Composite materials information

Composites can be defined as a combination of macroscopic two or more different materials, which there is match in their surface area. Because composite materials are mainly used for engineering or structural applications, the setting can be reduced   reserved  containing materials such as fibers or particles that are supported by material incorporated - matrix. Therefore, composite materials typically consist of fiber-phase or non-contiguous particles of the strength and stiffness exceeding those of the phase continuous incorporating them. In order to provide a proper armor, volumetric contents of the reserved must be generally between 10% to 65% of the material.
It is possible to divide the ingredients quaternion in to a few sectors in different ways  : by type of armor (continuous fibers, chopped fibers, flakes), by type of fiber, by type of matrix, by types of uses and more.

Composite materials have been developed initially because no other homogeneous structural material  produced desirable combination of properties required for a particular application as produced in these materials. These materials were developed initially for the aviation world, the demand to improve the performance of existing systems. Aluminum alloys which produced in a reasonable strength and low weight reasonable toughness, were the main ingredients in aviation for years. However, corrosion and fatigue problems pushed the end of World War II development of new materials, solve problems, while also providing improved .Plastic materials have been developed in response to fiber-based armored glass fiber, which served as aviation parts, mainly in the United States, already in the fifties.

Composite materials based on glass fibers are used today in a huge range of applications including inexpensive applications such as boats, consumer products such as furniture, car parts and trains, aircraft parts, building products, bridges and more. Over time, other fiber types have been developed which increased the attractiveness of these substances especially in aviation, but not suitable for commercial use due to the high cost of materials.

The materials benefits quaternion  

Low product weight.

Elite mechanical properties, such as strength and toughness.

Excellent resistance to corrosion and marine atmosphere.

Option to Tailor Making  it is possible to choose the features and their directions required areas.

 parts can be produced with the most complex geometric shapes.

Composite materials is another significant advantage in stiffly-fracture toughness; most other building materials that have high strength and toughness, are eventually failing due to the formation of defects or cracks. This problem is reduced to a great extent in composite materials because if there is a defect in the fiber, it will stopped in the  surface area and will not transferred to the following fiber. The fibers similar manner in some cases stop the existing defects in the matrix.

Types of fibers

As mentioned earlier, the glass fibers are the most common fiber composite materials, especially the car industry, railways, building, boats, and other consumer products. Glass fibers are based on aluminosilicates with high strength (S Glass), or on the basis of Calcium aluminoborosilicate with chemical resistance and electrical properties correspond to (E Glass). Both are used in applications as dielectrics like covering, covers antennas and so on. Another advantage of glass fibers is the low price compared with other fibers.

Another large family of fiber is carbon fiber family. These fiber has the properties of strength and toughness higher level, so they are mainly used for load-bearing structural parts such as the aviation industry,or transport load bearing parts or seamanship. There are carbon fiber with great strength or very long, or carbon fiber module with high stiffness or very high. In some cases the carbon fiber thermal process are becoming more and graphite fibers to obtain special properties like high thermal resistance or good dimensional stability . Budding carbon fibers produced on the basis Rayon relatively high cost, but over time developed another type based on PAN: Polyacrylonitrile at lower costs, so that it will became more common. Another type of carbon fiber is based on the tar, also in lower costs.

Other fibers are fibers Armide:  the Kevlar, which is a trademark of fiber development Aromatics Organic Poliamidim Du Pont Company. These fibers high strength glass fibers and its special feature of the energy absorption capacity is very high, and therefore they are also used industry-pressure tanks and ballistics protection, bulletproof vests, helmets, bulletproof protection boards and pieces  et cetera .

Other fibers are boron fibers, silica fibers, quartz fibers, nylon fibers, and more.

Types of resins (matrix) 

 Polyester resin the resin is the oldest and most common. Exist for him a variety of keys (Curing agent) such as styrene and fillers. Since mechanical properties are inferior to most of the Seraphim, and low price, it is mainly used with fiberglass boat industry, building and consumer products. He has served extensively in the auto industry.

Epoxy resin the most common resin in structural applications is epoxy resin. This resin with high mechanical properties and a good adhesion capacity of fiber. High cost of epoxy polyester, but is also more resistant to chemicals, humidity, wider temperature range and easy to work with a wide range of processes and production methods. Extensive use of resin in aviation and sea, led the creation of comprehensive databases with a wide range of fiber. Epoxy resin corresponding features temperature and humidity conditions (Hot / wet) required on airplanes.

Resin Hpoliaimidi  is an extremely durable material at high temperatures, used in particular rocket and aircraft industries, hot applications like Radomim (prow of transparent aircraft radar radiation) and in parts by the motors. From the resins that appear here, resin Hpoliaimidi have very high temperature resistance. The Tg (glassy transition temperature) this material is dry and comes to 380 ° C a resin Poliaimid. temperature structural applications work with resin Poliaimidi limited to 315 ° C.

Poliaimid resins fall into two groups 

resin that indulge  in reaction  compression - As a result during this hardening process many factors that are emitted volatile high voids content of the product - a relatively low mechanical properties.

resin that indulge  in reaction  annexation - These materials require a very high cure temperature, about 315 ° C, which requires special production facilities and reference materials resistant vacuum bag arrangement this temperature.
In general, mechanical properties resins Hpoliaimidim relatively low compared with other structural resins. In addition, many of these AMINOPLASTIC contains MDA, known human carcinogen (during production processes).

Resin Htziant Aster  Aster Htziant resins also belong to the family of resins to work at high temperatures. Tg temperature of the material that is dry and comes up to 232 ° C. A unique advantage to this material is hygroscopic dimensions excellent stability, low thermal expansion coefficient and good electromagnetic transparency.Ester resin Tziant therefore used in parts like reflectors antennas, associated structures telescope mirrors, solar panels and Bradomim. Acceptable working temperature structural applications based material systems Tziant Aster is about 175-200 ° C.

Burn the Bismaleimide) BMI) are designed to work at high temperatures, due to the temperature of the high Tg material is dry at all: to 315 ° C. Seraphim carbon fibers are combined good mechanical properties at a range of temperatures in their use.This resin also has good thermal dimensional stability even at high temperatures and good electromagnetic transparency. Typical working temperature structural applications in resin-based material BMI is about 200-230 ° C. therefore  the BMI resin is used in special projects were it required to work in high temperature like features sports cars such as Ferrari, hot parts near the engine, aircraft structural parts like wings, Radomim and parts for helicopters.  likewise it is also used at the new Airbus A380 aircraft where the hot parts is near the engines,at jet engines Rolls - Royce and at large structural parts of the new U.S. jet fighter the F22.

Another resin is phenolic resin.  The resins described above are substances thermosetting resins. There is also a large extended family of thermoplastic resins used in injection molding and stamping processes in consumer products and transportation.

Another area is relatively small and domain-metallic composite materials. In this area fiber and matrix are based on metals, Krbidiim or ceramic materials. Hence their resistance at their temperatures is very high as well as other special features. The cost of their production processes is extremely high, what means  that they are rare in the market.

Examples of metallic composite materials: TiO-ZAl, Al-SiC, Ti-C

Sources

Engineered Materials Handbook vol. 1 Composites, ASM international
Reinforced Plastics, vol. 48, 49, ISSN, Elsevier
Modern Plastic Encyclopedia, Mc Graw Hill