Classification of Composites
Composite are materials composed of two or more
distinct phases (matrix phase and dispersed phase) and having overall properties
significantly different form those of any of the constituents.
Matrix phase
The primary phase, having a continuous character, is called
matrix. Matrix is usually more ductile and less hard phase. It holds the
dispersed phase and shares a load with it.
Dispersed (reinforcing) phase
The second phase (or phases) is embedded in the matrix in a
discontinuous form. This secondary phase is called dispersed phase. Dispersed
phase is usually stronger than the matrix, therefore it is sometimes called
reinforcing phase.
Many of common materials (metal alloys, doped Ceramics and
Polymers mixed with additives) also have a small amount of dispersed phases in
their structures, however they are not considered as composite materials since
their properties are similar to those of their base constituents (physical
properties of steel are similar to those of pure iron).
There are two classification systems of composite materials.
One of them is based on the matrix material (metal, ceramic, polymer) and the
second is based on the material structure:
Classification of composites I
(based on matrix material)
Metal Matrix Composites (MMC)
Metal Matrix Composites are composed of a metallic matrix
(aluminum, magnesium, iron, cobalt, copper) and a dispersed ceramic (oxides,
carbides) or metallic (lead, tungsten, molybdenum) phase.
Ceramic Matrix Composites (CMC)
Ceramic Matrix Composites are composed of a ceramic matrix
and embedded fibers of other ceramic material (dispersed phase).
Polymer Matrix Composites (PMC)
Polymer Matrix Composites are composed of a matrix from
thermoset (Unsaturated Polyester (UP), Epoxiy (EP)) or thermoplastic
(Polycarbonate (PC), Polyvinylchloride, Nylon, Polysterene) and embedded glass,
carbon, steel or Kevlar fibers (dispersed phase).
Classification of composite materials II
(based on reinforcing material structure)
Particulate Composites
Particulate Composites consist of a matrix reinforced by a
dispersed phase in form of particles.
Composites with
random orientation of particles.
Composites with
preferred orientation of particles. Dispersed phase of these materials consists
of two-dimensional flat platelets (flakes), laid parallel to each other.
Fibrous Composites
Short-fiber
reinforced composites. Short-fiber reinforced composites consist of a matrix
reinforced by a dispersed phase in form of discontinuous fibers (length <
100*diameter).
Composites
with random orientation of fibers.
Composites with
preferred orientation of fibers.
Long-fiber
reinforced composites. Long-fiber reinforced composites consist of a matrix
reinforced by a dispersed phase in form of continuous fibers.
Unidirectional
orientation of fibers.
Bidirectional
orientation of fibers (woven).
Laminate Composites
When a fiber reinforced composite consists of several layers
with different fiber orientations, it is called multilayer (angle-ply)
composite.
