Preparation and characterization of inorganic colored coating layers on lamellar mica-titania substrate

The inorganic colored composite pigments, such as Fe2O3-, Bi4Ti3O12-, and CoAl2O4-coated mica-titania composites, were prepared by hydrolysis of FeCl3, Bi(NO3)3, and Co(NO3)2/Al(NO3)3 in the presence of mica-titania substrate and calcination at different temperatures. The inorganic coating layers on mica-titania substrate surfaces were explored by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Dense and uniform Fe2O3 coating layers were formed on the surfaces of mica-titania substrates. At lower Bi2O3 loading, Bi4Ti3O12 nanoparticles were formed on the surfaces of mica-titania substrates. But at higher Bi2O3 loading, Bi4Ti3O12 nanosheets were formed and perpendicularly oriented to the substrate surfaces. CoAl2O4 nanosheets were formed on the mica-titania substrates and perpendicularly oriented to the substrate surfaces. The pigmentary performances of the inorganic composite pigments were analyzed by CIE, indicating that red, yellow, and blue colored pigments were achieved by coating Fe2O3, Bi4Ti3O12, and CoAl2O4 on mica-titania substrate surfaces, respectively. The pigmentary performances of the inorganic composite pigments were significantly affected by the morphology and loading of inorganic coating layers.