Composite material is a kind of material which is composed of two or more different materials in different ways. It can give full play to the advantages of various materials, overcome the defects of a single material, and expand the scope of application of materials. Because the composite has the characteristics of light weight, high strength, convenient processing and forming, excellent elasticity, chemical corrosion resistance and good weather resistance, it has gradually replaced wood and metal alloys. Widely used in aerospace, automotive, electronic and electrical, construction, fitness equipment and other fields, in recent years has been rapid development.
With the development of science and technology, resin and glass fiber have made continuous progress in technology, and the manufacturing capacity of manufacturers has generally improved, so that the price cost of glass fiber reinforced composites has been accepted by many industries. However, the strength of glass fiber reinforced composites is not enough to match that of metals. Therefore, carbon fiber, boron fiber and other reinforced composites have come out one after another, making the polymer composite family more complete, and has become a necessary material for many industries. At present, the annual output of composite materials in the world has reached more than 5.5 million tons, and the annual output value has reached more than 130 billion US dollars. If the high-value products of military aerospace in Europe and the United States are taken into account, the output value will be even more amazing. From a global point of view, the production of composite materials in the world is mainly concentrated in Europe, America and East Asia. In recent years, the production and demand of composite materials in Europe and the United States have continued to grow, while Japan in Asia has developed slowly because of the economic downturn, but the market in China, especially in the mainland of China, has developed rapidly. According to the statistics of PPG, a major composite material manufacturer in the world, the global share of composite materials in Europe in 2000 was about 32%, with an annual output of about 2 million tons. At the same time, the average annual growth rate of composite materials in the United States in the 1990s was about twice the growth rate of GDP in the United States, reaching 4% to 6%. In 2000, the annual output of composite materials in the United States reached about 1.7 million tons. In particular, the rapid increase in automotive composite materials has led to the re-emergence of American cars in the global market. In recent years, the development of composite materials in Asia is closely related to the overall political and economic changes, and the share of countries has changed greatly. Overall, composite materials in Asia will continue to grow, with total production of about 1.45 million tons in 2000 and is expected to reach 1.8 million tons in 2005.
From the point of view of application, composite materials are mainly used in aerospace, automobile and other industries in the United States and Europe. In 2000, the use of composite materials for automotive parts in the United States reached 148000 tons, and that in Europe is estimated to reach 105000 tons by 2003. In Japan, composite materials are mainly used in residential construction, such as sanitary equipment, etc., with a consumption of 75000 tons in 2000 and only 24000 tons in automobile and other fields. However, from a global point of view, the automotive industry is the largest user of composite materials, the future development potential is still very huge, there are still many new technologies being developed. For example, in order to reduce the engine noise and increase the comfort of the car, the damping steel plate with thermoplastic resin between two layers of cold rolled plates is being developed. In order to meet the requirements of engine development in the direction of high speed, supercharging and high load, metal matrix composites have been used in engine pistons, connecting rods and bearings. In order to meet the requirements of automobile lightweight, more and more new composite materials will be used in automobile manufacturing industry. At the same time, with the increasing attention to environmental protection in recent years, the application of polymer composites to replace wood has been further promoted. For example, composites made of plant fibers and waste plastics have been widely used as pallets and packing boxes in North America to replace wooden products, and biodegradable composites have become the focus of development and research at home and abroad.
In addition, nanotechnology has gradually attracted people's attention, and the research and development of nanocomposites has become a new hot spot. Nano-modified plastics can change the aggregation and crystallization morphology of plastics, so that they have new properties, which can not only overcome the contradiction between rigidity and toughness of traditional materials, but also greatly improve the comprehensive properties of the materials.