CERAMIC MATERIALS I - Mühendislik Fakültesimetalurji.mu.edu.tr/Icerik/metalurji.mu.edu.tr/... · Probably as early as 75,000 B.C.E., long before human beings had learned how to

CERAMIC MATERIALS I

Asst. Prof. Dr. Ayşe KALEMTAŞ

[email protected], [email protected], Phone: 211 19 17Metallurgical and Materials Engineering Department

mailto:[email protected]







MATERIALS

CERAMIC METAL POLYMER COMPOSITED

GLASSES

GlassesGlass-

ceramics

CLAY

PRODUCTS

REFRACTORIESABRASIVES CEMENTS

ADVANCED

CERAMICS

INTRODUCTION


HISTORY DEFINITION PROPERTIES APPLICATIONS

INTRODUCTION


INTRODUCTION

Four of the major technological achievements in

glass which have had the most profound impact on

mankind.

Glass window – which enables sunlight to come into

dwelling unit

Lenses – opthamics for improved vision, microscope,

telescope optics

Light bulb envelope - lighting

Semiconducting glasses – for computer memory,

solar cell, photocopiers


Well Known Glass Products

www.toxel.comGlass Bathtub

http://www.wickedreport.comHirom Glass Violin is a product of Hario

Glass Co. Ltd., Japan. And also, The world’s first hand made glass violin.

www.whitersstreetglass.com.auGlass splashbacks

http://worlds-interior-design.blogspot.comWall-to-wall glass windows

http://freshome.comSuperdurable tempered glass

http://www.toxel.com/



http://www.wickedreport.com/



http://www.whitersstreetglass.com.au/




http://worlds-interior-design.blogspot.com/





http://freshome.com/





www.tripadvisor.com

Glass sink cabinets in the bathroom

www.aarticommercial.com/prod

ucts.php

Laminated Windscreen Glass

http://freshome.comhttp://www.ifjk.org

Tempered glass table

Heat resistant

glass door

http://www.tripadvisor.com/



http://www.aarticommercial.com/products.php







http://freshome.com/

http://www.ifjk.org/





Heat resistant glass

lidHeat resistant glassware

(microwave safe)Tempered Glass

Cutting Board

http://www.wolfard.com

Classic Wolfard Oil Lamp

http://members.commissionmonster.com/z/71576/5773/KGift_18cm_NonStick_Saucepan_with_Heat_Resistant_Bakelite_Handle_and_G/http:/www.oo.com.au/18cm_Non-Stick_Saucepan_with_H_P19647C242.cfm?AFID=21

http://www.glassinchina.com/viewPic.aspx?title=Heat+Resistant+Glassware+(Microwave+Safe)&picURL=images.glassinchina.com/ProductImage/p2008-9-25-19-08-51.JPG

http://www.glassinchina.com/viewPic.aspx?title=Glass+Cutting+Board&picURL=images.glassinchina.com/ProductImage/p2008-9-25-19-00-06.JPG

http://www.wolfard.com/



http://go2.wordpress.com/?id=725X1342&site=margotmystic.wordpress.com&url=http://margotmystic.files.wordpress.com/2008/09/magnifying-glass.jpg&sref=http://margotmystic.wordpress.com/2008/09/20/palmistry-use-a-magnifying-glass-medical-stigmata-lines/


INTRODUCTION

Any material that exhibits only a short-range order of atoms

or ions is an amorphous material; that is, a noncrystalline

one.

In general, most materials want to form periodic

arrangements since this configuration maximizes the

thermodynamic stability of the material. Amorphous

materials tend to form when, for one reason or other, the

kinetics of the process by which the material was made did

not allow for the formation of periodic arrangements.

Glasses, which typically form in ceramic and polymer

systems, are good examples of amorphous materials.


INTRODUCTION

Definitions of Glass

The origin of the word glass is the late Latin term glæsum used to refer to a

lustrous and transparent or translucent body.

Glassy substances are also called vitreous, originating from the word

vitrum, again denoting a clear, transparent body. Although glass became a

popular commodity in the growth of civilization, perhaps because of its

transparency, luster (or shine), and durability, the current understanding of

glass no longer requires any of these characteristics to distinguish it from other

substances.

Glass can be inorganic (non-carbon based) as well as organic (carbon-

based), and fusion is not the only method to make a glass.

Thus, the old ASTM definition that glass is an inorganic product of fusion which

has been cooled to a rigid condition without crystallizing is not appropriate.

Handbook of Ceramics, Glasses, and Diamonds, Charles A. Harper Editor-in-Chief, Chapter:5, Inorganic Glasses-

Structure, Composition and Properties, Arun K.Varshneya and Thomas P. Seward III, McGRAW-HILL


INTRODUCTIONMethods of Making Inorganic Glasses

The most common method for making glass is to:

Fuse various raw materials in appropriate proportions together with the application of

heat,

Gather and form into useful products,

Cool subsequently at a rate fast enough to avoid distortion of the shape yet slow enough

to avoid cracking.

Inorganic glasses may also be obtained by

Hydrolyzing an alcoholic solution of an organometallic compound,

Stirring the hydrolyzed product to allow rapid chelation to a gel state,

Drying the gel mass to drive off the organics,

Sintering at an elevated temperature to obtain a compact.

This method, called the sol-gel route to glassmaking, is often used to deposit thin films such as

antiref lection coatings.

The sol-gel process of making a glass avoids the normally high temperatures employed for the

fusion of glass. Chemical vapor deposition is yet another technique which completely avoids

fusion of constituent materials.


INTRODUCTION

The earliest written records of glass making are some

famous clay tablets, dating from around 650 BC, from the

library of Assur-bani-pal, but these are incompletely

understood because we have no dictionary to explain the

technical terms.

Many centuries passed before written accounts of glass

making contained any useful insight besides recipes to be

followed by rote.

The earliest development in glass making of which we have

a reasonably documented description seems to be theinvention of glass of lead by Ravenscroft around 1673-1676.


Glass from Nature

Natural Glass

Probably as early as 75,000 B.C.E., long before human beings had

learned how to make glass, they had used natural glass to fashion knives,

arrowheads, and other useful articles.

