Ammonium molybdate added in hybrid films applied on tinplate: effect of the concentration in the corrosion inhibition action

Abstract

One of the ways to improve the anticorrosive properties of the hybrid films is with the addition of corrosion in hibitors based on inorganic salts. The protection mechanism involves the release of molybdate ions inserted in coatings by sol gel during the immersion in the electrolyte, thereby minimizing the corrosion process. Silox ane PMMA hybrid films are constituted by a silica network, to which the chains of poly (methyl methacrylate) (PMMA) are connected by covalent bonds (Class II) or by physical interactions (Class I). The stability and trans parency enable the application of these materials in the coating of tinplate packagings in order to enhance corro sion resistance and reduce the brittleness of these products. In this context, the objective of this study is to coat the tinplate with a hybrid siloxane PMMA (Class II) film obtained from a sol constituted of the alkoxide precur sors: 3 (trimethoxysilylpropyl) methacrylate (TMSM), poly(methyl methacrylate) PMMA and tetraethoxysilane (TEOS), by varying the added corrosion inhibitor concentration from0.01 to 0.02 M. The films were obtained by a dip coating process and characterized according to their morphological and electrochemical behavior. The re sults showed that hybrid films dopedwith corrosion inhibitors showed an increase in the layer thickness in com parison to the inhibitor free film. Furthermore, the addition of a higher concentration of ammonium molybdate resulted in an increase of the corrosion performance of the hybrid films.