Enhanced antioxidation and microwave absorbing properties of SiO 2 -coated flaky carbonyl iron particles

Abstract SiO 2 was successfully coated on the surface of flaky carbonyl iron particles using a chemical bath deposition method in the presence of 3-aminopropyl triethoxysilane (APTES). The morphologies, composition, valence states of elements, as well as antioxidation and electromagnetic properties of the samples were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG) and microwave network analyzer. TG curve shows the obvious weight gain of carbonyl iron was deferred to 360 °C after SiO 2 -coated, which can be ascribed to the exits of SiO 2 overlayer. Compared with the raw carbonyl iron, SiO 2 -coated sample shows good wave absorption performance due to its impedance matching. The electromagnetic properties of raw and SiO 2 -coated carbonyl iron particles were characterized in X band before and after heat treatment at 250 °C for 10 h. It was established that SiO 2 -coated carbonyl iron demonstrate good thermal stability, indicating SiO 2 -coating is useful in the usage of microwave absorbers operating at temperature up to 250 °C.