Synergistic corrosion Inhibition of interfacially engineered Al-O/CNT composites through Al-O-C chemical anchoring

초록

Enhancing the corrosion resistance of aluminum (Al) matrix composites remains a significant challenge due to the inherent interfacial instability between the matrix and carbon nanotubes (CNTs). This study reports a superior corrosion inhibition mechanism in interfacially engineered Al-O/CNT composites, driven by the formation of robust Al-O-C chemical anchoring. We comparative analyzed the electrochemical degradation of pure Al, Al/CNT, and Al-O/CNT through salt spray tests and density functional theory (DFT) simulations. SEM analysis revealed that the Al-O/CNT composite exhibited the thinnest corrosion layer 0.45 mu m, significantly outperforming Al/CNT (0.86 mu m) and pure Al (2.45 mu m). Furthermore, the Al-O/CNT composite demonstrated a negligible net mass gain of only 0.15 mg/cm2, which is significantly lower than those of Al/CNT (1.84 mg/cm2) and pure Al (2.12 mg/cm2). XPS analysis demonstrated that the Al-O-C interface effectively suppresses the hydration of the Al2O3 passive film into unstable Al(OH)3, while enabling a near-complete (99.8%) immobilization of metal chlorides at the interface to prevent deep Cl- penetration. DFT calculations corroborated these findings, revealing a thermodynamic shift from weak mechanical interlocking (-3.52 eV) to stable chemical anchoring (-5.72 eV). This high interfacial binding energy provides an electronic barrier against electrolyte ingress and stabilizes the protective oxide layer. The synergistic effect of the physical CNT network and the chemically anchored interface establishes a multi-level defense system, offering a new paradigm for designing highly corrosion-resistant metal matrix composites.

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