Properties, Application , Fabrication methods of cyramics

Ceramics are a class of inorganic, non-metallic materials that exhibit a wide range of exceptional physical, chemical, and mechanical properties. They have been used by humans for thousands of years, dating back to ancient civilizations where they were primarily used for pottery, bricks, and tiles. In modern times, ceramics play a crucial role in various advanced applications, including aerospace, electronics, medicine, and industrial manufacturing. Their diverse range of properties, including high hardness, thermal stability, and corrosion resistance, make them indispensable in contemporary engineering and technology.

This introduction explores the fundamental properties of ceramics, their various applications across industries, and the different fabrication methods used to manufacture ceramic components.

1. IPE 105 - Engineering Materials
Ceramics
MOMINUL ISLAM
Lecturer , Department of IPE , MIST
Contacts >> Phone: [phone] Email: [email protected]

2. Introduction — Ceramics

Vv

MÁ

> Characteristics of ceramics are:

3. Processing and Applications of Ceramics

Ceramics are compounds between metallic and non
metallic elements for which the inter-atomic bonds are
either ionic or predominantly ionic. The term ceramics
comes from a Greek word which means ‘burnt stuff.

Based on their composition, ceramics are classified as:
Oxides, Carbides, Nitrides, Sulfides, Fluorides, etc. The
other important classification of ceramics is based on
their application, such as: Glasses, Clay products,
Refractory, Abrasives, Cements, Advanced ceramics.
Ceramic materials used for engineering applications can
be divided into two groups: traditional ceramics, and the
engineering ceramics).

4. Classification — Ceramics

> Ceramics are classified in many ways. It is due to
divergence in composition, properties and applications.

> Based on their composition, ceramics are:

- Oxides

- Carbides
- Nitrides
- Sulfides
- Fluorides
etc.

5. Classification — Ceramics

+ Based on their specific applications, ceramics are classified
as:

- Glasses

- Clay products

- Refractories

- Abrasives

- Cements

- Advanced ceramics for special applications

6. Classification — Ceramics

> Based on their engineering applications, ceramics are
classified into two groups as: traditional and
engineering ceramics.

> Traditional ceramics — most made-up of clay, silica and
feldspar

> Engineering ceramics — these consist of highly purified
aluminium oxide (Al,O;), silicon carbide (SiC) and
silicon nitiride (Si;N,)

7. Feldspars and Related Minerals

«+ Feldspar are anhydrous aluminosilicates
containing K+, Na+, and Ca2.; they are
present in virtually all igneous rocks.

«Most production comes from pegmatites
which are coarsely crystalline rock formed
in the later stages of crystallization of a
magma

8. Feldspars and Related Minerals

+ Nepheline syenite
“ Wollastonite
“+ Sillimanite

Sillimanite

Nepheline syenite
9/14/2021 Wollastonite

9. 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

10. ° Ceramic insulators - applications include
electrical transmission components, spark plugs,
and microelectronic chip substrates

° Magnetic ceramics 一 example: computer
memories

» Nuclear fuels based on uranium oxide (UO,)

« Bioceramics - artificial teeth and bones

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11. 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

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12. Electrical
Resistors — Create desired voltage drops
and limit current

Thermistors — Application of
heat regulates current flow

Rectifiers — Allow current to
flow in one direction

Heating elements for furnaces

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13. + Alumina(Al,O;) 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

14. Typical Applications of Ceramics 5

Silica, alumina, zirc
Silicon carbide, zirconia, 08000 hes

bisulphide

3. Barium titanate

4. Tin oxide, zinc oxide
5. Alumina

6. Iron based ceramic
7. Sodalime glass b
8. Alumina, magnesia Pe:
19. Uranium 2
10. Silicon carbide, Tı

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15. Fabrication and processing of ceramics

Ceramics melt at high temperatures and are brittle
Thus cannot be processed by the usual melting,
casting and thermo-mechanical processing routes.
Most ceramic products are made from ceramic
powders. However, post forming shrinkage is much
higher in ceramics processing because of the large
differential between the final density and the as-
formed density.

Glasses, however, are produced by heating the raw
materials to an elevated temperature above which
melting occurs. Most commercial glasses are of the

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16. Introduction — Processing ceramics

> The very specific character of ceramics — high
temperature stability — makes conventional fabrication
routes unsuitable for ceramic processing.

