Synthesis, characterization and resistant performance of α-Fe2O3@SiO2 composite as pigment protective coatings

Abstract

Abstract The natural pigment of hematite (red ocher, α-Fe 2 O 3 ) is coated homogenously with colloidal silica-nanoparticles (SiNP) by a sol-gel process to obtain a durable hematite pigment of Fe 2 O 3 @SiNP composite for artifacts preservation. The acid/alkali-resistance, color stability and UV shielding behavior of obtained Fe 2 O 3 @SiNP are investigated. The results indicate that 60 nm thickness of uniformed coating is acquired at pH = 1.3 with 90 nm particle size distribution. Fe 2 O 3 @SiNP reveals great thermal stability at 1400 °C with minor color variation and strong acid-alkali resistance properties compared to Fe 2 O 3 after 6 months' accelerated UV weathering, based on that the surface morphology of Fe 2 O 3 @SiNP remains intact while pure Fe 2 O 3 is faded with critical deterioration. Therefore, silica-nanoparticles coated on surface of Fe 2 O 3 could form a durable Fe 2 O 3 pigment against acid, alkali, thermal and long term of UV irradiation.