材料概論陶瓷雙語(yǔ)課件

Chapter3Ceramics

陶瓷材料龍志慶理工大學(xué)材料科學(xué)與工程學(xué)院《材料概論》IntroductiontoMaterialsChapter3Ceramics

陶瓷材料重慶理工大2InorganicNon-metallicMaterials2InorganicNon-metallicMateri材料概論陶瓷雙語(yǔ)ppt課件陶瓷材料的概念與分類 Conceptandclassification陶瓷的結(jié)構(gòu)StructureofCeramics陶瓷材料的制作工藝 Manufactureandprocessingtechnologies陶瓷材料的性能及應(yīng)用 Propertiesandapplications2.1陶瓷材料的概念與分類2.11陶瓷的概念和分類

ConceptandClassifications

1.1概念

Concept陶瓷Ceramic:

燒過(guò)的粘土。是陶器

(pottery)和瓷器(porcelain)的總稱。定義:陶瓷指經(jīng)過(guò)高溫處理所合成的無(wú)機(jī)非金屬材料(Inorganic&nonmetallicmaterials),簡(jiǎn)稱無(wú)機(jī)材料。3.1Introduction1陶瓷的概念和分類3.1IntroductionWhatistheceramicTheword“ceramic”canbetracedbacktoGreekterm“keramos陶器”whichisrelatedtoanoldSanskrit（梵語(yǔ)）rootmeaning“toburn”.Canbedefinedasinorganiccompoundsmadebyheatingclayorothermineralmattertoahightemperatureatwhichtheypartiallymeltandbondtogether.Ceramiccanbedefinedasinorganic,nonmetallicmaterials.WhatistheceramicTheword“c陶器---瓷器比較表面效果制作材料燒制溫度敲擊聲音陶器---瓷器比較表面效果制作材料陶瓷之別陶器瓷器胎料普通的粘土瓷土（高嶺土）溫度一般<1000度一般>1100度表層不施釉或低溫釉多施釉吸水性胎質(zhì)粗松，斷面吸水率高胎體堅(jiān)固致密，斷面基本不吸水，敲之發(fā)出清脆的金屬聲響陶瓷之別陶器瓷器胎料普通的粘土瓷土（高嶺土）溫度一般<1009Ceramicsarerefractorypolycrystalline（多晶）compoundsHighlyinert(惰性);biocompatible(生物適應(yīng)性的）Hardandbrittle（脆性）Highcompressivestrength（耐壓強(qiáng)度）Generallygoodelectricandthermalinsulators(絕緣)Goodaestheticappearance美觀9CeramicsarerefractorypolycUsuallycompound化合betweenmetallicandnonmetallicelementsAlwayscomposedofmorethanoneelementBondsarepartiallyortotallyionic,andmayhavecombinationofionic離子鍵andcovalentbonds共價(jià)鍵Majority多數(shù)hasionic(insaltcompounds)ormetallicandnonmetallicelements(asinoxidesAl2O3,MgO,SiO2)Usuallycompound化合betweenmet主要組分：硅酸鹽化合物在美國(guó)，陶瓷泛指硅酸鹽材料，又稱為傳統(tǒng)陶瓷或普通陶瓷。包括日用陶瓷、工業(yè)用陶瓷、一般玻璃、水泥、耐火材料等。

先進(jìn)無(wú)機(jī)材料(advancedinorganicmaterials):

用氧化物、氮化物、硅化物、碳化物以至各種無(wú)機(jī)非金屬化合物經(jīng)過(guò)

特殊的先進(jìn)工藝制成的材料。

主要組分：硅酸鹽化合物1.2分類Classification12Ceramicstraditionalceramics:derivedandprocessedfromclayornonclaymineralsincludingrefractories（耐火材料),whitewares,cement(水泥),porcelain(瓷器),andstructuralclayceramics.advancedceramics:highpurity,bettermechanical,electrical,magnetic,andopticalproperties

