High temperature metamaterial enhanced electromagnetic absorbing coating prepared with alumina ceramic

At present, a series of challenges are impeding large-scale application of high temperature radar absorbing coatings (RACs), such as complex preparation of raw material and complicated technology of processing. In this paper, we designed and experimentally demonstrated a high-temperature metamaterial RAC (MRAC) with strong absorption and thin thickness, which is composite of radar absorbing coating and a layer of metamaterial. To avoid complex preparation of raw materials, pure alumina was selected as the radar absorbing coating. Plasma spraying and screen printing were employed to simplify the sample preparation 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, which allows more EM waves to be absorbed. Therefore, excellent high temperature absorption was also achieved with relatively small thickness. At 800 °C, the MRAC reflection loss (RL) below −5 dB almost covered the frequency of 10–18 GHz with a thickness of only 1.5 mm. This new metamaterial has broad application prospects by the virtue of its simplicity and convenience in manufacture.