Preparation and characterisation of high performance yellow anticorrosive phosphomolybdate pigments

Abstract

Purpose

Owing to the ongoing demand for the elimination of chromate‐ and lead‐based pigments and the need to identify effective replacements, phosphate and molybdate are finding increasing application in coating industry. In the study reported here, phosphomolybdates, the newest of the second generation of molybdate and phosphate pigments had been prepared, characterised and evaluated as anti‐corrosive pigments for coating applications.

Design/methodology/approach

In this study, Ca, Zn and Ca‐Zn phospomolybdates were prepared and characterised by chemical analysis and spectrophotometric measurements, X‐ray diffraction (XRD) and scanning electron microscopy (SEM), in addition to thermal gravimetric analysis (TGA). The pigments were also evaluated according to international standard testing methods. The conditions for the preparation of the phosphomolybdate pigments were established. Their anticorrosive properties were evaluated by incorporation in anticorrosive paint formulations using medium oil alkyd resin as a binder. The paint films were tested in artificial seawater for 28 days.

Findings

The results showed superior anticorrosive protection properties of the pigments prepared over their phosphate and molybdate counterparts, in addition to the high tinting strength of their golden yellow colours.

Practical implications

The method for enhanced production of the eco‐friendly phosphomolybdate pigments was novel and economically feasible.

Originality/value

Phosphomolybdates, the newest of the second generation of molybdate pigments incorporate a synergistic combination of phosphate and molybdate compounds and are believed to have exceptional corrosion inhibiting activity, which has allowed for more optimised applications in specific types of coatings. They are considered the best known and most frequently utilised non‐toxic eco‐friendly inhibitive pigments.

Citation

Abd El‐Ghaffar, M.A., Youssef, E.A.M. and Ahmed, N.M. (2006), "Preparation and characterisation of high performance yellow anticorrosive phosphomolybdate pigments", Pigment & Resin Technology, Vol. 35 No. 1, pp. 22-29. https://doi.org/10.1108/03699420610638012