> Inorganic glasses, though, make use of lower melting
temperatures. Most other ceramic products are
manufactured through powder processing.

> Typical ceramic processing route: powder synthesis —
green component (casting, extrusion, compaction) —
sintering / firing.

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17. Processing ceramics — Glasses

> Most of them are silica-soda-lime variety.

> Raw materials are heated to an elevated temperature
where melting occurs.

> Glass melt is processed by different route to form
different products:
Pressing — to form shapes like plates and dishes
Blowing — used to produce objects like jars, bottles,
light bulbs.
Drawing — to form lengthier objects like tubes, rods,
whiskers. etc.

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18. Ceramic Fabrication Methods-|

一 一 一 | 一

GLASS
FORMING
1.Pressing:
5 PBR Pressing plates, dishes, cheap glasses
operation
--mold is steel with
== . graphite lining
・ 3.Fiber drawing:
a Compressed
・ 2.Blowing: Fr

suspended
Parison

i wind up
mold
Adapted from Fig. 13.8, Callister, 7e. (Fig. 13.8 is adapted from C.J. Phillips,
Glass. The Miracle Maker, Pittman Publishing Lid., London.) Chapter 13 - A?

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19. Glass Structure -

+ Glass is noncrystalline (amorphous)
+ Fused silica is SiO, to which no

: ._ a impurities have been added
Si0 4 tetrahedron + Other common glasses contain
si 4+ impurity ions such as Na*, Ca?*,
02- 시하, and BS

ㆍ Quartz is crystalline (soda glass)-

SiO2:

adapted trom Fig. 12.11,
Calister & Reinwscn 8e. 8

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20. Glass forming-pressing and blow

2. blow: UV

Free

and-bl hnique for

producing a glass bottle.
la

P
London.)

3.7 The press-

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21. 4.drawing

・ Sheet forming - continuous draw

— originally sheet glass was made by “floating” glass
on a pool of mercury

Figure 13.9 A Forming ml
process for the /
continuous drawing of Gesdeel fmmmgml | Waterco shield

sheet glass. (From W. D. \

Kingery, Introduction to ) \ SE
Ceramics. Copyright DER

1960 by John Wiley &
Sons, New York.
Reprinted by
permission of John
Wiley & Sons, Inc.)

—— N
Burner: Molten glass 5 Y

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22. HEAT TREATING GLASSES
1° Annealing: 退 火

--removes internal stress caused by uneven cooling rate between the

surface and interior regions.
2・Tempering: 回 火

--puts surface of glass part into compression

--suppresses growth of cracks from surface scratches.

--sequence: the glassware is heated to a temperature above the Tg rı
yet below the softening point. It is then cooled to room temperature
jet of air or, in some cases, an oil bath.

before cooling surface cooling further cooled

cooler pression
Cooler pression
: surface crack growth IS suppressed.

ww -

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23. Ceramic Fabrication Methods-llA

PARTICULATE

FORMING
+ Milling and screening: desired particle size

・ Mixing particles & water: pri
+ Form a "green" component
--1.Hydroplastic forming:
extrude the slip (e.g., into a pi
--2.Slip casting:

pour slip absorb water
into mold into mold

As: WE 6

solid component
・ Dry and fire the component

oduces a "slip"

force
pe)
die
pour slip drain
into mold mold dal

hollow component

die holder

Adapted from

extrusión 10 Ag Fig. 11.8 (이.

Callister 7e.

Adapted from Fig,
13.12, Callister 7e
(Fig. 13.12 is from
W.D. Kingery,
Introduction to
Ceramics, John
Wiley and Sons,
Inc., 1960.)

Chapter 13 -30 6”

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24. Ceramic powder processing

> Ceramic powder processing route: synthesis of powder,
followed by fabrication of green product which is then

consolidated to obtain the final product.

> Synthesis of powder involves crushing, grinding,
‘separating impurities, blending different powders.

