Polymeric coating reinforced with Co2O3 nanoparticles (1 wt%) for improved mechanical, thermal, and corrosion resistance on AISI 1018 carbon steel

This study analyzed the improvement of the mechanical, thermal, and anticorrosive properties ofpolyurethane (PU) coatings by incorporating cobalt oxide (Co₂O₃) nanoparticles at 1 wt%. Unlikeconventional additives, which act mainly through passivation or sacrificial mechanisms, Co₂O₃ wasevaluated as a multifunctional reinforcement. The synthesis was carried out by mixing polyols andantifoaming agents at 25 °C, incorporating the nanoparticles into the polymeric matrix. Thesamples were characterized by FTIR, XRD, TGA, tensile tests (ASTM D638), and electrochemicalmeasurements in 5% NaCl solution. FTIR confirmed the PU bands and a signal at 570 cm⁻¹associated with Co₂O₃, while XRD revealed crystallographic planes (311), (111), and (440). TGAshowed higher thermal stability in the reinforced system, with 82% mass loss at 456.39 °Ccompared to 90% at 440.15 °C in pure PU. In tensile tests, the Co₂O₃-reinforced coating reached16.55 MPa compared to 9.58 MPa for PU. However, electrochemical analysis revealed anincreased corrosion rate (0.047 mpy vs. 0.008 mpy), attributed to nanoparticle agglomeration anddefect formation. In conclusion, Co₂O₃ enhanced the thermal and mechanical performance butrequires optimized dispersion to ensure anticorrosive protection.