CERAMICSCERAMICS

Carasco, Allan Gabriel

Doliente, Lorenzo Miguel

Jacinto, Stephanie

Villanueva, Von Kirby

Ceramics

• One of the largest groups of materials with the properties of nonmetals and all are made by firing or burning, often including silicates and metal oxides.

• Greek term Keramos, meaning "a potter" or "pottery”.

Ceramic materials are attractive for several reasons :Cheap in terms of its starting materials.Compared to metals, lightweight and

retain their strength up to 1000˚C where metals tends to fail.

They have electrical, optical, and magnetic properties of value in the computer and electronic industries.

HistoryThe art of making pottery by forming and

burning clay has been practiced from the earliest civilizations.

Burnt clayware has been found dating from about 15,000 B.C. and as well developed as an industrial product in Egypt by about 5000 B.C.

Formed glass dates from the period 7000-5000 B.C. and was a stable industry in Egypt by about 1500 B.C.

Ceramics Industry

An important characteristic of the ceramics industry is that it is basic to the successful operation of many other industries.

In the Philippines, smuggled ceramics has cause severe effect on the ceramic industry locally. But exporting of ceramic materials is significantly increasing.

Uses of CeramicsThe ceramics industry is divided in the

manufacture of the ff. products: Structural Clay Products Whitewares Refractories Glasses Abrasives Cements Advance Ceramics

-Structural-Electrical-Coating

Classifications of the Ceramics

Traditional CeramicsNew Ceramics

Raw Material

WeighingBall Milling

Vibrating Screen and HomoTank

Spray Dryer

Powder Storage (SILO)

Dry Pressing Horizontal

Dryer Glazing

Silk Screen PrintingRoller Heart Kiln

Ceramic Tile Processes

Raw Materials

The traditional ceramics industry is largely based on various combinations of clay minerals, feldspar and silica.

The mineral raw materials used in the ceramic industry are mainly inorganic, nonmetallic, crystalline solids formed by complex geologic processes.

Raw Materials

Oxygen, silicon, and aluminum together account for 90% of the elements in the earth’s crust , These, together with other minerals compounds of oxygen, constitute the greatest bulk of naturally occurring ceramic raw materials.

Raw Materials

Clay MineralsTalc and Related

MineralsSilica and Silicate

MineralsFeldspars and related

minerals. Refractory Raw

Materials

TalcSilica

Clay

Common Types of ClayKaolin or China Clay Ball ClaysFire ClaysFlint ClaysPottery ClayShaleVitrifying ClaysBrick ClaysSlip Clays

Important Characteristics of Claysin Ceramic Bodies

Clays have the ability to form clay-water composition and to maintain their shape and strength during drying and firing

They fuse over a temperature range depending on their composition in such a way as to become dense and strong without losing their shape

Talc and Related Minerals

Talc is a hydrous magnesium silicate which has a layer structure similar to that of the clay minerals.

It is an important ceramic raw material for the manufacture of electrical and electronic components

Talc and Related Minerals

Pyrophyllite Block talc Asbestos

Silica and Silicate Minerals

Silica is a major ingredient in glass, glazes, enamels, refractories, abrasives, and whiteware compositions.

It is widely used because it is inexpensive, hard, chemically stable

Silica and Silicate Minerals

The major source of silica for the ceramic industry is sandstone, consisting of lightly bonded quartz grains.

The sand is frequently mined by loosening the quarts grains with a stream of high-pressure water.

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

Feldspars and Related Minerals

Nepheline syeniteWollastoniteSillimanite

Sillimanite

WollastoniteNepheline syenite

Refractory Raw Materials

AluminaMagnesiaDolomiteChrome Ore

Alumina

Dolomite Chrome Ore

Magnesia

Other Raw Materials

Soda ashBorate mineralsFluorsparPhosphate minerals Abrasive raw

materials

Soda Ash

Borate Minerals

Flourspar

Ball MillingSpheres mixed with

the stock to be comminuted are rotated inside a large cylindrical container.

These operations are often carried out with water

Ball Milling

Stock

Balls

Drive rolls

Container

Spray Dryer

Characterized by atominization of a solution or suspension into droplets, followed by drying.

Spray Dryer

Schematic Diagram of Spray Dryer

Particle Trajectory

Dry Pressing

Forming of the “greenware” tile body.

Non-clumping granulates are compressed in steel dies designed appropriately for the part to be manufactured.

Glazing

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

Roller Hearth KilnA roller tunnel kiln for firing a drying

refractory material advanced along the refractory rotatable rollers includes an upper section comprising a prefiring zone, a firing zone, a first forced cooling zone, a natural cooling zone and a second forced cooling zone.

Roller Hearth Kiln

Firing zone

Gear system

Entrance

Traditional Ceramic Processes

A. Preparation of Raw Materials• Crushing

Types of Equipments Useda) Jaw Crushers

b) Gyratory Crushers

c) Roll Crushers

d) Hammer Mills

Crushing

Jaw CrusherGyratory Crusher

Roll CrusherHammer Mill

Traditional Ceramic Processes

• Grinding

Types of Equipments Useda) Ball mill

b) Roller mill

c) Impact grinding

Grinding

Ball Mill Roller Mill Impact Grinding

Traditional Ceramic Processes

B. Shaping Processesa) Slip Casting

1. Drain Casting

2. Solid Casting

b) Plastic Forming

1. Manual Forming Hand modeling Hand molding Hand throwing

Drain Casting

Traditional Ceramic Processes

2. Mechanized Jiggering Plastic pressing Extrusion

c) Semi-dry Pressing

d) Dry Pressing

Semidry Pressing

Traditional Ceramic Processes

C. Drying

D. Firing

E. Glazing

New Ceramic Processes

A. Preparation of Raw Materials1. Freeze Drying

2. Precipitation from solution

B. Shaping1. Hot pressing

2. Isostatic pressing

3. Doctor-blade process

4. Injection molding

New Ceramic Processes

C. Sintering1. To bond individual grains into a solid mass

2. To increase density

3. To reduce or eliminate porosity

D. Finishing1. To increase dimensional accuracy

2. To improve surface finish

3. To make minor changes in part geometry

New Ceramic Processes

Doctor blade Process

Factors Affecting Ceramic Process

OxidationDecomposition ReactionsPhase TransformationsTrapped GasesNon uniform MixingOver firingHot Pressing

Common Errors in Ceramic Process

Firing ShrinkageWarping