A composite [5] 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, and non-metal and non-metal composite materials according to their composition. According to its structural characteristics, it is divided into: ① fiber reinforced composite materials. It is composed of various fiber reinforcements placed in the matrix material. Such as fiber reinforced plastics, fiber reinforced metals, etc. ② sandwich composite material. It is composed of surface materials and core materials with different properties. Usually the face material has high strength and thinness; the core material is light and low in strength, but has a certain stiffness and thickness. It is divided into two types: solid interlayer and honeycomb interlayer. ③ fine-grained composite materials. The hard fine particles are evenly distributed in the matrix, such as dispersion-strengthened alloys, cermets, etc. ④ Hybrid composite materials. It consists of two or more reinforcing phase materials mixed in one matrix phase material. Compared with ordinary single-reinforced phase composites, its impact strength, fatigue strength and fracture toughness are significantly improved, and it has special thermal expansion properties. It is divided into intralayer hybrid, interlayer hybrid, sandwich hybrid, intralayer/interlayer hybrid and super-hybrid composites.
Composite materials can be mainly divided into two categories: structural composite materials and functional composite materials.
Structural composite materials are materials used as load-bearing structures, and are basically composed of reinforcement components that can withstand loads and matrix components that can connect the reinforcements to form an integral material and at the same time transmit force. Reinforcements include various glass, ceramics, carbon, polymers, metals and natural fibers, fabrics, whiskers, sheets and particles, etc., while the matrix includes polymers (resins), metals, ceramics, glass, carbon and Cement etc. A wide variety of structural composite materials can be composed of different reinforcements and different matrices, and are named after the matrices used, such as polymer (resin) matrix composite materials. The characteristic of structural composite materials is that the component material selection design can be carried out according to the requirements of the material in use, and more importantly, the composite structure design, that is, the reinforcement arrangement design, can reasonably meet the needs and save materials.
Functional composite materials are generally composed of functional body components and matrix components. The matrix not only plays the role of forming the whole, but also can synergize or strengthen the function. Functional composites refer to composites that provide other physical properties in addition to mechanical properties. Such as: conductive, superconducting, semiconducting, magnetic, piezoelectric, damping, wave absorption, wave transmission, friction, shielding, flame retardant, heat protection, sound absorption, heat insulation, etc. highlight a certain function. Collectively referred to as functional composite materials. Functional composites are mainly composed of functional bodies, reinforcements and substrates. The functional body may be composed of one or more functional materials. Multifunctional composite materials can have multiple functions. At the same time, it is also possible to generate new functions due to compounding effects. Multifunctional composite materials are the development direction of functional composite materials.
Composite materials can also be divided into common and advanced categories.
Commonly used composite materials such as glass fiber reinforced plastic are made of glass fiber and other low-performance reinforcements and ordinary high polymers (resins). Due to its low price, it has been developed in large quantities and has been widely used in ships, vehicles, chemical pipelines and storage tanks, building structures, sporting goods and so on.
Advanced composite materials refer to composite materials composed of high-performance reinforcements such as carbon fiber, aramid and high-performance heat-resistant polymers, and later include metal-based, ceramic-based and carbon (graphite)-based and functional composite materials. Although their performance is excellent, their price is relatively high, and they are mainly used in the defense industry, aerospace, precision machinery, submersibles, robotic structural parts and high-end sporting goods.
