Formation of organic coating on ultrafine silver particles using a gas-phase process

Coating and encapsulation of powders are specialized technologies that impact a wide variety of products. In this work particle coating is achieved by condensing organic material onto ultrafine particles via an aerosol technique. Transmission electron microscopy was used to examine the coating morphology thus obtained and thickness of the coatings range from 1 to 7 nm. The experimental observation suggests that materials with a lower melting point such as stearic acid favor the formation of more uniform coating. No significant change in the coating morphology was discovered when enhanced mixing and longer residence time was used. However, substantial improvement of coating uniformity was obtained when cooling rate was significantly lowered which allowed more time for organic liquid to remain mobile to wet particle surface, suggesting surface wetting plays a significant role in the coating fort-nation process. (C) 2003 Elsevier Ltd. All rights reserved.