Composite material refers to a material composed of two or more different substances combined in different ways. It can play the advantages of various materials, overcome the defects of a single material, and expand the application range of materials. Due to the characteristics of light weight, high strength, convenient processing and forming, excellent elasticity, chemical corrosion resistance and good weather resistance, composite materials have gradually replaced wood and metal alloys, and are widely used in aerospace, automobile, electrical and electronic, construction, fitness equipment and other fields, in recent years has been developed rapidly.
With the development of science and technology, the technology of resin and glass fiber continues to improve, and the manufacturing capacity of manufacturers has generally improved, so that the price and cost of glass fiber reinforced composite materials have been accepted by many industries, but the strength of glass fiber reinforced composite materials is not enough. comparable to metal. Therefore, carbon fiber, boron fiber and other reinforced composite materials have come out one after another, making the polymer composite material family more complete, and has become an essential 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 included, the output value will be even more amazing. From a global perspective, 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 relatively slowly due to the economic downturn, but the market in China, especially in mainland China, is developing rapidly. According to the statistics of PPG, the world's major composite material manufacturer, in 2000, the global share of composite materials in Europe was about 32%, and the annual output was 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 US GDP, 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 composite materials for automobiles has given rise to a resurgence of American automobiles in the global market. The development of composite materials in Asia in recent years is closely related to the overall changes in the political economy, and the share of countries varies greatly. Overall, composites in Asia will continue to grow, with a total output of about 1.45 million tons in 2000 and a projected total of 1.8 million tons in 2005.
From the application point of view, composite materials are mainly used in aerospace, automotive and other industries in the United States and Europe. In 2000, the amount of composite materials used for auto parts in the United States reached 148,000 tons, and the amount of composite materials used in European auto parts was estimated to reach 105,000 tons in 2003. In Japan, composite materials are mainly used for residential construction, such as bathroom equipment. However, from a global perspective, the automotive industry is the largest user of composite materials, and the future development potential is still huge, and many new technologies are currently being developed. For example, in order to reduce engine noise and increase the comfort of cars, efforts are being made to develop vibration-damping steel plates with thermoplastic resin adhered between two layers of cold-rolled sheets; The connecting rod and bearing bush have begun to use metal matrix composite materials. In order to meet the lightweight requirements of automobiles, more and more new composite materials will be applied to the automobile manufacturing industry. At the same time, with the increasing emphasis on environmental protection issues in recent years, the application of polymer composite materials to replace wood has also been further promoted. For example, composite materials processed from plant fibers and waste plastics have been widely used in North America as pallets and packaging boxes to replace wooden products; and degradable composite materials have also 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 nanocomposite materials has also become a new hot spot. Nano-modified plastics can change the aggregate state and crystalline morphology of plastics, so that they have new properties. While overcoming the incompatible contradiction between rigidity and toughness of traditional materials, the comprehensive properties of the materials are greatly improved.
