Abstract
A high-velocity oxygen fuel (HVOF) system was employed to prepare a Fe49.7Cr18Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 amorphous coating on mild steel. The electrochemical behavior of the resultant coatings, namely as-sprayed coating and vacuum heat-treated coating (at 650 °C and 800 °C), were investigated in a 3.5% NaCl solution at variable temperatures using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, optical microscopy (OM), and XRD diffraction. Moreover, COMSOL Multiphysics version 5.5 software were employed for predicting the galvanic corrosion of amorphous material immersed in an aqueous NaCl solution, using the software finite element kit. The experiments demonstrated that the coatings’ pitting resistance was significantly affected by temperature. The results also showed that temperature affected the pitting corrosion rate and changed the shape of the pits. However, the changes were not as extreme as those observed in stainless steel. Furthermore, there was no significant difference between the as-sprayed coating and the vacuum-heat-treated coating at 650 °C. At low NaCl concentrations at and temperatures below the critical pitting temperature, the resulting pits were significantly small with a hemisphere-like. By contrast, at a higher NaCl concentration at 70 °C, particularly in the case of heating at 650 °C, the pits appearing on the Fe-based amorphous coating were vast and sometimes featured a lacy cover.
Highlights
Fe-based bulk metallic glasses (BMGs) have received significant interest in recent decades because of their superior performance, such as their high strength and hardness, good magnetic properties, and excellent corrosion and wear-resistance [1,2,3,4,5,6,7,8,9]
The experiment revealed that the high-velocity oxygen fuel (HVOF) deposition process is an effective technique for preparing amorphous coatings, practically for maintaining the powder initial amorphous structure
The powdered microstructure and sprayed coatings were examined using scanning electron microscopy (SEM; 6700F, JEOL, Tokyo, Japan)
Summary
Fe-based bulk metallic glasses (BMGs) have received significant interest in recent decades because of their superior performance, such as their high strength and hardness, good magnetic properties, and excellent corrosion and wear-resistance [1,2,3,4,5,6,7,8,9]. Compared to stainless steel and crystalline alloys with a similar composition, BMG boasts a uniform microstructure without any crystal imperfections, dislocations, or grain limits. They are leading coating products for marine and industrial applications [10]. The method can be used for steel substrate coating applications This method enhances the properties of steel surfaces, such as improved corrosion resistance compared to chrome plating and stainless-steel in NaCl solution [18,19]. Electrochemical tests in the simulated marine environment (3.5% NaCl solution) were used to measure and compare the different coatings’ corrosion rates. COMSOL Multiphysics software was employed to numerically simulate the experimental results
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