Abstract: Superfine-sized magnesium oxide powders were synthesized by direct precipitation method.The optimum synthesis conditions were investigated by an orthogonal test as follows:the optimum concentration of reactants is MgCl2 1.2 mol/L,NH3·H2O 0.2 mol/L,their volume ratio of reactants [V(MgCl2)∶V(NH3·H2O)] is 1∶10,temperature of reactants is 45 ℃,surfactants is 1.5‰,and time of the reaction is 25 min.The product were characterized by X-ray diffraction (XRD),infrared (IR) spectroscopy,scanning electron microscope (SEM),particle size analysis,and so on.Results showed that the yield of the superfine sized MgO is more than 60% with good dispersion behavior and narrow particles size of about 330 nm.

Key words: superfine magnesium oxide, direct precipitation method, orthogonal test