1

CERAMICS

Persian Guard. Iran, from Persepolis, Audience Hall (Apadana) of the Palace. Achaemenid Period, reign of Xerxes, 486–480 B.C. Limestone, 10 1/2 x 9 x 1 7/8 in. (26.6 x 22.8 x 4.7 cm).

Presented By:-

SANJOG DASHREG. NO.-13010614MADHUSUDAN MISHRAREG. NO.-13010615BISWAJEET ROUTREG. NO.-13010616

2

An inorganic compound consisting of a metal (or semi‑metal) and one or more nonmetals for which the interatomic bonds are ionic or predominantly ionic with some covalent character.

The term ceramics comes from the Greek word ‘keramikos’ ,which means “Burnt stuff”, indicating that desirable properties of these materials are normally achieved through high temperature heat treatment process called Firing.

They may be amorphous, partly crystalline or fully crystalline.

They are either formed from a molten mass that solidifies on cooling and matured by the action of heat, or chemically synthesized at low temperature using for example hydrothermal or sol-gel synthesis.

A wide-ranging group of materials whose ingredients are clays, sand and feldspar.

Ceramics Defined

3

EXAMPLES

Important examples: Silica - silicon dioxide (SiO2), the main ingredient in most

glass products Alumina - aluminum oxide (Al2O3), used in various

applications from abrasives to artificial bones More complex compounds such as hydrous aluminum

silicate (Al2Si2O5(OH)4), the main ingredient in most clay products

4

PROPERTIES OF CERAMICS Extreme hardness: High wear resistance Extreme hardness can reduce wear caused by friction.

Corrosion Resistance Heat resistance

Low electrical conductivity Low thermal conductivity

Low thermal expansionPoor thermal

shock resistance Brittle, virtually no ductility - can cause problems in both

processing and performance of ceramic products , Low fracture toughness.

Some ceramics are translucent, window glass (based on silica) being the clearest example

Low density

5

COMPARISON: METALS VS CERAMICS

CeramicsMetals

6

Taxonomy of Ceramics

Glasses Clay products

Refractories Abrasives Cements Advanced ceramics

-optical -composite reinforce -containers/ household

-whitewares -bricks

-bricks for high T (furnaces)

-sandpaper -cutting -polishing

-composites -structural

engine -rotors -valves -bearings-sensors

Adapted from Fig. 13.1 and discussion in Section 13.2-6, Callister 7e.

Types of Ceramics

7

Oxide Ceramics Non-Oxide Ceramics Composites

Oxidation Resistant Low Oxidation resistance Variable Oxidation resistance

Electricaly Insulating Extreme hardness Toughness

Low thermal conductivity High thermal conductivity

Variable thermal and electrical conductivity

Slightly complex manufacturing and high cost

Difficult energy dependent manufacturing and high cost

Complex manufacturing process and high cost

Oxide and Non-Oxide Ceramics

Zirconia(ZrO3), Alumina(Al2O3)

Carbides,Borides,Nitrides,

Silicides

Particulate reinforced combinations of oxide and non-oxide(Silicon Aluminium Oxynitride {Al6N6O2Si} )

Amorphous Ceramics Crystalline Ceramics Atoms exhibit only short range

Order Atoms are arranged in a regular

repeating pattern in three dimensions i.e. long range order

No distinct melting temperature(Tm) for these materials as there with crystalline material

Crystalline materials are “Engineering” ceramics:

High melting point Strong Hard Brittle Good Corrosion Resistance

Na2O,CaO,K2O Silicon Nitride(Si3N4),Silicon Carbide(SiC),Zirconia(ZrO2),Alumina

(Al2O3)

Amorphous and Crystalline Ceramics

9

AMORPHOUS CERAMICS (GLASSES)

Main ingredient is Silica (SiO2) If cooled very slowly will form crystalline structure. If cooled more quickly will form amorphous structure

consisting of disordered and linked chains of Silicon and Oxygen atoms.

This accounts for its transparency as it is the crystal boundaries that scatter the light, causing reflection.

Glass can be tempered to increase its toughness and resistance to cracking.

10

GLASS TYPES

Three common types of glass: Soda-lime glass - 95% of all glass, windows

containers etc. Lead glass - contains lead oxide to improve

refractive index Borosilicate - contains Boron oxide, known

as Pyrex.Based On Its Application Flat glass (windows) Container glass (bottles) Pressed and blown glass (dinnerware) Glass fibres (home insulation) Advanced/specialty glass (optical fibres)

Glass Containers

11

PRESSED GLASS PROCESSING

SoftenedGob

12

Based on mineral silicates, silica, and mineral oxides found in nature

Primary products are fired clay (pottery, tableware, brick, and tile), cement, and natural abrasives such as alumina

Products and the processes to make them date back thousands of years

Glass is also a silicate ceramic material and is sometimes included among traditional ceramics

Traditional Ceramics

13

Advanced ceramic materials have been developed over the past half century

Applied as thermal barrier coatings to protect metal structures, wearing surfaces, or as integral components by themselves.

