Enhancement of properties of red iron oxide – aluminium oxide solid solutions anticorrosive pigments

Abstract

PurposeSeveral solid solution combinations of aluminium oxide and iron oxide, for the preparation of a new pigment, were investigated to study the effect of aluminium oxide to iron oxide ratio on various properties of the resulting pigments.Design/methodology/approachThe conditions for the preparation of the pigments via solid solution interaction at 1,000°C had been estimated. Characterisation of three different combinations of aluminium oxide and iron oxide were carried out using spectroscopic methods of analysis via X‐ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM). Also, evaluation of the pigments prepared, in terms of oil absorption, specific gravity, water‐soluble matter, and pH, using international standard testing methods was performed. The pigments prepared were incorporated in anticorrosive paint formulations based on medium oil alkyd resin as a binder. The physico‐mechanical properties of the relevant paint films were obtained, while their anticorrosive properties were assessed by tests in 3.5 per cent NaCl solution for 28 days.FindingsThe results showed that the anticorrosive protection properties of the pigment prepared were better than their aluminium and iron counterparts.Research limitations/implicationsThe pigments prepared may be used in different applications other than paint formulations. As the concentration of iron oxide increases, the hardness and the anticorrosive protection performance of the paint film increase. As the concentration of aluminium increases, elasticity, impact resistance and ductility also increase. Application of different combinations of these pigments in paint films had been studied. However, investigation of the application of these pigments in other systems such as plastics could also be interesting.Practical implicationsThe pigments prepared can be used as reinforcing filler in different rubber and plastic composites, beside its ferro‐magnetic properties. As the concentration of alumina increased, the reinforcing and magnetic effects decreased and vice versa.Originality/valueIron oxide is an abundant ore in several world countries; it is an inorganic, environmentally friendly material, which exhibits good Moh's hardness. Adding aluminium oxide which is a very light element having a unique flaky structure to iron oxide gave a new pigment that can be used not only in paint formulations, but also in rubber and plastic composites as reinforcing fillers.