Novel multifunctional nanocomposites for superior barrier, hydrophobic and mechanical properties of Mg alloy in marine environment

The impact of surface functionalized titanium carbide (TiC) nanoparticles on the electrochemical and mechanical properties of epoxy nanocomposite was investigated. The functional TiC nanoparticles were synthesized using pyrrole (Py) and 2-amino-5-mercapto-1,3,4-thiadiazole (AMTD) and characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), and thermogravitric analysis (TGA) techniques. The resultant novel nanocomposite coating on Mg alloy in seawater was investigated by Tafel polarization, electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) studies. Electrochemical studies revealed excellent corrosion protection performance and a decreased corrosion current density for the EP-AMTD/TiC (Rc = 4861.25 kΩ.cm2 and icorr = 3.75 μA/cm2) and the EP-Py/TiC nanocomposite coated Mg alloy (Rc = 3182.71 kΩ.cm2 and icorr = 5.65 μA/cm2) in comparison with the plain epoxy coated Mg alloy (Rc = 244.67.25 kΩ.cm2 and icorr = 9.55 μA/cm2) after 60 days of immersion. The results indicated that the functional TiC nanoparticles dispersed uniformly and retarded the propagation of aggressive ions to the coating/alloy interface. SECM observations confirmed the observation of least current at the scratched area of the EP-AMTD/TiC (2.1 I/nA) and the EP-Py/TiC (4.8 I/nA) coated alloy compared to pure epoxy coating (14.9 I/nA) even after 60 d immersion in seawater. SEM observations showed that reactive TiC nanofillers are dispersed uniformly. The changes in surface morphology, phase structure and composition were analyzed using SEM/EDX and XRD techniques. It was found that the intercalation of functional TiC nanoparticles in the epoxy coatings exhibited a smooth microstructure surface producing superior corrosion protection and mechanical properties. The mechanism of corrosion protection has been proposed. [Display omitted] •Electrochemical studies revealed excellent corrosion protection performance for EP-AMTD/TiC nanocomposite coated Mg alloy•The results indicated that the AMTD/TiC nanoparticles retarded the propagation of ions to the coating/alloy interface•The intercalation of AMTD/TiC nanoparticles in the epoxy produced superior corrosion protection and mechanical properties•The mechanism of corrosion protection has been proposed