Engine applications are very common for this class of material which includes silicon nitride (Si3N4), silicon carbide (SiC), Zirconia (ZrO2) and Alumina (Al2O3)

Heat resistance and other desirable properties have lead to the development of methods to toughen the material by reinforcement with fibers and whiskers opening up more applications for ceramics

Advanced Ceramics

14

Traditional Ceramics

White wares

Abrasives

Refractories

Cement

Bricks and Tile

15

Mineral silicates, such as clays of various compositions, and silica, such as quartz, are among the most abundant substances in nature and constitute the principal raw materials for traditional ceramics

Another important raw material for traditional ceramics is alumina

These solid crystalline compounds have been formed and mixed in the earth’s crust over billions of years by complex geological processes

Raw Materials For Traditional Ceramics

Alumina ceramic components

16

CERAMIC PRODUCTS Clay construction products - bricks, clay pipe, and

building tile Refractory ceramics ‑ ceramics capable of high

temperature applications such as furnace walls, crucibles, and molds

Cement used in concrete - used for construction and roads

Whiteware products - pottery, stoneware, fine china, porcelain, and other tableware, based on mixtures of clay and other minerals

Glass ‑ bottles, glasses, lenses, window pane, and light bulbs

Glass fibers - thermal insulating wool, reinforced plastics (fiberglass), and fiber optics communications lines

Abrasives - aluminum oxide and silicon carbide Cutting tool materials - tungsten carbide, aluminum

oxide, and cubic boron nitride

17

tensile force

AoAddie

die

• Die blanks: -- Need wear resistant properties!

• Die surface: -- 4 mm polycrystalline diamond particles that are sintered onto a cemented tungsten carbide substrate. -- polycrystalline diamond helps control fracture and gives uniform hardness in all directions.

Courtesy Martin Deakins, GE Super abrasives, Worthington, OH. Used with permission.

Adapted from Fig. 11.8 (d), Callister 7e.

APPLICATION: DIE BLANKS

18

• Example: Oxygen sensor ZrO2

• Principle: Make diffusion of ions fast for rapid response.

APPLICATION: SENSORS

A Ca2+ impurity removes a Zr4+ and a

O2- ion.

Ca2+

• Approach: Add Ca impurity to ZrO2: -- increases O2- vacancies

-- increases O2- diffusion rate

reference gas at fixed oxygen contentO

2- diffusion

gas with an unknown, higher oxygen content

-+voltage difference produced!

sensor

• Operation: -- voltage difference produced when O2- ions diffuse from the external surface of the sensor to the reference gas.

19

20

• Tools: -- for grinding glass, tungsten, carbide, ceramics -- for cutting Si wafers -- for oil drilling

bladesoil drill bits• Solutions:

coated singlecrystal diamonds

polycrystallinediamonds in a resinmatrix.

Photos courtesy Martin Deakins,GE Superabrasives, Worthington,OH. Used with permission.

APPLICATION: CUTTING TOOLS

-- manufactured single crystal or polycrystalline diamonds in a metal or resin matrix.

-- optional coatings (e.g., Ti to help diamonds bond to a Co matrix via alloying) -- polycrystalline diamonds resharpen by microfracturing along crystalline planes.

21

Ceramic armor systems are used to protect military personnel and equipment.

Advantage: low density of the material can lead to weight-efficient armor systems.

Typical ceramic materials used in armor systems include alumina, boron carbide, silicon carbide, and titanium diboride.

The ceramic material is discontinuous and is sandwiched between a more ductile outer and inner skin.

Alumina ceramic/Kevlar composite system in sheets about 20mm thick are used to protect key areas of Hercules aircraft (cockpit crew/instruments and loadmaster station).

Applications: Advanced Ceramics

Ceramic Armour

22

Projectile

Outer hard skin

Ceramic-Discontinuous

Inner ductile skin

Personnel and Equipment

Ceramic Armor System

Ceramic - Composite Armor

23

APPLICATIONS: ADVANCED CERAMICS

Electronic Packaging Chosen to securely hold microelectronics &

provide heat transfer Must match the thermal expansion coefficient of

the microelectronic chip & the electronic packaging material. Additional requirements include:

good heat transfer coefficient poor electrical conductivity

Materials currently used include: Boron nitride (BN) Silicon Carbide (SiC) Aluminum nitride (AlN)

thermal conductivity 10x that for Alumina good expansion match with Si

24

APPLICATIONS: ADVANCED CERAMICS

Heat Engines Advantages:

Run at higher temperature

Excellent wear & corrosion resistance

Low frictional losses Ability to operate

without a cooling system

Low density

• Disadvantages: – Brittle– Too easy to have voids-

weaken the engine– Difficult to machine

• Possible parts – engine block, piston coatings, jet enginesEx: Si3N4, SiC, & ZrO2

Gears (Alumina)

Rotor (Alumina)

25

TURBOCHARGER

Ceramic Rotor

26

Ceramic Brake Discs

27

THANK YOU