22. Ceramics and Glass

Question 1

Ceramics are ____ and glasses are _____ (crystalline or non-crystalline)

Answer 1

ceramics are crystalline

glasses are amorphous or non-crystalline

Question 2

What causes ceramics to be so strong?

Answer 2

the restriction of dislocation motion (slip)

Question 3

what causes the wide distribution of fracture strength in ceramic materials?

Answer 3

the wide variability on the presence of flaws

Question 4

Why is fiber glass so strong?

Answer 4

because the fibers are so small that it is very unlikely they will contain a flaw

Question 5

Why are cermaics not machinable?

Answer 5

because they are very hard and brittle

Question 6

What are the 4 stages in the fabrication of ceramics?

Answer 6

1. powder
2. form
3. dry
4. fire

Question 7

Define firing

Answer 7

heat treatment that results in vitrification or sintering

Question 8

what happens in vitrification?

Answer 8

Liquid glass forms, which can flow
between SiO2 particles and make the part strong
and waterproof by filling voids

Question 9

what happens in sintering?

Answer 9

When firing a piece below the melting
temperature (no liquids are formed), the particles
coalesce due to an overall reduction in surface
area - gaps between particles are reduced