The evaluation of microstructure characteristic and corrosion performance of laser-re-melted Fe-based amorphous coating deposited via plasma spraying

Abstract

The laser re-melting treatment was performed on the plasma-sprayed Fe-based amorphous coating to ameliorate the corrosion performance of the coating. The re-melting depth was about 200 μm which was mainly controlled by laser energy input, beam speed and facular dimension. The microstructure was characterized by scanning electron microscope (SEM), and X-ray diffraction (XRD). The corrosion property of the coatings was addressed via electrochemistry methods in a 3.5 wt.% NaCl solution. The results indicate that the plasma-sprayed coating becomes much denser after laser re-melting treatment. The connected porosity ratio in as-sprayed coating dramatically reduces from 16.3% to 2.4% after laser re-melting. The as-sprayed coating mainly contains amorphous and much limited crystal phase, and some amorphous phase in the as-sprayed coating crystalizes during laser re-melting. Polarization test demonstrated that the as-sprayed coating has a significantly dramatical effect for improving corrosion performance of carbon steel, while the laser re-melting process is a more efficient method. The influence level of the coating compactness in this study is roughly two times as big as that of amorphous in coating, in the term of improving corrosion resistance of carbon steel.