COMPOSITE MATERIALSNurul Farahin bt Musa

Siti Salwa bt Shamsuddin

COMPOSITE MATERIALS Types of composite

materials Composition of composite materials Properties of composite materials Uses of composite materials

COMPOSITE MATERIALSA composite material is a material made up

of two or more materials that are combined in a way that allows the materials to stay distinct and identifiable. The purpose of composites is to allow the new material to have strengths from both materials, often times covering the original materials' weaknesses. Composites are different from alloys because alloys are combined in such a way that it is impossible to tell one particle, element, or substance from the other. Some common composite materials include concrete, fiberglass, mud bricks, and natural composites such as rock and wood.

Types of composite materialsComposite materials are usually classified by

the type of reinforcement they use. This reinforcement is embedded into a matrix that holds it together. The reinforcement is used to strengthen the composite. For example, in a mud brick, the matrix is the mud and the reinforcement is the straw. Common composite types include randomfiber or short-fiber reinforcement, continuous-fiber or long-fiber reinforcement, particulate reinforcement, flake reinforcement, and filler reinforcement.

Types of composite materialsMud BricksOne type of very old composite material

invented by early humans was the mud brick. A normal mud brick is sturdy and resistant to compression, but can break if bent. Straw is a material that has excellent tensile strength, meaning that it resists stretching. By combining both, early humans were able to create composite mud bricks that could resist weight and compression as well as stretching.

Concrete Concrete is a composite material made of

Fiberglass

Fiberglass is a material made of tiny glass shards held together by resin and other components. In the automotive industry, fiberglass is important for making body kits. The body shell for a car is made up of different layers of fiberglass, such as a gel-coat layer, tissue layer, matting and cloth. The final product is a complete, waterproof, lightweight and strong body kit. Fiberglass can also be a less

Natural composites : Woodis a good example of a natural composite. Wood

is a combination of cellulose fiber and lignin. The cellulose fiber provides strength and the lignin is the "glue" that bonds and stabilizes the fiber. Bamboo is a very efficient wood composite structure. The components are cellulose and lignin, as in all other wood, however bamboo is hollow. This results in a very light yet stiff structure. Composite fishing poles and golf club shafts copy this natural design. Plywood is a man-made composite combining natural and synthetic materials. Thin layers of wood veneer are bonded together with adhesive to form flat sheets of laminated wood

Composition of composite materials

a binder or matrix

a reinforcement

Composition of composite materialsA binder or matrixThe matrix holds the reinforcements in an

orderly pattern. Because the reinforcements are usually discontinuous, the matrix also helps to transfer load among the reinforcements. Matrix materials are usually some type of plastic, and these composites are often called reinforced plastics. There are other types of matrices, such as metal or ceramic, but plastics are by far the most common. There are also many types of plastics, but a discussion of them is beyond the scope of this week's column. Suffice it to say for now that the two most

Composition of composite materialsA reinforcementReinforcements basically come in three

forms: 1.particulate,

A particle has roughly equal dimensions in all

directions, though it doesn't have to be spherical. Gravel, microballoons, and resin powder are examples of particulate reinforcements

2.discontinuous fiber, Reinforcements become fibers when one dimension becomes long compared to others. Discontinuous reinforcements (chopped fibers, milled fibers, or whiskers) vary in length from a few millimeters to a few centimeters. Most fibers are only a few

Composition of composite materials3.continuous fiber. With either particles or short fibers, the matrix must transfer the load at very short intervals. Thus, the composite properties cannot come close to the reinforcement properties. With continuous fibers, however, there are few if any breaks in the reinforcements. Composite properties are much higher, and continuous fibers are therefore

Properties of composite materialsHigh Strength Composite materials can be designed to meet

the specific strength requirements of an application. A distinct advantage of composites over other materials is the ability to use many combinations of resins and reinforcements, and therefore custom tailor the mechanical and physical properties of a structure. To understand this, consider the following example: Compare a inch diameter steel rod to a inch diameter fiberglass composite rod. The steel rod will have higher tensile and compressive strength, but will weigh

Properties of composite materialsCorrosion Resistance Composites

products provide long-term resistance to severe chemical and temperature environments. Composites are the material of choice for outdoor exposure, chemical handling applications, and severe environment service. Light Weight Composites are materials that can be designed for both light weight and high strength. In fact, composites are used to produce the highest strength to weight ratio structures known to man.

