APTES-modified Al2O3 nanoparticles reinforced polyurea coating with enhanced wear and corrosion protection for Q235 steel

Polyurea coating offers robust protection against weathering and corrosion, yet the limited wear resistance remains a bottleneck for long-term service in marine environments. In this study, a high-performance polyurea coating incorporating APTES-modified Al 2 O 3 nanoparticles was developed on Q235 steel. The surface-grafted amino groups not only improve the compatibility between Al 2 O 3 nanoparticles and polymer matrix but also facilitate the establishment of strong interfacial bonds within the polyurea network, thereby significantly bolstering the coating's mechanical properties and environmental durability. Compared to pure polyurea, the composite coating achieves a 41.1% lower mass loss under a 1000 g load and 2000 wear cycles, demonstrating reliable wear resistance. Moreover, the nanoparticles enhance the structural compactness of the coating and increase the tortuosity of the diffusion pathways for corrosive mediums, leading to a remarkable enhancement in corrosion protection. After immersion in 3.5 wt% NaCl solution for 120 days, the low-frequency impedance modulus (| Z | f =0.01Hz ) of the composite polyurea coating remains above 10 11  Ω·cm 2 . Meanwhile, the composite polyurea coating exhibits superior resistance to UV aging. These findings demonstrate the great potential of this nano-alumina-reinforced polyurea composite for application in high-performance protective coatings.