The Corrosion Performance of Hybrid Polyurea Coatings Modified with TiO2 Nanoparticles in a CO2 Environment

To enhance the corrosion resistance of underground pipelines made of low carbon steel, nano-TiO2-modified polyurea was applied to their surface. The anti-corrosion performance of these nano-TiO2-modified coatings was tested by immersing them in a NACE (5 wt.% NaCl + 0.5 wt.% CH3COOH) solution under high temperatures and high CO2 pressures. The mass variation, SEM morphology, and open-circuit potential were determined. EIS tests, neutral salt spray tests, and contact angle measurements were carried out to analyze the effect of nanoparticles on corrosion resistance. Within the same pressure range, the polyurea coating shows the highest corrosion resistance when 5% TiO2 nanoparticles were added compared to that of polyurea coatings with 0%, 10%, and 15% TiO2 added. Coatings with 5% TiO2 nanoparticles showed rapid diffusion after being immersed for 96 h, indicating that the anti-corrosion performance of the coating weakened.