According to the chemical composition of materials, what kinds of materials are there? What are their main features?

-Inorganic nonmetals (including ceramic materials, semiconductor materials, etc.). )

-Metals (generally divided into iron-based metals (ferrous metals) and non-iron-based metals (nonferrous metals))

-Composite materials (composed of two or more materials). Generally, one material is used as the matrix and the other material is used as the reinforcing material. )

1. Materials based on polymer compounds. Include rubber, plastics, fibers, coatings, adhesives and polymer-based composites. Classification Polymer materials are divided into rubber, fiber, plastic, polymer adhesive, polymer coating and polymer-based composite materials according to their characteristics. ① Rubber is a linear flexible polymer. The valence between molecular chains is small, and molecular chains are flexible. Under the action of external force, great deformation can occur, and it can be restored to its original state quickly after removing external force. There are two kinds of natural rubber and synthetic rubber. ② Polymer fibers are divided into natural fibers and chemical fibers. The former refers to silk, cotton, hemp, wool and so on. The latter is made of natural polymer or synthetic polymer through spinning and post-treatment. Fiber has high valence, low deformability and high modulus, and is generally a crystalline polymer. ③ Plastic is made of synthetic resin or chemically modified natural polymer as the main component, and then additives such as fillers and plasticizers are added. Its intermolecular valence, modulus and deformation are between rubber and fiber. According to the characteristics of synthetic resins, they are usually divided into thermosetting plastics and thermoplastic plastics; According to the purpose, it is divided into general plastics and engineering plastics. ④ Polymer adhesive is an adhesive material with synthetic natural polymer compounds as the main component. There are two kinds of natural and synthetic adhesives. Synthetic adhesives are widely used. ⑤ Polymer coating is made of polymer as the main film-forming substance, adding solvents and various additives. According to the different film-forming substances, it can be divided into grease coatings, natural resin coatings and synthetic resin coatings. ⑥ Polymer-based composite material is a composite material based on polymer compounds and added with various reinforcing materials. It combines the performance characteristics of the original materials and can be designed as required.

2. Inorganic nonmetallic materials are materials composed of oxides, carbides, nitrides, halogen compounds, borides, silicates, aluminates, phosphates, borates and other substances of certain elements. It is the general name of all materials except organic polymer materials and metal materials. Traditional inorganic nonmetallic materials are essential basic materials for industry and capital construction. For example, cement is an important building material; Refractory is closely related to high temperature technology, especially to the development of iron and steel industry; Various specifications of flat glass, instrument glass, ordinary optical glass, as well as daily-use ceramics, sanitary ceramics, building ceramics, chemical stoneware, electric ceramics, etc., are closely related to people's production and life. They are large in output and widely used. Other products, such as enamel, abrasives (silicon carbide, alumina), cast stone (diabase, basalt), etc. ), carbon materials and nonmetallic minerals (asbestos, mica, marble, etc. ) also belongs to the traditional inorganic nonmetallic materials. Since the mid-20th century, new inorganic nonmetallic materials have been developed, which have special properties and uses. They are the indispensable material basis for modern new technologies, new industries, technological transformation of traditional industries, modern national defense and biomedicine.

3. Metal elements or materials with metallic characteristics mainly composed of metal elements. Including pure metals, alloys, intermetallic compounds and special metal materials. The development of human civilization and social progress are closely related to metal materials. After the Stone Age, the bronze age and the iron age were marked by the application of metal materials. In modern times, various metal materials have become an important material basis for the development of human society. Type: Metal materials are usually divided into ferrous metals, nonferrous metals and special metal materials. (1) ferrous metals, also known as steel materials, include industrial pure iron containing more than 90% iron, cast iron containing 2% ~ 4% carbon, carbon steel containing less than 2% carbon, and various structural steels, stainless steels, heat-resistant steels, superalloys and precision alloys. The generalized ferrous metals also include chromium, manganese and their alloys. (2) Non-ferrous metals refer to all metals except iron, chromium and manganese and their alloys, which are usually divided into light metals, heavy metals, precious metals, semi-metals, rare metals and rare earth metals. Generally, the strength and hardness of non-ferrous alloys are higher than those of pure metals, with large resistance and small temperature coefficient of resistance. ③ Special metal materials include structural metal materials and functional metal materials with different uses. Among them, there are not only amorphous metal materials obtained by rapid condensation, but also quasicrystal, microcrystalline and nanocrystalline metal materials. There are also special functional alloys such as stealth, hydrogen resistance, superconductivity, shape memory, wear resistance, vibration reduction and damping, and metal matrix composites.

4。 Composite material is composed of one material as matrix and another material as reinforcement. All kinds of materials complement each other in performance, resulting in synergistic effect, which makes the comprehensive performance of composite materials superior to raw materials and meets various requirements. Among composite materials, fiber reinforced materials are the most widely used. It is characterized by low specific gravity, high specific strength and high specific modulus. For example, the composite material of carbon fiber and epoxy resin has several times higher specific strength and modulus than steel and aluminum alloy, and also has excellent chemical stability, antifriction and wear resistance, self-lubrication, heat resistance, fatigue resistance, creep resistance, noise elimination, electrical insulation and other properties. Graphite fiber combined with resin can obtain materials with expansion coefficient almost equal to zero. Another characteristic of fiber reinforced materials is anisotropy, so the arrangement of fibers can be designed according to the strength requirements of different parts of the product. Carbon fiber and silicon carbide fiber reinforced aluminum matrix composites can still maintain sufficient strength and modulus at 500℃. The composite of silicon carbide fiber and titanium can not only improve the heat resistance of titanium, but also improve the wear resistance, and can be used as engine fan blades. The service temperature of silicon carbide fiber composite ceramics can reach 1500℃, which is much higher than the service temperature of superalloy turbine blades (1 100℃). Carbon fiber reinforced carbon, graphite fiber reinforced carbon or graphite fiber reinforced graphite constitute ablation resistant materials, which have been used in spacecraft, rocket missiles and atomic energy reactors. Because of its low density, non-metal matrix composites can reduce weight, improve speed and save energy when used in automobiles and airplanes. The stiffness and bearing capacity of carbon fiber and glass fiber composite leaf spring are equivalent to leaf spring with more than 5 times the weight.