Comparative Study on Corrosion Resistance of Cold Sprayed and High Velocity Oxy-fuel Sprayed FeCoCrNiMn High Entropy Alloy Coatings

In deep-sea drilling, drilling parts are subjected to the erosion of seawater drilling fluid. Corrosion media such as OH− and Cl−make their service environment very harsh, affecting drilling efficiency and even equipment safety. Therefore, it is of great significance to protect the surface of drilling parts. High entropy alloy is regarded as a new development direction of corrosion resistance materials and has a wide application prospect in remanufacturing engineering. FeCoCrNiMn high entropy alloy coatings prepared by CS and HVOF were immersed continuously (15d, 30d and 45d) in simulated seawater drilling fluid. The corrosion resistance of the two coatings at different immersion time is investigated. The results show that CS coating exhibits higher impedance and lower electron transfer rate than HVOF coating. Cr can form a protective passivation film based on Cr2O3 on the surface of the alloy, showing a better passivation performance. Cl element enriched pitting appeared on CS and HVOF coating surfaces after soaking for 45 days. With the extension of soaking time, the possible pitting area may peel off, resulting in gap corrosion inside the coating. Therefore, both CS coating and HVOF coating can protect the drilling parts in deep sea drilling. The corrosion resistance of CS coating is better than that of HVOF coating. © 2024 Chinese Mechanical Engineering Society. All rights reserved.