Investigation of composition and structure for a novel Ti-Zr chemical conversion coating on 6063 aluminum alloy

A novel chemical conversion coating was prepared by adding tannic acid and coating-forming accelerator in the treatment solution containing titanium and zirconium ions. Corrosion behavior of the coatings in contact with 3.5% NaCl solution was investigated using potentiodynamic measurement. The structure and composition of the coatings were determined with EDS, XPS and IR. The morphologies of the coatings were observed with scanning electron microscopy (SEM). According to the results, the modified Ti-Zr based conversion coating (MTZ) shows a smoother and more compact morphology characterization comparing with the traditional Ti-Zr treated (TZ) substrates; The Tafel results and the long-time immersion experiments also indicate that the MTZ coating presents a more effective corrosion protection property compared with the TZ coating; The MTZ coating is a multi-components chemical conversion coating which is mainly composed of metal oxide (TiO2, ZrO2, V2O5, Al2O3), fluoride (AlF3 and ZrF4) and metal-organic complex.