Influence of phytic acid on the microstructure, composition, and corrosion resistance performance of Zr-based painting pretreatment film

Zirconium (Zr)-based conversion films are considered an environmentally friendly technology with the potential to replace traditional painting pretreatment methods. However, the adhesion and corrosion resistance of single Zr films fail to meet industrial demands. Incorporating organic additives can offer critical functionalities and performance improvements to Zr films. In this study, a novel organic–inorganic hybrid Zr-based film doped with phytic acid (PA) was fabricated. Various analytical techniques, including X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and electrochemical methods, were employed to investigate the influence of PA on the formation of Zr-based films. The incorporation of PA resulted in alterations in the surface morphology, thickness, steel/film interface structure, and anticorrosion performance. When the concentration of PA was 0.1%, the fabricated film exhibited the best anticorrosion performance (74.9%). SEM images revealed a noticeable reduction in surface cracks and voids at the steel/film interface upon the addition of PA. XPS results indicated that PA or the complex formed between PA and Al ³⁺ could adsorb on the film surface, thereby constructing a double-layer structure of PA-doped Zr-based film. This study provides innovative insights into the impact of organic additives on the formation process of environmentally friendly and efficient Zr-based painting pretreatment films.