1.2分類Classification12Cerami1.2.1傳統(tǒng)陶瓷Traditionalceramics：又稱普通陶瓷，主要是指以天然無(wú)機(jī)物如粘土等為主要原料、經(jīng)高溫處理得到的制品，主要用于制造日用器皿、生活潔具等生活用具。瓷器Porcelain;Chinaware：細(xì)密的陶瓷器皿，質(zhì)硬、半透明、白色、發(fā)聲清脆以及無(wú)孔，以長(zhǎng)石(Feldspar)、石英（Quartz）和高嶺石(Kaolin)為基本原料經(jīng)一次燒成。131.2.1傳統(tǒng)陶瓷Traditionalceramic1414TraditionalCeramics15TraditionalCeramics15藝術(shù)陶瓷16藝術(shù)陶瓷16材料概論陶瓷雙語(yǔ)ppt課件材料概論陶瓷雙語(yǔ)ppt課件材料概論陶瓷雙語(yǔ)ppt課件材料概論陶瓷雙語(yǔ)ppt課件1.2.2先進(jìn)陶瓷Advancedceramics：又稱為精細(xì)陶瓷、新型陶瓷、高技術(shù)陶瓷、特種陶瓷等。New、technical、engineering、advancedceramics是指以精制的高純天然無(wú)機(jī)物或人工合成無(wú)機(jī)化合物為原料，采用精密控制的制造加工工藝燒結(jié)，得到的具有獨(dú)特性能的高功能陶瓷。211.2.2先進(jìn)陶瓷Advancedceramics：AdvancedceramicsAdvancedceramicsare

developedformrathersimplechemicalcompounds,andadvancesinprocessingwhichhaveprovidedgreatercontrolovertheirstructures.Advancedceramic:thescaleoftherawmaterialsandmicrostructures,includingthecrystalgrains,crystalinterface,poresanddefectsisatthelevelofmicrons.先進(jìn)陶瓷，從原料、顯微結(jié)構(gòu)中所體現(xiàn)的晶粒、晶界、氣孔、缺陷等在尺度上都是處在微米級(jí)的水平。AdvancedceramicsAdvancedceraClassificationbasedonapplicationsAdvanced(New)CeramicmaterialsOxidesNitridesCarbidesAbrasivesRocketEnginesAbrasives研磨料

BioceramicsGasTurbiness燃?xì)鉁u輪機(jī)ResistanceHeating電阻加熱

ElectricalCuttingToolsSteelAdditives(Steel)CuttingToolsHighTemperaturesRefractoryBrickSubstrates基板CuttingTools(cermets)

耐火磚ForICChips

GlassAdditivescoatingsArmorCeramicMatrixCompositesNuclearFuelsReinforcingFibersClassificationbasedonapplicAdvancedCeramicsCuttingtoolsZirconiatoughenedalumina氧化鋯增強(qiáng)氧化鋁24AdvancedCeramicsCuttingtools25紅色陶瓷系列黑色陶瓷系列黃色陶瓷系列25紅色陶瓷系列黑色陶瓷系列黃色陶瓷系列密封環(huán)陶瓷系列26密封環(huán)陶瓷系列26點(diǎn)火頭系列27點(diǎn)火頭系列271.2.3先進(jìn)陶瓷的分類組成composition：氧化物oxide、氮化物nitride、硅化物silicide、碳化物carbide

性能properties&applications：結(jié)構(gòu)陶瓷structuralceramics、功能陶瓷functionalceramics281.2.3先進(jìn)陶瓷的分類組成composition：2結(jié)構(gòu)陶瓷:以力學(xué)、機(jī)械性能為主。Mechanicproperties功能陶瓷:利用材料的電、磁、光、聲、熱等性能及其耦合效應(yīng)，如鐵電、壓電陶瓷、敏感陶瓷、快離子導(dǎo)體陶瓷等。主要從電性能上考慮有絕緣陶瓷、介電陶瓷、半導(dǎo)體陶瓷、導(dǎo)體陶瓷以至高臨界溫度的超導(dǎo)陶瓷。29結(jié)構(gòu)陶瓷:291.3陶瓷的發(fā)展30陶器

