Abstract A series of U-type hexaferrite ceramic powders B a 4 Z n 2 - x M n x F e 36 O 60 ( x = 0.5, 1, and 1.5) were synthesized through the solid-state reaction (SSR) method and used as electromagnetic (EM) waves absorbing inorganic pigments to fabricate radar absorbing paint (RAP) coatings containing polyurethane matrix and talc as a filler. The colour properties and chemical stability of powder pigments were determined. Also, the crystalline structure and morphology of the synthesized pigments were characterized by X-ray diff ;raction (XRD) and scanning electron microscope (SEM) analysis. The effect of addition of these pigments to the polyurethane (PU) matrix on mechanical properties, corrosion performances and microwave absorption performances was investigated. The EM parameters and microwave absorbing properties of the RAP coatings applied on the aluminum substrate were measured in the X-band (8.2–12.4 GHz) frequency range by using vector network analyzer (VNA) and the scattering parameters method. The results showed that the mechanical properties such as microhardness, wear resistance and roughness were increased due to the addition of Mn content in the Zn–U type pigment. Also, the impact resistance was seen to increase with addition of Zn (decreasing x). The corrosion performance and adhesion strength of the coatings were examined using the salt spray and tape adhesion test, which exhibited that both of them were higher than non-pigmented polyurethane (NPPU) matrix coatings. The pigment composition with x = 1 led to an optimum microwave absorption of 97.55 % (or reflection loss RL= −16.10 dB) at 9.82 GHz and 1.5 mm thickness. In addition, this composition coating displays a broad frequency bandwidth (∼4.03 GHz) for RL≤-10 dB (90 % MW absorption), in 8.2–12.4 GHz. This type of RAP coating, due to its small required thickness, light weight, wide band absorption and cost-effectiveness can be used for suppressing EM interferences and stealth applications.

中文翻译：

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(Ba4Zn2-xMnxFe36O60) U型六铁氧体颜料的合成及其对聚氨酯涂料涂层防护性能、力学行为和微波吸收性能的影响

摘要 采用固相反应(SSR)法合成了一系列U型六铁氧体陶瓷粉体B a 4 Z n 2 - x M nx F e 36 O 60 ( x = 0.5, 1, 1.5) 并用作电磁 (EM) 波吸收无机颜料以制造包含聚氨酯基质和滑石作为填料的雷达吸收涂料 (RAP) 涂料。测定了粉末颜料的颜色特性和化学稳定性。此外，合成颜料的晶体结构和形态通过 X 射线衍射 (XRD) 和扫描电子显微镜 (SEM) 分析进行表征。研究了将这些颜料添加到聚氨酯 (PU) 基体中对机械性能、腐蚀性能和微波吸收性能的影响。通过使用矢量网络分析仪 (VNA) 和散射参数方法，在 X 波段 (8.2-12.4 GHz) 频率范围内测量了涂覆在铝基板上的 RAP 涂层的电磁参数和微波吸收性能。结果表明，由于在 Zn-U 型颜料中添加 Mn 含量，显微硬度、耐磨性和粗糙度等机械性能提高。此外，还发现抗冲击性随着 Zn 的添加而增加（x 减小）。使用盐雾和胶带附着力试验检测涂层的腐蚀性能和附着强度，表明两者均高于非着色聚氨酯（NPPU）基体涂层。x = 1 的颜料组合物导致在 9 时的最佳微波吸收为 97.55 %（或反射损失 RL = -16.10 dB）。82 GHz 和 1.5 毫米厚度。此外，这种复合涂层在 8.2–12.4 GHz 范围内，对于 RL ≤ -10 dB（90 % MW 吸收）显示出较宽的频率带宽（~4.03 GHz）。这种类型的 RAP 涂层由于其所需厚度小、重量轻、吸收带宽广、成本效益好，可用于抑制电磁干扰和隐身应用。