The most common natural glass is obsidian, formed when the heat of

volcanoes melts rocks such as granite, which then become glassy upon

cooling. Other natural glasses are pumice, a glassy foam produced from

lava; fulgurites, glass tubes formed by lightning striking sand or sandy

soil; and tektites, lumps or beads of glass probably formed during

http://www.chemistryexplained.com/Ge-Hy/Glass.html#ixzz3G6sDTQBl

http://www.chemistryexplained.com/Ge-Hy/Glass.html











Glass from Nature

Obsidian

The first glass, used by early man is obsidian. Ryolite lava flows from volcanoes and swiftly cools, impeding

the formation of crystals and creating absidian glass. This glass has an irregular structure

and, therefore, fractured into smooth curved shapes with finer edges. Around the world, many early cultures

discovered these properties and utilized this glass in weapons, tools, and decoration.

Uses of Obsidian as a Cutting Tool

The conchoidal fracture of obsidian causes it to break into pieces

with curved surfaces. This type of fracturing can produce rock

fragments with very sharp edges. These sharp fragments may

have prompted the first use of obsidian by people.

The first use of obsidian by people probably occurred when a sharp

piece of obsdian was used as a cutting tool. People then

discovered how to skillfully break the obsidian to produce cutting

tools in a variety of shapes. Obsidian was used to make

knives, arrow heads, spear points, scrapers and many other

weapons and tools.

Once these discoveries were made, obsidian quickly became the

raw material of preference for producing almost any sharp object.

The easy-to-recognize rock became one of the first targets of

organized "mining". It is probably a safe bet that all natural obsidian

outcrops that are known today were discovered and utilized by

ancient people.

http://geology.com/rocks/obsidian.shtml


Glass from Nature

Freshly broken pieces of obsidian have a very high luster. Ancient people noticed that they

could see a reflection in obsidian and used it as a mirror.

Obsidian is a popular jewelry stone.

A thin piece of obsidian is often used as a "backing"

material for opal doublets and triplets. The black

obsidian adds stability to the opal and provides a

dark background color that contrasts with the opal's

fire.

Mahogany obsidian and snowflake obsidian

cabochons set in a sterling silver pendants.



Glass from Nature

Obsidian in Modern Surgery

Although using a rock as a cutting tool might sound like "stone age

equipment", obsidian continues to play an important role in modern

surgery.

Obsidian can be used to produce a cutting edge that is thinner and

sharper than the best surgical steel.

Today, thin blades of obsidian are placed in surgical scalpels used for

some of the most precise surgery.

In controlled studies, the performance of obsidian blades was equal to or

superior to the performance of surgical steel.



Glass from Nature

magma fulgurite

obsidian

tektites


Manmade (Synthetic) Glass

When, where, or how human beings discovered how to make glass is not known.

Very small dark-colored beads of glass have been dated back to

4000 B.C.E. These may well have been by-products of copper smelting or pottery

glazing.

By 2500 B.C.E. small pieces of true synthetic glass appeared in areas such as

Mesopotamia, but an actual glass industry did not appear until about

1500 B.C.E. in Egypt. By this time various small vases, cosmetic jars, and jewelry

items made of glass had begun to appear.

All the ancient glasses were based on silica (sand), modified with considerable

amounts of various metal oxides, mainly soda (Na2O) and lime (CaO). This is still

the most common glass being used today. It is known as soda lime glass.

However, the ancient glass was usually colored and opaque due to the presence

of various impurities, whereas most modern glass has the useful property of

transparency.

http://www.chemistryexplained.com/Ge-Hy/Glass.html#ixzz3G6so8r7V











GLASS

- 4000: Jewel in molted glass

-(Phoenicia)


GLASS

-1500: Vases and vessels

(Egypt)


GLASS

Egyptians

• First people torealize what couldbe done with glasswhen it is hot andplastic.

• Made vessels forcosmetics andperfumes by formingmolten glass arounda shaped core.

Romans

• By Roman timesglass being blownand molded, cut andengraved, andpainted.

Middle Ages

• Main achievementswere colored glasswindows.


INTRODUCTION

Amorphous solids

No crystal structure

No long-range order

Resemble“frozen liquids”

No melting point,

a glass transition

temperature

Crystalline materials have a definite structure, whereas amorphous ones do

not, and therefore only rather general statements can be made about a material

which, when hot, is ductile but when cold is brittle, and fractures if there is a

sudden change of temperature.

A glass is a solid that possesses no long-range atomic order

and which undergoes the glass transformation from solid to

supercooled liquid on heating.


INTRODUCTION

Glasses do not solidify at an

exact temperature (the

melting temperature, Tm,) as

is known for crystalline

materials, but instead in a

rather broad temperature

range.

Specifically, upon cooling, a

glass becomes increasingly

viscous (like honey).

Concomitantly, the specific

volume, Vs, of the glass (that

is, the volume per unit mass),

decreases continuously upon

cooling whereas for crystalline

solids a sudden drop of Vs at

the melting temperature is

observed.

Schematic representation of the temperature

dependence of the specific volume, Vs, for a glass

and a crystalline substance.

Understanding Materials Science, Rolf E. Hummel, Second Edition, Springer, 2004.


INTRODUCTION


The contraction of glasses

during cooling is a

combination of two effects.

The first one occurs, as in

most crystalline

substances, by reducing the

interatomic distances.

The second contraction

mechanism is due to a

rearrangement of atoms. As

the glass cools, the atomic

rearrangement becomes

slower until a temperature is

eventually reached at which

the viscosity is so high that any

further structural change is

nearly impossible.





INTRODUCTION


Below this temperature, Tg, the

volume of the glass contracts at a

fixed rate that is determined by the

present structure.

The intermediate range between

Tg and Tm is called the glass

transition or glass

transformation range.

Tg is then defined to be that

temperature at which, during

cooling, the Vs versus T curve

reaches an essentially constant

slope.

Above Tg, the material is defined to

be a supercooled liquid, or

eventually a liquid.

Below Tg, it is a solid (i.e., a glass).





