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Flexible radar-absorbing materials (RAM) have great application significance in stealth technology. In this paper, a novel RAM based on ferromagnetic nickel micron-fibers with 38-40 mm length and 10-12 µm diameter was successfully prepared through bundle-fiber drawing and electrochemical treatment. The characterization of morphology, chemical composition, magnetic and mechanical properties, including tensile strength, bending rigidity and friction, of the prepared ferromagnetic nickel micron-fiber are investigated. The results showed that compared with conventional radar absorbers, ferromagnetic nickel micron-fibers have many advantages in their appearance and magnetic performance. The total ferromagnetic metal fraction of Ni and Fe was above 90%. Irregular crosssection and large aspect ratio of 3800 of the fiber enabled the magnetic hysteresis loss and absorbing performance to be increased obviously. Its saturation magnetization Ms was 116 emu/g with coercivity Hc of 5.8×103A/m, initial permeability of 2036 H/m and Curie Temperature of 996K, confirming the fiber performed a relatively strong magnetic absorbing effect and high temperature stability. The tensile and friction properties of ferromagnetic nickel micron-fiber were also analyzed to evaluate the spinnability.Abstract: Flexible radar-absorbing materials (RAM) have great application significance in stealth technology. In this paper, a novel RAM based on ferromagnetic nickel micron-fibers with 38-40 mm length and 10-12 µm diameter was successfully prepared through bundle-fiber drawing and electrochemical treatment. The characterization of morphology, chemical composition, magnetic and mechanical properties, including tensile strength, bending rigidity and friction, of the prepared ferromagnetic nickel micron-fiber are investigated. The results showed that compared with conventional radar absorbers, ferromagnetic nickel micron-fibers have many advantages in their appearance and magnetic performance. The total ferromagnetic metal fraction of Ni and Fe was above 90%. Irregular cross-section and large aspect ratio of 3800 of the fiber enabled the magnetic hysteresis loss and absorbing performance to be increased obviously. Its saturation magnetization Ms was 116 emu/g with coercivity Hc of 5.8×10 3 A/m, initial permeability of 2036 H/m and Curie Temperature of 996K, confirming the fiber performed a relatively strong magnetic absorbing effect and high temperature stability. The tensile and friction properties of ferromagnetic nickel micron-fiber were also analyzed to evaluate the spinnability.

Although low‐cost sodium sulphide is used as a reducing agent in most sulphur dyeing processes, it is considered to be environmentally unfavourable because of the resultant contaminated wastewater and the toxic hydrogen sulphide generated during the dyeing process. In the present paper, hydrazine sulphate, glucose, and sodium borohydride in the presence of sodium hydroxide were used as ecologically safe reduction systems for the CI Sulphur Black 1 dyeing of cotton fabric, and results were compared with those obtained using sodium sulphide. Dyeing processes were carried out at 90 °C for 60 min, and the colour yield (the K/S value), dyeing fastness, and breaking strength of dyed fabrics after soaping were measured. Response surface methodology was employed for experimental design and optimisation of results. Mathematical model equations were derived and statistical analysis carried out by computer simulation programming using Minitab v.15. At a dosage of 0.8 g l−1 of CI Sulphur Black 1, the optimum sodium borohydride reduction system (sodium borohydride 0.47 g l−1, sodium hydroxide 0.65 g l−1) exhibited the highest colour yield and the lowest chemical oxygen demand of the residual dyebath.

This study fabricated flexible radar-absorbing knitted compound materials by weft knitting and blending ferromagnetic nickel micron-fibers and cotton fiber into structures with a concave–convex surface, including rhombic, mat, wavy, and leno stitches. The electromagnetic wave-absorbing capability and mechanical properties of the flexible radar-absorbing knitted compound materials were evaluated. The results showed that the rhombic, mat, and wavy stitches displayed high mechanical properties with high bursting strength and there were no significant differences among them. The rhombic stitch flexible radar-absorbing knitted compound material with a ferromagnetic nickel micron-fiber content of 14% had a maximum bandwidth of 13 GHz and achieved a minimum reflectance of −20 dB at 7 GHz, which was 150% that of mat fabric, and 200% that of wavy fabric and leno fabric. This was ascribed to the fact that the concave–convex surface with regular diamond-shaped block improved the dispersion of the electromagnetic wave, weakened the wave strength, and increased the interference. Therefore, the rhombic stitch flexible radar-absorbing knitted compound material was the most suitable for flexible radar-absorbing material in this study. The development of flexible radar-absorbing materials, by combining aerospace technology, military technology and textile technology, is important for the application in stealth of aircraft and weapons.

We report on the impregnation-based preparation of composite phase change materials (CPCMs) with thermal storage properties, using paraffin wax and multi-walled carbon nanotubes (MWCNTs). We coated the CPCMs on the fabric by scraper coating, then evaluated their shape stability, latent heat, thermal conductivity, thermal storage stability and photo-thermal effects. Results show that CPCMs with 10% acid-oxidized MWCNTs introduce only a small phase leakage when heated at 50℃ for 900 s; their latent heat energy reduces by 16.5%, while their thermal conductivity increases by 131.9% compared to pure paraffin. When exposed to sunlight at an ambient temperature of 12.5℃, the cotton fabrics coated with CPCMs record a 12.8℃ higher surface temperature than the pristine fabric, while their heat dissipation is delayed by 120–180 s. The fabric surface temperature increases to twice the ambient temperature during daytime. Overall, these findings indicate that the coated fabric has excellent thermal stability, affirming its potential as photo-thermal functional material.

Shear thickening gel (STG) is a promising substrate used for flexible protective materials, which has superior dimensional stability without gel side leakage and delamination when sustaining long-standing time. STG/high-performance fiber flexible composites exhibit high-energy absorption capacity for multivelocity impact. This article reveals the shear thickening mechanism of STG that lays a theoretical foundation for the performance analysis of STG composites. The preparation methods of STG/high-performance fiber flexible composites, including impregnation, hand lay-up, filling, and lamination methods, are compared. The energy absorption principle of STG/high-performance fiber flexible composites on multi-velocity impact and the destruction morphology was analyzed. The coupling effects and functional applications of STG functional composites with nanoparticles, magnetic particles, and conductive particles are summarized. It provides more suitable conditions for designing new multifunctional protective equipment and manufacturing advanced intelligent, protective devices.