According to the different classification of matrix, it can be divided into epoxy resin matrix composite, bismaleic resin matrix composite and polyimide resin matrix composite. This section introduces the properties of fiber-reinforced resin matrix composites at home and abroad.
1. Epoxy resin based composite
Epoxy resin is the most widely used resin matrix in aircraft composites. Epoxy resin has a series of advantages, such as good process performance, excellent mechanical properties, low curing shrinkage, large room for modification, low price and so on. It has become the most widely used composite resin matrix. In the field of aviation, epoxy resin matrix composites are generally divided into three categories according to the different curing temperature of epoxy resin: low temperature curing (curing temperature is less than 80 ° C), medium temperature curing (80 ~ 130 ° C), high temperature curing (curing temperature is 150 ~ 180 ° C, service temperature is generally below 130 ° C in wet state and below 150 ° C in dry state). The modification of epoxy matrix composite is mainly aimed at epoxy resin, improving toughness and maintaining excellent comprehensive performance of the system has been an important goal of the development of high-performance epoxy resin.
1.1 comprehensive evaluation of epoxy composite
(1) the epoxy resin matrix composite has excellent processability (see table 2-35).
Compared with bimax, polyimide and thermoplastic composite system, epoxy prepreg has good adhesiveness and coating, low curing temperature and forming pressure (generally less than 0.7MPa), and can be applied to different forming processes, such as autoclave, RTM, RFI and molding to prepare various shapes of composite components. At present, most of the developed epoxy resin systems are suitable for hot pot pressing and molding process. In addition, prepreg should be prepared first for hot pressing (mainly for autoclave and molding) composite materials. Compared with wet winding, the technology of prepreg prepared by hot melting has the characteristics of high production efficiency, good quality and less environmental pollution. At present, most epoxy resin systems can use hot melting technology to prepare continuous fiber and fabric prepreg.
(2) See table 2-36 for the introduction of domestic epoxy composite system and table 2-37 for the comprehensive evaluation of main properties.
1.2 introduction of domestic epoxy matrix composite system
(1) properties of high temperature epoxy composite
HT3 carbon fiber reinforced 648 epoxy resin is used as the first advanced composite component in China. It has been in service for more than ten years and accumulated comprehensive design and use data. 648 belongs to the first generation of high-temperature curing epoxy resin system. The prepreg has long storage period, good coating performance and simple curing process, but it has poor hygrothermal resistance and great brittleness. The second generation high temperature curing epoxy resin system developed in China is a 5222 resin system with TGDDM / DDS as the main component, which is equivalent to 3501-6, 5208 in the United States and bc-2526 in Russia. The heat resistance of the system is higher than that of the 648 system, the design data is complete, and the process performance is better, but the wet heat resistance and toughness are insufficient. From the end of 1980s to 1990s, a new generation of epoxy resin system has been developed in China. Its goal is to improve the Hygrothermal performance and toughness. The main representative brands are 5224, 5228, 5288, etc. 5224 has improved the hygrothermal resistance and toughness on the basis of the original good technology. 5228 and 5288 have outstanding toughness, but due to the addition of more thermoplastic resin components, Make the prepreg's covering worse. See table 2-38 for physical properties of high temperature curing epoxy composite.
(2) Properties of mid temperature curing epoxy composite
The mid temperature curing epoxy resin matrix composite has the characteristics of good performance, short forming cycle and low cost compared with the high temperature curing system. The highest service temperature is generally below 100 ° C. 3234 epoxy resin matrix composites reinforced by various carbon fiber fabrics have excellent comprehensive properties, good performance and stability of resin system, and the storage period of prepreg at room temperature is longer (2 months), which is suitable for popularization and application. G814nt / 3233 is a composite material system with flame retardancy, excellent impact resistance and fatigue resistance. HT3 / ny9200z is mostly used for composite repair; HT3 / HD58 is very limited. See table 2-39 for the physical properties of mid temperature curing epoxy composite.
