Table of Contents
International Journal of Metals
Volume 2013 (2013), Article ID 757049, 7 pages
Research Article

Optimization of Conversion Treatment on Austenitic Stainless Steel Using Experimental Designs

1Laboratoire de Spectroscopie, Modélisation Moléculaire, Matériaux et Environnement (LS3ME), Faculté des Sciences, Université Med V-Agdal, Avenu Ibn Battouta, BP 1014, Rabat, Morocco
2CIRIMAT-LCMIE, Université Paul Sabatier, 118 route de Narbonne, 31064 Toulouse Cedex 4, France

Received 27 August 2013; Accepted 17 November 2013

Academic Editor: Chi Tat Kwok

Copyright © 2013 S. El Hajjaji et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Conversion coating is commonly used as treatment to improve the adherence of ceramics films. The conversion coating properties depend on the structure of alloy as well as on the treatment parameters. These conversion coatings must be characterized by strong interfacial adhesion, high roughness, and high real surface area, which were measured by an electrochemical method. The influence of all the elaboration factors (temperature, time, and bath composition: sulphuric acid, thiosulphate as accelerator, propargyl alcohol as inhibitor, and surface state) and also the interactions between these factors were evaluated, using statistical experimental design. The specific surface area and optical factor (α) correspond to the quantitative responses. The evaluation showed, by using a designed experimental procedure, that the most important factor was “surface state.” Sanded surface allows the formation of conversion coating with high real surface area. A further aim was to optimise two parameters: treatment time and temperature using Doehlert shell design and simplex method. The growth of the conversion coating is also influenced by treatment time and temperature. With such optimized conditions, the real surface area of conversion coating obtained was about 235 m2/m2.