瓷器（傳統(tǒng)陶瓷）高鋁質(zhì)粘土和瓷土的應(yīng)用釉的發(fā)明原料純化陶瓷工藝的發(fā)展

陶瓷理論的發(fā)展

先進(jìn)陶瓷（微米級(jí)）納米陶瓷高溫技術(shù)的發(fā)展

顯微結(jié)構(gòu)分析的進(jìn)步性能研究的深入無(wú)損評(píng)估的成就相鄰學(xué)科的推動(dòng)1.3陶瓷的發(fā)展30陶器瓷器（傳統(tǒng)陶瓷）高鋁1.4ApplicationsThermalBarrierCoatings:熱屏蔽涂層Lowthermalconductivity傳導(dǎo)性reducesmetaltemperatures311.4ApplicationsThermalBarriElectronicsPackaging電子封裝:Ceramics:ProvidehightemperatureperformanceandthermalexpansioncoefficientmatchtoSiliconHighthermalconductivitydesired32ElectronicsPackaging電子封裝:CeCeramicArmour裝甲33CeramicArmour裝甲3334Someotherexamples34Someotherexamples1.4陶瓷的發(fā)展趨向納米陶瓷nano-ceramic特性：原材料粉末rawmaterialspowder顆粒為納米級(jí)nano-levelgrains；微觀結(jié)構(gòu)microstructures,晶粒grains,晶界interfaces，氣孔pores以及晶體缺陷defects同樣在納米級(jí)nano-level。351.4陶瓷的發(fā)展趨向納米陶瓷nano-ceramic35兩種晶型復(fù)合的復(fù)相陶瓷：同一化學(xué)組成的物質(zhì)經(jīng)適當(dāng)?shù)墓に嚳刂?得到不同晶型和不同的顆粒形貌的復(fù)相陶瓷，達(dá)到自補(bǔ)強(qiáng)的目的。有機(jī)和無(wú)機(jī)復(fù)合的復(fù)相陶瓷：介于有機(jī)與無(wú)機(jī)材料之間，不需要高溫處理而獲得的一種新型材料。金屬陶瓷：金屬與陶瓷復(fù)合的復(fù)相陶瓷。36

兩種晶型復(fù)合的復(fù)相陶瓷：同一化學(xué)組成的物質(zhì)經(jīng)適當(dāng)?shù)墓に嚳?.2StructureofCeramicsCrystallinesolidscomposedofmetallicandnonmetallicmaterialsCeramicsarecrystalstructuresmadeofmetallicionsandInorganicmaterialsBondingiseitherpartiallyorcompletelyionic離子鍵.（還有共價(jià)鍵covalentbonds）

VariablesincludeThemagnitude量級(jí)oftheelectricalcharge電荷ontheions;Therelativesizeoftheions離子373.2StructureofCeramicsCrysPropertiesofCeramicsCorrosionresistance抗腐蝕,chemicalinertness惰性,thermalshockresistance抗熱震性,wear-resistance耐磨Electricalproperties:solidelectrolytesinexperimentalbatteriesandfuelcells燃料電池Otheruses:includeautomotivesensors,packagingforintegratedcircuits,electronic/opticaldevices,fiberoptics,microchips,andmagneticheads38PropertiesofCeramicsCorrosi3.2.1Structureofceramics普通陶瓷的結(jié)構(gòu)Microstructureofordinaryceramics陶瓷是由金屬（類金屬）和非金屬元素之間形成的化合物，其中的原子（離子)主要以共價(jià)鍵或離子鍵相結(jié)合。陶瓷通常是一種多晶多相的聚集體。393.2.1Structureofceramics普通陶普通陶瓷的顯微結(jié)構(gòu)主要由晶相、玻璃相、氣相及晶界構(gòu)成。40普通陶瓷的顯微結(jié)構(gòu)主要由晶相、玻璃相、氣相及晶界構(gòu)成。40晶相

crystalphaseCrystalphase:themainphaseinceramicmaterials,andcomposedofsomesolidsolutionsandcompoundsh化合物.Itsstructureandmorphology形態(tài)decidethemicrostructure,propertiesandapplicationsofceramics.41晶相crystalphaseCrystalphase:IntroductionStructureofceramics:mostvariesfromrelativelysimpletohighlycomplex.Beingcompounds,ceramicsaremadeofdifferenttypesofatomsofvaryingsizes.42IntroductionStructureofceraSilicate硅酸鹽Thebasicstructureunit:SiO4tetrahedron四面體.Oxygen(O)and

silicon(Si)together

accountforabout

75%oftheearth’s

crust.43Silicate硅酸鹽ThebasicstructurTypes:>1000differentsilicatesoccurnaturally,dependingonthedifferentwaystheSiO4tetrahedracanbelinked.44Types:>1000differentsilicatClayClay:acomplexmixtureofsilicates.Silicates:arecomplexioniccompoundsthatareexceedinglynumerous數(shù)目眾多.Clays:have

sheetsoflinkedSiO4

tetrahedrawhichslideover

eachother,givingtheir

mineralsacharacteristicsoftfeeling.45ClayClay:acomplexmixtureoCharacteristicsoflayeredstructuresLayeredstructure:asalubricant潤(rùn)滑劑,watercanpenetrate,producingamaterialthatispliable(柔軟的)andslippery.Whenheated:>1100oCinakiln(窯),thewaterinclayisremoved;thelayeredsheetsbondorlockintoarigid

