Investigation on the bonding behavior of the interface within the supersonic plasma sprayed coating system based on the fractal theory

In order to investigate the relationship between the interfacial morphology of the coating system and its adhesion strength, the supersonic plasma spraying equipment is employed to fabricate Fe-based alloy coating. The (Ni, Al) coating is prepared as the undercoating with different flow of Ar gas, aiming at obtaining various rough morphologies. Interfacial morphologies of the coating system are quantificationally characterized by fractal dimension(FD). The pull-off method is used to test the adhesion strength. Result shows that the adhesion strength is obviously improved by fabricating an undercoating, and the FD of the interfacial morphology decreases with the increase of the flow rate of Ar gas, while the adhesion strength will be raised at the first beginning and then decreased to a certain value.