Fabrication of FeCoCrNiCuM (M=Ti, Al) coatings via laser cladding: Anti-corrosion and tribocorrosion performance

Abstract

304 stainless steel components in marine engineering experience severe material degradation due to the synergistic effect of corrosion and wear, which significantly shortens their service life. In this study, FeCoCrNiCuM (M = Al, Ti) high-entropy alloy coatings were designed and fabricated on 304 stainless steel through laser cladding to tackle this issue. The incorporation of Al and Ti induced a matrix phase transformation from the face-centered cubic (FCC) to the body-centered cubic (BCC) structure, promoting substantial grain refinement and greatly enhancing the strain hardening ability of the coatings. Simultaneously, Al and Ti facilitated the in-situ formation of dense Al2O3-Cr2O3 and TiO2-Cr2O3 dual-passivation films with excellent dynamic self-repair performance under tribocorrosion conditions, effectively preventing the penetration of aggressive ions. Owing to these regulatory mechanisms, the modified coatings demonstrated remarkably enhanced corrosion and tribocorrosion resistance. Specifically, the minimum self-corrosion current density (Icorr) in HCl, KOH, and NaCl solutions was 1.60 & times; 10-5, 0.02 & times; 10-5, and 0.002 & times; 10-5 A/cm2, respectively, which were only 0.18, 0.008, and 0.0008 times those of the FeCoCrNiCu reference coating. The lowest wear rates in the three media were 0.04 & times; 10-5, 0.21 & times; 10-5, and 0.23 & times; 10-5 mm3/N & sdot;m, which were merely 0.27, 0.10, and 0.36 times those of the reference coating. The outstanding performance was primarily attributed to the synergistic grain boundary strengthening and self-repairing passive films, which effectively suppressed the corrosion and wear synergistic effect. The dominant wear mechanisms were abrasive and adhesive wear. This research clarifies the regulatory mechanism of Al and Ti on the corrosion and tribocorrosion resistance of FeCoCrNiCu based coatings, offering a feasible strategy to prolong the service life of marine engineering stainless steel components.