Anna University 2 Marks Questions and Answers

Anna University TWO MARKS Questions & Answers

4. Composite Materials

 

1. Define a composite.

“A material system consisting a mixture of two (or) more micro-constituents, which are mutually insoluble, differing in form (or) composition and forming distinct phases”. Such a combination, possesses properties different from those of any of its constituents.

 

2. What are the constituents of composites?

Composites consist of two important constituents.

(i) Matrix phase (or) Matrix resin

(ii) Dispersed phase (or) Reinforcement.

 

3. What is matrix phase?

Matrix phase is the continuous body constituent, which encloses the composite. Matrix phase may be metals, ceramics (or) polymers (liquid resins), composites using these matrix are known as

 

4. What is cure reaction?

Formation of cross-linking in certain polymers is known as cure reaction.

Cure reactions are done by using a curing agent. These uncross-linked linear polymers contain functional groups (or) double bonds.

 

5. What is meant by reinforcement?

It is a process of improving the characteristics of the plastic matrix by adding reinforcing agents. The reinforcing agents may be organic (or) inorganic in nature. They may be in the form of powder, flakes, fibres.

 

6. Write some characteristics of fibre.

(i) Fibre possesses high tensile strength.

(ii) It possesses high stiffness.

 (iii) It lowers overall density of composites.

 

7. What are whiskers. Give examples.

Whiskers are thin strong fibre like material made by growing a crystal.

Example: Graphite, silicon carbide, silicon nitride

 

8. What are the characteristics of FRP?

1. It possess superior properties like higher yield strength, fracture strength and fatigue life.

2. Since fibre prevents slip and crack propagation, the mechanical properties of FRP gets increased.

3. It possess high corrosion resistance and heat resistance property.

 

9. What are the uses of ceramic matrix composites?

They are used in re-entry thermal shields in space vehicles and tiles, pump seal, round rings, brake linings etc.

 

10. What are hybrid composites?

Hybrid composites are new class of materials composed of a suitable polymer matrix reinforced with two different fibres (or) fillers.

 

11. What are the types of hybrid composites?

Functionally hybrid composites are of three types

1. Structurally hybridized composites

2. Materials hybridized in chemical bond

3. Functionally hybridized composites.

 

12. Write about the uses of hybrid composites.

1. It is used in light-weight transport (land, water (or) oil) structural components.

2. It is also used in light weight orthopedic components and sporting goods.

3. It is used to make furniture like chair, table and bath tubs

4. It is used in railway coach interiors.

5. It is also used in making daily used applications like plates and spoons.

6. Automobile industry utilizes hybrid composites in many of the interior and exterior applications.