INTRODUCTION


For practical reasons, the

“melting point” of glasses is

defined to be that temperature at

which the viscosity is 10 Pa.s.

The intersection of the two

straight portions of the Vs versus

T curve for glasses is called the

fictive temperature, Tf.

Because of the high viscosity of

most glasses and the

consequential low mobility of the

atoms, any crystallization (called

deglassing or devitrification) is

very sluggish.

Nevertheless, extremely slow

cooling rates or prolonged

heating at high temperatures

eventually causes devitrification.





INTRODUCTION

As a matter of fact, glass is a

material that has quite a low linear

expansion coefficient, which is

about 1/5 of that for crystalline

silica.

Incidentally, the expansion

coefficient of crystalline silica

changes abruptly at the

temperature at which the allotropic

transformation between -quartz to -

quartz takes place.

Commercially important is Pyrex, a

borosilicate glass whose thermal

expansion coefficient is only 1/3 of

that for common soda–lime glass.

Comparison of the linear expansion l/l of

glass, crystalline silica, and a typical metal

as a function of temperature



INTRODUCTION

Glass is a very

brittle material

Glass is a linear elastic and

isotropic material with no plastic

behavior at normal

temperatures, which can explain its

brittle fracture. It follows Hooke’s

law.


INTRODUCTION

Glasses brittle fracture !!!


INTRODUCTION

• Glass has amorphous structure

• Crystalline materials have some periodic crystal structure that results inlong term order

Glass is a state of matter. It is a solid produced by cooling molten material so that the internal

arrangement of atoms, or molecules, remains in a random or disordered state, similar to the

arrangement in a liquid. Such a solid is said to be amorphous or glassy. Ordinary solids, by

contrast, have regular crystalline structures.

http://www.chemistryexplained.com/Ge-Hy/Glass.html#ixzz3G6raJsdx





INTRODUCTION

Two-dimensional illustrations of the structures of (a) crystalline

silica, (b) liquid or glassy silica and (c) glassy or vitreous silica

containing some sodium oxide


General Characteristics of Glasses

Short range atomic order but

no long-range order

Structure is isotropic, so the properties are uniform in all

directions

Typically good electrical and

thermal insulators

Soften before melting, so they can be formed

easily by various forming

techniques


INTRODUCTION

General properties of glasses

High hardness / brittle

Low density compared to high strength

Low thermal expansion coefficient

Low heat / electrical conductivity

High melting point

Good chemical resistance / chemically inert

Wide range of optical transmission

Transparent

Translucent

Opaque


INTRODUCTION

Advantages

Inert

Does not corrode

Durable

Optical transparency

Many forming method

Many composition

Cheap

Disadvantages

Brittle

Breakable

Heavy


INTRODUCTION

Starting ceramicpowders

Batching andmixing of raw

materials

Batch melting Fining

Homogenisation

Final product

Glass is prepared by

cooling from a liquid

state without

crystallization


GLASS COMPOSITION

1. Glass forming oxides: usually the dominant constituent

SiO2, B2O3, P2O5, etc.

2. Fluxes: reduce melting temperatures

Na2O, PbO, K2O, Li2O, etc.

3. Property modifiers: added to tailor chemical durability,

expansion, viscosity, etc.

CaO, Al2O3, etc.

4. Colorants: oxides with 3d, 4f electron structures; minor additives

(<1 wt%)

5. Fining agents: minor additives (<1 wt%) to help promote bubble

removal

As-, Sb-oxides, KNO3, NaNO3, NaCl, fluorides, sulfates


ORDINARY GLASS FABRICATION

SAND SODA LIME OTHER GLASS

Percentage of Ingredients in Glass


INTRODUCTION

NETWORK

FORMERS

INTERMEDIATESMODIFIERS

RAW MATERIALS


INTRODUCTION

NETWORK

FORMERS

The most essential component of any glass batch is always the glassformer. Every

glass contains one or more components which serve as the primary source of the

structure. If most of the glassformer present in a specific sample is silica, for example,

that glass is called a silicate. If a significant amount of boric oxide (B2O3) is also

present, in addition to silica, the sample is termed a borosilicate glass. The primary

glassformers in commercial oxide glasses are SiO2, B2O3, and P2O5, which all readily

form single component glasses.

A large number of other compounds may act as glassformers under certain

circumstances, including GeO2, Bi2O3, As2O3, Sb2O3, TeO2, Al2O3, Ga2O3, and

V2O5. With the exception of GeO2 these oxides do not readily form glasses by

themselves unless very rapidly quenched or vapor deposited, but can serve as

glassformers when mixed with other oxides. The elements S, Se, and Te act as

glassformers in chalcogenide glasses. Although halide glasses can be made in

many systems, with many different compounds acting as glassformers, the two

most common halide glassformers are BeF, and ZrF,.

INTERMEDIATES

MODIFIERS

The degradation in properties is usually countered by addition of property

modifiers, which include the alkaline earth and transition metal oxides. While these

oxides partially counter the reduction in processing temperature obtained by addition

of fluxes, they also improve many of the properties of the resulting glasses. The

properties are thus modified, or adjusted, by careful control of the amount and

concentration of these oxides to obtain precisely the desired results.

RAW MATERIALS


INTRODUCTIONRAW MATERIALS

Division of the oxides into glass

formers, intermediates, and modifiers

Glass Formers Intermediates Modifiers

B2O3

SiO2

GeO2

P2O5

V2O3

TiO2

ZnO

PbO2

Al2O3

BeO

Y2O3

MgO

CaO

PbO

Na2O


INTRODUCTIONRAW MATERIALS

Colorants are used to control the color of the final glass. In most cases, colorants are oxides of

either the 3d transition metals or the 4f rare earths. Uranium oxides were once used as

colorants, but their radioactivity obviously reduces their desirability for most applications. Gold

and silver are also used to produce colors by formation of colloids in glasses. Colorants are

only used if control of the color of the glass is desired, and are usually present in small

quantities. Iron oxides, which are common impurities in the sands used to produce commercial

silicate glasses, act as unintentional colorants in many products. When colorants are used to

counteract the effect of other colorants to produce a slightly gray glass, they are referred to as

decolorants.

