.t-.3/-f/-

att!

Chemical composilions of ceramic materialsi"lit,iniioli;dit ) from simple compounds. torfrfffi;T-mefry comPlex Phases oonoeo

DEFINITIONCERAIJICS ) solid compounds that are forme!by the application of heat, and sometimes heatand pressure, where:-

comprising at lea:: c:: retal and a nonmetallicelemental-solid or a nonmetal, exp: MgO' SiO2' TiC'Zr B,

- a combination of at least two nonmetallic elementalsolids, exP SiC

- or a combination of at least two nonmetallic elemental.otias ano a nonmetal, exp: BaTo., YBarCu.ot andI3SiC2

Ceramic n-terials can be calegorized irliolL'FE-S i_j2 classes.

Jgto",I^oS

together.. The orooerties of ceramic materia.ls-also vary

due tb ofuferences in bonding. -, Siu2F \$ cltrnua. ln oeneralceramic materials are.tpically;|ard

afi-cfE-rittle rvith low tqugh-qes.s and quqr!qy:-(:; tEffi-icJ are usfEilv good crectricdl andfiErmij--inJutators drie -to the ab^ence otconduction electrohs 't

. Normallv ceramic materials have relatively highmetting iemperalures and high chemical stabilityof their slrong bonds

li*" J-^ttungot^ b-'^"'* t{h&n}cl

'!k-.q4

t?t . Made ftom three basirc components ) clay'silica (flint), and feldsPar'

.1 I ,^,1- A/a712-'

-Advanced / high performarEo, / erlgineeringceramics) automotive, circui cbips. Al2o3, sic' si3Nl

,./toYo

*dnu

'drnaMiCS-ffi1*7le\,\- 6,t;n lrno

, U-f,'0\rtn +"r.,ctp i:or"*r

l-anoar Fr"Jy irvhq^ Lih^6

tl,:'l

. Advanced ceramics materials can be classifiedinto two majortlpes:-

Monoli$ic-

Composite. The maJor ditrerence behrcen these two is a

reinforcing phase. Composite -) Adding a clisconlinuous phase )

such as V{hil|grs, plalelets, or particulites. composiie TAooit(Tat;ffious fibers can

reinforce ceramic malerials

. Among the family of advanced ceramicmaterials, ceramic composites will find widerapplications when increased loughness, due totiber or whisker-reinforcement, is combined withthe inherent refractory properties of tne ceramicmaterials. l+ sr1o.{ trr-.r,^,L f rl l, )r,Ir,no atuLQat {orb4\4^ 'r

. lts developmenl will allow the use of ceramics altemperalures beyond the temperalures limifs formetals, but without the familiar fraclure ofconveniional ceramics

Processing and structure ofmonolithic ceramics

. Advanced ceramics-

MosUy crystalline-

Bonding t ionic, covalent mixd covalent-ionic-

Cwalent bonding I stronger than ionic, and it isdjqclaql, sec,a[,-

Due to the bonding, the ceramics hlye hiqh mehinopoints. Complex crystal otructure mgke th-e ,"i"ii"i,britde and strong-

Most of rnodem advancd ceramici. such as aluminaare produced by potder route

2

Ceramic materiars + exist as lGriine and noncr)6tallineBonding ) ionic, covalent and mixd bondingc

Cmmb Bonding atoms S lon'Ebcrding

tr covC..lbondrrg

Mofrngr-{. *)

McoArqsio,sl:st,N.

Mg -OAl _o

si -osi -csi -N

73635111

30

493749E9m

27s62050171525@19m

Crystal structure ) FCC and HCp

tl^t^ 'Powder Route

'6a.n?A"( > ?cJ.green "

.^cfu

o A\^i',r

Pr66irt:ghprFue, bhm

(apdi:atim dp(w! haf

'fbtndo, r (ern v'fl-arfl lul

Processing and structure of

Wet ProcessingA sEpe.Efon d sadc pords h

ru@tgibel.G tia frrDl

Cct174s r"

- Processing: Appropiate rarr materiab (usuafy sonrer:cyrled gtass), rnelt to produce into tfre req*edshape (can use bblv-fiddr, spin cdnng afidpressing)

- Jn formrng process, viscosity dglass is verymportaflt it b a func*ion of ternperdrre andcompcition \

Processing and structure ofmonolithic ceramics

Glass-ceramics-

Und.er a certain conditions, il I possible tocryda.Sze a glass to form a glass-ceramic

-Are defined as fin+grained polycrystallinernaterials

- ttct * glasses can be crystallized to formgilass-cerafirics

- 5Oi5 to g8% o{ the volurne may be cqatalline

- Pro*fxfon mthod -fourder route

1}-"..^. Gz.r=.,alytrw^^ (7o*--

{^no^

Ceramic Matrix ComPosites (CMC). The main objective in producing CMC is to

increase the toughness. A reinforcing phase (particle, short fiber or

continuous fiber) can imProve thetoughness, while maintaining theadvantages of ceramic materials such asenhanced wear resistan@, hardness,

sistance and high temPeralurecapabilitY

*y" af".l

Properties and aPPlications ofadvanced ceramics

.-,(. Traditionalceramics ) from sdiitary ware '

to fine Chinas and porcelains to glassproducts

' Ct,,.",,iiy i. q."-,.--*lceramics))ceramics engines to opticalcommunications, electrooptic to lasermaterials, substrates in eledronic circuitsto electrodes in photoelecirochemicaldevices.

lr^Isn . /|qn,Et/

. Thermal-

insulation ) high-temperature fumace liningsfor insulation (oxide fibers such as silica,alumina, and zirconia).

- Refracloriness t high lemPeralure fumacelinings for insulation and conlainmeni ofmolten melals and slags

- Thermal conductivity ) Heat sinks forelectronics packages

lJ\ 1lr'' ,1 2, -. {t,e;t;tt{

. Electrical and dielectric-

Conductivity ) Heating elemenls for fumace(SiC, ZOt, MoSi,

- Fenoeleclrocity ) Capacitors @a-tilanate-based materials

- Low-vottage insulators ) ceramic insulations(porcelain)

- lnsulators in eledronic apSications )substrates for electronic packaging andelectrical insulalors in general (AlzOs)

- Gas-sensitive conductivity ) gas sensors(SnOr, ZnO)

4

t_

lc c.^.*^,1. -a r 6 ceV n\ex ( aAt [- ?El"rI-!cf" i M-4

. Magnetic and suPerconductive-tvtagnet ) Fenite magnets (Ba' S0O' 6FqO'-

SuPerconductivitY ) wires. OPtical

-Transparency ) winoows tsoua-ot's gE))!'cableior optical communication (uttra puresilica)

-Translucency and chemical linertness ) heat-

and conosion-resistance materials' usually

-. -==

for Na lamPs (AltOr' MgO)

Chemical-

Catalyst t fiters (zeolite), purifrcation of exhaustgases I

- Lticonosion propaties ) heat ex&nges (Sc)'chemical equipment h conoaive environments,membranes

- Biocompalibility ) afificiral jrint prosthses (Al2os)

Mechanical-

Hardness ) cutthg loob (SiC wtrislker-teinlorcedAbq.sLN'

- niln-t"tp"r"ture strength retentbn ) Stators andrufone uioes, ceramic engins (sLN,

- Wear resistance ) Bearings (S'lgNr)

5