Preparation and properties of Al/Si coating with excellent formability and corrosion resistance on steel plate

Abstract

In order to simultaneously improve formability of the coated steel and corrosion resistance of steel, Al/Si coating with tailored Si content, controllable composition and structure were prepared on Q235 by combining magnetron sputtering and then treated by heat treatment. The effect of Si content on the thickness, composition, structure of Al/Si coating on the surface of Q235 steel, and corrosion resistance and formability of Al/Si coated Q235 steel were systematically investigated. With 160 W of Al target power and different Si target power (0, 60, 80 and 100 W), the thickness of the coating on Q235 steel for 1.5 h is about 5 µm. Al/Si coating thickness with 80 W of Si target power is 5.33 ± 0.32 µm. The coating on Al/Si80-Q235 is uniform and dense, and mainly consists of FeAl2Si, Fe3Al, Fe2Al5, and Al2O3. Al/Si80-Q235 demonstrated excellent formability and Al/Si80 coating improved corrosion resistance of Q235 steel. When immersed in NaCl solution, the self corrosion current density of Al/Si coated Q235 was significantly lower than Al coated Q235. Especially, the self corrosion current density of Al/Si80-Q235 was only 1/51 that of Al coated Q235. The corrosion resistance of Al/Si coated steel was remarkably improved compared with Al coated steel due to the addition of Si.