EFFECTS OF PROCESS PARAMETERS ON FE2O3/ ALPHA AL2O3 LUSTER PIGMENTS PRODUCED BY PRECIPITATION METHOD

Common known examples of substrate-based pigments are mica/TiO₂ and mica/Fe₂O₃ luster pigments produced using wet chemical methods and gas-phase reaction techniques. Luster coatings, in particular those prepared using iron(III) oxide, come into prominence thanks to their characteristics of good hiding power and weather resistance, to name a few. Mica/Fluorphlogopite/Silica-based luster pigments have certain disadvantages due to following reasons: natural mica contains iron (Fe₂O₃) impurity which imparts a yellow color to the material, synthetic fluorphlogopite is quite expensive compared to natural mica and silica has a high production cost. In addition to these, fragility of mica bases due to their low mechanical strength adversely affects the luster effect. Reaction kinetics control is easier in wet chemical methods than in gas-phase reaction techniques since the coarse substrate particles can be kept suspended more easily by stirring. In this study, α-Al₂O₃/Fe₂O₃ luster pigments were produced using the wet chemical method/precipitation method by preferring plate-like alumina substrates in order to eliminate the afore-said problems. The pigments produced were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) methods and color analysis was performed. As a result, it was determined that the increase in titration flow rate and stirring rate in the production process of Fe₂O₃/α-Al₂O₃ luster pigment using the wet chemical method had no effect on the crystal structure of the resulting coating. However, while the stirring rate does not have a significant effect on the quality of coating, the increase in titration flow rate adversely affects the quality of coating.