Engineering Ceramics For Advanced Applications

Question 1

Define a ceramic

Answer 1

A solid compound formed by heat and pressure with a non metal and a metal

Question 2

Characteristics of a ceramic

Answer 2

Hard
Wear resistant
Prone to thermal shock 
Refractory
Electrically/thermally insulative 
Non magnetic
Chemically stable 
Oxidation resistant

Question 3

Define refractory

Answer 3

A non metallic material having those chemical and physical properties that make them applicable for structures

Question 4

Name all applications of ceramics

Answer 4

Glass 
Clay products 
Refractories (fireclay silica)
Abrasives 
Cements
Advanced ceramics

Question 5

What is the difference between a functional ceramics?

Answer 5

Functional - physical and chemical properties are sensitive to change in the environment

Question 6

What is the piezoelectric effect

Answer 6

The internal generation of electrical charge resulting from a an applied force

Question 7

Define glass

Answer 7

Super cooled no crystalline amorphous high viscous fluid

Question 8

Define viscosity

Answer 8

Measure of a fluids resistance

Question 9

Define specific volume

Answer 9

Volume/mass

Question 10

What is Crystallisation

Answer 10

Long order arrangement of atoms during processing

Question 11

What is annealing

Answer 11

Removing internal stress caused by uneven causes cooling

Question 12

What is tempering

Answer 12

When a hot piece of glass has the surface out into compression to suppress the growth of cracks

Question 13

What is sintering ?

Answer 13

Conversion of powder and grains into an object by heat and pressure

Question 14

What desired microstructure is needed for the following:

High strength
High toughness
High creep resistance 
Transparency 
Low dielectric loss 
Good varistor behaviour
Catalyst

Answer 14

Strength - small grains
Toughness - duplex microstructure 
Creep - large grains and no amorphous grain boundary 
Transparency - pore free microstructure 
Dielectric - small uniform grains 
Catalyst - large surface area

Question 15

Benefits of hot pressing

Answer 15

Industrially viable
Up scalable
Economical
Complex designs

Question 16

Mechanical properties or ceramics

Answer 16

All ceramics are brittle (amorphous and polycrystalline)

Question 17

What is brittleness?

Answer 17

Fracture propagates at high speed and little energy absorption
Can occur well below the yield strength of the material

Question 18

Advantages of tensile testing

Answer 18

Uniform stress

Large effect volume

Question 19

Disadvantages of tensile testing

Answer 19

Expensive samples 
Complex shape 
Difficult to machine 
High surface quality 
Difficult to grasp
Difficult alignment

Question 20

Advantages of Compression testing

Answer 20

Ceramics are more resistant to compression testing than tension.
Uniform stress
Simple shapes

Question 21

Disadvantages of compressive testing

Answer 21

Need a jig for testing

Flat simple bases

Question 22

What does a flexural testing test for?

Answer 22

Indication of a materials stiffness when bended

Question 23

What is the formula for flexural strength

Answer 23

3PL/2BD^2