What is Composite?

So far we have discussed about Metals, Ceramics and Polymeric materials. A brief overview of all of them may help you to become conscious about the vast choices of materials that one have in the initial stage of any mechanical design. However, at times, the design objective and the service conditions may become difficult to fulfill using the above material resources. There is a popular word among design communities known as "unobtainium" implying the impossibility of implementing a design concept due to the absence of suitable material. Consider for example, the problem faced in selecting material for Space Shuttle. Apart from high strength and stiffness, the challenges were:

. Density of the material to be less than 3 Mg/m³

. Short term Temperature resistance up to 1200⁰C

. Long term temperature resistance up to 1000⁰C

. Resistance to Oxidation

. Industrial economic producatability

. Ease of Fibre handling during the manufacturing of the Composite

. Compatibility between Fibre and the Matrix that holds the composite

The last two conditions indicates the composites as the only suitable choice under the given condition. The first group of composites designed to meet the conditions are Boron-Aluminium and Boron-Tungsten in 1970.