Ceramics

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.t -.3 /-f /- att ! Chemical composilions of ceramic materials i"lit,iniioli;dit ) from simple compounds. to rfrfffi;T-mefry comPlex Phases oonoeo DEFINITION CERAIJICS ) solid compounds that are forme! by the application of heat, and sometimes heat and pressure, where: - comprising at lea:: c:: retal and a nonmetallic elemental-solid or a nonmetal, exp: MgO' SiO2' TiC' Zr B, - a combination of at least two nonmetallic elemental solids, exP SiC - or a combination of at least two nonmetallic elemental .otias ano a nonmetal, exp: BaTo., YBarCu.ot and I3SiC2 Ceramic n-€terials can be calegorized irliol L'FE-S i_j 2 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 and fiErmij--inJutators drie -to the ab^ence ot conduction electrohs 't . Normallv ceramic materials have relatively high metting iemperalures and high chemical stability of 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, / erlgineering ceramics) 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

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Transcript of Ceramics

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    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

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    . 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

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    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

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    493749E9m

    27s62050171525@19m

    Crystal structure ) FCC and HCp

  • tl^t^ 'Powder Route

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    Processing and structure of

    Wet ProcessingA sEpe.Efon d sadc pords h

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    - 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

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    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

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    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.

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    . 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

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    . 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)

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    . 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

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    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)

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