Abstract
Fe-based amorphous coatings are typically fabricated by high-velocity oxygen-fuel spraying using industrial raw materials. The bonding mode between the coating particles and the corrosion mechanism of the coating in the chloride-rich environment were studied. The results indicate that some fine crystallites such as α-Fe and Fe3C tend to precipitate from the amorphous matrix as the kerosene flow rate increases or the travel speed of spraying gun decreases. Moreover, some precipitates of the (Cr, Fe)2O3 nanocrystal were detected in the metallurgical interfaces of the amorphous coating. The relationship among the amorphous volume fraction, porosity, and spraying parameters, such as the kerosene flow rate and the travel speed of the spray gun, were established. Due to an oxidation effect during spraying process, atomic diffusion, crystallite precipitation and regional depletion of Cr occur in the area along the pre-deposited side near the metallurgical bonding interface, leading to the initiation of pitting. A model of pitting initiation and expansion of Fe-based amorphous coatings is proposed in this paper.
Highlights
Owing to their excellent corrosion resistance and low material cost, Fe-based amorphous coatings offer considerable potential for industrial application in fields such as the military, nuclear power, oil and gas, and manufacturing
No significant irradiation damage phenomena appear in the Fe80Si7.43B12.57 metallic glass, while blistering, flaking, and other damage occurs on the surface of the metallic W in an environment subjected to H+ irradiation [3]
The Fe-based amorphous coating with the composition of Fe54.2Cr18.3Mo13.7Mn2W6B3.3C1.1Si1.4 used on marine pump impellers has an erosion rate that is two to three times that of SUS304, and it is believed to enhance the lifetime of pump impellers that need to work in sand-containing seawater [4]
Summary
Owing to their excellent corrosion resistance and low material cost, Fe-based amorphous coatings offer considerable potential for industrial application in fields such as the military, nuclear power, oil and gas, and manufacturing. The in-transmission neutron absorption cross section for thermal neutrons of Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 (SAM2X5) with a high boron content is four times greater than that of borated stainless steel, and twice as that of nickel-based alloy (C–4) with added Gd. In addition, SAM2X5 amorphous coatings are being used as corrosion-resistant anti-skid decking for ships. The corrosion rate of the Fe-based amorphous coating is 1/1000 that of 20G steel in the artificial simulation environment of a power-plant boiler [5], which demonstrates that the amorphous coating has an excellent anti-corrosion performance with controllable moderate investment cost that can promote the engineering application of waste heat utilization in power plants
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