Fe-based metallic glass composite coatings by HVOF spraying: Influence of Mo on phase evolution, wear and corrosion resistance

Abstract

Developing Fe-based metallic glass (MG) composite coatings with exceptional amalgamation of enhanced mechanical and corrosion properties have attracted wide interests recently. In this work, Fe-based MG composite coatings were developed from two distinct compositions of Fe 63 Cr 9 B 16 C 7 P 5 and Fe 57 Cr 9 Mo 5 B 16 C 7 P 6 (at. %). The coatings were prepared using optimized parameters of high velocity oxy-fuel (HVOF) spraying for eliminating the porosity effect and to only investigate the influence of minor Mo addition on phase evolution, wear and corrosion resistance. Microstructural and compositional characterization results exhibited lower and similar porosity content for both the MG composite coatings and higher level of amorphicity for Mo-containing coating compared to the other one. The Mo-containing coating displayed superior wear resistance, because of increment in amorphous content and minor amount/absence of softer α-Fe phases, and this was correlated with higher hardness (H) and ratios of H / E r and H 3 / E r 2 . Moreover, an enhanced corrosion resistance was also observed in case of Mo-containing coating, ascribed to the improved passivation ability resulting from increased fraction of protective and stable Cr- and Mo-oxides in passive film due to incorporation of Mo in the alloy. Thus, the addition of a minor amount of Mo was observed to be advantageous for improving the wear and corrosion properties of this Fe-Cr-based MG composite coating. Interestingly, both composite coatings showed improved wear and corrosion properties than that of SS316L coating synthesized with industrially optimized parameters. • Minor Mo addition effect on wear and corrosion resistance of Fe-based MG coating studied. • Increased amorphous phase content resulted after Mo incorporation. • Enhanced wear resistance due to higher amorphicity and absence/minor presence of α-Fe. • Superior corrosion resistance due to increased amount of Cr- and Mo-oxide in passive film. • Better combination of wear and corrosion resistance for protective coating.