Synthesis of Zn_xMg_yAl₂O₄ spinels for use in protective coatings

Abstract

Purpose

The purpose of this paper is to describe the process of synthesizing lamellarly‐shaped anticorrosion pigments having a chemically active layer whose core consists of metal aluminium on which a thin spinel film is synthesised.

Design/methodology/approach

Anticorrosion pigments were synthesised by reaction of metal aluminium lamellar particles whose surface was oxidised to Al₂O₃ during the first stage and by subsequent reaction with ZnO and/or MgO at 800‐1,150°C producing a thin spinel layer that is chemically bonded to the metal core of the pigment particles. Core‐shell pigments including MgAl₂O₄/Al, Mg_0.8Zn_0.2Al₂O₄/Al, Mg_0.6Zn_0.4Al₂O₄/Al, Mg_0.4Zn_0.6Al₂O₄/Al, Mg_0.2Zn_0.8Al₂O₄/Al and ZnAl₂O₄/Al were synthesised. The prepared pigments were characterised by means of X‐ray diffraction analysis and scanning electron microscopy. The synthesised anticorrosion pigments were used to prepare epoxy coatings that were tested upon application for their anticorrosion properties and resistance against a chemical environment.

Findings

The lamellar shape of the particles, as well as good‐quality coverage with a thin spinel layer, was identified in the prepared pigments. All of the synthesised pigments exhibit good anticorrosion efficiency in epoxy coatings. Compared to lamellar kaolin and metal core of aluminium without coverage, the protective function of the synthesised pigments in coatings is demonstrably better.

Practical implications

The synthesised pigments find convenient applications in coatings protecting metal bases from corrosion.

Originality/value

Synthesis of a spinel layer on the metal core of aluminium is a novel method; so is the application of these substances in coatings designed for the protection of metals from corrosion. Of great benefit is the fact that the synthesised pigments are free of any substances harmful to the environment.

Citation

Veselý, D. and Kalendová, A. (2008), "Synthesis of Zn_xMg_yAl₂O₄ spinels for use in protective coatings", Pigment & Resin Technology, Vol. 37 No. 3, pp. 151-160. https://doi.org/10.1108/03699420810870995