Structure and corrosion behavior of iron-based metallic glass coatings prepared by LPPS

Low pressure plasma spraying (LPPS) has been used to prepare coatings from the spraying powders of FeCrMoWSiBC at different hydrogen flow rates. X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were used to study the microstructural characteristics of the spraying powders and as-sprayed coatings. Vickers hardness tester was used to measure the hardness of spraying powders and coatings. At the same time, the corrosion behavior of coatings was evaluated by potentiodynamic polarization test and immersion test. Along with the increase of hydrogen flow rate, the denseness of the as-sprayed coatings increases. Amorphous coatings were obtained at the hydrogen flow rates of 4 and 6 L min−1, while partial crystallized coating was obtained at hydrogen flow rate of 8 L min−1. In general, the as-sprayed coatings possess good corrosion resistance in aqueous solutions of 3.5% NaCl and 1 N HCl. It is found that the denseness of coatings affects the corrosion resistance positively. Moreover, in this study, the partially crystallized coating shows better corrosion resistance than amorphous coatings. The partially crystallized coating even shows much higher hardness than amorphous coatings and spraying powders. This implies that such coating may find more promising application in engineering owing to desired corrosion resistance in association with good wear resistance.