Surface coating modification of iron powder based on atomic layer deposition and its electromagnetic properties

The improvement in the electromagnetic and antioxidation capacity of iron powder as a high-performance radar wave absorber has always been a research hotspot. In this study, trimethylaluminum (TMA) and water (H 2 O) were used as precursors for atomic layer deposition (ALD) to modify the surface of iron powder absorbents. Nanoscale aluminum oxide (Al 2 O 3 ) films were successfully prepared on the surface of micro iron powder particles, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), conductivity analyzer, thermal analyzer, and vector network analyzer. The results show that the ALD coating method can deposit a durable and structurally complete Al 2 O 3 nanofilm on the surface of micro iron particles, after which, their electrical resistivity is significantly increased, as well as oxidation resistance; in addition, the complex permittivity of the iron powder absorbent is significantly reduced, while the change in complex magnetic permeability is relatively small, which improves the electromagnetic properties and potential absorption performance of the iron-powder-contained absorbent.