Composite material is a mixture. It has played a great role in many fields, replacing many traditional materials. Composite materials are divided into metal and metal composite materials, non-metal and metal composite materials, non-metal and non-metal composite materials according to their composition.
According to its structural characteristics, it can be divided into:
① Fiber reinforced composites. It is composed of various fiber reinforcements placed in the matrix material. Such as fiber reinforced plastic, fiber reinforced metal, etc.
② Sandwich composite material. It is composed of surface materials and core materials with different properties. Generally, the surface material is high and thin; The core is light in material and low in strength, but has certain rigidity and thickness. It is divided into solid sandwich and honeycomb sandwich.
③ Fine-grained composite materials. The hard particles are uniformly distributed in the matrix, such as dispersion strengthened alloy, cermet, etc.
④ Hybrid composite materials. It is composed of two or more reinforcing phase materials mixed in a matrix phase material. The impact strength, fatigue strength and fracture toughness of the composite are significantly higher than those of the common single reinforced phase composite, and it has special thermal expansion properties. It is divided into interlayer hybrid, interlayer hybrid, sandwich hybrid, interlayer/interlayer hybrid and super hybrid composite materials.
Composite materials can be divided into structural composite materials and functional composite materials.
Structural composite materials are materials used as load-bearing structures, which are basically composed of reinforcement components that can bear loads and matrix components that can connect the reinforcement to form a whole material and transfer forces. The reinforcements include various kinds of glass, ceramics, carbon, polymers, metals and natural fibers, fabrics, whiskers, sheets and particles, while the matrix includes polymers (resins), metals, ceramics, glass, carbon and cement. A wide variety of structural composites can be formed by different reinforcements and different matrices, and named after the matrix used, such as polymer (resin) matrix composites. The characteristic of structural composite materials is that it can carry out component material selection design according to the stress requirements of materials in use, and more importantly, it can also carry out composite structure design, that is, reinforcement layout design, which can reasonably meet the needs and save materials.
Functional composites are generally composed of functional body components and matrix components. The matrix not only plays the role of forming a whole, but also can produce synergy or strengthen functions. Functional composite materials refer to composite materials that provide other physical properties besides mechanical properties. For example, conductivity, superconductivity, semiconductivity, magnetism, piezoelectricity, damping, wave absorption, wave transmission, friction, shielding, flame retardant, heat protection, sound absorption, heat insulation, etc. highlight a certain function. They are collectively referred to as functional composites. Functional composites are mainly composed of functional body, reinforcement and matrix. The functional body can be composed of one or more functional materials. Composite materials with multiple functional bodies can have multiple functions. At the same time, there may be new functions due to compound effects. Multifunctional composites are the development direction of functional composites.
Composite materials can also be divided into common and advanced types.
Common composite materials, such as glass fiber reinforced plastics, are composed of glass fiber and other reinforcements with lower performance and ordinary polymers (resins). Because of its low price, it has been widely used in ships, vehicles, chemical pipelines and storage tanks, building structures, sporting goods and other aspects.
Advanced composite materials refer to composite materials composed of high-performance heat resistant polymers such as carbon fiber and aramid fiber, and later include metal matrix, ceramic matrix, carbon (graphite) matrix and functional composite materials. Although their performance is excellent, their price is relatively high, and they are mainly used in defense industry, aerospace, precision machinery, deep submersibles, robot structures and high-end sports goods.