ABSTRACT
In nature, materials that exhibit magnetic properties are invariably solids. Magnetizable fluids, then, are not naturally occurring substances. They are man-made composite materials consisting mainly of a solid phase and a liquid phase. The solid phase is magnetic in nature, and the liquid phase is a functional fluid that imparts fluidity to the composite. The bulk properties of the composite are derived from the two main phases and their interaction with the environment. This chapter discusses two very different kinds of magnetic fluids that have found uses in engineering. These are ferrofluids and magnetorheological (MR) fluids. The two materials are distinguished most basically by the size of the individual particles that make up the solid, magnetic phase.