COLORANTS AND REFINERS

Fining agents are added to glass forming batches to promote the removal of bubbles from the

melt. Fining agents include the arsenic and antimony oxides, potassium and sodium

nitrates, NaCl, fluorides such as CaF,, NaF, and Na,AlF,, and a number of sulfates. These

materials are usually present in very small quantities (< 1 wt%), and are usually treated as if

they have only minor effects on the properties of the final glasses. Their presence, however, is

essential in many commercial glasses, which would be prohibitively expensive to produce

without the aid of fining agents in reducing the content of unwanted bubbles in the final

product.


INTRODUCTION

Logarithm of viscosity versus temperature for fused silica and three silica glasses. (From E. B.

Shand, Engineering Glass, Modern Materials,Vol. 6, Academic Press, New York, 1968, p. 262.)

Important

temperatures

in glasses

can be defined

by viscosity


INTRODUCTION



On the viscosity scale, several

specific points that are important

in the fabrication and processing

of glasses are labeled:

1. The melting point

corresponds to the

temperature at which the

viscosity is 10 Pa.s (100 P); the

glass is fluid enough to be

considered a liquid.

2. The working point

represents the temperature at

which the viscosity is 103 Pa.s

(104 P); the glass is easily

deformed at this viscosity.


INTRODUCTION



3. The softening point, the

temperature at which the viscosity is

4x106 Pa.s (4x107 P), is the maximum

temperature at which a glass piece may

be handled without causing significant

dimensional alterations.

4. The annealing point is the

temperature at which the viscosity is

1012 Pa.s (1013 P); at this

temperature, atomic diffusion is

sufficiently rapid that any residual

stresses may be removed within about

15 min.

5. The strain point corresponds to

the temperature at which the

viscosity becomes 3x1013 Pas (3x1014

P); for temperatures below the strain

point, fracture will occur before the

onset of plastic deformation. The glass

transition temperature will be above the

strain point.


INTRODUCTION



Most glass-forming

operations are carried out

within the working range-

between the working and

softening temperatures.

The temperature at which

each of these points

occurs depends on glass

composition.


INTRODUCTION

Three largest consumers

Glass packaging, domestic commodities and construction industry

Glass Consumers

Glass package, 43 %

Sheet glass, 30 %

Housekeeping, 12 %

Electrotechnical needs, 10 %

Plant and cunduits, 5 %


GLASS FAMILIES

Vitreous Silica

Soda-Lime Glass

Other Non-Silica-Based

Oxide Glasses

Other Silica-Based Oxide

Glasses

Amorphous Semiconductors

HalideGlasses

Glassy Metals

Borosilicate Glass

Chalcogenide and Chalcohalide

Glasses

Oxyhalide, Oxynitride and Oxycarbide

Glasses

Lead Silicate Glass

AluminosilicateGlass

Commercial glasses are

primarily based on

silica, but can include any

of the other common glass

formers as well.

The properties of these

glasses cover as wide a

range as those of other

major types of

materials, i.e., metals or

polymers.

Although soda-lime-silica

glasses provide the bulk of

commercial glasses by

weight, the economic

value of other, more

specialized commercial

glasses is comparable to

that of the generic soda-

lime-silica products.

Fundamentals of inorganic glasses, Arun K. Varshneya, ISBN 0-12-714970-8, 1994 by Academic Press, Inc.


Soda-Lime Glass

Soda-lime glass or soda-lime-silicate glass is perhaps the least expensive and the most

widely used of all the glasses made commercially.

Most of the beverage containers, glass windows, and incandescent and fluorescent

lamp envelopes are made from soda-lime glass.

It has good chemical durability, high electrical resistivity, and good spectral transmission

in the visible region.

Because of its relatively high coefficient of thermal expansion (~100x10-7/°C), it is prone

to thermal shock failure, and this prevents its use in a number of applications.

Most of the commercial glass by weight is based on the soda-lime-silica ternary

system, with minor additions of other oxides to adjust the properties for specific

applications.

Large-scale continuous melting of inexpensive batch materials such as soda ash

(Na2CO3), limestone (CaCO3), and sand at 1400-1500°C makes it possible to form the

products at high speeds inexpensively.



Soda-Lime Glass

Development of soda-lime-silica glass compositions represents a

compromise between the outstanding properties of pure silica, and the cost

of producing the massive quantities of glass required for

windows, containers, and electrical lighting.

Addition of soda to silica results in a large decrease in the temperature

required for melting. Unfortunately, large amounts of soda also lead to

unacceptably poor chemical durability of the glass.

Replacement of a portion of the soda by lime (CaO), which is not as

strong a flux as soda, partially offsets the reduction in chemical durability

and results in a glass with a reasonable melting temperature

(~1500C), while maintaining acceptable properties for most consumer

applications.


Borosilicate Glass

Many of these glasses, especially those based on the ternary sodium borosilicate

system, rely on the existence of phase separation for their desirable properties, while

many others are homogeneous.

As a result, the properties of these glasses also vary over a wide range. In

general, however, these glasses are chosen for their applications because they have

either better thermal shock resistance, better chemical durability, or higher electrical

resistivity than soda-lime-silica glasses.

The improvement in thermal shock resistance results from a lower thermal expansion

coefficient, with values for typical borosilicate glasses lying between that of vitreous

silica and those of soda-lime-silica glasses.

The improved chemical durability and higher electrical resistivity of these glasses can

result from either a carefully planned morphology for the phase separated

borosilicate glasses, or the absence of mobile monovalent ions for many of the

homogeneous borosilicate glasses.


Borosilicate Glass

http://www.jigchemuniversal.com/

borosilicate-glass-969453.html http://www.sundanceglass.com/pyrex-

glass-colored-tubing.htm

http://www.chinagreen-

tea.com/china-

pagoda_clear_borosilicate_glass_te

apot_with_infuser_filter_900ml-

1812997.html http://www.aliexpress.com/item-

img/borosilicate-glass-rod-low-

expansion-ratio-3-3/552667359.html

http://www.qorpak.com/vials-tubes/glass-

chromatography-vials/bulk-borosilicate-

glass-chromatography-vials

http://www.armedforces-int.com/gallery/glass-and-

ceramics-for-military-applications/schott-

supremax-rolled-borosilicate-glass_01.html


Vitreous Silica

Vitreous silica is the most refractory glass in commercial use. In addition to

its refractoriness, it has a high chemical resistance to corrosion (particularly

to acids), a very low electrical conductivity, a near-zero (~5.5 x 10-7/C)

coefficient of thermal expansion, and good UV transparency.

