Search

When the thickness of the wave-absorbing material is low, there exists the problem of the narrow wave-absorbing frequency band, making it difficult to regulate the position of the wave-absorbing peak. In this study, FeNi@SrFe-MOF composite powders were synthesized using a hydrothermal method and a liquid-phase reduction method. The composite powder was spherical, with a particle size of about 50 μm–60 μm; the core layers of the powders were porous SrFe-MOF powders with permanent magnetization, and the outer layers were FeNi alloy nano-powder coatings with a particle size of 100 nm–120 nm, which took into account both the soft magnetization and the permanent magnetization properties of the composite powders. Additionally, a directional magnetic field was applied to the powder coating. By regulating the intensity and direction of the magnetic field, the electromagnetic parameters of the composite powder coating underwent sensitive changes, allowing for the precise regulation of the electromagnetic wave absorption performance of the composite powders. With the increase in magnetic field intensity, the ε′ value decreased significantly. The ε′ values were 8.56–7.35 for H453mT and 6.73–6.12 for H472mT. When no magnetic field was applied, the Snoke limit frequency of the μ′ value was 6.0 GHz. When the magnetic field intensity increased, the Snoke limit frequency of the μ′ value increased from 6.0 GHz, without the magnetic field, to 8.3 GHz; the Snoke limit of the composite powders was shattered. After the H453mT magnetic field regulation treatment, the powder coating exhibited good impedance matching characteristics with air. When the magnetic field intensity was 453mT and the thickness of the composite powders coating was 3.5 mm, the composite powders coating showed the strongest absorption peak when the R-value was −59 dB at 7.8 GHz, and the effective absorption bandwidth reached 3.2 GHz, exhibiting superb absorbent qualities. The wave absorption property of the coating can be sensitively changed by the magnetic field regulation treatment at the condition without changing the powder structure or coating structure, which provides a new strategy for the regulation of the wave absorption property and has broad application prospects. [ABSTRACT FROM AUTHOR]

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]

Hydroxyapatite (HAP)/polyetheretherketone (PEEK) composites are widely used in the new generation of bone implant materials. The use of weak magnetic fields can promote the biocompatibility of PEEK materials. In this paper, Fe 50 Ni 50 alloy nanopowders and Fe 50 Ni 50 /HAP/PEEK composites were prepared by liquid phase chemical reduction and liquid phase mixing. The prepared Fe 50 Ni 50 alloy nanopowders have a particle size of about 100 nm and good chemical activity and magnetic properties. The saturation magnetization ( M s ) of the Fe 50 Ni 50 alloy powders is 70 emu g -1 . Fe 50 Ni 50 nano-powders in Fe 50 Ni 50 /HAP/PEEK composites are uniformly distributed in the matrix in the form of individual particles, achieving nano-level dispersion. With the increase of Fe 50 Ni 50 alloy powders content, the magnetic properties of the composites are significantly enhanced. The biocompatibility of Fe 50 Ni 50 /HAP/PEEK composites is significantly better than that of PEEK and HAP/PEEK materials. The 2% Fe 50 Ni 50 /HAP/PEEK composite has the best comprehensive performance, and its biocompatibility is good. The contact angle is only 55.85°. The M s reaches 1.5 emu g -1 and the hardness reaches 42 HBa., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)