Microstructure, corrosion-resistance, and wear-resistance properties of subsonic flame sprayed amorphous Fe–Mo–Cr–Co coating with extremely high amorphous rate

The low-cost Fe-based amorphous coating with the composition of Fe49.9Mo32.9Cr9.32Co4.55Si2.28Al1.55 (wt.%) were deposited on 316L stainless steel substrate by subsonic flame spraying under optimum spraying parameters. The microstructure, phase composition, microhardness, corrosion-resistance, and wear-resistance properties of the coatings were systematically investigated. The prepared coating primarily consists of amorphous phase (calculated amorphous phase content was 90.23%), and the hardness of the prepared coating can reach 981.6 HV0.1, which is much larger than that of the substrate material 316L stainless steel. The corrosion potential and corrosion current density of the prepared Fe-based amorphous coating in 3.5 wt.% NaCl solution are −438 mV and 6.9 μA/cm2, respectively. Compared with 316L stainless steel and some newly published Fe-based amorphous coatings, the prepared coating shows better corrosion resistance properties. The dry sliding wear rate of the coatings with 0.45% C steel balls at 19.6 N is 1.68 × 10−5 mm3/Nm. The friction coefficient of the coating is at an ultra-low level (about 0.26) and can keep relatively steady throughout the sliding test. The study shows that the prepared Fe-based amorphous coating has high amorphous phase content, high hardness, superior corrosion-resistance, and wear-resistance properties.