原子层沉积氧化铝包覆羰基铁粉的抗腐蚀性及吸波性能

为了提高羰基铁粉的抗腐蚀能力及改善其电磁性能, 以TMA和H₂O为前驱体, 利用原子层沉积(ALD)方法对羰基铁粉进行表面包覆改性, 在羰基铁粉表面包覆不同厚度的氧化铝。通过扫描电镜(SEM)、透射电镜(TEM)、综合热分析仪(TGA)、红外光谱(FTIR)和矢量网络分析仪等技术手段系统分析了改性前后羰基铁粉性能指标。结果表明, 通过ALD方法可在羰基铁粉表面生长纳米级别具有良好保型的氧化铝薄膜, 形成了极佳的羰基铁/氧化铝壳层结构复合材料。与原样品相比, 包覆改性后的羰基铁粉热稳定性与抗腐蚀性有极大的提高, 且随着包覆厚度的增加, 抗氧化能力增强, 最大抗氧化温度可超过550℃。同时羰基铁粉包覆氧化铝后, 其介电常数明显减小, 磁导率变化相对较小, 改善了原羰基铁粉的电磁参数与吸波性能。

Corrosion Resistance and Wave Absorbing Property of Carbonyl Iron Powder Coating with Alumina by Atomic Layer Deposition

To improve the corrosion resistant capability and electromagnetic performance of carbonyl iron powders (CIPs), alumina thin films were coated on carbonyl iron powder by atomic layer deposition (ALD) using trimethylaluminum and water as precursors. Original and modified carbonyl iron powder was characterized comprehensively via scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analyzer (TGA), Fourier Transform infrared spectroscope (FTIR), and vector network analyzer. The results indicated that nano-alumina films were conformably grown on the surface of carbonyl iron powders via ALD, forming an excellent core-shell CIP/alumina structure. Compared to the original sample, thermal stability and corrosion resistance of the modified carbonyl iron powders were greatly improved. Antioxidation capability of CIPs was found enhanced with the increase of alumina coating thickness, and the maximum antioxidation temperature can exceed 550℃. It was also found that the complex permittivity of core-shell CIP/alumina decreased greatly while the complex permeability was almost the same. Therefore, the electromagnetic parameters and microwave absorption properties of the modified CIPs was also improved.