Ceramics are important engineering materials from engineering applications point of view.This presentation gives briefly important properties and applications of ceramics

1. CERAMICS
Mr.H.P.Varade
Assistant Professor
Sanjivani College of Engineering
Kopargaon,Dist:Ahmednagar

2. Ceramics
An inorganic compound consisting of a metal (or semi-metal) and
one or more nonmetals
 Examples:
Silica - silicon dioxide (SiO2), the main ingredient in most glass
products
Alumina - aluminum oxide (Al2O3), used in various applications
from abrasives to artificial bones
More complex compounds such as hydrous aluminum silicate
(Al2Si2O5(OH)4), the main ingredient in most clay products

3. Ceramic Bonding -

4. Ceramic Crystal Structures-
Oxide structures:
1. Anions are larger than cations.
2. Close packed oxygen in a lattice (usually FCC).
3. Cations fit into interstitial sites among anions.

6. ABX3 Crystal Structures -
6
• Perovskite (calcium titanium
oxide) structure
Ex: complex oxide
Barium Titanate
(BaTiO3)

7. Silicate Ceramics -
• Most common elements on earth are Si & O
• SiO2 (silica) polymorphic forms are quartz, crystobalite, &
tridymite
• The strong Si-O bonds lead to a high melting temperature
(1710ºC) for this material
7
Si4+
O2-
crystobalite

8. 8
Glass Structure -
• Quartz is crystalline
SiO2:
• Basic Unit:
• Glass is noncrystalline (amorphous)
• Fused silica is SiO2 to which no
impurities have been added
• Other common glasses contain
impurity ions such as Na+, Ca2+,
Al3+, and B3+
(soda glass)-
Adapted from Fig. 12.11,
Callister & Rethwisch 8e.
Si0 4 tetrahedron
4-
Si 4+
O 2 -
Si 4+
Na +
O 2 -

9. Properties of Ceramic Materials-

10. Properties of Ceramic Materials-

12. Properties of Ceramic Materials

13. Properties of Ceramic Materials
• High hardness, electrical and thermal insulating,
chemical stability, and high melting temperatures
• Brittle, virtually no ductility - can cause problems
in both processing and performance of ceramic
products

14. Processing of Ceramics-
1.Slip Casting-
• A suspension of ceramic powders in water, called a slip, is poured into a
porous plaster of paris mold, so that water from the mix is absorbed into
the plaster to form a firm layer of clay at the mold surface .
•The slip composition is 25% to 40% water

15. Figure - Sequence of steps in drain casting, a form of slip casting:
(1) slip is poured into mold cavity,
(2) water is absorbed into plaster mold to form a firm layer,
(3) excess slip is poured out, and
(4) part is removed from mold and trimmed

16. • Drying: as water is removed - interparticle spacings decrease
– shrinkage .
2.Drying and Firing -
Drying too fast causes sample to warp or crack due to non-uniform shrinkage
wet body partially dry completely dry
• Firing:
-- heat treatment between
900-1400ºC
-- vitrification: liquid glass forms
from clay and flux – flows
between SiO2 particles. (Flux
lowers melting temperature).

17. • Mill (grind) and screen constituents: desired particle size
• Dry and fire the formed piece
ram
billet
container
container
force
die holder
die
A o
A
d
extrusion
3. Hydroplastic forming:-

18. 4. Powder Pressing:
used for both clay and non-clay compositions.
• Powder (plus binder) compacted by pressure in a mold
-- Uniaxial compression - compacted in single direction
-- Isostatic (hydrostatic) compression - pressure applied by
fluid - powder in rubber envelope
-- Hot pressing - pressure + heat

19. Ceramic Products
• Clay construction products - bricks, clay pipe, and building tile ,cement
concrete
• Refractory ceramics - ceramics capable of high temperature applications
such as furnace walls, crucibles, and molds
• White ware products - stoneware, fine china, porcelain, and other
tableware, based on mixtures of clay and other minerals
• Glass - bottles, glasses, lenses, window pane, and light bulbs
• Glass fibers - thermal insulating wool, reinforced plastics (fiberglass), and
fiber optics communications lines
• Abrasives - aluminum oxide and silicon carbide
• Cutting tool materials - tungsten carbide, aluminum oxide, and cubic
boron nitride

20. • Ceramic insulators - applications include electrical transmission
components, spark plugs, and microelectronic chip substrates
• Magnetic ceramics – example: computer memories
• Nuclear fuels based on uranium oxide (UO2)
• Bioceramics - artificial teeth and bones

21. Ceramic Materials- Applications
Clay – Shaped, dried, and fired
inorganic material
Examples: Brick, tile, sewer pipe,
chimney flue, china, porcelain, etc.
Refractory – Designed to provide
acceptable mechanical or chemical
properties while at high temperatures
Example: Space shuttle all-silica
insulating tiles

22. Applications of Ceramic Materials
Rectifiers – Allow current to
flow in one direction
Heating elements for furnaces
Electrical
Resistors – Create desired voltage drops
and limit current
Thermistors – Application of
heat regulates current flow

23. • Alumina(Al2O3) is used as insulators in spark plug and
electronic packaging, rocket nozzles etc.
• Tungsten carbide and Titanium carbide along with metal
binders like Ni, Co, Cr, Mo are known as cermets which are
used as cutting tool materials.
• Tungsten carbide is used as an abrasive material for grinding
and polishing operations

24. Typical Applications of Ceramics

25. THANK YOU