Synthesis and Characterization of Chrom-Free Zr-Ti-Ni Pale Green Coating on AA6063 Aluminium Alloy

Abstract

With K2ZrF6as the main film-forming material, Ni2SO4• 6 H2O as colorants, K2TiF6for coloring promoters, chrome-free conversion and treatment for Al6063 at room temperature has been developed, fluid can be of steady function without adding oxidants additionally, fast film forming within 6 minutes. By adding Ni element to make the conversion coating changed from gray to pale green, K2TiF6can promote color and uniform color. Analyzed sample through SEM observation, XPS and XRD analysis, the passivation was composed of Al, Ni, NiZr, Ti and NiZr3; By electrochemical tests, the corrosion current decreased to 0.067μA of passivation membrane, corrosion resistance increased nearly one hundred times, membrane layer structure circuit is C1 / R1 / (L2 + R2)/(L3 + R3)/(L4 + R4).