What are composite materials?
Composite materials may be defined as materials made of two or more dissimilar materials, brought into adhesive combination by the application of heat and pressure over a period of time. The properties of composite materials are different from and superior to any of their 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 transfer the load to and between reinforcement materials. The other component is called reinforcement. The reinforcing material provides strength, stiffness, and low thermal expansion.
Materials for Composites
Matrix Composite Materials
The following materials are used as a matrix:
Reinforcing Composite Materials
The following materials are used as reinforcing materials:
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, whiskers, wires, or fiber (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 blending with alternative materials to serve specific needs and show desirable properties.
Fiber-reinforced polymer components are grouped into thermosets and thermoplastics. Thermoset composite parts are fabricated by laying up 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 fiber combination into a stiff structural component.
Thermoplastic resins are polymerized before the fiber reinforcements are added. These are capable of being softened by increasing temperature and hardened by a decrease in 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 fibers in numerous proportions. Several methods are used to manufacture vehicle parts from thermoplastics. Selection of the material is formed from the final nature of the part, and 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, which have an impact on the thickness and weight, ought to give enough savings to render them more effective than steel. It, however, demonstrates higher machining waste than reinforced plastics. The manufacturing costs of reinforced plastics are steered by the devices and tooling used for building them up. In turn, it is subjected on the basis of the number of components needed.
An important consideration in the utilization of composites is that they are 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.