Preparation and Wave Absorption Properties of Urea-Formaldehyde Resin-Based Flower-Like Carbon Microspheres

As electromagnetic wave absorption material, a kind of porous carbon microsphere was obtained through the high-temperature carbonization of the pre-prepared flower-like urea-formaldehyde resin microspheres. The study investigated urea-formaldehyde resin-based carbon microspheres prepared under different formaldehyde-to-urea molar ratios and carbonization temperatures. The morphology and structure of the carbon microspheres were analyzed by SEM and Raman spectroscopy. The results show that the carbon microspheres have abundant folds and pores, good dispersion and high specific surface area. Through the evaluation of electromagnetic wave absorption performance, it was determined that urea-formaldehyde resin-based carbon microspheres synthesized under the conditions of the formaldehyde-to-urea molar ratio of 1.0 and carbonization temperature of 800°C exhibited optimal performance. At a thickness of 2 mm, the maximum reflection loss at 16.38 GHz reached –40.66 dB, with the maximum effective absorption bandwidth exceeding 6.02 GHz. The excellent electromagnetic wave absorption performance of the materials can primarily be attributed to the complex reflection and scattering processes induced by its porous structure and irregular morphology, as well as the effective attenuation of microwaves facilitated by the porous carbon structure.