Agricultural wastes such as rice husks (RHs) are valuable due to their feasibility to be converted into carbon materials, low cost, and abundancy in contrast to the conventional carbon material sources. In this study, RHs are carbonized at various temperatures from low to high temperatures, and their electromagnetic (EM) wave absorption properties are evaluated. Carbon materials, silicon carbide (SiC) whiskers, and SiC particles are obtained from RHs carbonized at 1500 °C (CRH1500) for 0.5 h with presence of Ar gas at 1 atm. In order to evaluate their EM wave absorption performance, complex permittivity and permeability are measured by using vector network analyzer, and the values are utilized in the reflection loss (R.L.) calculation according to the transmission line theory. CRH1500, 40 wt% with thickness of 1.6 mm exhibits minimum R.L. of ≈−55.4 dB (>99.9997% absorption) at 11.37 GHz and response bandwidth (R.L. < 10 dB, > 90% absorption) of 4.21 GHz. Low‐cost and abundant RHs, carbonized at various temperatures, show significant absorption performance. Their absorption performance and response bandwidth are highly dependent on matching thickness, indicating that they can be easily modulated for promising electromagnetic wave absorber materials.

中文翻译：

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不同温度下炭化稻壳的电磁波吸收性能。

与传统的碳材料来源相比，稻壳（RH）等农业废物由于其可转化为碳材料、成本低且丰富而具有价值。在这项研究中，RHs在从低温到高温的不同温度下被碳化，并评估了它们的电磁（EM）波吸收特性。碳材料、碳化硅 (SiC) 晶须和 SiC 颗粒是由在 1 atm 的 Ar 气体存在下在 1500 °C (CRH1500) 下碳化 0.5 小时的 RH 获得的。为了评估它们的电磁波吸收性能，使用矢量网络分析仪测量复介电常数和磁导率，并将这些值用于根据传输线理论的反射损耗（RL）计算。CRH1500，40 wt%，厚度为 1.6 mm，在 11.37 GHz 时表现出最小 RL 约−55.4 dB（>99.9997% 吸收），响应带宽（RL < 10 dB，> 90% 吸收）为 4.21 GHz。低成本且丰富的 RH，在不同温度下碳化，表现出显着的吸收性能。它们的吸收性能和响应带宽高度依赖于匹配厚度，这表明它们可以很容易地调制为有前景的电磁波吸收材料。