On the bonding strength in thermally sprayed Fe-based amorphous coatings

Bonding strength is one of the most important properties in thermally sprayed coatings as it plays crucial roles in the performance and lifetime of the coatings. This study aims to explore different factors that affect the bonding strength of the Fe48Mo14Cr15Y2C15B6 amorphous coating prepared by high velocity oxygen fuel (HVOF) thermal spraying. The results demonstrate that the substrate roughness and the coating thickness have significant influence on the bonding strength of the amorphous coating, e.g. the bonding strength increases when the substrate roughness is above a certain threshold, and decreases with the increasing coating thickness. In addition, the bond strength can be effectively enhanced via the addition of an intermediate NiCrAl layer between the substrate and the amorphous coating due to the occurrence of metallurgical reaction and the improved interfacial structure. Finally, the fracture mechanism of the coatings was also discussed.

► Bonding strength of amorphous coating increased with an increasing substrate roughness.
► Bonding strength of the coating decreased with the increasing coating thickness.
► Bonding strength was significantly enhanced via an intermediate NiCrAl coating.
► Crack mostly initiated at the boundaries of un-melted particles in the coating