What is a Composite materials?
Composite materials may be defined as materials made of two or more dissimilar materials, brought into adhesive combination by application of heat and pressure over a period of time. The property of composite materials is different from and superior to any of its constituents and constituents do not react chemically. One of the constituents of the composite material is called the Matrix. It acts as a binder. Its function is to retain the shape of the structure, protect and stabilize reinforcement and to transfer load to and between reinforcement materials. The other component is called Reinforcement. The reinforcing material provides strength, stiffness and low thermal expansion.
Materials of Composites
Matrix Composite Materials
The following materials are used as a matrix:
Reinforcing Composite Materials
The following materials are used as a Reinforcing material:
1. Alumina ( Al2O3)
2. Aluminium (Al)
3. Boron Nitride (BN)
4. Beryllium (Be)
5. Glass graphite
6. Aramid (Kevlar)
7. Silicon carbide (Sic)
8. Silicon nitride (Si3N4)
9. Titanium (Ti)
10. Tungsten (W)
Reinforcing materials are used as particles, whisker, wire or fibre (Continuous, Discontinuous, Woven or Foils)
Thus we have:
Composites are one of the most broadly utilized materials due to their adaptability to diverse circumstances and the relative simplicity of blend with alternative materials to serve specific needs and shows desirable properties.
Fibre reinforced polymer components are grouped into thermosets and thermoplastics. Thermoset composite parts are fabricated by lay up of unidirectional tape on a mold of desired shape and configuration. The laid up tape is compacted and subjected to a cure operation. This operation turns the resin and fibre combination into a stiff structural component.
Thermoplastic resins are polymerized before the fibre reinforcements are added. These are capable of being softened by increasing temperature and hardened by a decrease of temperature. These materials are commercially available as pre-pregs, tapes and sheets.
Utilizing a diversity of reinforcements, polyester has continued to be employed in improving the system and other applications. The vast majority of thermoplastics are combined with reinforcing fibres in numerous proportions. Several methods are used to manufacture vehicle parts from thermo plastics. Selection of the material is formed from the final nature of the part, the volume required, aside from cost-effectiveness and mechanical strength.
A reinforced-plastic composite is likely going to cost more than sheet steel, when considered on the premise of expense and performance. In such a case, different qualities should essentially justify the high expenditure. Mechanical properties of the parts, that have an impact on the thickness and weight, ought to give enough savings to render them more effective than steel. It however demonstrates a higher machining waste than reinforced plastics. The manufacturing costs of reinforced plastics is steered by the devices and tooling used for built-up them. In turn, it is subjected on the basis of the quantity of components needed.
An important consideration in the utilization of composites is lightweight. Experimental studies of specific components have demonstrated that utilizing all composite structures a saving of 20 to 45% can be attained whereas selectively reinforced metal structures offer around 10 to 25% only.