Effects of incorporation of silanized titanium nitride on the electrochemical and mechanical properties of polyurethane in aircraft coating

The surface modified titanium nitride (TiN) nanoparticles with mercaptopropylmethyldimethoxysilane (MPMDMS) were incorporated into polyurethane (PU). The electrochemical impedance spectroscopic (EIS) studies revealed excellent protection behaviour for the PU-MPMDMS/TiN coated AA7055 in 3.5% NaCl solution. The coating resistance of the PU-MPMDMS/TiN nanocomposite was found to be 6917.19 k ohm.cm(2). It was also found that the coating resistance of PU-MPMDMS/TiN nanocomposite was over 44.58% higher than that of the PU coating. The measured current by scanning electrochemical microscopy (SECM) over the PU-MPMDMS/TiN nanocomposite coating was very low (1.5 nA) compared to pure PU coated AA7055 (14.9 nA). The surface morphological studies of the coated AA7055 by SEM/EDX analysis and X-ray diffraction (XRD) analysis revealed that the TiN nanoparticles were enriched at the corrosion products which prevented corrosion initiation processes. The enhanced mechanical properties were noticed for the PU-MPMDMS/TiN nanocomposite. The results showed that the newly developed PU-MPMDMS/TiN nanocomposite coating possessed enhanced hydrophobic behaviors (WCA: 157o). Therefore, it was concluded that the newly synthesized PU-MPMDMS/TiN nanocomposite provided excellent barrier, hydrophobic, and mechanical properties due to the addition of MPMDMS/TiN nanoparticles to the polyurethane resin which prevented the degradation of materials and helped to prolong the life of the coated AA7055 aluminium alloy.