applications and processing of ceramics

Question 1

• Main properties of glasses

Answer 1

• Tm for glass is moderate, but large for other ceramics
• Low toughness, ductility; large moduli & creep resist.
• optical transparency
• relatively easy manufacturing/shaping of objects etc.
• Hard (at room temperature)
• Vacuum tight (bulbs etc)
• Chemically resistant

Question 2

glss soldfction at spcfc tm?

Answer 2

Glasses do not solidify at one temperature like crystalline materials
(ceramics & metals).

Question 3

abt viscsity of glasses

Answer 3

They increase in viscosity as temperature drops - considered as “supercooled liquids”

Question 4

about tg

Answer 4

Gradual shrinking as temperature decreases with a change in slope at Tg
- Glass Transition Temperature (fictive temperature).
* Below Tg have a glass (solid)

Question 5

melting point:

Answer 5

the glass is fluid enough to be considered a liquid

Question 6

• working point:

Answer 6

the glass is easily deformed at this viscosity

Question 7

softening point: t

Answer 7

maximum temperature at which a glass piece may be handled
without causing significant dimensional alterations

Question 8

annealing point

Answer 8

at
this temperature, atomic diffusion is sufficiently rapid that any residual
stresses may be removed within about 15 min

Question 9

strain point:

Answer 9

for temperatures below the strain point, fracture will occur
before the onset of plastic deformation. The glass transition temperature
will be above the strain point

Question 10

Adding impurities does what

Answer 10

Adding impurities to glass
lowers working range

Question 11

working range

Answer 11

usually between softening and working points

Question 12

Ceramic Fabrication Techniques

Answer 12

• Instead form compacts from powders
• Ceramic fine powder plus
  additives Formed into “green” compact by a process such as pressing, slip-casting,
  extrusion
  Compact is then fired/sintered: heated to high T, (below TM) for time

Particles join by atomic diffusion

Question 13

Sintering

Answer 13

Once powder compact (called a “green” compact) is formed we need to
make it a solid
* “Green” heated to below melting point
* powder touches - forms neck & gradually neck thickens
* add processing aids to help form neck
* little or no plastic deformation

Question 14

Advanced Ceramics

Answer 14

Sensors
Microelectromechanical Systems (MEMS)
Nanocarbons
Medical and Bioengineering

Question 15

Nanocarbons

Answer 15

Fullerenes
* Antioxidants in personal care products
* Biopharmaceuticals
* Organic solar cells
Carbon nanotubes
* Electric field emitters
* Cancer treatment
* Solar cells
Graphene
* Transistors
* Supercapacitors
* Biosensors

Question 16

Medical and Bioengineering

Answer 16

• Bone replacement
• Artificial joints
• Tooth implants
• Biocompatible implant that promotes bone regeneration
• Drug delivery with controlled release system

Question 17

Advanced Ceramic Coatings

Answer 17

• Thermal barrier coatings
• Erosion resistant coatings
• Superhydrophobic coatings