Kompozit Malzemeler

Composite materials are made from two or more constituent materials with significantly different physical or chemical properties, that when combined, produce a material with characteristics different from the individual components. The individual components remain separate and distinct within the finished structure. The new material may be preferred for many reasons: common examples include materials which are stronger, lighter or less expensive when compared to traditional materials.

Composites are made up of individual materials referred to as constituent materials. There are two main categories of constituent materials: matrix and reinforcement. At least one portion of each type is required. The matrix material surrounds and supports the reinforcement materials by maintaining their relative positions. The reinforcements impart their special mechanical and physical properties to enhance the matrix properties. A synergism produces material properties unavailable from the individual constituent materials, while the wide variety of matrix and strengthening materials allows the designer of the product or structure to choose an optimum combination.

Many commercially produced composites use a polymer matrix material often called a resin solution. There are many different polymers available depending upon the starting raw ingredients. There are several broad categories, each with numerous variations. The most common are known as polyester, vinyl ester, epoxy, phenolic and others. The reinforcement materials are often fibers.

RESINS

EPOXY:

Most commonly used as 2 component and after a while the physical form changes from liquid to solid. At the end of the 2 weeks the resin matrix gets the final shape and hardness. Glass fiber or carbon fiber and epoxy based composite materials have excellent mechanical strength for this reason preferred in automotive, medical applications, aviation and marine sectors.

Advantages:

1. Good abrasion resistance
2. No VOC and high chemical resistant
3. Epoxy resin/ hardener combinations will cure at ambient temperature or high temperature

Disadvantages

1. Expensive solutions compared with polyester systems.

POLYESTER:

Unsaturated Polyester resins are the most widely used thermoset resin systems for FRP production in Turkey and all around the world. It is easy to process for different production method such as hand lay up to the pultrusion. There are two principle types of unsaturated polyester resin used in the composites industry. Orthophthalic polyester resin is the standard economic resin, Isophthalic polyester resin is now becoming the preferred material in industries such as marine where its superior water resistance is desirable.

Advantages:

1. Low viscosity to get more compatibility with fibers.
2. Low cost
3. Good weatherability

VINYLESTER

Vinyl ester resins can be used as an alternative to polyester and epoxy materials in composite materials, where its characteristics, strengths, and bulk cost intermediate between polyester and epoxy. Vinyl ester has lower resin viscosity (approx 200 cps) than polyester (approx 500cps) and epoxy (approx 900cps). These systems commonly use for the pipe, chemical plants and storage tank applications due to the chemical resistance.

FIBERS

GLASS FIBER:

Glass fiber also called glass fibre is a material consisting of numerous extremely fine fibers of glass. It has high mechanical properties and low cost due to these features most common reinforcement material for composite production. Despite the fact that it is compatible with various resin matrix, the main usage is FRP.

CARBON FIBER:

Carbon fiber is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The properties of carbon fibers, such as high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion, make them very popular in aerospace, civil engineering and military applications. However, they are relatively expensive when compared to similar fibers, such as glass fibers.

PROPERTIES AND ADVANTAGES

1. High Strength-to-weight ratio
2. High wear resistance
3. Corrosion and Chemical Resistance
4. Stiffness
5. Thermal conductivity
6. Low-Electrical condactivity
7. Thermal insulation
8. Temperature-Dependent behavior
9. Radio translucent
10. Visual Attractiveness
11. Acoustical Insulation
12. Fatigue life
13. Innovative designs
14. Flame retardancy
15. Compatibilty with differend materials.
16. Easy productivity

APPLICATION AREA

1. Marin
2. Aerospace
3. Automotive and Transportation
4. Defence Industry ( Military application )
5. Energy and Electric
6. Storage Tanks, Pipe and Infrastructure
7. Construction
8. Sports Equipment
9. Furniture and Aarchitechtural applications
10. Medical

CONCLUSION

Composite materials are special products that provides certain advantages. In global supplying chains, easy obtainability and different process methods enable to produce various combinations for the end users. To have sustainable quality and acceptable cost the high tech production method must be used.

The certain disadvantage of composite materials compared with traditional systems is high cost. Despite this they are effective and cost saving solutions for the end-users. This issue will be door opener for the future of composite materials.