GOALI: Environmentally Benign Dry Particle Coating Processes for the Synthesis of Engineered Particulates

Abstract CTS-9985618 R. Pfeffer and R. Dave, NJIT GOALI: Environmentally Benign Dry Particle Coating Processes for the Synthesis of Engineered Particulates (Technology for a Sustainable Environment) 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 early 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. This proposal is aimed at research and development of these dry particulate processes with the long-term goal of making them a viable option for replacing many current wet coating applications, creating new applications, and advancing the technology so as to be ready for the anticipated high demand for particle coatings in the future. It is proposed to investigate 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) Mechanofusion, in which high normal and shear stresses are applied to the powder mix to achieve coating. These processes will be systematically studied both experimentally and by computer modeling, so as to determine the conditions (operating parameters of the devices as well as the characteristics of the particles, including size, shape, and mechanical and other properties) under which they will work, and the type of coatings (discrete, continuous, embedded or film type) they can achieve. Computer modeling will be based on discrete element simulation studies. It is expected to develop a predictive capability, which is currently non-existent, and is necessary not only to determine which of the devices would give the best results for a specific application, but also to scale-up and optimize the operating conditions for obtaining the best possible coated particles. Successful completion of this project will have a major scientific and environmental impact on a number of industries that deal with particulates. Through collaboration with industrial partners, it is expected that some of these new applications will be successfully demonstrated. Furthermore, it is expected that systematic research study will serve as an impetus for more work in this area and the eventual replacement of many wet coating processes by dry coating processes in industry will help to prevent pollution at the source. A secondary objective of this proposal involves training of undergraduate and graduate students in particle technology, a relatively neglected area in engineering education of extreme technological, economic and environmental importance. This will be carried out by incorporating the results of research into the newly developed interdisciplinary three-course concentration in particle technology at NJIT.