Intelligent processing of composite materials

Using the dielectrophoretic effect, it is possible to fabricate polymer/ceramic composite materials in which the filler phase can be manipulated to form a desired microstructure. This is performed via the application of an electric field to a colloidal suspension consisting of a filler material dispersed in a fluid polymer medium. Field induced dipole-dipole interactions cause particles to experience a mutual attractive potential resulting in distinct particle chains which exist parallel to the applied electric field direction. This chained microstructure can then be `frozen in' by curing the polymer matrix. The chaining phenomena is dependent on both the magnitude and the frequency of the applied field. Optimum assembly conditions for this process are determined via optical microscopy and electrorheological behavior. The dielectrophoretic assembly process is projected to be utilized for electrical, structural, and thermal composite applications. The dielectrophoretic assembly process also has the advantage of `in-situ' quality control through dielectric measurements. Both the degree of alignment and the batch uniformity can be confirmed via dielectric measurements.