YOUR AIMS

On completion of this lesson you should be able to:
- understand what constitutes a ceramic material
- know the main engineering ceramics
- appreciate the engineering properties of ceramics.

SELF-ASSESSMENT QUESTIONS

1. ‘Silicon nitride and silicon carbide are suitable for use as combustion chambers in gas turbine engines.' By considering properties discuss the validity of this statement. Why are ceramics not more commonly used for high temperature engineering applications?

2. For a ceramic compound, what are the two characteristics of the component ions that determine the crystal structure?

3. The flexural strength and volume fraction porosity of two specimens of a ceramic are shown below:

S (MPa)               p
100                   0.05
50                     0.2

Compute the strength for a completely non-porous material, and the strength for 0.1 volume fraction porosity.

4. Use a materials data source to determine the relative density, thermal expansion and melting points of (a) tungsten carbide (b) magnesium oxide.