Because of the high cost of manufacture, the uses of vitreous silica are

mostly limited to astronomical mirrors, optical fibers, crucibles for melting

high-purity silicon, and high-efficacy lamp envelopes.

In one technique, the glass is obtained by melting high-purity quartz crystals

or beneficiated sand at temperatures in excess of 2000°C.

In a second technique, SiCl4 is sprayed into an oxy-hydrogen flame or

water-vapour-free oxygen plasma. Silica vapors deposit on a substrate and

are consolidated subsequently at ~ 1800°C.



Vitreous Silica

While vitreous silica has many properties

which make it desirable for application as

a flat, container, or lamp glass, the high

melting temperature required to produce

vitreous silica (> 2000 C) precludes its

application for the more common

consumer products, where cost is a

driving force behind the choice of glass

composition.

http://www.technicalglass.com/product_pages/fused_quartz_labware/labware/fused_quartz_labware.html

Vitreous silica is the generic term used to describe

all types of silica glass, with producers referring to

the material as either Fused Quartz or as Fused

Silica. Originally, those terms were used to

distinguish between transparent and opaque

grades of the material. Fused Quartz products were

those produced from quartz crystal into transparent

ware, and Fused Silica described products

manufactured from sand into opaque ware.

http://www.hebo-glass.com/public/pdf/datasheet_quartz.pdf


Vitreous Silica

http://www.technicalglass.com/product_pages/fused_quartz_labware/labware/fused_quartz_labware.html

Fused quartz tubing Fused quartz rod

Microscope Slides and Cover SlipsThe quartz heater soaks the shell, the light bulb shell


Lead Silicate Glass

This family of glasses contains PbO and SiO2 as the principal components

with small amounts of soda or potash.

These glasses are utilized for their high degree of brilliance (as stemware or

"crystal"), large working range (useful to make art objects and intricate

shapes without frequently reheating the glass), and high electrical resistivity

(e.g., for electrical feedthrough components).

PbO additions increase the fluidity of glass and its wettability to oxide

ceramics.

Hence, high lead borosilicate glasses (generally without any alkali additions)

are used extensively in microelectronics (e.g., for conductor, resistor, and

dielectric pastes).



Lead Silicate Glass


• Lime and soda replaced with PbO

• High refractive index- clarity sparkle

• Softer –cut and engrave

• Good electrical resistance - electronics

Lead Glass


Lead Silicate Glass



Halide Glasses

http://www.houzz.com/photos/6186239/50W-Metal-Halide-WP1-Glass-Lens-

Wallpack-120V-modern-outdoor-lighting

http://www.totaltackle.com.au/Clothing/Spotters-Pivot-Black-Halide-Glass

http://www.amazon.com/RAB-Lighting-WPTGHN70-PC-

Prismatic/dp/B00415MOSG

http://www.horticulturesource.com/faq.php


Chalcogenide and Chalcohalide Glasses

Chalcogenide glass is glass containing one or more

chalcogenide elements. Modern chalcogenide

compounds are Ge, Sb and Te used for CD/DVD

http://4textile.blogspot.com.tr/2012/10/226.html

-Low loss robust chalcogenide fibres for fibre

lasers, supercontinuum generation and delivery

-Fibre end caps and splicing technology for soft glass fibres

http://minerva-project.eu/technology/

Chalcogenide materials could enable faster data streaming. These materials

promise to bridge the gap between glasses such as fibre optics and semiconductors

such as silicon — potentially resulting in faster data streaming and more efficient

solar cells, among many other applications.

‗With chalcogenides we can form the material into fibres, thin

films, microspheres, nanophotonics — anything that you can make glass in to, but

they also have the electronic properties of semiconductors, so it‘s almost a

marriage of the two worlds,‘

http://www.theengineer.co.uk/more-sectors/electronics/news/chalcogenide-

materials-could-enable-faster-data-streaming/1009575.article#ixzz3KitazK11


























http://www.theengineer.co.uk/more-sectors/electronics/news/chalcogenide-materials-could-enable-faster-data-streaming/1009575.article
















OPTICAL FIBRES

Communications are increasingly based on electro-optic

systems in which telephones, television and computers are

linked by fibre optic cables which carry information by light.

Making glass optical fibres is a highly specialised aspect of

glass manufacture. Optical fibres consist of two distinct

glasses, core of highly refracting glass surrounded by a sheath

of glass with lower refractive index between the two glasses, it

is guided by total reflection at the core-sheath interface to the

other end of the fibre.

In theory, a wide range of glasses can be used as long as the

difference in refractive index is appropriate but the higher the

refractive index of the core relative to that of the sheath

glass, the greater the carrying capacity of the fibre. A typical

system available commercially comprises a germanium doped

silica core and a borosilicate cladding.


FLAT GLAS

Annealed glass (ordinary glass) is the end product of the float glass process.

It is carefully cooled through the range of temperatures where the glass solidifies

so that no residual stresses develop.

Float glass is made using a bath of molten tin, where molten glass is floated along

the surface. The perfectly flat surface of the tin is transferred to the glass.

There are two main flat glass manufacturing methods for producing the

basic glass from which all processed glass products are made:

the drawn glass process and

the float glass process.

Since the introduction of the float process in 1959 by Pilkington it has

gradually replaced other processing techniques.


FLAT GLASDRAWING

A solid metal plate is dipped into a bath of molten glass and then slowly withdrawn from the

melt. This process would present no problems if we were interested in producing a glass rod.

Producing a planar sheet is problematic because the sheet would neck down to a narrow

ribbon. This difficulty is overcome by cooling the sheet as it is drawn. These coolers solidify

the glass and produce a sheet of fixed width.

