Ceramics (Final) -$-

8/19/2019 Ceramics (Final) -$-

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CER MICS

The term ceramics is used to indicate the potter’sart or articles made by the potter. It is derived

from the Greek word keramos meaning the

potter’s earth.


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CL Y

Ceramic clay is a water-based

substances made from clay mineralsmixed with other raw materials. They

are baked at high temperatures, in a

process known as firing.

Clay is naturally occurringaluminum silicate composed of

fine-grained minerals.

CER MIC CL Y


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CLASSIFICATION

Earthenware

Terracotta

Stoneware

Vitreous China

Fireclay

Porcelain


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INTRODUCTION

• The surfaces of clay

products are sometimes

glazed.

• A glaze is a glassy coat of

thickness about 0.1 to 0.2

mm applied on the surfaceof an item and then fused

into place by burning at

high temperature.


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Before Glazing After Glazing


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Following are the purposes for which the glazing is

done:-

• To improve the appearance.

• To make the articles durable and impervious.

• To produce the decorative effects.

• To protects the articles from action of atmospheric

agencies, chemicals, sewage etc.• To provide smooth surface.

PURPOSES


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METHODS OF GL ZING

•

The glazing may be transparent like glass or it may beopaque like enamels.

• For obtaining coloured glazes, the oxides and salts of various

metals or special refractory colouring agents are added.

Glazing

Opaque GlazingTransparent Glazing

Salt Glazing Lead Glazing


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• Small quantity of wet sodium

chloride (salt) is added in the

kiln at a high temperature of

about 13000 C.• The quantity of wet salt and

throwing it at proper time

should be done with extreme

care.

• Colour of articles glazed by

this method is brownish.

• Useful for sanitary pipes and

chemical stonewares.

• The article is once burnt and it isthen dipped in a bath containingoxide of lead and tin.

•

Then it is taken out from the bathand it is re-burnt at a hightemperature.

• The particles of oxide of lead andtin melt and they form a film ofglass over the exposed surfaces of

the articles.• For getting articles of better

quality, the lead glazing is preferred to the salt glazing.

• Used for terra-cotta, fire-clay

wares and earthenwares.

Transparent Glazing

Lead GlazingSalt Glazing


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Transparent Glazing

TransparentGlaze Frit

Granules


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• The superior clay is finely

powdered and dried andsufficient amount of water isadded to it to make a plasticcream like substance , known asthe slip.

• The articles to be glazed aredipped in the slip before

burning and they aresubsequently heated.

• The burning of articles results into the flow of clay particles andan opaque glaze surface isformed.

• The sanitary articles are glazed

by this process.

Opaque Glazing

Ceramic Super White Opaque FritGlaze


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earthenware


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I

NTRODUCTION

• The term earthenware is used to indicate wares or

articles prepared from clay which is burnt at low

temperature and cooled down slowly.


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• The clay is mixed with required quantity of sand, crushed

pottery, etc.

• The addition of such material prevents the shrinkage during

drying and burning.

•

Earthenware’s colors ranges from white to dark brown.• It is fired at lower temperatures than stoneware or porcelain.

• Red clay is the most commonly available and most commonly

used.

•

Terra-cotta is also a kind of earthen ware.


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P

ROPERTIES

• Soft

• Porous

• Usually unglazed; but they can be glazed or enameled.

• Lacks strength and toughness.

• Economical i.e. less expensive.

• Easily workable.

•

Due to its higher porosity, it must usually be glazed inorder to be watertight.


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U

SES

The earthenware are mainly used for making:-

• Ordinary drain pipes.

• Electrical cable conduits.

• Partition blocks.

• Decorative objects.

• Pots and utensils.


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Terra-cotta


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I

NTRODUCTION

• Terra means earth and cotta means baked .

• Terracotta is a type of earthenware & is a clay based

unglazed or glazed ceramic, where the fired body is

porous.• Terracotta is prepared from clay which is having

sufficient percentage of iron & alkalis matter.

•

Sand glass, ground glass, old terracotta or pottery areadded to clay to provide strength & rigidity to

resulting terracotta and also for the prevention of

shrinkage during drying.


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TYPES

POROUS TERRACOTTA

• To obtain porousterracotta saw dust orground cork is mixed

during preparation of clay.• Fire & sound proof.

• Structurally weak & lightin weight.

• Can be nailed, screwed &

sawn like timber.

POLISHED TERRACOTTA

• To obtain polishedterracotta, product is first

burnt at low temperature &

then removed from kiln andallowed to cool at normaltemperature. Cooled

product is coated withglazing and burnt again inkiln.

• Polished terracotta is alsoknown as Faience .

• Used in ornamental work,substitute for stone tile,hollow cast units.


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DV NT GES

• Strong and durable.

• Available in differentcolours.

• Cheaper then finely

dressed stones.• Easily cleaned.

• Easily molded.

• Fireproof.

•Light in weight.

• Not affected byatmospheric agencies andacids.

