Multifunctional nanocomposite coating for aluminium alloy: Corrosion resistance, flame retardancy, and mechanical enhancement for automotive components

Aluminium alloys are utilized in the automotive industry for components such as engine blocks, wheels, chassis, and body panels. Their lightweight nature helps reduce vehicle weight, leading to improved fuel efficiency and lower emissions. The development of nanocomposites incorporating impermeable two-dimensional materials holds significant promise for safeguarding metals against corrosion. By introducing N-aminoethyl-3-aminopropyltrimethoxysilane (AAMS) functionalized molybdenum nitride (MoN) into a coating matrix, the barrier effect can be significantly enhanced owing to its remarkable chemical and thermal stability. This enhancement is further amplified through the incorporation of functionalized MoN into graphitic carbon nitride (GCN) within a polyurethane (PU) matrix, resulting in improved corrosion protection and fire-retardant properties. Through electrochemical techniques conducted in marine environments, the protective efficacy of aluminium coated with polyurethane, alongside varying concentrations of functionalized MoN/GCN, was assessed. The resulting PU composite exhibited superior flame-retardant capabilities, manifesting in substantial reductions in peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) compared to pure PU formulations. Electrochemical impedance spectroscopy (EIS) measurements revealed a notable enhancement in coating resistance (5.65×1011 Ω.cm2), even following 500 hours of exposure to the electrolyte. Furthermore, the newly formulated PU composite, featuring functionalized MoN/GCN, demonstrated exceptional water repellency with a water contact angle (WCA) of 157°. This remarkable hydrophobicity underscores its potential for applications requiring protection against moisture ingress. Additionally, the PU composite exhibited commendable mechanical properties, boasting an adhesive strength of 19.1 MPa within the PU substrate. This enhanced adhesive strength ensures the coating's integrity even after prolonged immersion periods. Given its multifaceted benefits, the PU composite incorporating functionalized MoN/GCN emerges as a promising candidate for integration into automotive industries as a viable coating component. Its ability to concurrently provide corrosion protection, flame retardancy, water repellency, and mechanical robustness underscores its potential to enhance the durability and longevity of automotive components, thereby contributing to improved performance and longevity in harsh operating environments.