先進陶瓷材料概論(英文)第二章

Aquick

reviewofthelastclassStructuralAdvancedCeramicsFunctionalAdvancedCeramicsClassicCeramicsAdvancedCeramicsCeramicsPropertiesApplicationPropertiesApplicationDefinition

Classification

Branch

Vocabulary共三十五頁

1.TrytogetaReferencebook(hardcopy

or

e-book)byeverypossiblemeans.(Foreveryone)

2.Watch

moviesorreadbookstofind

aapplicationofAdvancedCeramics,andgivea5-minstalkinthenextclassusingPPT.(Foreachgroup)‘Homework’Pleaseshareyourmethodwithallofus共三十五頁共三十五頁PartII:AdvancedStructuralCeramics共三十五頁OxideCeramicNon-OxideCeramicAdvancedStructuralCeramic共三十五頁Alumina(Al2O3)Aluminaisthemostcost-effectiveandwidelyusedstructuralengineeringmaterialinthefamilyofadvancedceramics.Therawmaterialsfromwhichthishigh-performance,technicalgradeceramicisproducedarereadilyavailableandreasonablypriced,resultingingoodvalueforthecostinfabricatedaluminashapes.掌握詞匯(cíhuì)：rawmaterial原料，

corundum

[k?‘r?nd?m]

剛玉，

inertness

[i’n?:tnis]惰性，

ceramicarmor陶瓷裝甲，biomedical生物醫(yī)學的，

dielectricpermittivity

[,p?m?‘t?v?ti]介電常數(shù)，

dielectricloss介電損耗，integrated

[’?nt?ɡret?d]

circuit

[‘s?:k?ts]

集成電路，

sparkplug火花塞Hence,alumina(corundum,α-Al2O3)isconsideredthe“workhorsematerial”ofthestructuralceramicsindustry.Itshighhardness,abrasionresistance,andchemicalinertnessmakesitanidealmaterialtoperformwellinavarietyofaggressiveenvironments,rangingfromminingindustrytochemicalindustrytometalmanufacturingandprocessing,toceramicarmorandbiomedicalapplications.Itselectricallyinsulatingnature,coupledwithitsmoderatethermalconductivity,reasonablylowdielectricpermittivity,andlowdielectricloss,offeraplethoraofapplicationsthatincludeelectronicsubstratesforintegratedcircuits(ICs)andautomotivesparkplugs.共三十五頁AnoverviewoftheimportantpropertiesofaluminaceramicsisprovidedinTable7.1.Thewiderangeofvaluesatteststothefactthataluminaceramicsdependonprocessing

parameters,includingthesintering

temperature,sinteringatmosphere,impuritycontent,grainsize,andotherextrinsicandintrinsicfactors.Forexample,theextremelypureandfine-grainedaluminaspecificationsusedinfemoralheads

forhipendoprostheses

demonstratenoticeablyhigherstrengths,toughness,andhardnesscharacteristics.掌握詞匯：processingparameter工藝參數(shù)(cānshù)，

sinteringtemperature燒結(jié)溫度，

sinteringatmosphere燒結(jié)氣氛，

impuritycontent雜質(zhì)含量，

grainsize晶粒尺寸，femoralhead股骨頭，hipendoprostheses髖關(guān)節(jié)假肢

，

characteristics特性共三十五頁掌握詞匯：相對密度熱膨脹系數(shù)抗壓強度抗拉強度(kànɡlāqiánɡdù)抗彎強度抗磨損強度斷裂韌性熱導率比熱彈性模量剪切模量體積彈性模量顯微硬度介電強度介電常數(shù)體積電阻共三十五頁High-purityaluminapartsanddevicescanbeutilizedinbothoxidizingandreducingatmospheresto1925?C.Themasslossinvacuumbetween1700?Cand2000?Crangesfrom10?5to10?7gcm?2

?s?1.Aluminaresistsattackbyallgasesexceptforwetfluorine,andisresistanttoallcommonreagentsexceptforhydrofluoricandhotorthophosphoricacids.Anelevatedtemperaturecorrosionoccursinthepresenceofalkalimetalvapors,particularlyatlowerpuritylevels(<90%Al2O3

content).Theadditionsofeitherchromiumoxideormanganeseoxideisknowntoimprovethematerial’shardnessandtoughness.Otheradditionscanbemadetoimprovetheeaseandconsistencyofmetalfilmsfiredtoaluminaceramicsforsubsequentlybrazedandsolderedassemblies.掌握詞匯：

massloss質(zhì)量損失，fluorine['fl?rin]