• Cannot be fixed during the progress of work. But it is to be fixed when the work is infinal stage of completion.

• Twisted due to unequal

shrinkage in drying and burning.

DIS DV NT GES


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USES

• As hollow terracotta blocks for ornamental

work as facing work, arches etc.• As a decorative material in place of stone for

ornamental parts of buildings.

• For the manufacturing of tiles which are

widely used for roofing and flooring.


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Porcelain


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I

NTRODUCTION

• A fine earthenware which is white and semi transparent.

• Due to its colour it is also known as White ware.

• A clay of sufficient purity and possesing high degree of

plasticity is used in preparing porcelains.


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T

YPES

SOFT PORCELAIN

• Made from pure white clay, towhich some amount of crushedflint(melted glass) is added.

•

Used in – Crockery like plates,dishes, etc.

HARD PORCELAIN

• Made from china clay, to

which some percentage offeldspar and quartz have beenadded.

• Used in – Electricalinsulations, bathroom fixtures,sanitary fittings, sanitary ware,storage vessels, crucibles etc.

LOW VOLTAGE PORCELAIN

• Prepared by dry process.

• Mainly used for switch blocks,

insulating tubes, lamp socketetc.

HIGH VOLTAGE PORCELAIN

• Prepared by wet process.


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SOFT PORCELAIN

HARD PORCELAIN HIGH VOLTAGE PORCELAIN

LOW VOLTAGE PORCELAIN


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P

ORCEL IN

T

ILES

• Porcelain tiles are ceramic tiles with a

water absorption rate of less than

0.5 percent and are used to cover floors

and walls.

• They can either be unglazed or glazed.

• Porcelain tiles are the strongest fired product that you can purchase in tile

form and many are commercially rated;

strong enough to be used outdoors or in

a shopping mall.


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Properties Porcelain Tiles Ceramic Tiles

Manufacturing

Made from clay which is of denser type than ceramic.

Porcelain tiles are baked at very high temperatures for long

periods of time so that almost all the water is removed

which makes the tile much harder and denser.

Made from natural clay, sand and water.

These materials are molded to form square/rectangular tiles

and then baked in a kiln to remove most of the moisture.

FeaturesWhite or grey in colour and usually left unglazed.Chips in porcelain are not noticeable due to homogeneous

color throughout.

Known for its natural red terra-cotta finish and it may beglazed to create different surface colors or designs.

Chips in the glaze can be highly visible.

UsesCan safely be used indoors or out.

Has a lower moisture content and is less likely to crack due

to freezing.

Designed only for indoor use.

Higher moisture content makes it more susceptible to

freezing- and thawing-related cracks.

Cost

Costs more than ceramic tile.

More durable and longer lasting, so it may be the cheaperof the two over the life of the installation and is also less

porous, making it easier to clean and less likely to stain.

Stained ceramic may require replacement due to thedifficulty of removing stains from porous tiles.

DurabilityCan be expected to last longer than ceramic in almost any

application and at can withstand high levels of traffic and

increased levels of wear and tear.

It is likely to chip or crack if objects are dropped on it, and

the tiles are not expected to hold up for as long as porcelain

units. Ceramic should not be used in commercial

applications.

Installation

Very hard and durable, which can be a problem during

installation. Its dense nature makes it difficult to cut,

especially when special shapes or rounded edges areneeded.

For do-it-yourself installers, ceramic is often the better

choice because it requires fewer special tools. It is also

better to use ceramic when working in an oddly shaped areathat requires a large number of special cuts.

Comparison between Porcelain Tiles

and Ceramic Tiles


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U

SES

• Porcelains are used for

numerous purposes such as

crockery wares, sanitary

wares, electric insulators,

storage vessels, reactor

chambers, electric

chambers, refractory bricks,

etc.

• It is also used for the

manufacturing of tiles which

are used for covering walls,

ceilings, countertops etc.


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I

NTRODUCTION

• The term stoneware is used to indicate the ware prepares from

non- refectory clay, which are mixed with stone & crushed

pottery.

• Stoneware is a vitreous or semi-vitreous ceramic ware.

• Stoneware, which, though dense, impermeable and hard

enough to resist scratching by a steel point, differs

from porcelain because it is more opaque, and normally only

partially vitrified.


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P

ROPERTIES

• It is usually colored grey or brownish because of impurities

in the clay used for its manufacture, and is normally glazed.

• It is non porous.

• It is strong.

• It is Durable

• Corrosion resistant

• Easily capable to withstand the affect of atmospheric

agencies.• More capable & dense in compression to earthenware.


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S

NIT RY

P

URPOSES


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G

L ZED

T

ILES


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Properties Earthenware Stoneware

ConstituentsPrepared from clay which is burnt at low

temperature and cooled down slowly.

Prepared from non- refractory clay, which are

mixed with stone and crushed pottery.

Surface It is common ceramic ware. It is a vitreous or semi vitreous ceramic ware.

