Microstructure and Electrochemical Behavior of Fe-Based Amorphous Metallic Coatings Fabricated by Atmospheric Plasma Spraying

A Fe48Cr15Mo14C15B6Y2 alloy with high glass forming ability (GFA) was selected to prepare amorphous metallic coatings by atmospheric plasma spraying (APS) process. The as-deposited coatings present a dense layered structure and low porosity. Microstructural studies show that some nanocrystals and a fraction of yttrium oxides formed during spraying process, which induced the amorphous fraction of the coatings decreasing to 69% compared with fully amorphous alloy ribbons of the same component. High thermal stability employs the amorphous coatings to work below 910K temperature without crystallization. Corrosion behavior of the amorphous coating was investigated by electrochemical measurement. The results show that the coatings exhibit extremely wide passive region and low passive current density in 3.5% NaCl and 1mol/L HCl solutions, which illustrate their superior ability to resist localized corrosion. Moreover, the corrosion behavior of the amorphous coatings in 1mol/L H₂SO₄ solution is similar to their performance in chlorine ions contained conditions, which manifests their flexible and extensive ability to withstand aggressive environments.