氟，

hydrofluoricacid氫氟酸，orthophosphoricacid磷酸(línsuān)，

elevatedtemperature高溫，

alkalimetalvapors堿金屬蒸汽

，chromiumoxide氧化鉻，manganeseoxide氧化錳共三十五頁ProcessingofAluminaTheprocessofproducingpurealuminafrombauxiteore(Bayerprocess)haschangedverylittlesinceitsinceptionin1893,andcanbedividedintothreestagesofextraction,precipitation,andcalcination.掌握(zhǎngwò)詞匯：

bauxite]ore鋁土礦，

Bayerprocess拜耳法，extraction[?k'str?k??n]

萃取，precipitation[pr?'s?p?'te??n]沉淀，calcination[,k?ls?'ne??n]煅燒共三十五頁Theoreiswashed,crushedandmilled

(stepA)toreducetheparticlesizeandmakethemineralsmoreavailableforextraction.Itisthencombinedwiththeprocesscausticliquorandsentasslurrytoaheatedpressuredigesterforextraction(stepB).Althoughtheapplicationofhighertemperatureswould,intheory,beadvantageous,thereareseveraldisadvantagesthatincludecorrosionproblemsandthepossibilityofoxidesotherthanthealuminadissolvingintothecausticliquor.Followingtheextractionstage,theinsolubleoxideresiduemustbeseparatedfromthealuminum-containingliquorbyaprocessknownassettling(stepC).Here,theliquorispurified

byfilteringbeforebeingtransferredtotheprecipitators.Theinsoluble,so-called“redmud”fromthefirstsettlingstageisthickenedandwashedtorecoverthecausticsoda,whichisthenrecycledbackintothemainprocess.ExtractionThealuminumhydroxide(gibbsite,γ-Al(OH)3)andoxyhydroxide(boehmite,γ-AlOOH;diasporeα-AlOOH)mineralsinbauxiteoreareselectivelyextractedfromtheinsolublecomponents(mostlyquartz,clayminerals,andironandtitaniumoxides)bydissolvingtheoreinasolutionofsodiumhydroxide(causticsoda)accordingto:

Al(OH)3

+OH?→[Al(OH)4

]?掌握(zhǎngwò)詞匯：aluminumhydroxide氫氧化鋁

,gibbsite三水鋁礦

,oxyhydroxide氫氧化物

,boehmite勃姆石,diaspore水鋁石,insoluble不溶的

,quartz石英,sodiumhydroxide氫氧化鈉

,causticsoda苛性鈉,crushed壓碎,milled磨

,causticliquor腐蝕性液體,slurry漿料

,digester蒸煉器,purified精煉，純化,filtering過濾,precipitator沉淀器,共三十五頁PrecipitationCrystallinepurealuminumhydroxide(gibbsite)isthenprecipitatedfromtheso-called“pregnant”digestionliquoraftercoolinganddiluting,andaddingseedcrystals(stepD)accordingto:[Al(OH)4]?→Al(OH)3+OH?Thisisessentiallythereverseoftheextractionprocess,exceptthattheproduct’snatureiscarefullycontrolledbytheplantconditions,includingseedingorselectivenucleation,precipitationtemperature,andthecoolingrate.Thegibbsitecrystalsarethenclassifiedintosizefractionsandfedintoarotaryorfluidized-bedcalcinationkiln

(stepE).Undersizedparticlesarefedbackintotheprecipitationstage.掌握詞匯(cíhuì)：diluting稀釋的，seedcrystal晶種，sizefraction粒級，kiln窯爐共三十五頁Thecalcinationprocessmustbecarefullycontrolledsinceitdictates（影響(yǐngxiǎng)）

thepropertiesofthefinalproduct.Asecondaryprocessstreamcontainingdriedgibbsitecanbeseparatedtoproducealuminates,zeolites,fillermaterialsfortoothpaste,fireretardants,andothers(stepsF–H).CalcinationThegibbsite（三水鋁礦）

crystalsarecalcined(stepE)toformhigh-purityalumina(α-Al2O3)astheprecursormaterialforavarietyofaluminaceramicsaccordingto:2Al(OH)3→Al2O3+3H2O掌握詞匯(cíhuì)：precursor[pri'k?s?]前驅(qū)體，aluminate

