New types of phosphate pigments which are appropriate alternatives for hazardous chromate pigments have been prepared and evaluated. These new pigments were prepared via a new technique named core-shell. The core-shell materials consist of at least two separate phases with different chemical compositions. Recently, these materials have become more significant because they have the advantage of gathering the properties of both cores and shells that help to overcome the defects that they might possess individually. The purpose of this research is to develop a modified silica fume-phosphate core-shell pigment that contains 80-90 per cent of waste material (silica fume) and at the same time can offer promoted mechanical and anticorrosive properties than silica fume and they can also be compared with phosphates. The pigments have shells of Zn, Mn, Zn.Mn phosphates comprising about 10-20 per cent.
The prepared core-shell pigments have been characterized using several methods, which have then been integrated in alkyd paint formulations. The physical and mechanical properties of dry films and their corrosion prevention using accelerated laboratory test in 3.5 per cent NaCl for 28 days are estimated.
This study showed that the performance of these new pigments is highly efficient in corrosion protection, and it can be a suitable alternative to phosphate pigments despite containing phosphates which does not exceed 20 per cent of the composition.
Waste materials were reused in paints and only simple modification was used; their effectiveness was high and can be compared with well-known pigments.
Silica-phosphate core-shell pigments are environmentally friendly pigments that can replace other hazardous pigments (e.g. chromates and phosphates) with almost the same quality in their performance.
This work was supported by Science and Technology Development Fund in Egypt (STDF) under project number 12650.
Ahmed, N.M., Mohamed, M.G. and Abd El-Gawad, W.M. (2018), "Corrosion protection performance of silica fume waste-phosphates core-shell pigments", Pigment & Resin Technology, Vol. 47 No. 3, pp. 261-271. https://doi.org/10.1108/PRT-07-2017-0069
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