structure.Thematerialwithsuchasolidstructureiscalledaceramic.46CharacteristicsoflayeredstrStructuresofsilicatesChainorringstructures:linkbysharingtheatomsintwocornersoftheSiO4tetrahedrons.Layeredsilicates:sharingthreecorneratoms.Suchas:talc滑石,kaolinite高嶺石clay,mica云母.Framework框架silicates:sharingfourcorneratoms.47StructuresofsilicatesChainoSilica二氧化硅Puresilica:threepolymorphs晶型cristobalite方石英tridymite鱗石英:hightemperaturequartz石英:lowtemperatureItisthebasicstructureforglassesandmanyceramics.48Silica二氧化硅Puresilica:threeStructures~PropertiesAtoms原子areheldstrongly:theatomsaredifficulttomoveorslipinrelationtoeachother.theductility延展性ofceramicsisverylowandtheyarebrittle.HighshearstressesLowductilityHighcompressivestrength抗壓強(qiáng)度Lowtensilestrength抗張強(qiáng)度.49Structures~PropertiesAtoms原Bendstrength:themaximumbendingstressintensionoffailure.MetalsVSceramics:atroomtemperature:theyarecompetitive;>850oC,metalsweakenwhileceramicsretainmuchoftheirstrength.Ceramics:goodheatresistance.alumina:1800oCsiliconcarbide:1700oCBendstrength:themaximumbenCeramicPhaseDiagramsMicrostructures:dependingonthecompositions,andthevariablesoftemperatureandpressure.Thedesiredmicrostructure:comingfromtheprocessing.Asthecompositionbecomesmorecomplex,themorethenumberofphasespresentthemselves.51CeramicPhaseDiagramsMicrosphasediagram相平衡狀態(tài)圖，相圖Thephasediagram,equilibrium,orconstitutionaldiagram:Themapthatshowsthedifferentcompositionsandthetemperaturesunderequilibriumconditions.（Mullite莫來(lái)石3Al2O3-2SiO2）52phasediagram相平衡狀態(tài)圖，相圖Thepha莫來(lái)石（或莫乃石）是一系列由鋁硅酸鹽組成的礦物統(tǒng)稱，

這一類礦物比較稀少。莫來(lái)石是鋁硅酸鹽在高溫下生成的礦物，人工加熱鋁硅酸鹽時(shí)會(huì)形成莫來(lái)石。天然的莫來(lái)石晶體為細(xì)長(zhǎng)的針狀且呈放射簇狀。莫來(lái)石礦被用來(lái)生產(chǎn)高溫耐火材料。耐火度:

1800oC時(shí)仍很穩(wěn)定,1810

oC分解為剛玉和液相莫來(lái)石是一種優(yōu)質(zhì)的耐火材料，它具有膨脹均勻、熱震穩(wěn)定性極好、荷重軟化點(diǎn)高、高溫蠕變值小、硬度大、抗化學(xué)腐蝕性好等特點(diǎn)，目前主要有高純電熔莫來(lái)石、普通電熔莫來(lái)石、全天然鋁礬土精礦燒結(jié)莫來(lái)石和輕燒莫來(lái)石。適用于石油裂介爐、冶金熱風(fēng)爐、陶瓷輥道窯、隧道窯、電瓷抽屜窯、玻璃坩堝窯及各種電爐的內(nèi)襯，可直接接觸火焰53莫來(lái)石（或莫乃石）是一系列由鋁硅酸鹽組成的礦物統(tǒng)稱，

這一類3.2.2MicrostructuresofCeramicsPorosityandDensityMassdensity質(zhì)量密度,whichusesthemassofamaterialdividedbyitsvolumereferstothistheoreticaldensityAtomicweightisamajorfactorindeterminingthedensityofamaterialClose-packed密實(shí)的metalsaremoredensethanopen-structuredmaterials.543.2.2MicrostructuresofCeramBrittleFractureofCeramics脆性斷裂Defects缺陷inceramicscandevelopduetointernalstresses(內(nèi)應(yīng)力)