[?'lj?m?,net]

鋁酸鹽類

，

zeolites[‘zi?,la?t]

沸石，fillermaterial填充材料，

fireretardants阻燃材料共三十五頁StructureofAluminaPolymorphs(‘FundamentalsofInorganicnon-metallicmaterials’fordetails)α-Al2O3(corundum),Thethermodynamicallystablepolymorphbetweenroomtemperatureandthemeltingpointat2050?Cisα-Al2O3(corundum),whichformsalatticeofhexagonallyclose-packedoxygenatomswithstackingorderAB-AB…,inwhichtwo-thirdsoftheoctahedralsitesareoccupiedbyAlcations(Figure7.2).Corundumcrystallizesinthesymmetrygroup3m[spacegroup(S.G.)Rc3]withditrigonalscalenohedraasthegeneralformsandalatticeconstanta=513pm,α=55°16′.Theoxygenoctahedrashareedgestoformsix-memberedringsthatarelinkedintogibbsite-likesheetsparallel(0001).Thesheetsarestackedintoaframeworkstructurebysharingthefacesandcornersofoctahedra.Inthehexagonalcell(a=475pm,c=1298pm),sixgibbsite-likesheetsarestackedinsuchawaythatpositionsABCDEFindicatedinFigure7.2lieononecommonlineparallel[0001].掌握詞匯：

Polymorphs多晶型，

thermodynamically熱力學的hexagonallyclose–packed六方緊密堆積(duījī)octahedralsites八面體位Cation陽離子ditrigonalscalenohedra復三方偏三角面體（中級晶族單形）共三十五頁SelectedApplicationsofAluminaCeramicsOftheapproximately6milliontonsofnon-metallurgicalaluminaproducedworldwidein2006,about50%wasusedtoproducerefractoryandwearceramics,20%abrasives,15%whitewareandsparkplugs,and15%othertechnicalceramics.Owingtoitsfavorablemechanical,electricalandchemicalproperties,thetypicalusesofpolycrystallineα-aluminaceramicsinclude:?Wearpads?Sealingringsandwashers(e.g.,forhotwatermixingbatteriesandautomotivewaterpumps)?High-temperatureelectricalinsulators?High-voltageinsulators,asinsparkplugs?Abrasion-anderosion-resistantpipeandelbowliners?Cuttingtoolbits?Grindingmedia?Ballisticarmor?Electronicsubstrates?Noseconesandradomesformissiles,infrareddetectorwindowsforshort-rangeattackmissiles共三十五頁敢不敢講點兒我們感興趣的啊，老師？PartII:AdvancedStructuralCeramics共三十五頁Sapphire(Al2O3+Ti,Fe)Ruby

(Al2O3+Cr)StarSapphire(Al2O3+Rutile)Spinel(MgAl2O4)掌握(zhǎngwò)詞匯：

Sapphire['s?fa??]

藍寶石Ruby

['rubi]紅寶石Rutile['r?til]金紅石(TiO2)Discussion：Howtotellthemapart?PartII:AdvancedStructuralCeramics共三十五頁GeneralPropertiesandApplicationsTheimportantphysicalandmechanicalpropertiesofsinteredtitaniaaresummarizedinTable7.10.Thestructuralapplicationsofsinteredtitaniaarelimitedbyitsrelativelypoormechanicalproperties,inparticularitslowmodulusofrupture,compressivestrength,andfracturetoughness(Table7.10).Today,thepredominantapplicationoftitaniaisstillinpigments,owingtoitsopticalpropertiesandstabilityagainstultraviolet(UV)radiation.However,otherapplicationshaveemergedincludingoxygensensors,antimicrobialcoatings,photocatalyststocleanwastegasesandliquids,andpotentialphotovoltaiccellswithahighdegreeofenergyconversion.Titania(TiO2)掌握詞匯：

modulusofrupture斷裂(duànliè)模量，pigment['p?gm?nt]顏料，

ultraviolet[,?ltr?'va??l?t]紫外線，

antimicrobial[,?nt?ma?'kr??b??l]抗菌的，photocatalyst[,f?ut?u'k?t?list]光催化劑，photovoltaic[,f??t??v?l'te??k]

cells光伏電池，

energyconversion能量轉(zhuǎn)換共三十五頁損耗(sǔnhào)角正切共三十五頁ProcessingofTitaniaPureprimarytitaniumdioxidedoesnotoccurnaturally,butisderivedbyweatheringfromilmenite(FeTiO3

