Corrosion-inhibited wear in Fe-based amorphous alloy coatings: Role of antagonistic interactions and rapid repassivation in chloride media

The coupled electrochemical-mechanical degradation of a high-velocity oxygen-fuel (HVOF) sprayed Fe₅₇Cr₁₅Mo₈P₁₀C₇B₃ amorphous alloy coating (AAC) was systematically investigated in a 3.5 wt% NaCl solution and benchmarked against 316 L stainless steel (316 L SS). By coupling in-situ electrochemical techniques with wear-track topometry and X-ray photoelectron spectroscopy (XPS) depth profiling, the fundamental mechanisms governing dynamic wear–corrosion interactions were elucidated. Notably, despite exhibiting a higher static corrosion rate than the 316 L SS, the AAC demonstrated a localized antagonistic contribution to wear-corrosion interaction during sliding. Specifically, the electrochemically driven passivation process actively suppressed mechanical attrition, yielding a negative corrosion-accelerated wear volume (ΔW_fc = - (2.75 ± 0.91) × 10⁻³ mm³). Conversely, the 316 L SS suffered from severe positive synergy (ΔW_fc= + (2.22 ± 0.47) × 10⁻³ mm³), resulting in a nearly threefold higher total material loss. In-situ tribo-electrochemical analyses revealed that the homogeneous amorphous structure of the AAC facilitates ultra-fast repassivation kinetics (t_rep = 4.4 s, vs. 15.4 s for the 316 L SS), dynamically sustaining a highly stable duplex passive film. XPS profiling further corroborated that this rapidly regenerated tribofilm is significantly thicker (10.55 nm vs. 7.84 nm) and strongly enriched in gel-like FeOOH and protective Mo oxides. Under continuous sliding contact, these tribochemically generated species are proposed to contribute to the formation of a shear-accommodating solid boundary layer, which may reduce direct asperity contact and mitigate abrasive damage. This study provides fundamental insights into the "corrosion-inhibited wear" mechanism of Fe-based AACs, demonstrating that the synergistic coupling of rapid self-healing kinetics and tailored tribofilm chemistry is a highly effective design principle for robust marine tribological applications.