Preparation of Single-, Double- and Mixed-Layer-Coated Composite Particles by Injection Method.

Abstract

Single-, double- and mixed-layer-coated particles were prepared by the raw material injection method. In this study, mica was used as the core particle, and Al(NO 3 ) 3 , SnCl 4 , TiCl 4 or ZrOCl 2 was used as the raw material for coating layers. In the raw material injection method, a raw material solution is injected into a precipitant solution in which core particles are readily dispersed. In this study, three kinds of injection methods were applied. The simple injection (SI) method was performed by injecting one of the raw materials listed above. The mixed solution injection (MI) method was performed by injecting a mixed solution of Al(NO 3 ) 3 and one of the other raw materials (second raw material (SRM): SnCl 4 , TiCl 4 or ZrOCl 2 ). The two stage injection (TI) method was performed by injecting a raw material solution in the order of Al (NO 3 ) 3 -SRM. Using the SI method, it was possible to prepare coated particles when SnCl 4 , TiCl 4 or Al(NO 3 ) 3 was used as the raw material, and their morphology was affected by the kind of raw material used. During the MI process, the ratio of the metal element of SRM to Al in the coating layers for each product increased with the injection time for SRM=TiCl 4 or ZrOCl 2 , whereas it showed no obvious change when SRM=SnCl 4 . In particles prepared from Al(NO 3 ) 3 and TiCl 4 by the TI method, the structure of the product resembled that of a titanium compound layer over an aluminum compound layer coating the core mica particle.