Self-limiting film formation mechanism of zirconium based conversion coating on mild steel

Abstract

Purpose

The purpose of this paper is to investigate the film formation mechanism of zirconium-based conversion layer on mild steel. In this way, different approaches were used to show the self-limiting film formation mechanism.

Design/methodology/approach

To determine this mechanism, film formation was detected using DC polarization, spectrophotometric technique and surface analysis techniques, including field emission scanning electron microscope (FE-SEM) and atomic force microscopy (AFM).

Findings

DC polarization resistance of surface increased with increasing of mild steel immersion time in the conversion coating bath, reaching to a plateau region. On the other hand, zirconium ion concentration decreased during the beginning of the film formation process and continued with a constant concentration, showing the expiry of the process after some minutes.

Originality/value

This paper deals with the film formation mechanism of the zirconium-based conversion layer that includes valuable findings to monitor the process.

Citation

Ghanbari, A. and Attar, M.M. (2016), "Self-limiting film formation mechanism of zirconium based conversion coating on mild steel", Anti-Corrosion Methods and Materials, Vol. 63 No. 2, pp. 137-144. https://doi.org/10.1108/ACMM-04-2014-1371