),perovskite(CaTiO3),andtitanite(sphene)(CaTiSiO5

).ThemostprevalentoccurrenceoftitaniaisinrutileorilmenitemineralsandsminedinCanada,Australia,theUSA,andSouthAfrica.Theseoresaretheprincipalrawmaterialsusedinthemanufactureoftitaniumdioxidepigment.Thefirststeptopurifytheoreisbasicallyarefinement,usingeithersulfuricacid(sulfateprocess;Gesenhuesetal.,2003)orchlorine(chlorideprocess)asanextractionagent.(‘ClassicandAdvancedCeramics’Ch7P236fordetails)掌握(zhǎngwò)詞匯：ilmenite['?lm?na?t]鈦鐵礦，perovskite[p?'r?vzkait]鈣鈦礦，titanite['ta?tn,na?t]榍石，sulfuric[s?l'fj?r?k]acid硫酸，chlorine['kl?rin]氯共三十五頁StructureofTitaniaTitaniumdioxideoccursasamineralinthreepolymorphicmodifications:tetragonal(四角形的)rutile

(P42

/mnm(136));tetragonalanatase（銳鈦礦）

(I41/amd(141);andorthorhombic（斜方）brookite

（板鈦礦）(Pbca(61)).Thecrystalstructureofthethermodynamicallystablerutileconsistsofedge-sharingTiO6octahedrathatformstraightchainsparallel[001].Thechainsarelinkedbysharingcornersoftheoctahedra.AsevidentfromFigure7.46a,thisconfigurationresemblesanf.c.c.lattice.However,theclose–packedoxygensheetsareslightlykinked(byabout20°)topermitonlyatetragonalsymmetrywitha42screwaxis.ThiscausesalsoadistortionoftheindividualTiO6

octahedra.Inanatase,theTiO6

octahedrasharefouredgestoformapseudo–tetragonalframeworkstructure,andinbrookitetheoctahedrasharethreeedges.Eachdistorted

（扭曲(niǔqǔ)的）octahedronislinkedwiththreeotherstoformzigzagchains,witheachoctahedronsharingoneedgewithanoctahedronoftheneighboringchainthusformingnetsparallel(100)(Figure7.46a,b).共三十五頁敢不敢再講點兒我們感興趣的啊，老師？PartII:AdvancedStructuralCeramics共三十五頁TiO2，ZnOReflection共三十五頁Zirconia(ZrO2)Overthepastfortyyears,zirconiahasbeendevelopedintoahighlysophisticatedadvancedceramicmaterialthatisutilizedinmanyimportantapplicationsviatheexploitationofitssuperiormechanicalanduniquefunctionalproperties.Theexceptionalmechanicalpropertiesofzirconiaaremainlybasedonthephenomenonoftransformationtoughening(thisisdescribedindetailbelow).Thedelayedmartensitictransformationofthetetragonalhigh-temperaturemodificationintothemonocliniclow-temperaturemodificationbyaddingstabilizingoxidesleadstoincreasedstressintensityfactorsKIcandalsoR-curvebehavior.Hence,appropriatelystabilizedzirconiahasbeendubbed“ceramicsteel”(Garvieetal.,1975).掌握(zhǎngwò)詞匯：transformationtoughening相變增韌，martensitictransformation馬氏體相變共三十五頁Tetragonal,t-ZrO2Cubic,c-ZrO2

Monoclinic,m-ZrO21170?C950?C2370?C2370?C共三十五頁TransformationTougheningofZirconiaCeramicsThetetragonal–monoclinicphasetransformationinzirconiashowsamartensiticnature;thatis,adiffusionlessshearprocessatclosetothevelocity