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Application status and development of marine composite materials

application status and development of marine composite materials

November 21, 2019

compared with traditional metal structural materials, composite materials have higher strength/mass ratio. Using composite materials to build hull and structures has lighter weight and better performance in fuel consumption and improving speed. At the same time, composite materials also have the advantages of corrosion resistance, non-magnetic, good plasticity and so on. Therefore, since the advent of composite materials, they have been playing an important role in the shipbuilding industry, and the application research on ships has always been the focus of attention of major shipbuilding countries. In this paper, marine composites are briefly introduced, and the development history and application status of marine composites at home and abroad are described. On this basis, the development trend of marine composites is analyzed and the coating is prospected. 1 definition of composite material composite material is a multiphase solid material composed of two or more substances with different physical and chemical properties. Although the components of the composite still maintain their relative independence, the properties of the composite are not a simple addition of the properties of the components, but far better than the two. Usually, there is a continuous phase in the composite, called matrix, which is used to bond, fix and maintain the reinforcement into a certain shape; The other phase is dispersed phase, which is called reinforcing phase or reinforcement. The reinforcing material does not form a continuous phase in the composite, which provides strength and stiffness under the support of the matrix. The dispersed phase is distributed in the whole continuous phase in an independent form, which can be reinforced fiber or granular dispersed material. The morphology of different reinforcement materials is shown in Figure 1

there are many classification methods of composites. The most basic ones can be divided into: polymer matrix composites, whose matrix is organic polymer; Metal matrix composites, whose matrix is metal, such as aluminum matrix composites, iron matrix composites, etc; Inorganic nonmetallic matrix composites, whose matrix is ceramic materials (including glass, cement, etc.). 2 classification of marine composites at present, marine composites, especially those used in hull structures, are mainly polymer matrix composites, which can be divided into two types according to structure: laminated plates (fiber reinforced composites) and sandwich structure composites, including three important composites: reinforcement materials, resins (i.e. matrix) and core materials. Marine composite materials can be divided into main load-bearing structure, secondary load-bearing structure, non load-bearing structure, etc. according to different load-bearing parts. According to their functions, they can be divided into five series of materials: structure, damping, acoustics (including sound absorption, sound insulation and sound transmission), stealth (including wave absorption, wave transmission, reflection and frequency selection), and protection. The classification and application parts of marine composite materials are shown in Figure 2

