Ceramics

CERAMICS 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.

History
The 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 Ceramics
The 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 Ceramics
New Ceramics

Ceramic Tile Processes Raw Material Weighing Ball Milling Vibrating Screen and HomoTank Spray Dryer Powder Storage (SILO) Dry Pressing Horizontal Dryer Glazing Silk Screen Printing Roller Heart Kiln

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 Minerals
Talc and Related Minerals
Silica and Silicate Minerals
Feldspars and related minerals.
Refractory Raw Materials
Talc Silica Clay

Common Types of Clay
Kaolin or China Clay
Ball Clays
Fire Clays
Flint Clays
Pottery Clay
Shale
Vitrifying Clays
Brick Clays
Slip Clays

Important Characteristics of Clays in 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 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

Pyrophyllite
Block talc
Asbestos

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

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 syenite
Wollastonite
Sillimanite
Sillimanite Wollastonite Nepheline syenite

Refractory Raw Materials
Alumina
Magnesia
Dolomite
Chrome Ore
Alumina Dolomite Chrome Ore Magnesia

Other Raw Materials
Soda ash
Borate minerals
Fluorspar
Phosphate minerals
Abrasive raw materials
Soda Ash Borate Minerals Flourspar

Ball Milling
Spheres 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 Kiln
A 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
Preparation of Raw Materials
Crushing
Types of Equipments Used
Jaw Crushers
Gyratory Crushers
Roll Crushers
Hammer Mills

Crushing Jaw Crusher Gyratory Crusher Roll Crusher Hammer Mill

Grinding
Types of Equipments Used
Ball mill
Roller mill
Impact grinding

Grinding Ball Mill Roller Mill Impact Grinding

B. Shaping Processes
Slip Casting
Drain Casting
Solid Casting
Plastic Forming
Manual Forming
Hand modeling
Hand molding
Hand throwing

Drain Casting

Mechanized
Jiggering
Plastic pressing
Extrusion
Semi-dry Pressing
Dry Pressing

Semidry Pressing

Drying
Firing
Glazing

New Ceramic Processes
Preparation of Raw Materials
Freeze Drying
Precipitation from solution
Shaping
Hot pressing
Isostatic pressing
Doctor-blade process
Injection molding

New Ceramic Processes
Sintering
To bond individual grains into a solid mass
To increase density
To reduce or eliminate porosity
Finishing
To increase dimensional accuracy
To improve surface finish
To make minor changes in part geometry

New Ceramic Processes Doctor blade Process

Factors Affecting Ceramic Process
Oxidation
Decomposition Reactions
Phase Transformations
Trapped Gases
Non uniform Mixing
Over firing
Hot Pressing

Common Errors in Ceramic Process
Firing Shrinkage
Warping

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Ceramics

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