Drawing from molten glass: (a) a circular rod; (b) problem of pulling a planar sheet; (c) use of a débiteuse

and cooling to allow the formation of a sheet of constant width.


FLOAT GLAS

Float glass can be produced in very large sizes with an extremely high

flatness. Within the production technique the surface finish is improved

and glass sections with visible internal defects are removed.

The production technique requires that residual stresses are introduced.

This creates compressive stresses in surface regions which is an

advantage in practical use.

Float glass has opened the possibility to use glass in new and

demanding applications.

A new series of glass products known as structural glass has been

introduced. This type of glass dominates completely today.


FLOAT GLAS

Based on float glass

various products have

been introduced in the

market.

There is a continuous

development regarding

glass products to meet

new needs on the market.

Some of the mentioned

products have been on

the market for longer

period of time but not

being used in structurally

demanding applications.

• Laminated glass

• Heat strengthened

glass

• Toughened glass

• Insulating glass

• Coated glass


FLOAT GLAS

http://educationcenter.ppg.com/glasstopics/learn_about_glass.aspx


FLOAT GLAS

More than 90% of the world‘s flat glass is now made by the float process, where

molten glass, at approximately 1000C, is poured continuously from a furnace on to

a large shallow bath of molten tin.

The liquid glass floats on the tin, spreads out and forms a level surface. Since the

melting point of the tin is much less than that for glass, the glass solidifies as it

slowly cools on top of the molten tin.

Thickness is controlled by the speed at which the solidifying glass ribbon is drawn off

the bath. Once the glass solidifies, it is fed into an annealing lehr where it is slowly

cooled in a process where the residual stresses are controlled.

This process results in the production of an annealed float glass with residual

compressive stresses around 8 MPa in the surface. After annealing the glass

emerges as a ―fire‖ polished product with virtually parallel surfaces.

This method, in which the glass pane is formed by floating the melt on a bath of

liquid tin, revolutionized the manufacture of high quality glass and large sizes. Float

glass is available in thicknesses ranging from 2 mm up to 25 mm.


ANNEALED GLAS

Advantages

– Cost

Limitations

– Breaks in sharp pieces

– Not as strong as tempered glass

– Size limitations


ANNEALED GLAS

Images of annealed glass failure (left), heat-strengthened glass failure (centre), and

fully tempered glass failure (right)


TEMPERED GLASS

Crazed fracture pattern on left intempered glass on an elevatorwall. Fracture origin is shownabove.

Tempered glass also know as

toughened glass is made by quickly

cooling the annealed glass when it

is heated near compression is

formed over the glass surface while

tensile formed inside the glass

plate.

Tempered glass is made by heating

annealed glass to approximately

700C then cooling the outer surfaces

rapidly. This process makes the glass

very strong and shock resistant thus

more durable.

Shatter pattern of tempered glass

http://www.ajjglass.com/products/m17_sectionid/2/m17_imageid/2



http://www.nmsi.ac.uk/piclib/subjectdetail.asp?sub=TRA


TEMPERED GLASS

Primary processing is a treatment of the basic glass after its manufacture.

Since surface flaws only lead to fracture when a tensile stress opens

them, any method of putting the glass surface into permanent compression

is advantageous.

An applied tensile stress would have to overcome this built-in compression

before it begins to open up a flaw and hence the glass would be able to

resist higher loads. Toughened glass and heat strengthened glass use this

principle.

The stress distribution in toughened glass enables it to withstand tensile

stresses of much higher levels than ordinary annealed glass. Annealed

glass has a residual surface compression stress of around 8-10

MPa, because of production reasons. Any external stress level has to

exceed this threshold stress to cause a failure which will be time and size

dependent. The thickness of the glass may influence the actual residual

compressive stress.


TEMPERED GLASS

Toughened glass, or tempered glass as it is also known as, is first cut to its

final size and it is edge treated and drilled if required. Afterwards the glass

pane is heated to approximately 650C, at which point it begins to soften. Its

outer surfaces are then cooled rapidly, creating in them a high compression

stress, where the rate of the cooling will determine the amount of built-in

compression stress and hence the final strength of that glass.

Its bending strength is usually increased by a factor of 4 or 5 to that of

annealed glass and hence a new and raised threshold stress has been

achieved. The maximum tensile stress in the middle is half of the surface

compressive stress.

When broken, it fractures into small harmless dice and it is known as safety

glazing material. Heat strengthened glass is similarly produced, but with

strengths approximately half that of toughened glass and without the safety

glazing characteristic. Toughened glass cannot be subsequently surface or

edge worked or cut because this would initiate a failure.


TEMPERED GLASS

• Resists fractures because surface is compressed

• Crumbles when cracked because inside is tense

Advantages

– 4 times the stronger than annealed

– Breaks into small, harmless pieces.

– Qualifies as Safety Glazing

Limitations

– Must be cut to size before tempering

– Optical distortion (roller wave, strain pattern)


TEMPERED GLASS

Tempering glass

– Cool outside of glass quickly, outside stiffens while inside is still hot

– Shrinking inside compresses outside, compressed outside stretches inside


TEMPERED GLASS

Toughened is derived from heating typical flat glass, including patterned, to a

plastic like state of around 600-700 C in a specially designed furnace or oven.

After the desired state is achieved it is rapidly cooled with a burst of air to both

surfaces.

Different types of glass have different recipes to allow it to be toughened.


TEMPERED GLASSUsage Range of Tempered Glass:

Construction curtain wall

Glass doors & windows

Support bar of staircases & escalators

Different types of the glass artdecorations

Location of near the intense heat and the

impact severed by the hotcold.

Laminated glass is widely used for

Blaustrading

Showerscreens

Display Cases

Revolving Doors

Shopfronts

Lifts and Foyers

Partitions

Furniture

Pool surrounds, etc.


LAMINATED GLASS

Laminated glass is a kind of safety glass which is combined

from one or more layers of PVB through heating and pressing

processes by autoclave.

