Composites
Introduction
Composites, also known as composite materials, are materials made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure, differentiating composites from mixtures and solid solutions.
History
The history of composites dates back to ancient times, where materials like straw and mud were combined to create bricks for building construction. Ancient Egyptians also made a similar use of composites, combining wood and glue to create a composite material that was used in furniture, tombs, and ships. In modern times, the development of advanced composites has been driven by the aerospace industry, with materials such as fiberglass and carbon fiber composites being used extensively in aircraft and spacecraft construction.
Types of Composites
Composites can be categorized into three main types: particle-reinforced, fiber-reinforced, and structural composites.
Particle-Reinforced Composites
Particle-reinforced composites are composed of a matrix material, which can be either a metal, polymer, or ceramic, and a dispersed phase, which is typically a ceramic or metallic material. The dispersed phase is in the form of particles that are distributed uniformly throughout the matrix. Examples of particle-reinforced composites include cermets (ceramic and metal composites) and metal matrix composites.
Fiber-Reinforced Composites
Fiber-reinforced composites consist of a matrix material and a reinforcing fiber material. The matrix material can be a polymer, metal, or ceramic, while the reinforcing fibers can be made from glass, carbon, or aramid. The fibers provide strength and stiffness to the composite, while the matrix material binds the fibers together and transfers loads between them. Examples of fiber-reinforced composites include fiberglass, carbon fiber composites, and Kevlar composites.
Structural Composites
Structural composites are composed of both homogeneous and composite materials. They are designed to exploit the mechanical properties of both types of materials. Examples of structural composites include sandwich panels, which consist of two thin, high-strength faces separated by a lightweight core material.
Properties of Composites
Composites exhibit a range of properties that make them suitable for a variety of applications. These properties include high strength and stiffness, low weight, resistance to corrosion and wear, and excellent thermal and electrical insulation properties. The properties of a composite can be tailored by varying the type, quantity, and arrangement of the constituent materials.
Applications of Composites
Composites are used in a wide range of industries due to their versatile properties. In the aerospace industry, composites are used in the construction of aircraft and spacecraft due to their high strength-to-weight ratio and resistance to corrosion. In the automotive industry, composites are used to reduce the weight of vehicles and improve fuel efficiency. In the construction industry, composites are used in the production of building materials due to their durability and resistance to environmental conditions. Other industries that use composites include the sports equipment industry, the medical industry, and the electronics industry.
Future of Composites
The future of composites looks promising, with ongoing research and development aimed at improving the properties of composites and expanding their applications. Areas of focus include the development of bio-based composites, nanocomposites, and smart composites that can respond to changes in their environment.