andporosityThermalstressesduetoan-isotropicthermalexpansion（各向異性熱膨脹）tendtocrackweakgrainboundaries5596%densealuminaBrittleFractureofCeramics脆56PoresinpartiallysinteredAlumina部分燒結(jié)氧化鋁中的孔隙56PoresinpartiallysinteredGreendensity壓坯密度isthebulkdensity體積密度ofacompactpriortoitsdensification密實(shí)化.Inpreparingparticlesfortheproductionofpowderedmetalsorceramics,thepackingofsphericalshaped球形,monosized單一尺寸(0.1μm)particles,evenwhenvibrated振動(dòng)tosettletheparticles,doesnotachieveadensitylevelmuchhigherthan60%.57Greendensity壓坯密度isthebulkDespitetappingorvibrating,theseparticlesdonotrearrangethemselvescompletelytoeliminate除去pores.Theoptimumdensityofsphericalparticlescanbereachedbyvaryingthesizedistributionofparticlestopermitsmallerparticles(50nmorless)tolocateintheinterstices(空隙)ofthelargerones.58

Despitetappingorvibrating,Ceramicsare,bynature,generallyporous孔隙的materialswithvaryingdegreesofporosity.Bulkdensity體積密度isusedinthisinstancetorefertoaceramic’sdensity,anditincludesthematerial’sporosityandthefactthatmostceramicscontainbothacrystallineandanoncrystallinephase.59Ceramicsare,bynature,generOpenporosity開(kāi)口孔referstothenetworkofporesinamaterialthatisopentothesurfaceandintowhichaliquidsuchaswatercanpenetrate滲透ifthepartweresubmerged浸入init.Closedporosity閉口孔referstothoseporesthathavebecomesealedwithinthegrainstructure.60Openporosity開(kāi)口孔referstothePoresaffectthestrengthofceramicsintwoways：First，theyproducestressconcentrations應(yīng)力集中.Oncethestressreachesacriticallevel,acrackwillformandpropagate擴(kuò)展.Second，poresreducethecross-sectionalareasoverwhichaloadcanbeappliedand,consequently,lowerthestressthatthesematerialscansupport.61PoresaffectthestrengthofcTheamount,size,distribution分布,andthecontinuity連續(xù)性ofvoids空隙inaceramicaretheprincipalfactorsthatdetermineitspropertiesIngeneral，porosityisdetrimental有害的toceramicsproperties.Grainboundary晶粒界線sliding,creeprate,andchemicalreactionsthatattacktheceramicorreduceitsmeltingpointaremoreadverse不利的conditionsproducedbyimpuritiesandporosity.62Theamount,size,distribution63收縮a收縮b收縮無(wú)氣孔的多晶體c說(shuō)明：a:顆粒聚集b:開(kāi)口堆積體中顆粒中心逼近c(diǎn):封閉堆積體中顆粒中心逼近63收縮a收縮b收縮無(wú)氣孔的c說(shuō)明：3.3CeramicProcessingTraditionalProcessingstructuralclayproductsandthewhitewares.Formation→Drying→Firing3.3CeramicProcessingTraditio成型Forming：將粉料直接或間接地轉(zhuǎn)變成具有一定形狀、體積和強(qiáng)度坯體，稱為素坯或生坯(roughcast)。成型的方法有很多，主要有可塑法、注漿法與壓制法。成型Forming：將粉料直接或間接地轉(zhuǎn)變成具有一定形狀可塑成型利用泥料的可塑性。將粉料與一定水份或塑化劑混合均勻，使之成為具有良好塑性的料團(tuán)，再用手工或機(jī)械成型制成坯體?？伤艹尚屠媚嗔系目伤苄浴⒎哿吓c一定水份或塑化劑混合均勻，注漿成型即漿料成型法，是將原料配制成膠狀漿料注入具有所需形狀的模具中成型，又可分為注漿成型和熱壓注漿成型。注漿成型即漿料成型法，是將原料配制成膠狀漿料注入具有所需形狀壓制成型將粉料填充在模型中，施加壓力，制成具有一定現(xiàn)狀和強(qiáng)度的坯體。分類：普通壓制成型和等靜壓制成型。適宜于干料(含水3～7％)或半干料(含水8～15％)。