Preparation of single-, double- and mixed-layer-coated composite particlesby injection method

Single-, double- and mixed-layer-coated particles were prepared: by the raw material injection method. In this study, mica was used as the core partic le, and Al(NO3)(3), SnCl4, TiCl4 or ZrOCl2 was used as the raw material for coating layers. In the raw material injection method, a raw material solut ion is injected into a precipitant solution in which core particles are:rea dily dispersed. In this study, three kinds of injection methods were applie d. The simple injection (SI) method was performed by injecting one of the r aw materials listed above. The mixed solution injection (MI) method was per formed by injecting a mixed solution of Al(NO3)(3) and one of the other raw materials (second raw material (SRM): SnCl4, TiCl4 or ZrOCl2). The two sta ge injection (TI) method was performed by injecting a raw material solution in the order of Al (NOB)B-SRM. Using the SI method, it was possible to pre pare coated particles when SnCl4, TiCl4 or Al(NO3) (3) was used as the raw material, and their morphology was affected by the kind of raw material use d. During the MI process, the ratio of the metal element of SRM to Al in th e coating layers for each product increased with the injection time for SRM =TiCl4 or ZrOCl2, whereas it showed no obvious change when SRM = SnCl4. In particles prepared from Al(NO3)(3) and TiCl4 by the TI method, the structur e of the product resembled that of a titanium compound layer over an alumin um compound layer coating the core mica particle.