Anticorrosive performance of ion‐exchange zeolites in alkyd‐based paints

Abstract

Purpose

Organic coatings remain the most widely used way of protecting steel structures from corrosion. Traditional anticorrosive paints contain lead or hexavalent chromium compounds as active pigments. The use of these classical chromates is nowadays restricted by increasing environmental awareness and stringent national and international regulations. An alternative is the use of ion‐exchangeable pigments. The purpose of this paper is to show that cation‐exchanged zeolites can be considered as a safe and efficient alternative to traditional hazardous pigments in protecting steel surfaces.

Design/methodology/approach

The new pigments were characterised using different analytical and spectro‐photometric techniques. Characterisation of these pigments using X‐ray diffraction and scanning electron microscopy were done. X‐ray fluorescence was employed to elucidate the concentration of different elements in the prepared pigments. Evaluation of the ion‐exchanged and initial zeolite pigments using international standard testing methods (ASTM) was estimated. Testing the anticorrosive protection of cation‐exchanged zeolites in alkyd paints formulated based on their pigment volume concentration/critical pigment volume concentration was studied, and then these new pigments were applied on cold‐rolled steel panels. The physico‐mechanical properties of dry films and their corrosion properties using accelerated laboratory test in 3.5 per cent NaCl for 28 days were tested.

Findings

The results of this work revealed that paint films containing initial Na‐zeolite performed the least protection behaviour, while films including Zn, Ca and Mg‐zeolites were better in their corrosion protection performance, and they can be arranged as Zn‐zeolite>Ca‐zeolite>Mg‐zeolite.

Practical implications

These pigments can be applied in other polymer composites, e.g. rubber and plastics as reinforcing agent and fillers.

Originality/value

The paper shows that these prepared pigments are environmentally friendly pigments which impart high anticorrosive behaviour to paint films with great economic savings.

Citation

Ahmed, N.M., Emira, H.S. and Selim, M.M. (2011), "Anticorrosive performance of ion‐exchange zeolites in alkyd‐based paints", Pigment & Resin Technology, Vol. 40 No. 2, pp. 91-99. https://doi.org/10.1108/03699421111113747