Surface Modification of Powders

Abstract

Materials in powder form find vast applications that range from structural applications to food items. Many situations demand different or even contradicting set of bulk characteristics and surface characteristics of powders employed in certain applications. The solution of this problem is an appropriate surface engineering process to tailor the properties of the powders according to the particular set of required characteristics. Various processes developed for this purpose include physical as well as wet chemical methods. Chemical Vapor deposition (CVD) has many advantages over other competing processes like rigorous mixing, excellent heat and mass transfer, homogeneous temperatures and consequently uniform coating. Fluidized Bed Chemical Vapor Deposition (CVD-FBR) process, a variant of CVD is a novel method for coating of powders and whiskers. This paper reviews some of the important processes used for this purpose. The salient features of the major processes used for surface modification have been discussed with a reference to their areas of application. The limitations of the processes have also been highlighted.