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1MFGT104MaterialsandQualityCeramicsandGlassesProfessorJoeGreeneCSU,CHICOAddRefractoryInformation!!!AddtensilepropertiesofnonferrousMFGT104天天影视http•Objectives–Understandthecompositionsandapplicationsofvariousceramicmaterialsandproducts,includingglass,stone,clay,cement,brick,andrefractorymaterials.–Describethedevelopmentofthesematerialsaswellasthevariousproductsmadefromthem.–Explainthemajortypesandusesofmodern,syntheticabrasives3Introduction•Ceramicsare–complexcompoundsandsolutionsthatcontainbothmetallicandnonmetallicelements,–heatedatleasttoincandescenceduringprocessingapplications,–typicallyhardandbrittle,–exhibithighstrengthandhighmeltingpoints,–exhibitlowthermalandelectricalconductivity.•Applications–Pottery,brick,tile,glass,ovenware,magnets,refractories,cuttingtools.–Furnaceliningsandtilesforspaceshuttleduetohighresistancetoheat.–Superconductivityapplications4Ceramics•Traditionalceramicsaremadefromclay,silica,andfeldspar•Structuralclaysforbricks,sewerpipes,draintiles,andfloortilesaremadefromnaturalclaysmadefromthreebasiccomponents•Traditionalceramicproductsarechina,dentalporcelain,andsanitary-ware•Technicalceramicsaremainlypurecompoundsornearlypurecompoundsofprimarilyoxides,carbides,ornitrides.•Normallyhotpressedindrypowderformontousefulproducts.5Ceramics•CeramicscomesfromGreekwordkeramos,whichmeanspotter’sclay.•Ceramicsarediversegroupofnonmetallic,inorganicsolidcompoundswithawidevarietyofcompositionsandproperties.•Ceramicsarecrystallinecompoundsmadeupofmetallicandnonmetalliccompoundswithpropertiesthatdifferfromtheconstituents.•Ceramicsintheformofpotteryareamongtheoldestproductsmanufacturedbyhumans.–Clayisinexpensivematerialandisfoundthroughouttheworld.–Earlyclayproductsweresundriednotfired.–Firingasusedinpotterydatesbacktoaround2000to3000B.C.6CeramicsProperties•Ceramicsarecrystallinelikesteelbuthavefewfreeelectronsatroomtemperatureandthusarelowconductivity.•Ceramicsstrengthshavehighercompressivethantensile.•Ceramicsaretotallyelastic,exhibitingnoplasticitywhenloadisappliedwithlittleornodeformationpriortofracture.•Ingeneralceramicshavethehighestmeltingpointsofanymaterials.Rangefrom3500Ftoashighas7000F.•Manufacturingofceramicsinvolves–blendingfinestartingmaterialswithwatertoformmassthatisshaped–formationincludesextrusion,pressing,andcasting,–useofpotter’swheelforcups,bowls,saucers,etc.–extrudedtomakebarshapesorpouredintomoldasslipslurry–afterformingproductisdriedtoremovewaterandfiredforstrength–formingprovidesfusion(sintering)andchemicalreactionforbonding–glazingwithceramiccoatingforsmoothsurface7CeramicsMaterialsandUses•Table7-18CeramicsMaterials•Properties–Varydependingoncomposition,microstructure,andprocessing.–Excellentresistanceto•compressiveloads,abrasion,heat,andstaining•chemicalattacks,weatherattacks,bending(excellentrigidity)–Poorresistancetotensileloads,spalling(thermalcrackingceramics)–Mostceramicswillcrackifthermalcycled,exceptPyrexglasswhichcontainsboricoxidetoprovideexpansionproperties.•Applications–dielectricmaterialsforcapacitorswithdiskcapacitors(mainlybariumtitanate)beingthemostcommon.–Semiconductorapplicationswithsinteredoxides,e.g.,thermistors,whicharethermallysensitiveresistorsusedfortemperaturecontrol–Piezoelectricceramics(Bariumtitanate)isusedinaccelerometersandspeakers.Thetransducersconvertinputsoundenergyintoelectricalresponseorconvertelectricalinputsintosoundenergy.–Nanocompositesforplasticsandcomposites9Glass•Glassesaredescribedassuper-cooledliquids.–Glassesdonotbehavelikemetalsbutmorelikepolymerswhencooledfrommoltencondition•Metalsexhibitadefinitequantityofheatgivenoffwhencooledandformacrystaline(orregular)structurewhencooled.–Heatiscalledheatofsolidification•Polymersexhibitchangesinvolumewhencooledwhichmayformacrystallineoramorphousstructuredependinguponthenatureofthepolymerandversustemperaturethathasaninflectionpoint,knowasglasstransitiontemperature.•Glassisatransparentsilicaproductwhichmayformanamorphousorcrystallinestructuredependinguponheattreatmentduringproduction.•Glassdonotexhibitanyindicationoftransitionoraclearpointofinflectionwhencoolingfrommoltenstate.•Glassisconsideredaviscousliquidwhencooledfrommoltenstate.•Glasshastheappearanceandfeelofasolidmaterialbutwillflowlikealiquidgiventime,e.g.,thickerglassatbottomofwindowpane.–CrystallinityofglassesismeasuredwithXraysandX-raydiffraction.•Morecrystallinetheglassthemoreraysarediffracted10GlassFlow•Glassflowsovertime(Figure7-1)11GlassHistory•Glassisoneoftheoldestmanufacturedmaterialswithoutaknowndiscoverydate.Naturemakesnaturalglass.•Naturalglass–Obsidianisacommonnaturalglassproductformedbyintensevolcanicheatandisusuallyblack,butcanbered,brown,orgreen.–Obsidianwasusedbyearlypeoplestomakejewelry,weapons,tools.–5000B.C.:glasswasfoundaroundcampfiresonsandybeaches.–5000B.C.:FirstattemptstomakeglassinregionofSyria.–4000B.C.:GlassbeadsandbottlesfoundnearMesopotamia–Egyptiansusedglassproductsasadornmentsfortherichandpowerfulbecauseglassproductionwasveryexpensive.–200B.C.:Babyloniansinventedtheprocessofgl