Innovative nanocomposite coating for aluminum alloy: superior corrosion resistance, flame retardancy, and mechanical strength for aerospace applications

Nanocomposites containing impermeable two-dimensional materials are attracting considerable attention for their ability to shield metals from corrosion. Incorporating m-aminophenyltrimethoxysilane functionalized niobium nitride (NbN) into a coating matrix can bolster the barrier effect owing to its remarkable chemical and thermal stability. When integrated into graphitic carbon nitride (GCN) within polyurethane (PU), functionalized NbN enhances corrosion protection and imparts fire-retardant properties. Utilizing electrochemical techniques in chloride-rich environments, the protective efficacy of aluminum coated with polyurethane containing varying proportions of functionalized NbN/GCN was investigated. Electrochemical impedance spectroscopy measurements demonstrated improved coating resistance (Rcoat: 5.65 x 1011 ohm cm2) for PU/functionalized NbN/GCN, even after 600 h of electrolyte exposure. Furthermore, the resulting PU composite exhibited superior flame-retardant capabilities, manifesting significant reductions in peak heat release rate, total heat release, and total smoke production compared to pure PU. Featuring a water contact angle of 165 degrees, the newly developed PU/functionalized NbN/GCN coating showcased exceptional water repellency. In terms of mechanical properties such as adhesion strength and hardness, PU/functionalized NbN/GCN demonstrated favorable characteristics within the PU substrate, maintaining structural integrity even after prolonged immersion. Consequently, the PU/functionalized NbN/GCN nanocomposite presents itself as a promising coating component for aerospace applications.