壓制成型將粉料填充在模型中，施加壓力，制成具有一定現(xiàn)狀和強(qiáng)度DryingandFiring/SinteringDrying:decreaselayersizeandspacingDryingandFiring/SinteringD常規(guī)燒結(jié)、熱壓燒結(jié)、氣焚燒結(jié)、放電等離子燒結(jié)、微波燒結(jié)造粒成型燒結(jié)加工檢測(cè)配料預(yù)燒根據(jù)確定的化學(xué)組成干壓、注模、注漿、擠塑等平整度材料性能粘接劑（PVA等），噴霧干燥Schematicillustration示意圖常規(guī)燒結(jié)、熱壓燒結(jié)、氣焚燒結(jié)、放電等離子燒結(jié)、微波燒結(jié)造粒成Sintering/firing梭式窯Sintering/firing梭式窯Therolesofclayminerals:Hydroplasticity含水塑性:byaddingwater,theclaysbecomeveryplastic.Dense&strongceramics:clayfuses融合ormeltsoverarangeoftemperatures;then,producingadenseandstrongceramicsduringfiringwithoutcompletemeltingsothatthedesiredshapeismaintained.Therolesofclayminerals:Hyd等離子放電燒結(jié)過(guò)程示意圖等離子放電燒結(jié)過(guò)程示意圖AdvancedCeramicProcessing制備工藝：不再以熔爐為主要燒結(jié)工具,如真空燒結(jié)、氣氛燒結(jié)、熱壓燒結(jié)、氣壓燒結(jié)等。性能：高強(qiáng)度、高硬度、耐腐蝕、導(dǎo)電、絕緣以及磁、電、光、生物相容性等。AdvancedCeramicProcessing制備工ChemicalprocessesSol-gelprocessingMeltprocessingProducingsingle-crystalmaterialsVaporprocessingDirectedmetaloxygenprocessChemicalprocesses固相法：包括熱分解法(thermaldecomposition)；非晶合金退火結(jié)晶法（在玻璃轉(zhuǎn)變溫度下結(jié)晶）；自蔓延高溫合成方法（制備金屬?gòu)?fù)合材料）。液相法：包括沉淀法；水解法；溶膠-凝膠法（通過(guò)水解金屬醇鹽或金屬無(wú)機(jī)鹽來(lái)合成氧化物的一種化學(xué)方法）。固相法：包括熱分解法(thermaldecomposi氣相法：包括氣相合成法；氣相熱分解法。機(jī)械法：球磨、振動(dòng)磨、高能球磨、氣流粉碎。溶劑蒸發(fā)法：酒精干燥法、冷凍干燥法、熱石油工作法、噴霧工作法液相法和氣相法是制備超細(xì)粉的主要方法。氣相法：包括氣相合成法；氣相熱分解法。3.4PropertiesofCeramicsMechanicalpropertiesPhysicalpropertiesChemicalPropertiesFabricabilityOtherproperties3.4PropertiesofCeramicsMecMechanicalpropertiesNoyieldstrength:ceramicsdonotplasticallydeformbeforereachingtheirtensilestrength.Nopermanentelongationorreductioninarea:ceramicscannotbeplasticdeformedbyroomtemperature.MechanicalpropertiesNoyieldMechanicalpropertiesCompressivestrength:excellent,betterthanmetals,plastics,andcomposites.Hardness:highestintheengineeringmaterials.Thelong-termservicecharacteristicsofceramics:Fatigueresistanceandcreepstrength:goodTensilefatiguestrength:poor.MechanicalpropertiesCompressiSpecialMechanicalproperties:GoodincompressionVeryhighhardnessandgreaterstiffnessthanotherengineeringmaterials.Weakness:brittlenessSpecialMechanicalproperties:PhysicalpropertiesComparedtometals:ceramicsarelightweight,butlowdensitymayalsobeanindicatoroftoomuchporosityinaparticulargrade.Asastructuralmaterial:thedesignershouldselectaceramicwithhightheoreticaldensity(99%).PhysicalpropertiesComparedtoThemeltingpointsofceramics:areamongthehighestofallengineeringmaterials.Thethermalconductivityandelectricalconductivity:coveralargespectrum.Mostceramics:electricalinsulators,butsomearesemiconducting.Thermalexpansion:lowerthanmetalsandplastics.ThemeltingpointsofceramicsChemicalPropertiesResistanttochemicalattack:theengineeringceramics,aluminumoxide,siliconcarbide,zirconia,siliconnitride,andothers,areveryresistanttochemicalattackinawidevarietyofsolutes.ChemicalPropertiesResistantFabricabilityTheycannotbeplasticallydeformedtoshapesatroomtemperatures.Ceramicscannotbemeltedandcasttoshapeslikemetals,mostlybecauseoftheirhighmeltingtemperatures.Themachiningofceramicsissocostlythatitisnotanoptionformanymachineparts.FabricabilityTheycannotbeplOtherpropertiesWearResistanceThermalShockResistanceOtherpropertiesWearResistancApplicationsofCeramicsCanwithstandvolatileandhigh-