Corrosion resistance of plasma-sprayed Fe-based coatings by using core-shell structure powders

Abstract

Fe-based amorphous powder and shell-core-structured composite powder prepared by ball-milling Fe-based amorphous powder with 10 wt.% Ni/Al powder, were used to fabricate Fe-based amorphous coating and Fe-based amorphous composite coating by plasma spray process, respectively. X-ray diffraction (XRD) analysis results showed that the composite coating was comprised of multi-component amorphous Fe62.8Ni13.6Cr9.9Mo8.6Si1.6C2.3B0.9 layer and crystalline Ni3Al layer. Compared with Fe-based amorphous coating, the composite coating exhibited a more compact structure. The corrosion resistance of Fe-based amorphous coating, which was tested by potentiodynamic polarization method in 3.5 wt.% NaCl solution, was significantly improved by using shell-core-structured composite powder. The composite coating showed lower corrosion current density (12.5 μA/cm2) and passive current density (9.0 mA/cm2) than Fe-based amorphous coating. The improved corrosion resistance of the composite coating is attributed to the dense structure and the formation of passivation film.

Keywords

• Fe-based amorphous coating
• Plasma spray
• Coating
• Corrosion resistance