Coated Nanoparticles: A New Way to Improved Nanocomposites

This paper introduces the new concept of coated nanoparticles as starting material for improved nanocomposites. The very special properties of nanomaterials often are properties of isolated particles. After combining nanoparticles to a macroscopic workpiece, usually these special properties are lost. Therefore, to obtain macroscopic parts exhibiting the properties of the isolated particles it is necessary to avoid or at least reduce the interaction of the particles. This can be achieved by coating each individual particle with a second ceramic or polymer layer. This type of materials can be synthesised only by using the microwave plasma process, because in this process the particles leave the plasma zone with electrical charges thwarting agglomeration. Additionally, by proper selection of the coating material it is possible to avoid grain growth during densification of the powder by sintering or hot pressing. As an example of application and as a proof of concept, the properties of macroscopic superparamagnetic parts are explained. Possibly, coated nanoparticles are the only starting material to produce macroscopic parts showing the very special properties of nanomaterials.[PUBLICATION ABSTRACT]