UsesUsed for ordinary drain pipes, electrical cable

conduits, partition block, decorative objects.Used for sanitary purpose, glazed tiles, acid jar.

Physical Properties Generally soft and porous.

Non- porous, strong, durable, corrosion

resistant, easily capable to withstand the affect

of atmospheric agencies. More compact and

dense in compression to earthenware.

GlazingUsually unglazed, but can be glazed or polished,

Glazed earthen ware are impervious & not

affected by acid.

Always glazed.

Comparison between Earthenware and

stoneware


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Vitreous china


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I

NTRODUCTION

• It is a ceramic material that has been glazed with enamel.

• When an intense amount of heat is applied to powdered glass,

the result is a liquid glass that is used to coat ceramic objects.

When this glass is allowed to cool, the final product created is

vitreous china.

• Colored vitreous china is made by mixing crushed glass with

various minerals like cobalt & iron.


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U

SES

It is excessively used for the manufacturing of flush

toilets, sinks, basins, urinals and other plumbing and

sanitary utilities.


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REFRACTORIES


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• High resistance to rapid changes in temperature i.e. thermal shocks.

• Dimensional stability i.e. resistance to change in volume at hightemperature.

• Withstand abrasion and rough usage.

• Durability.

• Non brittle at high temperatures.

• High melting point.

• Good thermal conductivity.

• Strong enough to resist compression, crushing and tension in hotand cold conditions.

Introduction

• The term refractories is used to indicate substances that are able

to resist high temperatures.

Properties


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fireclay


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INTRODUCTION

• Fire clay is a term applied to a range of refractory clay used inthe manufacture of ceramics, especially fire brick.

• Fire clay are clays which can resist very high temperature

without getting soft or melting.

TYPES

The Fire clay can be classified into three categories depending

upon the fire resisting capacity-

• Low duty

• Medium duty

•

High duty


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P

ROPERTIES

• Resistance to high temperatures

• Durable

• Fusion point higher than 1,600 0C

•

Hard• Stability during firing in the kiln

• As insulation

• Good plasticity

• Withstands high pressure• Fire resistant


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USES

• Lining of furnaces, kilns, fireboxes, and fireplaces.• Refractory insulating bricks.

• It is suitable for manufacture of utensils used in the metal

working industries, such as crucibles, retorts and glassware.

• Because of its stability during firing in the kiln, it can be used tomake complex items of pottery such as pipes and sanitary ware.


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firebricks


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Fire Brick

• A fire brick, or refractory brick is a block

of refractory ceramic material used in

lining furnaces, kilns, fireboxes, and fireplaces.

•Built to withstand high temperature, but will alsousually have a low thermal conductivity for greater

energy efficiency.

• In the making of firebrick, fireclay is fired in the kiln

until it is partly vitrified, and for special purposes may

also be glazed.


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• They are weaker, but

they are much lighter,

easier to form, andinsulate far better than

dense bricks.

• There are two standard

size of fire-brick: – 9 " × 4½ " × 3 " (230 mm

× 115 mm × 75 mm).

– 9" × 4½" × 2½".


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Miscellaneous

products


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Ceramic Tiles

• Widely used for furnishing bathrooms, toilets, and

kitchens.

• The Mangalore tiles are a common and preferred

roofing material.• Ceramic floor and wall tiles offer a wide range of

colors, textures and patterns to lure architects and

designers.

• Tiles in the exterior are preferred for the water-

resistant, fire resistant, anti corrosive, easy

maintenance, wide color range.


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T

YPES

OF

T

ILES

• These tiles have differentshapes and size. They aremainly used for paving,

flooring and roofing.

• Types :-

– Drain Ti les

– F loor or Paving Tiles

– Roof Tiles• Allahabad

• Manglore

• Pan

• Pot etc.

• These tiles are used fordecorative purposes infloors, walls, ceilings and

roofs.

• Has 3 layers :-

– Body : made up of coarserclay.

– Face : made up of finer clayfor making the ground ofthe pattern.

– Back : thin coat of clay forthe prevention from

warping.

COMMON TILES ENCAUSTIC TILES


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Clay blocks

• The blocks can be prepared

from clay and they are used

in the construction of

partitions.

• Such blocks may either be

solid or hollow.

• Partition of clay block are

efficient in preventing the

fire and passage of sound.

• They are light in weight and

are non-shrinkable.


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BURNT BRICKS

• Bricks that has been

treated in a kiln at an

elevated temperature to

harden it, give it

strength and improve its

resistance to moisture,compare to unburned

bricks.


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BRICK TILES

• Brick tiles is also called

thin brick or brick

veneer .

•Brick tiles are becomingincreasingly popular in

the as it is fireproof and

easy to maintain, as well

as having the classicappearance of real bricks

at a fraction of the cost.


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Conclusion

In today’s times, the use of ceramics can beseen everywhere in architecture, be it the

daily kitchen wares, the sanitary fixtures,

garden accessories and planters, or the mostnoted and obvious tiles.


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Ceramics (Final) -$-

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