Study on the performance of nano boron nitride composite phosphate film modified on carbon steel surface

Purpose The purpose of this paper is to study the effect of nano polypyrrole-modified boron nitride on the performance of phosphate film. Design/methodology/approach By adding polypyrrole-modified boron nitride to the phosphate solution, a phosphate film is formed on the metal surface, improving its corrosion resistance. The effect of different concentrations of polypyrrole-modified boron nitride on the corrosion resistance of Q235 carbon steel surface was studied. The corrosion resistance of the phosphate film was evaluated using the copper sulfate drop test. The electrochemical corrosion performance of the phosphate film was assessed using the weak polarization curve method and electrochemical impedance spectroscopy. The surface of the samples was characterized using scanning electron microscopy and X-ray diffraction analysis. Findings The results show that samples containing polypyrrole-modified boron nitride have a denser and more uniform phosphate film. When the concentration of polypyrrole-modified boron nitride is 0.6 g/L, the drop time of copper sulfate on the formed phosphate film can reach 219 s, which is a 189% increase compared to the performance of the sample without the additive. The current density is 1.06 × 10 −6 A/cm 2 lower than that of the pure phosphate film, indicating the best corrosion resistance. Polypyrrole-modified boron nitride effectively promotes the formation of the phosphate film. Originality/value This study used the modification of phosphate solution using nanoparticles to investigate the influence of different nanoparticle concentrations on the phosphate film. The corrosion resistance of the phosphate film was enhanced, providing a method and theoretical guidance for the improvement of phosphate solution formulation.