The electromagnetic wave (EMW) absorbing materials used in harsh working environments are susceptible to thermal degradation and dielectric constant drift caused by humidity fluctuation, which severely restricts their practical applicable in aerospace, marine engineering and advanced electronics. Herein, a hierarchical nanoarchitecture consisting of silica-coated carbon nanofibers uniformly anchored with NiFe₂O₄ nanosheets (denoted as CFNOS) is fabricated via a combined electrospinning-hydrothermal-carbonization route. This ternary structural design circumvents the inherent drawbacks of pristine carbon nanofibers through synergistic dielectric and magnetic loss: NiFe₂O₄ introduces dominant magnetic loss, while the outer silica shell strengthens interfacial polarization to realize efficient EMW dissipation. The optimized CFNOS-2 delivers a minimum reflection loss (RL_min) of -59.10 dB at 1.68 mm, together with an effective absorption bandwidth (EAB) of 5.04 GHz at 1.60 mm, exceeding most previously reported carbon-based absorbers. Benefiting from the protective silica layer, CFNOS-2 possesses robust environmental adaptability, featuring a water contact angle of 139.1°, residual mass exceeding 80% upon heating to 800°C, as well as favorable thermal insulation and infrared stealth performance (surface temperature maintained at 120°C over 45min). This work provides a facile structural strategy toward high-performance EMW absorbers applicable for extreme environments, paving a feasible route for next-generation stealth devices and high-density electronic packaging.

the changes in viscosity or rheological properties during the static process of mullite sol have a significant impact on its spinnability. Herein, mullite spinning sols were prepared by vacuum concentration using aluminum chloride and acidic silica sol, and polyvinyl alcohol as the spinning aid. The influence of storage temperature and time on the stability of sol were studied. And focused on the influence of temperature changes and time on the rheological properties of mullite sols, such as non Newtonian index, structural viscosity index, and viscous flow activation energy. The stretchable fiber length of the sol is used as an evaluation of its spinnability. The results showed that low temperature is beneficial for the preservation of the internal structure of the sol and for maintaining its spinnability for a long time. High temperatures can accelerate the aggregation of rubber particles to form large particles, and lose spinnability in a short time. Furthermore, the sol stored at low temperature for 14 days can continuously draw the gel fiber over 100 m, and mullite ceramic fibers with good morphology, small grains and uniform diameter distribution were obtained after calcination at 1200 ℃.