Changing the grain size of FeSiAl powders to improve corrosion resistance and wave absorbing property

Abstract

FeSiAl (FSA) is easily corroded by corrosive media in marine environment, which can reduce the microwave absorption performance. Therefore, it is necessary to improve the corrosion resistance of FSA. In this work, Cr atoms replace part of Si atoms in FSA to obtain FeSiAlCr flaky powders via rapid quenching and ball milling. The X-ray diffractometer test results show that the average grain size of the flaky powders was decreased from 12.21 nm to 11.16 nm with the increase of Cr content. The electrochemical corrosion behavior of FeSiAlCr was measured by potentiodynamic and potentiostatic electrochemical impedance spectroscopy (EIS) in 5 wt% NaCl solution. The results show that the free corrosion potentials of FeSiAlCr move towards positive values, the corrosion currents are reduced, and therefore the corrosion rates become slower with the increase of Cr content. In addition, FeSiAlCr possesses enhanced microwave absorption performance with a minimum reflection loss (RLmin) of −6.58 dB at 2.19 GHz with a matching thickness of 1.5 mm. Therefore, FeSiAlCr flaky powders are promising microwave absorbing materials in terms of low frequency absorption and corrosion resistance.