Rajesh N. Dave, Robert Pfeffer, Dongguang Wei, Moinuddin Malik,
Bodhisattwa Chaudhuri, Michelle Ramlakhan, Ajit Mujumdar

Particle Processing Research Center

New Jersey Institute of Technology

Newark, NJ 07102

Dry particle coating can be used to produce advanced powder composites or engineered particulates with tailored surface properties. In addition to forming a barrier between the particle and its environment, dry particle coating can be used for changing the functionality or the properties of the original host particles producing composites that show improved flowability, wettability, dispersibility, electrical, electro-magnetic, optical thermal and other specific physical or chemical properties. In this process, tiny, sub-micron sized (guest or fine) particles are coated onto relatively larger, micron sized (host or core) particles in order to create value-added composite particulate materials. In contrast to wet particle coating, which requires organic solvents, liquid melts, or aqueous solutions/suspensions, the guest particles are brought into close contact with the host particles through the application of mechanical forces, creating either discrete or continuos coatings. Hence these processes are environmentally friendly, requiring no solvents, binders or even water. However they are relatively new, are still in the R & D stage of development and are rarely used commercially. Yet they have potential applications in many industries including pharmaceuticals, food, cosmetics, ceramics, electronics and specialty chemicals.

At NJIT, we are involved with experimental and modeling studies of several of these processes. The following state-of-the-art dry coating devices available at NJIT: (1) Magnetically Assisted Impaction Coating (MAIC), in which intense particle fluidization and random collisions created by magnetic media produce coatings; (2) Hybridizer, in which very high speed blade rotation and powder recirculation creates energetic particle-gas flow with high velocity impacts for coating; (3) Mechanofusion, in which high normal and shear stresses are applied to the powder mix to achieve coating; and (4) Rotating Fluidized Bed Coater (RFBC) in which fluidization of the powder mix under high centrifugal force creates intense mixing and coating. This talk will provide a brief overview of the coating research involving these techniques and several commercial applications.