Preparation of Magnetic Pearlescent Pigment Mica/Fe3O4 by Thermally Decomposing Ferric Formate Composite Containing Hydrazine

Abstract

Mica/Fe3O4 pearlescent pigment was synthesized via thermal decomposition of ferric formate composite containing hydrazine (composite salts), which was deposited on the surface of mica. The obtained product showed good dispersity, magnetic property and special black luster. The effects of pH value, sodium hydroxide concentration, molar ratio, stirring speed and temperature on composited salt coating rate and smooth on the mica surface were investigated. The optimum parameters were obtained including the pH value, the concentration of sodium hydroxide, the molar ratio of formic acid to Fe3+, the velocity of magnetic stirring, calcination temperature and time. It was also found that coating properties such as smoothness, compactness and color deepness were influenced by different pH, temperatures, sodium hydroxide concentration and so on. The products were characterized by X-ray diffraction, high resolution scan electron microscopy, vibrating sample magnetometer, color measurement and element analysis. The results indicates that a concentration 1.0 mol/L, a pH value between 4.0 and 4.5, a formic acid/Fe3+ ratio = 3, a stirring speed at 180 rpm/min at room temperature are the best conditions to obtain a good coating performance and a suitable pearly luster effect. Pearlescent pigment was prepared by the decomposition of composite salt on micron surface. Different parameter were evaluated separately to obtain suitable products having a significant pearly luster effect. The best results were observed when sodium hydroxide concentration is 1.0 mol/L, the value of pH is between 4.0 and 4.5, the molar ratio [formic acid]/[Fe3+] is 3:1 and the stirring speed is 180 rpm/min and the products is prepared under room temperature.