(Ni@SiC)_p 复合吸波材料的制备及性能表征

With the continual advancements in technology, increasingly intense electronic and information warfare, electromagnetic radiation, and electromagnetic interference have become key factors that affect military operations. Composite absorbing materials are considered an important method to deal with electromagnetic interference as well as an effective means to enhance national military defense capabilities and combat effectiveness. (SiC)_p is a semiconductor material with excellent performance, low cost, oxidation and corrosion resistance, and high strength. Its resistivity ranges from 10⁻² to 10⁶ Ω·cm and can be continuously adjusted with the manufacturing process, making it a preferred choice for composite absorbing materials. However, the microwave absorption efficiency of (SiC)_p has not yet met the requirements for wide bandwidth and strong absorption, and the poor wettability between the material and substrate owing to different chemical bonds significantly affects its application range. Silicon carbide / nickel core-shell structured composite particles, abbreviated as (Ni@SiC)_p, were prepared to improve the electromagnetic properties of SiC further and prepare composite absorbing materials with excellent carbide. To investigate the performance, a simple, controllable, rapid, and high-precision chemical deposition technique was used to modify the surface of the Si. The experimental process included preprocessing of (SiC)_p and its surface chemical deposition. The preprocessing introduced catalytically active sites, including oxidation etching, hydrophilic treatment, sensitization, and the activation of (SiC)_p. The pretreated (SiC)_p was then added to the chemical deposition solution for surface modification with a deposition time of 1-2 h. Scanning electron microscopy, energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were used to characterize the morphology, composition, and phase of the samples before and after modification, and a vector network analyzer was used to measure the electromagnetic absorption properties of SiC before and after modification. The results showed that (SiC)_p is light gray before modification and turns black after modification, indicating substantial changes on the SiC surface. The micromorphology revealed that the surface of (SiC)_p is smooth before modification, with a small amount of broken powder adhering because of processing. After modification, the particle surface is no longer smooth, with new substances deposited and no smooth (SiC)_p exposed. The EDS showed that before modification, there are obvious Si peaks and a certain amount of C and O peaks; after modification, new Ni and P peaks appear, indicating that the newly deposited substances are Ni and P. EDS mapping of the modified SiC revealed the presence of Si, Ni, P, C, and O elements uniformly distributed in the surface deposition layer of the SiC, further indicating that the new substance deposited on the surface is Ni. The XRD results showed that the (SiC)_p used in the experiment was α-(SiC)_p, with only SiC diffraction peaks (SiC PDF^#29-1131) observed before modification. After modification, obvious Ni diffraction peaks (Ni PDF^#04-0850) are visible, and the diffraction peaks show a broad peak, indicating that the Ni particles on the surface of the modified SiC are amorphous, with fine sizes, forming ultra-fine Ni powder. A comparison of the electromagnetic properties before and after modification revealed a significant improvement in the absorption performance after modification, with the real part of the dielectric constant increasing by 3 to 6 times and the imaginary part by 2 to 7 times; the electromagnetic loss increases by 2 to 4 times and the dielectric loss increases by 3 to 5 times. At a frequency of 11.6 GHz, the reflection loss (R_L) of (Ni@SiC)_p is −41.25 dB, with an effective bandwidth of 7.28 GHz. Finally, a detailed analysis of the electromagnetic enhancement mechanism of (Ni@SiC)_p was conducted. From a microscopic perspective, the composite structural unit endows each (Ni@SiC)_p with the dual attributes of electrical and magnetic loss. From a macroscopic perspective, the absorbing performance of the new material is significantly enhanced, which is more conducive to achieving the goals of lightweight, thin, wideband, and high-strength absorbing materials. This work provides new methods and ideas for exploring and researching the preparation of absorbing materials in the national defense field that are simple to operate, well controlled, inexpensive, and suitable for large-scale promotion.