Composites are engineered materials made from two or more constituent materials with significantly different physical or chemical properties. These individual materials remain separate and distinct at the macroscopic or microscopic level within the finished structure. When combined, they produce a material with properties that are superior to, or different from, the individual components alone. This synergistic combination allows engineers to tailor material properties for specific applications, often achieving high strength-to-weight ratios, improved stiffness, enhanced durability, and resistance to harsh environments.

Fundamental Components of a Composite Material

Every composite material typically consists of at least two main parts:

1. Matrix:
   • This is the continuous phase that surrounds and binds the reinforcement together.
   • Its primary functions are to transfer stress to the reinforcement, hold the reinforcement in its desired orientation, and protect the reinforcement from environmental degradation (e.g., moisture, chemicals, UV radiation) and mechanical damage.
   • The matrix largely determines the composite’s temperature resistance, chemical stability, and surface finish.
2. Reinforcement:
   • This is the discontinuous phase embedded within the matrix.
   • Its main purpose is to provide the composite with enhanced strength, stiffness, and other specific mechanical properties.
   • Reinforcements bear the majority of the applied load.

In addition to these core components, composites can also include:

• Core Materials: Used in sandwich structures (e.g., honeycomb, foam) to increase bending stiffness without significantly increasing weight.
• Fillers and Additives: Incorporated to modify properties (e.g., reduce cost, improve fire resistance, enhance electrical conductivity, alter color, improve processing).
• Surface Finishes: Applied for aesthetic purposes, UV protection, or additional environmental resistance.