Enduring effect mechanism of Co(Ni) layers on excellent microwave absorption performance of carbonyl iron in seawater

The microwave absorbing materials (MAMs) applied in marine environment are confronted with corrosion, therefore, in order to guarantee the long-term function, the MAMs need to possess excellent microwave absorption performance and seawater corrosion resistance simultaneously. Carbonyl iron powder (CIP) has the characteristic of broadband response caused by magnetic loss, playing an important role in practical application as an MAM. Herein, to avoid the deterioration of microwave absorption property of CIP by seawater corrosion, protective layers of electroless plating Co(Ni) are introduced with less influence on magnetic loss. The CIP coated with Co layer (CIP@Co) shows the RL min of −57.93 dB and an effective absorption bandwidth (EAB) of 8.56 GHz, after a long-time continuous immersion in seawater, its RL min and EAB is −71.11 dB and 8.00 GHz, respectively. The EAB of CIP@Ni after immersing in seawater is also preserved 94 %, illustrating the long-life stability of the microwave absorption performance in seawater. The little effect of Co layer on the magnetic loss of CIP and the additional anticorrosion ability of electroless plating layers are two guarantees for enduring the excellent microwave absorption performance of CIP@Co in seawater. This work provides a solution to obtain MAMs with long-life excellent microwave absorption in seawater.