ABSTRACT
A composite material is a combination of two or more chemically different materials with a distinct interface between them. The constituent materials maintain their separate identities (at least microscopically) in the composite, yet their combination produces properties and characteristics that are different from those of the constituents. One of these constituents forms a continuous phase and is called the matrix. The other major constituent is a reinforcement in the form of fibers or particulates that is, in general, added to the matrix to improve or alter the matrix properties. The reinforcement forms a discontinuous phase that is dispersed uniformly throughout the matrix. The reinforcement surface may be chemically treated or coated with a very thin layer to improve wetting of the reinforcement by the matrix as well as to control or enhance interfacial bonding between the reinforcement and the matrix. The surface treatment may also serve to protect the reinforcement surface from degradation by environmental attack, such as by moisture and chemicals, or by adverse chemical reaction with the matrix at high temperatures.
