Effect of Ar and H₂ Flow Rate on Properties of Fe-Based Amorphous Coating Prepared by Plasma Spraying

Fe-based amorphous coating was prepared by plasma spraying technique using Fe-based amorphous alloy powder as raw materials. The effects of simultaneous increase of Ar flow rate (40-80 L·min^-1) and H₂ flow rate (6-10 L·min^-1) on the microstructures, bonding strength with substrate, microhardness, wear resistance and corrosion resistance of the coating were investigated. The results show that the amorphous content of the prepared coatings was relatively high, and the area fraction reached 92.4%-94.8%. Good bonding was formed between the coating and the substrate and no obvious crack was observed. With increasing flow rate of Ar and H₂, the porosity of the coating decreased first and then increased, and bonding strength between the coating and the substrate and microhardness of the coating increased first and then decreased. The corrosion resistance of the coating in 0.5 mol·L^-1 H₂SO₄ solution became better and then worse. When Ar flow rate was 60 L·min^-1 and H₂ flow rate was 8 L·min^-1, the coating had the most compact structure with the lowest porosity, the highest bonding strength and microhardness and the best wear and corrosion resistance.