先進(jìn)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P(yáng)artII: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(xué)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(duì)密度熱膨脹系數(shù)抗壓強(qiáng)度抗拉強(qiáng)度(kànɡlāqiánɡdù)抗彎強(qiáng)度抗磨損強(qiáng)度斷裂韌性熱導(dǎo)率比熱彈性模量剪切模量體積彈性模量顯微硬度介電強(qiáng)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P(yáng)rocessingofAluminaTheprocessofproducingpurealuminafrombauxiteore(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P(yáng)recipitationCrystallinepurealuminumhydroxide(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(jí)，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(xué)的hexagonallyclose–packed六方緊密堆積(duījī)octahedralsites八面體位Cation陽離子ditrigonalscalenohedra復(fù)三方偏三角面體（中級(jí)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(diǎn)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(lán)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P(yáng)rocessingofTitaniaPureprimarytitaniumdioxidedoesnotoccurnaturally,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(diǎn)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?cè)鲰g，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