope (FESEM), X-ray Diffractometer(XRD) and Vector Network Analyzer, and the electromagnetic parameters and electromagnetic loss mechanism of the alloy powders prepared by different nitriding processes in 0.3–8.5 GHz band were focused, and wave-absorbing properties were optimized according to the transmission line theory finally. FESEM showed that holes were formed on the surface of the powders after nitriding, which was easy for electromagnetic waves to be absorbed. XRD confirmed that the physical phase structure of the alloy powder prepared after salt bath nitriding was ε-Fe 3 N, and average crystallite size of ε-Fe 3 N increased with the complete nitriding reaction. The generation of ε-Fe 3 N phase lead to an increase in the real part of the complex permittivity of the alloy powder, and the real part of the permeability decreases slightly, however, larger average crystallite size of ε-Fe 3 N is beneficial for the improvement of the permeability. After the nitriding reaction at 580 °C *1h, the loss mechanism of alloy powders is changed from magnetic loss dominated to a dual loss mechanism of dielectric loss dominated and magnetic loss supplemented, and the loss angle tangent value increased from 0.6 to 0.7 to 2.3–1.0, and the thickness values of interference absorption decreased significantly, which is conducive to the realization of the effect of strong absorption of thin material. Taking a multilayer laminate thickness of 5.0 mm as the design index, the optimized GF/FeSiBPCu-N powders (thickness of 1 mm)/GF composite plate has excellent wave absorption in the C-band with reflectivity R < −10 dB in the frequency band of 5.52 ∼ 8.5 GHz and a bandwidth of nearly 3 GHz, which has achieved a breakthrough. [ABSTRACT FROM AUTHOR]

In this paper, a kind of zero valent FeNi alloy nano powder was coated on the surface of SrFe-MOF powder by a simple, efficient and pollution-free method, forming a core-shell type FeNi p @SrFe-MOF Magnetic powder (FSM). The FSM powder has a porous structure and a specific surface area of 9.16 ​m2/g. Under normal temperature and without changing the pH value of the wastewater, the FSM magnetic powder has an immediate and efficient removal effect on Congo Red (CR) dye wastewater. Furthermore, the powder has good cycling performance, with the CR removal rate remaining above 90% after five cycles. Also at room temperature and without changing the pH value of the wastewater, the FSM magnetic powder provides some immediate, efficient, and repeated use degradation of Cr(VI) wastewater. The FSM magnetic powder has good magnetic properties so that can be easily separated and recovered by magnetic field treatment, which solves the problem of efficient recovery of raw materials in wastewater treatment. FSM magnetic powder has broad application prospects for treating wastewater. In this paper, a kind of zero valent FeNi alloy nano powder was coated on the surface of SrFe-MOF powder by a simple, efficient and pollution-free method, forming a core-shell type FeNi p @SrFe-MOF Magnetic powder (FSM). Under normal temperature and without changing the pH value of the wastewater, the FSM magnetic powder has an immediate and efficient removal effect on Congo Red (CR) dye wastewater. Furthermore, the powder has good cycling performance, with the CR removal rate remaining above 90% after five cycles. Also at room temperature and without changing the pH value of the wastewater, the FSM magnetic powder provides some immediate, efficient, and repeated use degradation of Cr(VI) wastewater. The FSM magnetic powder has good magnetic properties so that can be easily separated and recovered by magnetic field treatment. [Display omitted] • FSM powder has an immediate and efficient removal effect on CR at room temperature and without changing the pH value of the wastewater. • FSM powder has some removal effect on Cr(VI) at room temperature and without changing the pH value of the wastewater. • FSM powder has good magnetic properties, which can be separated and recycled by magnetic field treatment. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the collapsing fracture of 60Si2Mn spring flat steels during cold-punching is analyzed by use of an optical microscope, a scanning electronic microscope, an optical stereomicroscopy, an energy dispersive spectrometer, an inductively coupled plasma-mass spectrometry, the hardness testers and a Charpy impact tester. The results show that the collapsing fracture of 60Si2Mn spring flat steels during cold-punching is due to the non- homogenization of microstructures and the nonmetallic inclusions. When the spring flats are cold-punched, the different deformation properties of the inclusions, the ferrites and the cementites initiated micro-cracks. The micro-cracks propagate along the interfaces of ferrites and cementites. The collapsing fracture is characteristic with transgranularity, cleavage and pearlites. The large space lamella pearlites with low strength are the main reason of the cleavage transcrystalline fracture. The prevention measurements are suggested. [Copyright &y& Elsevier]

A quadrature fiber optic Fabry–Perot cavity microphone based on a differential cross multiplication algorithm consists of a pair of fibers and a membrane. It has many advantages such as high sensitivity, a simple structure, and resistance to electromagnetic interference. However, there are no systematic studies on its key performance, for example, its frequency response and dynamic range. In this paper, a comprehensive study of these two key parameters is carried out using simulation analysis and experimental verification. The upper limit of the frequency response range and the upper limit of the dynamic range influence each other, and they are both affected by the data sampling rate. At a certain data sampling rate, the higher the upper limit of the frequency response range is the lower the upper limit of the dynamic range. The quantitative relationship between them is revealed. In addition, these two key parameters also are affected by the quadrature phase deviation. The quadrature phase deviation should not exceed 0.25π under the condition that the demodulated signal intensity is not attenuated by more than 3 dB. Subsequently, a short-step quadrature Fabry–Perot cavity method is proposed, which can suppress the quadrature phase deviation of the quadrature fiber optic Fabry–Perot cavity microphone based on the differential cross multiplication algorithm. [ABSTRACT FROM AUTHOR]

Based on the study of microwave loss percolation effect of FeNi p /PP nanocomposites, the microwave healing technology of FeNi p /PP nanocomposites was proposed and its mechanism was studied. There is a unique microwave loss percolation characteristic between the microwave loss factor (tanδ) of FeNi p /PP nanocomposites and the content of FeNi powders (0–20 wt%), and the percolation area is the range of 2–10 wt%. The microwave healing technology can realize the self-healing property of the PP-based composites. When the composites received the microwave signal, the magnetic nanopowders generate heat effect to heat the resin matrix, which forms a mobile phase. The mobile phase, melted PP matrix with some magnetic nanopowders, moved toward the microcracks, thereby healing or reducing microcracks inside the composite. The optimum time for microwave treatment was 15 min. After microwave healing, the microcracks of the composites were closed, and the tensile strength of FeNi p /PP nanocomposites can be restored to 90% of that before damage. Capsule self-healing materials cannot provide effective crack healing due to the limited volume of healing agent transported by capsules. Moreover, the packaging technology of capsule is complex and the repeatability is poor. Hollow fibers networks can deliver a large number of healing agents to the injured area, but they are not suitable for multiple healing at specific locations, especially for low-level injury events that do not intersect hollow fibers or capsules[10]. The patch has good resistance to cyclic loading damage, strong corrosion resistance and good shape adaptability, but the matching and bonding force between patch and structural materials need to be specially considered. The healing model [11] focuses on the analysis and calculation of the activation mode of the healing mechanism, the interaction between the healing agent and the crack, and how to restore mechanical properties. It can only be used as an evaluation method. [ABSTRACT FROM AUTHOR]