Environmental friendly multifunctional orange pigment for cool coating applications

Abstract

The present study illustrates the development of an environmentally benign intense orange inorganic pigment, by substituting Si4+ metal ion at the Bi3+ site of Bi4V2O11 via solid-state method. The partial replacement of Si4+, induced a strain in the crystal lattice of the compound, which resulted in a substantial improvement in the visible light reflectance. A reduction in oxygen deficiency in the lattice structure facilitated the colour tuning of the pigment series from brownish red to orange and then on to yellowish orange. The composition Bi3.8Si0.2V2O11+δ exhibited a bright orange hue with colour co-ordinates a* = 39, b* = 34 and L* = 52. Furthermore, NIR solar reflectance of the pigment was 86 %, which is superior than the reported and commercial orange pigments. Compared to commercial pigment coatings, Bi3.8Si0.2V2O11+δ achieved a temperature reduction of 2 °C inside a foam model house. An exceptional corrosion resistance of 1.6 × 1010 Ωcm2, was registered by the pigment loaded epoxy coating with good stability. The corrosion inhibition mechanism of the pigment operates through the hand in hand working of passive Bi-O and Si-O, active FeOOH and vanadate moiety. On the whole, the new multifunctional orange pigment has the potential to be a viable replacement for the toxic commercial pigments in the market.