Ceramic

Material Science

© Su-Jin Kim, GNU

Ceramics (세라믹)

Su-Jin Kim

Gyeongsang National University

Ceramic

Material Science

© Su-Jin Kim, GNU

OCW

Ionic crystal structures

https://youtu.be/A3cPHn_OgVQ?list=PL8EAOgbez9XIWGbmcihctMO4bXSB4V8hm

Ceramic Crystal Structures

https://youtu.be/JILO8IppZis

Ceramicshigh temperature, hardness, chemical stable > brittle

https://youtu.be/9DopxIV4Css

Space Shuttle Heat Protection

https://youtu.be/oZg3x7yy80o

Ceramic

Material Science

© Su-Jin Kim, GNU

OCW

Cement and Concrete

https://youtu.be/heDKi42CD1A

Metals & Ceramics

metals, alloys, ceramics, clay, cement, glass-ceramic

https://youtu.be/NOK1nMiiTWU

Ceramic

Material Science

© Su-Jin Kim, GNU

KOCW

세라믹결정구조

http://www.kocw.net/home/cview.do?lid=0f4393f1fb61cdd3

세라믹, 유리, 탄소, 강도시험

http://www.kocw.net/home/cview.do?lid=2f87428d88f9a817

한국세라믹기술원https://youtu.be/SKNCFCPfa2c

Ceramic

Material Science

© Su-Jin Kim, GNU

Contents

Ceramics

Cristal structures: Salt, Silicate, Alumina, Zirconia, Carbon, CBN

Properties

Traditional and Advanced ceramic

Ceramic

Material Science

© Su-Jin Kim, GNU

Ceramic

Porcelain Silicon wafer

Traditional C.: china, porcelain, tile, brick

Advanced C.: Optoelectronic, Energy, Bio-Nano

Ceramic

Material Science

© Su-Jin Kim, GNU

Crystal structures : Rock salt (소금)

Ionic bonding (이온결합)

Metallic cation(양이온)+ < Nonmetallic anion(음이온)-

ex)NaCl Al2O3 , SiO2

Sodium chloride (Salt)

+ -

Na+ + Cl-

Ceramic

Material Science

© Su-Jin Kim, GNU

Crystal structures : Silicate (규산염)

Most common elements on earth

Covalent bonding (공유결합)

Silicate cristal : Quartz(석영)

SiO2 Quartz

O

SiSi

-

-

--

O

-

-

-

-

-

-

SiO44-

Ceramic

Material Science

© Su-Jin Kim, GNU

Crystal structures : Silicate (규산염)

Noncrystalline silicate + CaO Na2O : Glasses (유리)

Layard silicate, (Si2O5)2- + (Al2OH4)2+ layer: Kaolinite Clay (점토)

ClayGlass

Ceramic

Material Science

© Su-Jin Kim, GNU

Alumina, Al2O3 (알루미나)

Bauxite(Al2O3 H2O) + Fe2O3 +SiO2 : Aluminum mineral

Alumina (Al2O3) : White powder, SiO2 + Al2O3 ceramic

Aluminum (Al) electrolysis

Bauxite Alumina Aluminum

Ceramic

Material Science

© Su-Jin Kim, GNU

Zirconia, ZrO2 (지르코늄다이옥사이드)

• ZrO2 + 5% CaO : Stabilized zirconia

• Melting point (2700C) : Refractories for iron casting

• Ion conductivity : Oxygen sensor, fuel cell membrane, electro ceramic

• Chemically unreactive: Zirconia implant (machining sintering polishing)

Refractory Inplant

Ceramic

Material Science

© Su-Jin Kim, GNU

Carbon, C : Graphite(흑연)

• Graphite is a layered structure of carbon C.

• Weak van der Waal’s forces between layers

• Planes slide easily over one another – low friction good solid lubricant

Graphite Layer structure

Ceramic

Material Science

© Su-Jin Kim, GNU

Carbon, C : Diamond SCD (Single Cristal Diamond) 단결정 is covalent bonded single crystal of Carbon C

It is hardest in the world but decompose in air at 973 K.

PCD (Poly Crystal Diamond) 다결정 is used to cut aluminum alloys, ceramics, and stone. But it is soluble in iron Fe alloy to give carbides.

Cristal structure PCD sawSCD

Ceramic

Material Science

© Su-Jin Kim, GNU

CBN, Cubic boron nitride, (질화붕소)

2nd Hardest material, Insolubility in iron alloys at high temperatures

Grinding abrasive, Cutting tool

Cubic BN Grinding wheel Turning insert

Ceramic

Material Science

© Su-Jin Kim, GNU

Properties of ceramics

Chemical stability

Electrical & thermal insulator

High melting temperature

High hardness

Brittle fracture

Tensile strength << Compression

Ceramic

Material Science

© Su-Jin Kim, GNU

Brittle fracture (취성파괴)

Flexural strength (굴곡강도): Transvers bending test

Room T behavior is usually elastic, with brittle failure

250

50

Str

ess (

Mp

a)

0.0008Strain

Glass

Aluminum oxide

Bending test

Brittle frature

Ceramic

Material Science

© Su-Jin Kim, GNU

Porosity (기공) Strength (강도)

Porosity decreases modulus of Elasticity and fracture Strengths.

Stress concentration decrease Tensile strength << Compression

Volume fraction porosity

Mo

du

lus o

f e

lasticity (

GP

a)

Fle

xu

ral str

en

gth

(M

pa

)

0 0.1 0.2 0.3 0.4 0.5 0.6

200

100

Ceramic

Material Science

© Su-Jin Kim, GNU

Traditional Ceramic

Structural: bricks, floor and roof tiles

Refractories: iron making crucible

Whitewares: tableware, pottery, bathroom

Special: implants, disk brake, bearing

Ceramic

Material Science

© Su-Jin Kim, GNU

Porcelain (도자기)

Fine particle(Quartz, Clay, Feldspar) + wet state plasticity form dry state Sintering(소결) by fire Porcelain

Ceramic

Material Science

© Su-Jin Kim, GNU

Advanced Ceramic

Electronic: Dielectric, Piezoelectric, Semiconductor, Magnet, Sensor, Optical

Energy: Secondary battery, Filters and membranes, Catalytic

Bio-Nano: Hard tissue(teeth, bones), Biomass separation, Nano powder wire sheet, Glass fiber

Ceramic

Material Science

© Su-Jin Kim, GNU

Summary

Ceramics

Crystal structure: Salt, Silicate, Alumina, Zirconia, Carbon, CBN

Properties

Traditional and Advanced ceramic