2 sheets of glass are bonded with a thin film ofplastic such as polyvinyl butyrate underpressure at a temperature of about 100°C

The sandwiched plastic bonds well to the 2glass surfaces and helps absorb energy inimpacts, stops glass shattering anddisintegrating if stressed to failure so that itoften remains secure and weatherproof.

This provides a high degree of resistance toinjury from flying glass in case of impact.


LAMINATED GLASS

SafetyLaminated glass absorbs energy of the impact

• Ordinary window glass is brittle and breaks into long sharp pieces

Will not shatter

Holds up against

• hurricanes

• cyclones

• earthquakes


LAMINATED GLASS

Laminated glassis widely used for

bullet proof

burglar-proof

showcase

counter

aquarium

skylight

long corridor

sidelite, etc.

http://www.livingetc.com

Glass staircase

www.aarticommercial.com

Laminated Windscreen Glass

If the laminated glass is made from “ordinary” float glass, it is still

workable (cutting and drilling is possible) and the PVB helps the

fractured glass to stay put inside the construction.

http://www.livingetc.com/



http://www.aarticommercial.com/




LAMINATED GLASS

http://qddarley.en.made-in-china.com

Sound Control Application

Another important element of laminated

glass is acoustical performance in

commercial applications.

Laminated glass reduces noise

transmission due to sound damping

characteristics of the pvb interlayer.

While glass is inherently a poor acoustical

performer, higher performance levels can

be achieved by using laminated glass

alone or combined with additional glass

plies to form a sealed insulating glass

unit.

http://image.made-in-china.com/2f0j00weqaClGgCopv/Laminated-Glass-DLGL001-.jpg


LAMINATED GLASS

UV Protection

With time, sunlight can cause considerable damage to buildingsfurnishings, carpets, artwork, photographs, plants and other valuables. These itemsneed special protection from the damaging effects of the sun's ultraviolet (UV) rays.

Laminated glass made with resin can be effective in screening out the harmful UVrays, controlling glare and decreasing solar energy transmittance. Glazing solarcontrol is accomplished in laminated glass by the interlayer ability to reflect and/orabsorb and re-radiate much of the solar UV radiation.

Laminated glass made with resin screens out more than 99% of damaging UV light.

While protecting buildings from harmful and damaging solar UV radiation, laminatedglass made with resin has no adverse affect on the health of indoor plants. Infact, laminated glass is commonly used in greenhouses and atriums to help protectflower color and reproductive development from the damaging effects of UVradiation. Photoreceptors in plants are still able to absorb sunlight the resininterlayer allows to be transmitted.


LAMINATED GLASS

The City of Arts and Sciences is

an entertainment and educational

complex that is an amazing work

of craftsmanship and design.

Architect Santiago Calatrava

primarily designed this gorgeous

project.

Laminate glass is widely used

not just in the grand windows

and ceilings but also found in

the planetarium’s floor.

The glass floors are four ply

laminated glass that consist of acid

etched, anti-slip, 6 mm tempered

glass on the top with three 10 mm

layers of glass. This keeps right in

line with the modern design of the

building.

www.homedesignfind.com

http://www.homedesignfind.com/




LAMINATED GLASS

BULLETPROOF GLASS

Bulletproof glass is made of laminated glassesand films which have special shielding capabilitytowards bullets.

The different levels of bullet proof glasses areable to shield the bullets from penetration andprevent the broken parts from injuring people.They are widely applied in

bank,

counters of jewelry and gold shops,

cash trucks and

other regions requiring special safetyprevention.

www.bmw-security-vehicles.com

22-millimetre glass/plastic laminate with a

polycarbonate coating on the inside to prevent flying

splinters. The 22-millimetre glass protects against:

• Blunt instruments

.44 Magnum with full-jacket flat-nose bullets

.357 Magnum with coned bullets

9-millimetre Luger with round-nose bullets

http://www.bmw-security-vehicles.com/








GLASS COMPOSITION

Choice of Glass Compositions

Choosing a glass composition is a more complicated exercise

than may at first appear. One must first establish the properties

important to the final user, next consider those properties

important to the glass maker, then achieve a balance between

these and lastly determine what choice of batch materials will

produce either the best quality or, perhaps, the cheapest glass

meeting the quality requirements.


GLASS COMPOSITION

Properties Important to the User

Which properties are important depends very much on the application. From a designer's point

of view, strength would nearly always be the first to be considered. However, because the

practical strength of glasses is determined more by surface flaws than anything else strength

can generally be taken to be weakly dependent on composition and omitted from the

specification. So far as strength is concerned commercial glasses can usually be considered as

being either pure silica or "the rest" and only two sets of strength data need be considered.

The next most important property, which may not always come immediately to mind, often is

resistance to corrosion. Good glasses are generally stable, already being oxides, but can be

leached by water or other chemicals, something which is only rarely desirable. Chemical

durability is strongly dependent on composition, especially alkali and alumina contents, and

thus should always be included. Next we come to the properties essential for the specific

application. These may include refractive index, electrical resistivity, thermal

expansion, transparency to or absorption of radiation, softening temperature, and so on. These

properties fall into two classes, those for which a specific value is needed, like refractive index

in an optical glass or thermal expansion for a sealing glass, and those that need to be better

than some particular limit, like chemical durability or thermal expansion when thermal shock

resistance is important.


GLASS COMPOSITION

Properties Important to the Glass

Maker

Apart from the criteria set by the final

user, several properties are very important

to the glass manufacturer. The viscosity-

temperature characteristic is crucially

important to efficient forming.

Also the liquidus temperature must be

below the temperature at which the melt

must be held to begin forming operations.

The actual devitrification characteristics

may be less important but it can be useful

to know whether crystal growth may be

rapid if it does occur. The glass

manufacturer also wants to have a glass

as easy as possible to melt, refine, and

homogenize but these factors are not

capable of being specified in terms of

standard properties.


GLASS COMPOSITION

Properties Important to the Glass Maker

Some glasses contain significant proportions of elements which can exist in more than

one valence state and these may need their oxidation states to be controlled. The most

familiar example is the decolorizing of glass in which iron is oxidized, as far as

possible, to the ferric state which gives a paler tint than the same concentration of iron

reduced to ferrous.