the advantages of marine composite materials are mainly reflected in: light weight and high strength, which can effectively improve the reserve buoyancy of the hull; The structure and function are integrated, and the performance can be designed under the condition of meeting the structural load. It usually has other properties such as acoustics, radar, vibration reduction, protection, low magnetism and so on. The general material forming process is also the structure forming process; Corrosion resistant, which can meet the requirements of harsh marine environment such as high salt, high humidity, UV, etc; It is aging resistant and can meet the requirements of long life of ships. The above characteristics are different from other ship structural materials, and are also the embodiment of its advantages. Figure 2 main types and typical applications of marine composite materials and structures. Starting from small speedboats, the application of composite materials in ships has probably gone through three stages. In the first stage, it is mainly used on small ships such as minesweepers, with low performance requirements and can be formed as a whole. In the second stage, it was partially used on large and medium-sized ships, but the use concept is still limited to the traditional hull design, and composite materials only play an auxiliary role in reducing the mass and improving the corrosion resistance of components on board. In the third stage, at the beginning of the design, the ship fully considered the complex situations faced in use, and used composite materials as the main hull materials to achieve the effects that other materials cannot or are difficult to achieve. At present, marine composites have broken through the second stage and developed to the third stage. 3 development and application status of marine composites at home and abroad 3.1 development and application status abroad early composites were used in small patrol boats and landing ships. The relatively poor manufacturing quality and hull stiffness limit the length of the ship to no more than 15 m and the displacement to no more than 20 t. In recent years, with the reduction of the design and preparation cost of composite materials, as well as the improvement of mechanical properties, composite materials began to be applied in large ships, such as mine hunting boats and light frigates. With the development of technology, the length of ships has increased steadily. Now there are 80~90 m long full composite naval ships. The United States is the country with the most advanced development of Composite Science and technology, the widest application and the largest consumption of composite materials, and its scale and technology are in the forefront of the world in the application of marine composite materials. In 1946, the U.S. Navy built a traffic boat with polyester FRP, which is the world's first composite ship, and then manufactured FRP landing boats, workboats, etc. In order to speed up the development of FRP ships, the US Navy stipulated in the mid-1950s that ships below 16 m must be made of composite materials. Around 1954, the hand paste molding process in the United States became more and more mature. In 1956, two small minesweepers with different structural forms were built, and the application research of FRP in minesweepers began. In the early 1960s, the U.S. Navy built the first all glass fiber reinforced plastic patrol boat. In the late 1980s and early 1990s, the composite material mine hunting/sweeping boat was built. The hull was made of high-grade m-phenylene polyester resin and semi-automatic dipping operation. At the same time, the patrol boat was made of Kevlar reinforced polyester resin single shell structure. Subsequently, the US Navy introduced composite materials into the manufacture of deep submersibles. The diving depth of the submersible, which was built with graphite fiber reinforced epoxy resin in 1966, can reach 6096m. After entering the 21st century, the United States has further strengthened the application of composite materials in ship construction, using the sandwich structure of new high-strength carbon fiber/vinyl resin to replace traditional low-strength fibers such as glass fiber. The new ship has high stability, fast speed, and stealth, anti submarine and anti mine capabilities. European composite shipbuilding industry is also very developed. In the mid-1960s, Britain successively manufactured 450 t large minesweepers and 625 t mine hunting boats with FRP. In 1973, it built all FRP anti mine boats with composite materials. Its successful application promoted the rapid development of composite materials. In the early 1980s, more than 200 all composite anti mine ships were manufactured. In the 1990s, Britain successfully used carbon glass hybrid fibers to build motorboats and patrol boats. With the development of technology, it has also successfully used recycled plastic bottle reprocessing materials to build ships in recent years, which not only reduces the cost, but also conforms to the development direction of material biodegradation and recycling. Sweden built the first FRP Minesweeper with sandwich structure in 1974, successfully developed the world's first composite stealth test boat in the 1990s, gradually developed and formed a construction method characterized by high-performance carbon fiber and sandwich structure, developed and built a series of light destroyers integrating advanced composite technology and stealth technology, and has been successfully launched into service. Italy began to build a number of FRP minesweepers in the mid-1980s. Japan has been building FRP boats since the 1950s, and has made great achievements in the construction of high-performance boats, racing boats and luxury yachts. In the 21st century, Japan began to research and manufacture high-performance composite military ships. At present, the first FRP composite Minesweeper has been successfully built and put into use. Composite products used in the navies of various countries also include ship superstructure, propeller, mast, etc. The French Navy began to use composite materials in the superstructure of ships in 1992, which can effectively reduce the quality of ships. The former Soviet Union was the first to use composite propellers in real ships [18-19]. Sweden began to develop composite propulsion shafts in 1989. Thousands of different materials and surface treatment methods for strengthening durability were tested and evaluated to obtain the best performance of the shafts. The propulsion shafts produced are light in weight, good in elasticity, strong in adaptability, non-conductive and corrosion resistant. The United States has used composite materials to research advanced fully enclosed masts since 1995, and has successfully equipped them in destroyers, aircraft carriers, etc. In addition, because composite materials can reduce the radar signal characteristics and infrared (thermal) signal characteristics of ships, composite materials are also widely used in secondary load-bearing structures such as chimneys, bulkheads, decks, rudders, etc., and have made significant contributions to stealth and structural weight reduction. 3.2 domestic development and application status the research and application of composite materials in ships in China began in 1958, and the first FRP workboat was born in Shanghai. In the mid-1970s, a mine sweeping test boat with a total length of nearly 39 m was developed. Since then, the research and development of grp/cm anti mine ships has been suspended for more than a decade. Since the 1990s, with the development of technology and the introduction of technology, China has used composite materials to produce a large number of yachts, sailboats, rescue boats, as well as high-speed patrol boats, law enforcement boats, anti smuggling boats and other paramilitary boats such as public security, armed police, Marine Surveillance, customs, etc., but so far, a high-tech naval anti mine ship has not been designed and built. In terms of composite ship components, China successfully developed composite sonar fairings in the late 1960s and applied them to submarines, which has formed a relatively mature application so far. In the late 1980s, the composite radome and mine shell were developed and put into use. In the 1990s, the composite mast and superstructure applied to large surface ships were successfully developed. Compared with foreign countries, the application scope and scale of marine composites in China are still small. In terms of raw materials, at present, China has been able to produce most kinds of FRP reinforcements in the international market, but compared with the world's industrial developed countries, there is still a big gap in product technology level, variety, specification, quality and other aspects. High performance fibers such as carbon fiber and aramid fiber are still dependent on imports, and the resin production capacity is also seriously backward. In terms of molding processing, RTM process has been widely concerned and developed rapidly with its advantages of good product quality and high production efficiency. It has developed quite mature in industrial developed countries and is constantly improving. However, China has introduced RTM process and equipment since the 1980s, with less production and low equipment utilization. At present, RTM process is still in the development stage. Compared with foreign countries, China is still relatively backward in the application technology and research and development in the field of marine composite materials at this stage, and there is still much room for development. 4 existing problems although composite materials have a long history of application in foreign naval powers, and China's speedboats, deflectors and other aspects have also been applied, the progress is slow. The reason is that the characteristics of composite materials are different from traditional metal materials, so as to avoid affecting the final measurement results. Composite materials have strong designability, and their material properties are closely related to the manufacturing process. At present, there is a lack of relevant design specifications through

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