Enhanced corrosion resistance and mechanical integrity of Bi-Sn doped basalt fiber epoxy composites in seawater environments

This study investigates the efficacy of eco-friendly Bi-Sn-doped basalt fiber reinforced polymer (BFRP) epoxy composites in seawater environments and its mechanical durability. Bi-Sn nanoparticles were synthesized via sol-gel and surface doped on basalt fibers using solution dipping and hydrogen reduction in a Chemical vapor deposition (CVD) reactor. Crystallinity and surface morphology were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Over 45 days, electrochemical impedance spectroscopy (EIS), contact-angle measurements (82°-89°), were conducted. The results indicated that Bi-Sn surface doping significantly reduced corrosion defects, as evidenced by the diminished appearance of pitting, rusting, and cracking on the treated surfaces. This morphological improvement highlights the potential of Bi-Sn doping to enhance corrosion resistance. Electrochemical impedance spectroscopy showed dynamic corrosion behavior, with initial high impedance and series resistance from 1275 ohm.cm2 to 7 × 105 ohm.cm2, decreasing significantly at day 45. Mechanical properties of the samples were well preserved (Ref:152 MPa; S1:30.3 MPa; S4:132.4 MPa). These findings demonstrate Bi-Sn surface doping enhance basalt fiber corrosion resistance and mechanical durability in marine environments.