Glasses and Composites - C5

Question 1

Name 5 types of composite:

Answer 1

• Concrete (aggregate and cement).
• Plywood, (layered).
• Ceramic composites.
• Metal composites, (ie - steel wool).
• Reinforced plastics, (plastics with strong fibres).

Question 2

Modern composites can be made s….r but there are limits to this. D….d is very strong. C….n atoms have strong bonds in a lattice which scientists are trying to develop.

Answer 2

Stronger, diamond, carbon.

Question 3

What are benefits to composites?

Answer 3

• They can fulfil properties the materials on their own cannot.
• Can be stronger, lighter, and cheaper.
• Can be made to fulfil a purpose.
• Can be ordered, (ie - plywood).
• Made tougher with plastic or metals to resist crack propagation.

Question 4

The bonds in composites are usually d….l, meaning atoms are held in place.

Answer 4

Directional.

Question 5

Carbon composites consist of a …. matric reinforced by carbon f….s which are woven into a 3D structure. The bonds are very strong, more so than …..

Answer 5

carbon, fibres, graphite.

Question 6

Fibre-glass reinforced plastic. What is the matrix? What are the reinforcements? What properties to these give?

Answer 6

Matrix, (most of composite): Plastic resin which gives toughness.
Reinforcement (holds composite together): glass fibres which give tensile strength.
Higher toughness reduces crack propagation.

Question 7

Reinforcements are usually..

Answer 7

Strong and brittle.

Question 8

The matrix is usually…

Answer 8

Tough.

Question 9

What is concrete made of and what does it have a high strength of compared to it’s weak strength in another respect? What does silica fume give, and what do the carbon nanofibers give? How about the carbon products?

Answer 9

Concrete: aggregate, cement, sand, and water.
Has a low tensile strength.
Has a high compressive strength, (20-30 MPa).
Silica fume: Strength and durability.
Nanofibres: Young’s modulus and strength.
Products: electrical conductivity.

Question 10

In fibre glass what is the reinforcement and what is the matrix? Why is it tough?

Answer 10

Reinforcement: Glass, brittle and experiences crack propagation.
Matrix : Tough plastic.
The material gains strength and toughness as when the plastic is stretched and the fibre breaks, the plastic absorbs most of the stress, preventing plastic propagation.
Fibres reduce movement.