Study of Nano Metal Oxide Incorporated Zinc Phosphate Coatings as Corrosion Inhibitors on Mild Steel

Abstract

The existing corrosion prevention processes and methods are incapable of predicting all environmental conditions. On the other hand, the local metal coating and paint industries continue to suffer from a lack of appropriate advanced phosphating technology as a surface pre-coating technique. The incorporation of ceramic nanoparticles into the phosphate coating has improved the properties such as high corrosion resistance and secondary coating adhesion. As a result, the goal of this research was to create and improve a corrosion prevention method suitable for the metal coating industries by incorporating nano TiO₂ into a phosphate precoating. To facilitate the coating via chemical conversion, the cleaned mild steel specimens were dipped in the prepared phosphating bath containing the nano TiO₂. Under the given conditions, the optimum coating time was determined to be 90 minutes. Significant changes in coating weight, adhesion quality, surface porosity, and corrosion resistance were observed with the addition of nano TiO₂ (average particle size ~ 25 nm). X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and a gemmological microscope were used to investigate the crystal phases and surface morphology of zinc phosphate coatings. XRD data clearly showed that nano TiO₂ has successfully incorporated into the phosphate layer. The addition of nano TiO₂ to the zinc phosphate coating improved its properties, such as coating thickness and surface area, promising an improvement in corrosion resistance. With minor modifications aiming to lower the coating time, the findings of this study could be easily implemented in the metal coating industries and extended to other metals such as steel, aluminium, and alloys.

Keywords:  Chemical Conversion, nano -TiO₂, Mild steel, Phosphating