On the other hand, to make a heat absorbing glass one would wish to reduce the iron to

ferrous which has a broad absorption peak in the near infrared.

Control of oxidation is generally achieved largely by the selection of oxidizing or

reducing materials added to the batch but partly by control of furnace atmosphere.

In small scale laboratory melting oxidation can be controlled by bringing the melt to

equilibrium with a specific atmosphere but this is not necessary and would be difficult to

achieve in large scale manufacture.


GLASS COMPOSITION

The batch materials can considerably influence ease of melting, degree of

segregation during melting, volatilization losses, refining, and homogeneity

of the glass.

Both control of oxidation and overall melting performance can also be

affected by minor constituents, that is to say cations or anions added at

levels usually below 1%, which control oxidation through mutual interactions

or have beneficial effects on melting, refining, and homogeneity.

The interactions between iron and arsenic, antimony or cerium can play an

important part in decolorizing. Sulfate is the most commonly used refining

agent: arsenic is often efficient but now rarely used because of legal

controls on its use and halides can be effective. The glass maker will usually

expect to be allowed to modify slightly the user's composition specification

to optimize these factors.


GLASS COMPOSITION

Typical composition (wt %) ofsome of the common commercial glasses


GLASS-CERAMIC

By definition, glass-ceramics are

materials which are melted and formed

using standard glass manufacturing

techniques, and then heat treated to

produce a highly crystalline material

with properties which are very different

from those of the original glass.

The most common glass-ceramics are

based on either the lithium, sodium, or

magnesium aluminosilicate systems.

Although the best known glass-

ceramics are used for

cookware, applications of glass-

ceramics include other consumer

products such as electric stove tops

and construction materials, and

specialty applications such as

telescope mirrors, electronic

substrates, and missile radomes.

Processing cycle for a glass-ceramic


GLASS-CERAMIC

Production of glass-ceramics usually involves a two-step process.

A small amount of a ―nucleating agent‖ is added to the batch. When heat treated at

the proper temperature, this agent will either form very small crystals, i.e., nuclei, or

will induce phase separation.

Once this phase has formed, the material is heated to a higher temperature where a

second, major phase will grow to yield the final product.

In general, a very fine grained microstructure is desired, since such microstructures

produce very strong materials.

Many applications of glass-ceramics are based on their superior resistance to failure

due to thermal shock. Since thermal shock resistance is primarily determined by the

thermal expansion coefficient of a material, the crystalline phase in these materials

should have a low thermal expansion coefficient. A a low thermal expansion

coefficient is obtained by a combination of a low expansion crystalline phase and a

low expansion residual glass.


GLASS-CERAMIC

Glass-Ceramics

• ―Glass-ceramic‖ refers to materials which are fabricated from glass melts by a

process of controlled crystalisation.

• Glass-ceramis is a partially crystalline material which is fabricated by an

incomplete crystallisation (―Ceraming‖) of suitable glasses.

• Brands: Ceran, Zerodur, Robax, Neoceram, Macor


GLASS-CERAMIC


GLASS-CERAMIC


GLASS-CERAMIC

LAS

(PYROCERAM

ZERODUR

VISION)

Crystalline phase in these materials is a lithium aluminosilicate, which is either a -quartz solid solution phase

for Vision, or spodumene for Corningware. A mixture of TiO2, and ZrO2, in the batch results in a very efficient

nucleation process. Heat treatment below 900C yields very small (<100 nm) particles of the -quartz solid

solution phase, which has a refractive index close to the residual glass (very high silica concentration). The

resulting material is transparent even though it is highly crystalline. Heat treating the same material at a

temperature > 1000C results in the transformation of the -quartz solid solution. phase into -

spodumene, accompanied by grain growth to produce crystals in the 1 to 2 m range.

Machinable glass-ceramics are derived from the K2O–MgO–Al2O3–SiO2 system containing some

fluorine. In Macor the crystalline phase is potassium fluorophlogopite [KMg3(AlSi3O10F2)].

Phlogopite is a mica mineral and the plate-like mica crystals are randomly oriented in the glass

phase. Macor can be machined to precise tolerances (±0.01 mm) and into intricate shapes using

conventional steel tools: they can be drilled, cut, or turned on a lathe.

MACOR

APATITE

Calcium phosphate, Ca3(PO4)2, glasses can be made into glass-ceramics to form a material resembling the mineral

part of bone. Since bone is porous, the first step is to produce a foam glass. This is achieved by decomposing

carbonate in the glass melt. The foam glass simultaneously undergoes a controlled crystallization, transforming it into

a porous glass-ceramic. The dimensions of the interconnections between the pores must be sufficient to allow the

ingrowth of living bone tissue, which ensures a permanent joint with the surface of the prosthesis.

Another commercial fluoromica glassceramic called Dicor® has been developed for dental restorations.

Dicor has better chemical durability and translucency than Macor. It is based on the tetrasilicic

mica, KMg2.5Si4O10F2, which forms fine-grained (∼1μm) anisotropic flakes. Dicor dental restorations are

very similar to natural teeth both in hardness and appearance. They are easy to cast using conventional

dental laboratory methods and offer significant advantages over traditional metal–ceramic systems.

DICOR


GLASS-CERAMIC

Glass-ceramic teeth

From left to right parent glass, glass ceramic

with 97% crystallinity and glass-ceramic with

50% crystallinity. Grain size is about 20

micrometers.

Edgar Dutra Zanotto, A bright future for glass-ceramics, American Ceramic Society Bulletin, Vol. 89, No. 8

http://www.schott.com/advanced_optics/english/products/optical-materials/zerodur-extremely-low-expansion-glass-ceramic/zerodur/index.html?so=turkey&lang=turkish

http://www.ceramic-substrates.co.uk/machinable-ceramics/macor

Zerodur mirror substrates for

large segmented and monolithic

astronomical telescopes

Macor substrates

The fracture surface of Macor



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CERAMIC MATERIALS I - Mühendislik Fakültesimetalurji.mu.edu.tr/Icerik/metalurji.mu.edu.tr/... · Probably as early as 75,000 B.C.E., long before human beings had learned how to