16-07-2013, 04:26 PM
METAL-MATRIX COMPOSITE
METAL-MATRIX COMPOSITE.pptx (Size: 807.67 KB / Downloads: 79)
What is a composite Material?
A broad definition of composite is: Two or more chemically distinct materials which when combined have improved properties over the individual materials. Composites could be natural or synthetic.
Wood is a good example of a natural composite, combination of cellulose fiber and lignin. The cellulose fiber provides strength and the lignin is the binding materials (glue) that bonds and stabilizes the fiber.
Bamboo is a very efficient wood composite structure. The components are cellulose and lignin, as in all other wood, however bamboo is hollow. This results in a very light yet stiff structure. Composite fishing poles and golf club shafts copy this natural design.
ADVANTAGES OF METAL MATRIX COMPOSITES
Composites have a higher specific strength than many other materials. A distinct advantage of composites over other materials is the ability to use many combinations of resins and reinforcements, and therefore custom tailor the mechanical and physical properties of a structure.
The lowest properties for each material are associated with simple manufacturing processes and material forms (e.g. spray lay-up glass fibre), and the higher properties are associated with higher technology manufacture (e.g. autoclave moulding of unidirectional glass fibre), the aerospace industry.
DISADVANTAGES OF METAL MATRIX COMPOSITES
The strength in composites vary as the direction along which we measure changes (most engineering structural materials are isotropic). As a result, all other properties such as, stiffness, thermal expansion, thermal and electrical conductivity and creep resistance are also anisotropic. The relationship between stress and strain (force and deformation) is much more complicated than in isotropic materials.