Ceramics refer to polycrystalline materials formed by baking clays and minerals at high temperatures or sintering metal oxides. They are hard and brittle solids. Ceramics have high compressive strength and hardness making them resistant to abrasion, but low tensile strength. They are durable in acids/alkalis and resistant to corrosion and high temperatures. Common ceramic products include bricks, tiles, refractories, glass, and advanced materials. Sintering increases strength by bonding powder particles through solid/liquid phase bonding below melting points. Vitrification converts liquid radioactive waste into a stable solid glass for storage.

1. CERAMIC

2. Ceramics
 Ceramics refer to polycrystalline materials and products formed by baking
natural clays and mineral admixtures at a high temperature and also by
sintering oxides of various metals and inorganic substances having high
melting point.
 The word is of Greek origin and derives its name from Keromos meaning
potter’s earth or clay.
 As a building material, ceramics, may include brick, stone, concrete, glass,
abrasives, porcelain, high temperature refractories, etc.
 Ceramics are usually hard and brittle and are in the form of amorphous (non-
crystalline) or glassy solids.

3. PROPERTIES OF CERAMICS
 Mechanical Durability
 The mechanical durability of ceramics is evidenced by their strength and hardness.
 The compressive strengths of ceramic materials are extremely high, normally
50,000 to 100,000 lbs/sq. in.
 The hardness makes ceramic materials very resistant to abrasion. It is this
property which makes them useful for floors, and for the grinding of metals and
other materials.
 They have low tensile strength and zero ductility.
 High young modulus
 Low fracture toughness
 High compression resistance

4. PROPERTIES OF CERAMICS
 Physical properties
 low density
 low coefficient of friction
 Good cell tissue adhesion
 Good polishable surface properties
 High surface tension
 High humidity

5. PROPERTIES OF CERAMICS
 Chemical Durability
 The high chemical durability of the great majority of ceramic products makes them
resistant to almost all acids, alkalis, and organic solvents.
 Of further importance is the fact that ceramic materials are not affected by
oxygen. The materials generally contained in the ceramic products have already
combined with all of the oxygen for which they have an affinity, and therefore, are
not affected further by the presence of oxygen in their environment.
 corrosion resistance

6. PROPERTIES OF CERAMICS
 Thermal Durability
 Most ceramics have the ability to withstand high temperatures. This is why they
are useful in the production of all types of heat-containing equipment such as kilns
for the ceramic industry, and such products as the inner linings of fireplaces and
home heating furnaces.
 It has high melting point
 low coefficient of expansion
 They are good thermal insulator and high electrical resistance.

7. CLASSIFICATION OF CERAMIC
 Clay Product
 Refectories
 Glass

8. Ceramic Products
Glasses Clay
products
Refractories Abrasives Cements Advanced
ceramics
-optical
-composite
reinforce
-containers/
household
-whiteware
-structural
-bricks for
high T
(furnaces)
-sandpaper
-cutting
-polishing
-composites
-structural
-engine
rotors
valves
bearings
-sensors
Ceramic Materials

9. Sintering Process
 Sintering is defined as thermal treatment of powder or compact at
temperature below melting point of main constituent, for purpose of
increasing the its strength by bonding together of the particles

10. TYPES OF SINTERING
 Solid Phase Sintering
 Only Solid phase are present at Sinter Temperature.
 Liquid Phase Sintering
 Small Amount of Liquid are present during Sintering.
 Reactive Sintering
 Product react with each other to form new product phase.

11. Parameter governing Sintering
 The sintering process is governed by the following parameters:
 Powder preparation
 Particle size
 Shape
 Size distribution
 Distribution of
 Dopant
 Second phase
 Powder Consolidation
 Density
 Pore size distribution
 Firing
 Heating Rate
 Temperature
 Applied pressure
 Atmosphere

12. STAGE OF SINTERING
 STAGE I
 Burning of organic additive take
place
 Two thing occur in powder
particle
 Mobility of surface atoms become
high
 Initial rough surface of particle
become smooth and neck
formation occur
 STAGE II
 Densification and pore shrinkage.
 if grain boundary are formed
after stage I , these are new
source of atoms for filling up
concave area which diminishes
the outer surface of particle.
 STAGE II

15. Vitrification process
Vitrification is a proven and reliable technology used at
U.S. and foreign defense waste processing facilities.
The process converts
 liquid radioactive and chemical waste into a solid,
stable glass, eliminating environmental risks.

16.  Waste is mixed with silica and other glass-forming materials at the Low-Activity Waste
Facility.
 The mixture is sent to high-temperature melters where they are heated to 2,100 degrees
Fahrenheit to form molten glass.
 Molten glass is poured into containment vessels where it cools to become solid glass.
 The stabilized waste is safely stored at a federal repository.