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25. A. Preparation of Raw Materials

Crushing
Types of Equipments Used
a) Jaw Crushers
b) Gyratory Crushers
c) Roll Crushers
d) Hammer Mills

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26. Crushing

CTI rn

に tocaron

に 매 네 마애

Gyratory Crusher

ゅ

Hammer Mill

9/14/3091 Roll Crusher 26

27. Grinding

Types of Equipments Used
a) Ball mill
b) Roller mill
c) Impact grinding

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28. Grinding

Container Gnnding roller

= Container

Stock
‘ Balls
Rotating
table
Drive rolls 一
\ > Drive shaft
(a) (b)
Ball Mill Roller Mill

Stock

Impact Grinding

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29. Processing of Ceramics-
1.Slip Casting-

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30. Slip Plaster mold
Eva LD
06
(1) (2) (4)

(3)
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

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31. Drain Casting

Plaster mold

(1)

D.
의

32. Ceramic powder processing - Casting

> Slurry of ceramic powder is processed via casting
routes — tape casting, and slip casting.

> Tape casting — also known as doctor blade process —
used for making thin ceramic tapes. In this slurry of
ceramic powder + binders + plasticizers is spread over
plastic substrate. Tape is then dried using hot air. Later
tape is subjected to binder burnout and sintering.

> Slip casting — here aqueous slurry of ceramic powder is
poured into plaster of Paris mold. As water begins to
move out due to capillary action, thick mass builds
along mold wall. It is possible to form solid piece by
pouring more slurry.

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33. Ceramic powder processing — Extrusion
& Injection molding

> Extrusion — viscous mixture of ceramic particles,
binder and other additives is fed through an extruder
where continuous shape of green ceramic is produced.
Then the product is dried and sintered.

> Injection molding — it is similar to the process used for
polymer processing. Mixture of ceramic powder,
plasticizer, thermoplastic polymer, and additives is
injected into die with use of a extruder. Then polymer is
burnt off, before sintering rest of the ceramic shape. It
is suitable for producing complex shapes.

> Extrusion and Injection molding are used to make
ceramic tubes, bricks, and tiles.

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34. Ceramic powder processing — Compaction

> Ceramic powder is compacted to form green shapes of
sufficient strength to handle and to machine.

> Basis for compaction — application of external pressure
from all directions.

> In cold iso-static pressing (CIP), pressure is applied
using oil/fluid, then green product is subjected to
sintering.

> In hot iso-static pressing (HIP), pressure is applied at
high temperatures thus compaction and sintering occurs
simultaneously. Its is expensive, but have certain
advantages.

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35. Ceramic powder processing — Compaction, HIP

> HIP is used
- when during CIP not enough strength is gained
- almost nil porosity is the requirement
- for Refractories and covalently bonded ceramics.

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36. 2.Drying and Firing -

・ Drying: as water is removed - interparticle spacings

decrease
030750
mE
wet body partially dry completely dry
Drying too fast causes sample to warp or crack due to non-uniform:
‘shrinkage
+ Firing:
ー heat treatment between

-- vitrification: liquid glass
forms: from clay and flux —
flows
between SiO particles.
(Flux ‘lowers melting
temperature).

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37. > Sintering — process of subjecting the green ceramic to
elevated temperatures with the purpose of gaining
mechanical integrity.

> Driving force for sintering — reduction in total surface
area and thus energy.

> Diffusion (atomic- and bluk-) is responsible for growth
of bonds at contact points of particles (necks). This lead
to coalescence of particles, and eventual mechanical
integrity.

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38. Glazing

“The application of glassy coatings on
ceramic wares to give them decorative
finishes and to make them EEE to
moisture -

as

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39. Ceramics materials:

An organic compound which containing of metals and
one or more non-metals.

i.e. Al203 and pottery ete.
Types:-

Traditional ceramic
Advance ceramic

Glasses

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40. _ Those ceramic which are composed of clay mineral
(porcelain) as well as cement and glass

‚Traditional ceramic are include pottery ,brick and tiles etc.

Product:-
Advance ceramic are include Al203:;bio-ceramie:etc.

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41. Traditional Ceramics vs. new ceramics

Ingredient Mainly determined by the origin of clay, feldspar, |The raw materials are pure compounds, which are
nal ‘and quartz [determined by the artificial ratio
|Forming [Main grouting and plastic forming aaa O
|Firing ~ 년 ceramics need to be precisely contr at the
10009 temperature. The fuel is mail
gas, and oil.
Processing |Generally no processing Often need to cut, punch, grind, grind and polish
Mainly based on internal quality, often showing
‘Mainly on appearance effect.
Performance | nd thermal properties optical, thermal,
PT sensitive and biological properties
¡Tableware, furnishings, wall and floor tiles, sanitary [Used ray, metallurgy,
Application ware, etc.

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42. THANK YOU