glass and ceramics industry

glass

a rigid, under cooled liquid having no definite melting point and sufficiently high viscosity to prevent crystallization.

transparency, high resistance to chemical attack, electrical insulator, ability to contain a vacuum

optical and physical properties of glass make it suitable for different applications

fused silica

alkali silicates

soda-lime glass

lead glass

borosilicate glass

glass fibers

special glasses

types of glass

glass

a hard, brittle, transparent amorphous solid

fused silica

Sometimes erroneously referred to as quartz glass

1700

temperature at which sand by itself can be fused to produce glass

fused silica

high melting point and does not shrink or expand greatly with changing temperatures, it is suitable for laboratory apparatus and for such objects subject to heat shock as telescope mirrors

alkali silicates

Sand and soda ash are simply melted together

alkali silicates

a mixture of 75% silica (SiO2) and 25% of sodium oxide (Na2O)

800

temperature of fusion of alkali silicates

water glass

water-soluble alkali silicates

alkali silicates

uses include fireproofing, sealant, adhesive

for paper, for detergents and as soap

builders

soda-lime glass or commercial glass

Most manufactured glass; used to make bottles, tableware, lamp bulbs, and window and plate glass.

FeO

impurities of soda lime glass that causes a green tint (0.1% wt)

lead glass

heavy and has an enhanced capacity to refract

light, which makes it suitable for lenses and prisms, as well as for imitation jewels.

lead glass

used in shields to protect personnel in nuclear installations.

lead glass

made by using lead oxide instead of calcium oxide and potassium oxide instead of sodium oxide

24%

percent PbO of lead crystal

30%

% PbO of traditional english full lead crystal

George Ravenscroft

discovered that by adding lead oxide to the glass composition, a far more brilliant, sparkling glass could be produced than had ever been made before

borosilicate glass

Noted for its durability and resistance to chemical attack and high temperatures

borosilicate glass

widely employed for cooking utensils, laboratory glassware, and chemical process equipment

pyrex

example of borosilicate glass in the form of ovenware and other heat-resisting ware

borosilicate glass

low expansion coefficient, superior resistance to shock, excellent chemical stability and high electrical resistance.

glass fibers

produced from special glass compositions that are resistant to weather conditions

optical glass, photosensitive glass, glass ceramics

examples of special glasses

optical glass

differs from other glass in the way in which it bends, or refracts, light.

refractive index

measure of how much the glass bends light.

dispersion

measure of the way the glass splits white light into the colors of the rainbow

photochromic glass

darkens when exposed to light but fades to its original clear state when the light is removed.

glass ceramics

formed typically from lithium aluminosilicate glass

flux

compounds that lower the melting point of sand thereby facilitating the melting of the raw materials and promotes fusion

stabilizers

compounds added to increase the durability of the glass

mixing and melting

shaping/forming

annealing

finishing

manufacturing procedure of glass

casting

glassblowing

pressing

drawing

rolling

five methods of shaping/forming

casting

molten glass is simply poured into a mold and allowed to cool and solidify

centrifugal casting

the glass is forced against the sides of a rapidly rotating mold

drawing

used to make tubing, sheets, fibers, and rods of glass that must have a uniform cross section

lehr

oven used in annealing

annealing

process to relieve stresses built up within the glass as it cools

cutting

etching

sandblasting

cold painting

enamel painting

gilding

examples of finishing processes

etching

intaglio decoration is achieved with acid, the results varying from a rough to mat finish.

sandblasting

fine grains of sand, crushed flint, or powdered iron are projected at high speed onto the glass surface, leaving a design in mat finish.

cold painting

lacquer colors or oil paints are applied to glass but are not affixed by firing.

enamel painting

enamel colors are painted and then fused onto the

surface in a low-temperature firing.

gilding

gold leaf, gold paint, or gold dust is applied to glassware and sometimes left unfired; low-temperature firing, however, is necessary for

permanency.

egypt and mesopotamia

origin of ceramics

ceramics

clay products or silicate industries.

Chou and Han Dynasty

started developing the ceramic industry

Withstand high temperatures

Resist greater pressures

Have superior mechanical properties

Possess special electrical characteristics

Can protect against corrosive chemicals

Characteristics of Ceramic Products

whitewares

structural clay products

refractories

specialized ceramic products

enamels and enameled metal

types of ceramic products

whitewares

generic term for ceramic products which are usually white and of fine texture; selected grades of clay bonded together with varying amounts of fluxes and heated to a moderately high temperature in a kiln (1200 to 1500 C)

earthenware

chinaware

porcelain

sanitary ware

stoneware

whiteware tiles

examples of whitewares

earthenware

sometimes called semi-vitreous dinnerware, is porous and non-translucent with a soft glaze

chinaware

vitrified translucent ware with a medium glaze which resists abrasion to a degree; it is used for non-technical purposes

porcelain

vitrified translucent ware with a hard glaze which resists abrasion to the maximum degree

porcelain

highest quality of clayware

sanitary ware

formerly made from clay, usually porous; hence a vitreous composition is presently used.

stoneware

one of the oldest ceramic wares, regarded as crude porcelain not so carefully fabricated from raw material of poorer grade

whiteware tiles

generally classified as floor tiles, which are resistant to abrasion and impervious to stain penetration and may be glazed or unglazed

structural clay products

• building bricks, face brick, terra-cotta, sewer pipe and drain tile

• made from the cheapest of common clays with or without glazing.

refractories

- acidic, basic or neutral; materials of high resistance to thermal, physical and chemical effects suitable for furnace construction

firebricks

silica

chromite

magnesite

magnesite-chromite bricks

silicon carbide and zirconia

aluminum silicate

alumina products

examples of refractories

clay

feldspar

sand

three main raw materials in making ceramic products

clay

earthly or stony aggregate consisting essentially of hydrous silicates of alumina and it is plastic when sufficiently pulverized and wetted, rigid when dry, and vitreous when fired at sufficiently high temperature

kaolinite

Al2O3.2SiO2.2H2O

montmorillonite

(Mg, Ca)O.Al2O3.5SiO2.nH2O

illite

K2O, MgO,Al2O3,SiO2,H2O in variable amounts

kaolinite

montmorillonite

illite

tyoes of clay

feldspar

fluxing constituent in ceramic formulas

microline

albite

anorthite

3 types of feldspar

microline

potash feldspar

albite

soda feldspar

anorthite

lime feldspar

sand or flint or quartz

refractory constituent which must contain low iron if chosen for light-colored ceramic products

nepheline syenite

- a quartz-free igneous rock used extensively in whitewares

- it is a more active flux than feldspar

SiO2, Al2O3, CaO,and MgO

Principal refractory oxides

Na2O, K2O, B2O3 and SnO2 with fluorides.

Principal fluxing oxides

drying

dehydration or chemical smoking

calcination

oxidation of ferrous iron and organic matter

amorphous alumina transferred to crystalline alumina

silicate formation

chemical conversions in ceramic formation

20 - 150

drying temperature

150 - 650

Dehydration or chemical smoking temperature

600 - 900

calcination temperature

350 - 900

Oxidation of ferrous iron and organic matter temperature

940

temperature of Amorphous alumina transferred to crystalline alumina

900 or 1000 and above

silicate formation temperature

mullite, cristobalite

Any ceramic body is composed of a vitreous matrix plus crystals of which _____ and ______ are two of the most important

slip

creamy mixture of raw materials

burnishing

surface is rubbed with a hard or smooth object to polish the surface