Corrosion Performance of Fe-Based Amorphous Coatings via Laser Cladding Assisted with Ultrasonic in a Simulated Marine Environment

Fe-based amorphous alloys are considered potential coating materials for applications in marine corrosive environments owing to their high resistance to chloride ion corrosion. Fe-based amorphous alloy (Fe41Co7Cr15Mo14C15B6Y2) was deposited on AISI 1020 steel using ultrasonic-assisted laser cladding. The research findings revealed a gradient structure generated at the junction of the coating and substrate. Ultrasonic promoted crystallization and increased the gradient structure's average thickness, reducing coating surface cracks. However, ultrasonic had little effect on the amorphous content of the prepared coating surface, which still had a high amorphous content. The Fe-based amorphous coating prepared via laser cladding with ultrasonic demonstrated good corrosion resistance. The corrosion resistance of the coating without ultrasonic was reduced significantly due to cracks. EIS results confirmed that corrosion resistance was related to crystallization and crack issues. Cr element segregation due to crystallization hindered passivation film forming, reducing its corrosion resistance. Crack corrosion enlarged the crack gap and hollowed out the coating and the substrate's binding zone, accelerating coating failure.