Definition:-Substances that are formed by the combination of two ormore materials having different physical and chemicalproperties is what is called a composite.•Constituents remain separate and distinct, but at thesame time work together to give the compositeproperties.•They do not dissolve or blend into each other.Hence composites are engineered materials that satisfythe requirement of modern technology, as they haveseveral advantageous features like high specific strength,high specific modulus and other desired properties.
CONSTITUENTS OF COMPOSITES Composites consists minimum of two parts, a bulk or a continuous phase called matrix and dispersed phase called the reinforcement.MATRIX:-1. Surrounds the individual reinforcing elements protecting against surface damage.2. It maintains their relative positions.3. Prevents the propagation of brittle cracks between individual reinforcing elements .e.g-thermoplastic and thermo setting polymers, metal, carbon etc.REINFORCEMENT:- It imparts special electrical and mechanical properties to enhance the matrix properties.e.g-gravel, ceramics etc.
CLASSIFICATION OF COMPOSITES1. Particle Reinforcement composites.2. Structural Composites.3. Fiber Reinforcement composites. i. Continuous fibers with unidirectional aligned. ii. Discontinuous fiber and unidirectional aligned. iii. Discontinuous fiber and randomly oriented.
PARTICLE REINFORCED COMPOSITEThese are the cheapest and most widely used.They fall in two categories depending on the size of the particles:-1. Large-Particle Composites Consist of a high volume fraction of large sized hard particles embedded in a relatively soft matrix. e.g- concrete, ceramics, filled polymers etc.2. Dispersion-Strengthened Composites Contains extremely small sized particles dispersed in the matrix at low concentration which increases the particle matrix attractions at the atomic level thereby enhancing the strength of the matrix against deformation. e.g- TDNickel with 3% of Thoria.