Properties of composite materialsDesign Flexibility Composites have an advantage over other

materials because they can be molded into complex shapes at relatively low cost. The flexibility of creating complex shapes offers designers a freedom that hallmarks composites achievement. Boats are a good example of the success of composites. Boats can be made out of a variety of materials wood, aluminum, steel, and even cement! Why are most pleasure boats today built from fiberglass composites? The reason is that composites can be easily molded into complex shapes which improve boat design.

Properties of composite materialsDurability Composite structures have an exceedingly

long life span. Coupled with low maintenance requirements, the longevity of composites is a benefit in critical applications. In a half-century of composites development, well-designed composite structures have yet to wear out. There are numerous examples of boats, buildings, and other composites structures built in the 1950s, which are still in service. The bodies of the original 1953 Corvette are fiberglass, and with the exception of cosmetic repairs, are still structurally sound.

Uses of composite materialsComposite materials are used to make

various substances in daily life because of the following reasons:Metals corrode and are ductile and

malleable Glass and ceramics break easily Metals are good conductors but have high resistance, leading to loss of electrical energy as heat Plastics and glass can withstand heat to certain level only.Composite materials have been created to

overcome these problems and to make materials stronger, more long-lasting and

Uses of composite materialsReinforced concreteconcrete (cement, sand, stones), steel Ordinary concrete is strong but heavy.

Concrete pillars must be big to support the weight. They take up space and cannot withstand stress for example from earthquakes. Steel pillars are too expensive and can rust. Reinforced concrete, containing steel rods in the concrete pillars, can make them stronger and able to support larger loads. It also does not rust.

Uses of composite materialsOptical fibreSiO2, Na2CO3, CaO This is a fine transparent glass tube that is

made of molten glass. Glass cannot conduct electricity or electronic data in the form of electrons. But optical fibre allows light to be transmitted through the tube so that data is transmitted at a faster rate. In telecommunications, light has replaced electrons as the transmitter of signals. This light transmits signals through optical fibre and the field is called optoelectronics. Optical fibre is also used in the medical field as laser to do operation endoscope to examine the internal organs of

Uses of composite materialsPhotochromic glassglass, AgCl (or AgBr Glass is transparent and not sensitive

towards light. Photochromic glass contains AgCI or AgBr which causes the glass to darken in sunlight and lighten in the absence of sunlight. It is used to make photochromic lenses of spectacles and protects our eyes from extreme sunlight.

Uses of composite materialsPlastic reinforced with glassfibreglass and polyster resin While plastic is light and hard, it is brittle.

Glass is harder than plastic but breaks easily. Thus fibre glass is obtained by adding a polyster resin to molten glass. It cannot be compressed easily and is more tensile than the original materials. Fibre glass is light, withstands corrosion, can be cast into different shapes, is impervious to water, not very flammable, not brittle and stronger than even steel. It is used to make racquets, construction panels, electrical appliances, pipes, and

Uses of composite materialsSuperconductorItrium oxide (Y203), BaCO3, CuO It is a substance with almost nil resistance.

Thus it saves electricity. Copper shows superconductor properties only at -270C. Thus the superconductor, a mixture of CuO, Y203, and BaO, results in a ceramic called perovskite or YBCO. All the materials used to make this composite substance are not electrical conductors in their original forms, but as a superconductor, it conducts electricity without loss of energy.

REFERENCE

http://www.ehow.com/about_5868282_types-com

http://www.acmanet.org/professionals/index.cfm http://

http://composite.about.com/od/aboutcomposites

wiki.one-school.net/index.php/Evaluating_uses