(3) Properties of low temperature curing epoxy composite
Low temperature curing epoxy resin matrix composite can greatly reduce the high cost mainly brought by expensive high energy consumption equipment and high-performance process auxiliary materials, and the cost of composite components is low. At the same time, the low temperature curing composite components have small deformation, high dimensional accuracy, and can improve the dimensional stability of composite components. The mechanical properties of HT3 / lto1 composite system cured by autoclave at low temperature and medium temperature are close to or equal to that of epoxy composite system cured at medium temperature. The highest temperature is about 80 ~ 10C. Hf7lt is formed by vacuum pressure forming at low temperature- -03 composite materials, free of the high energy consumption and size limitation during the forming of autoclave, more effectively play the advantages of low-temperature curing composite materials, especially suitable for preparing large-scale, low-cost composite components, can be used in - 55 ~ 80 ° C for a long time. See table 2-40 for physical properties of low temperature curing epoxy composite.
2. Bismaleimide based composite
(1) See table 2-41 for a brief introduction of domestic bismaleic resin composite system.
(2) See table 2-42 for technological data of domestic bismaleic resin matrix composite.
(3) See table 2-43 for the comprehensive performance evaluation of domestic bismaleic resin matrix composite.
3. Polyimide resin based composite
See table 2-44 for the introduction of domestic polyimide resin based composite system.
4 fiber reinforced aluminum alloy laminate
(1) introduction of fiber reinforced aluminum alloy laminate
Aramid aluminum alloy laminate is a kind of interlaminar hybrid composite material. It is composed of aramid / sy-14 epoxy resin prepreg and LY12CZ aluminum alloy sheet, which are laid alternately and cured by heating and pressing, as shown in Figure 2-20. Main components: Kevlar-49 aramid fiber, sy-14 epoxy resin, LY12CZ aluminum alloy sheet. Materials are supplied in the form of laminates, 3.5m long and 1.2m wide. This kind of material combines the advantages of aluminum alloy and fiber / resin composite. It has the advantages of small density, high strength, excellent fatigue resistance, high damage tolerance, environment resistance, lightning resistance, damping and processability. The aramid aluminum alloy laminate based on sy-14 epoxy resin system has good comprehensive properties at a temperature of 55 ~ 150 ℃.
The aramid aluminum alloy laminate is formed by hot pressing tank or hot press. Its typical forming process is: heating to 140 ° C at the speed of 1 ~ 2 ° C / min, holding for 10min under vacuum or contact pressure, pressurizing to 0.8MPa, and holding for 10min. Keep the pressure unchanged, raise the temperature to 180 + 3 ° C at the speed of 1 ~ 2 ° C / min, cool down naturally to below 60 ° C after holding for 2h, and take out the laminate.
Aramid aluminum alloy laminates are developed and manufactured by Beijing Institute of aeronautical materials, AVIC-I group. In 1997, it was certified by the former China Aviation Industry Corporation and has been used to manufacture fighter rudder, etc.
(2) Properties of fiber reinforced aluminum alloy laminates
a. Physical properties of prepreg. See table 2-45 for the physical properties of aramid fiber / sy-14 epoxy resin prepreg.
b. Physical properties of composite laminates. The density of aramid aluminum alloy laminate is 2.3g/cm3.
c. The mechanical properties of aramid aluminum alloy laminates can be divided into free laminates (laminates with unadjusted residual stress), prestressed laminates (prestressed laminates with 775mpa applied), and prestrain laminates (residual strain 0.4% - 0.6%).
5. Properties of foreign advanced resin matrix composites
There are many kinds and brands of foreign advanced resin matrix composite materials for structure, with excellent performance, which can meet the needs of aviation and aerospace. The mechanical properties of several foreign carbon fiber composite materials are listed in table 2-46. Only a few representative and commonly used resin matrix composite materials are selected here for reference only.
High temperature curing epoxy composite T300 / 5208 and AS4 / 3501 are early developed and applied materials with comprehensive basic data and are listed as reference composite materials. T300 / 913 and T300 / 914C are two old resin matrix composites. Although they have been used for nearly 30 years, they are still used in aircraft. Im7 / 381 and 8552 resin matrix composites are mostly used in helicopter structures. Some of the 977 series composite materials are used for civil aircraft and some for military aircraft. 3900 series composite materials are widely used in civil aircraft. Bismaleimide resin matrix composites are mostly used in military aircraft (fighter), while polyimide resin matrix composites are used in engine structure.
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