High Temperature Metamaterial Enhanced Electromagnetic Absorbing Coating Prepared With Alumina Ceramic

At present, a series of challenges are impeding the large-scale application of the high temperature radar absorbing coatings (RACs), such as the complex preparation of raw material and the complicated technology of processing. In this paper, a new, thin and high-temperature metamaterial RAC (MRAC) with strong absorption was designed and experimentally demonstrated, composing of a radar absorbing coating and a layer of metamaterial. To avoid the need for the complex preparation of raw materials, pure alumina was selected as the radar absorbing coating. Meanwhile, plasma spraying and screen printing were employed to simplify the manufacture technology to produce the absorbing coating and the metamaterial layer, ensuring its feasibility and practicality. The metamaterial layer was prepared with a high temperature conductive paste and it improved the impedance matching of the coating and regulated the electromagnetic (EM) resonance. With the ability to consume more incident EM waves, excellent absorption performance at high temperature was achieved with relatively small thickness. In the 8 ~ 18 GHz band, the MRAC bandwidth for reflection loss (RL) below -5dB almost covered the frequency of 10 ~18 GHz with a thickness of only 1.5 mm at 800 ℃. This new metamaterial has broad application prospects by the virtue of its simplicity and ease of production.