Paraphenylenediamine modified graphene oxide for enhancement protection performance of epoxy coating on Q235 steel

Abstract

Among the array of strategies deployed to combat corrosion, coating protection stands out as a method both simple and cost-effective. In this paper, paraphenylenediamine (PPDA) was used to modify graphene oxide (GO) to obtain a nano-filler with excellent dispersibility and barrier properties. Integration of this PPDA modified reduced graphene oxide (FRGO) into the epoxy resin matrix yields a composite coating boasting remarkable resistance against corrosion. Through a comprehensive analysis involving FT-IR, Raman, XPS, and XRD, the optimal reduction temperature for GO was discerned to be 500 °C. The optimal modified addition amount of PPDA to GO is 1:1. Subsequent to the preparation of PPDA modified reduced graphene oxide composite coating composite coatings featuring varied concentrations, an assessment of the coatings' corrosion resistance ensued through electrochemical workstation analysis and salt spray testing. After immersed in a 3.5 wt% NaCl solution for 120 h, the low frequency impedance modulus value (|Z|_{0.01 Hz}) of composite coating with 0.1 wt% FRGO reached a peak value of 1.94 × 10⁹ Ω·cm². Even after immersion for 240 h, the |Z|_{0.01 Hz} remained significantly high at 4.01 × 10⁸ Ω·cm², indicating a significant improvement in corrosion resistance.