Polymer‐derived porous SiNiOC ceramics with enhanced electromagnetic wave absorption performance

Abstract

Abstract In this work, porous SiNiOC ceramics with enhanced electromagnetic wave (EMW) absorption performance are successfully prepared by the hydrothermal method and the polymer‐derived ceramics (PDCs) process. The influence of the annealing temperature on the microstructure and EMW absorption performance of the SiNiOC ceramics is also systematically studied. It is shown that the increased annealing temperature can induce phase separation in SiOC, yielding SiC and SiO 2 , while Ni 2 ⁺‐catalyzed graphitic carbon promotes the carbothermal reduction of SiO 2 into more SiC. The large amount of SiC generated by the two reactions significantly improves the low dielectric constant of SiOC. After annealing treatment at 1400°C, the porous SiNiOC ceramics exhibit the best EMW absorption performance, achieving a minimum reflection loss of −55.62 dB when the thickness is 1.97 mm and an effective absorption bandwidth of 3.93 GHz when the thickness is 1.33 mm. Such a thin matching thickness in our as‐prepared porous SiNiOC ceramics can meet the requirement of future EMW absorbing applications, exhibiting significant potential as a high‐performance EMW absorbing material.