Functional materials refer to materials with specific functions. According to the characteristics and uses of materials, functional materials can also be defined as high-tech materials with excellent electrical, magnetic, optical, thermal, acoustic, mechanical, chemical and biological functions, and their mutual transformation functions are used for non-structural purposes. Compared with common structural materials, functional materials generally have other functional properties besides mechanical properties, such as optical and electrical functions, magnetic functions, separation functions, shape memory functions and so on.
Functional materials are not only the basic materials for the transformation and upgrading of basic industries and traditional industries, but also important basic materials for the development of information technology, biotechnology and energy technology. Therefore, the application range of functional materials is very wide, including aerospace, biological medicine, environmental ecology and so on.
- Aerospace: Functional materials have a wide range of applications in aerospace. Shape memory alloy is one of the most common functional materials used in aerospace. Shape memory alloys can be made into low temperature fit connectors for use in military aircraft hydraulic systems. The shape-memory alloy material can also be made into a trajectory controller for aircraft blades, which can be used for intelligent horizontal rotors to reduce vibration and noise.
Figure 1. Working principle of shape memory alloy
- Biomedicine: Functional materials are widely used in biomedicine. As an important part of high technology, biomedical functional materials have entered a new stage of rapid development and become a pillar industry. For example, bioactive ceramics are one of the most commonly used functional materials in the field of biomedicine. Bioactive ceramics can be made into porous, biological tissue that can grow in and bond with its surface, and are often used in artificial bone, artificial joint, and artificial implant teeth. Biodegradable polymer material is an important research direction of medical polymer material. In the presence of water, biodegradable polymer materials can be hydrolyzed and degraded by enzymes or microorganisms, so that the main chain of the polymer breaks down and the molecular weight becomes smaller and smaller, eventually becoming monomers or metabolized into carbon dioxide and water. Therefore, biodegradable polymers are often used in the preparation of medical devices and drug packaging.
Figure 2. Functional ceramic material used in medicine
- Artificial intelligence: Intelligent materials are one of the important development directions of modern high-tech new functional materials, which will support the development of high-tech in the future. Common smart materials include piezoelectric materials, shapes and alloys and electrorheological fluids. Piezoelectric materials, which convert electrical and mechanical energy, are often used to make sensors, transducers, actuators and robots.
Figure 3. Rare earth materials are used in LEDs
- Other aspects: In addition to the application of the above aspects, functional materials in many other fields also have a broad development. For example, practical superconducting materials represented by NbTi and Nb3Sn have been commercialized and have been applied in many fields such as magnetic resonance imaging (NMRI), superconducting magnets and large accelerator magnets. Some functional materials, such as biomimetic materials, alternative materials for harmful substances like freon, asbestos and green new materials, are very important ecological/environmental materials and can be used in the field of environmental protection. Rare-earth materials are also common functional materials that can be used to make catalysts for chemical synthesis and LED energy-saving lamps for everyday use.
Through different classification methods, functional materials can be divided into different subtypes. For example, functional materials can be divided into metallic functional materials, inorganic non-metallic functional materials, organic functional materials and composite functional materials according to the types of materials. According to the different physical properties of materials, functional materials can be divided into magnetic materials, electrical materials, optical materials, acoustic materials, mechanical materials, chemical functional materials. According to different application fields, functional materials can also be divided into electronic materials, information industrial materials, and energy materials.
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