High-Performance HVOF-Sprayed Fe-Based Amorphous Coating on LA141 Magnesium Alloy via Optimizing Oxygen Flow and Kerosene Flow

Abstract

To solve the problem of poor corrosion and wear resistance of Mg-Li alloys, Fe-based amorphous coatings were prepared by high velocity oxygen-fuel spraying technology (HVOF) on the LA141 magnesium alloy substrate with a Ni60 intermediate layer. The microstructure and performance of Fe-based amorphous coatings with different oxygen flow and kerosene flow were characterized and analyzed. The results demonstrate that there is an optimal oxygen/kerosene ratio where the porosity of Fe-based amorphous coating is the lowest. Moreover, the amorphous content increases with the decrease in the oxygen/kerosene ratio. In particular, when the oxygen flow is 53.8 m3/h and the kerosene flow is 26.5 L/h, the Fe-based amorphous coating possesses the lowest porosity (0.87%), the highest hardness (801 HV0.1), the highest bonding strength (56.9 MPa), and an excellent corrosion and wear resistance. Additionally, it can be seen that the Fe-based amorphous coating is composed of amorphous splats and amorphous oxides, but the Ni60 intermediate layer exhibits an amorphous and crystalline multi-phase structure. The high bonding strength of the coating is attributed to the low porosity of Fe-based amorphous coating and the localized metallurgical bonding between different layers. Finally, the mechanisms on corrosion and wear of Fe-based amorphous coatings are also discussed.

Effects of Temperature and Pressure on Corrosion Behavior of HVOF-Sprayed Fe-Based Amorphous Coating on the Mg-RE Alloy for Dissolvable Plugging Tools

“…There are various HVOF-sprayed coatings on magnesium alloys, such as Al coatings [ 22 ], 316L coatings [ 23 , 24 ], SiC-Al coatings [ 25 , 26 ], WC-Co coatings [ 27 ], hydroxyapatite coatings [ 28 , 29 ] and Fe-based amorphous coatings (AMCs) [ 30 , 31 , 32 , 33 ]. Among these coatings, the AMCs attract more and more attention due to their superior corrosion resistance.…”

“…Among these coatings, the AMCs attract more and more attention due to their superior corrosion resistance. Currently, HVOF-sprayed AMCs have been prepared for the corrosion protection of commercial magnesium alloys, such as AZ31, AZ61, WE43 and LA141 magnesium alloys [ 30 , 31 , 32 , 33 ]. Under normal temperature and pressure, the corrosion current densities of the coated magnesium alloys in 3.5 wt.% NaCl solution are one to two orders of magnitude lower than those of the bare magnesium alloys.…”