陶瓷ceramics材料概论

Introductiontomaterials,Ceramicsforfinalexamination,Editors:卜娇娇苏洁琼孟梦马世行耿玉华余炜,Ceramics,Ceramicscanbedefinedasinorganic,nonmetallicmaterials.Theyaretypicallycrystallineinnatureandarecompoundsformedbetweenmetallicandnonmetallicelements.,Ceramics,Traditionalceramics,Advancedceramics,Introduction,Traditionalceramics,Traditionalceramicsarederivedandprocessedfromclayornonclayminerals.,Theyarechemicallycomplex,buttheyarecommon,inexpensive,andeasytomanufacture,Characteristics:,fragile,notconsideredforuseasstructuralorload-bearingmaterials,heavy,Advancedceramics,Thegreatestdemandinland,sea,air,andspaceindustriesmakesAdvancedceramicsappear.,Someexamplesofadvancedceramicsincludeoxideceramicssuchasalumina,beryllia,andzirconiaandnonoxideceramicswhichcanberepresentedbycarbidesandnitridessuchasboroncarbide,andsiliconnitride.,Clays,Refractories(耐火材料),Glasses,Cement,Abrasives,TraditionalCeramicsMaterials,TaxonomyofTraditionalCeramicsMaterialsBasedonApplications,Advanced(new)CeramicsMaterials,Oxides,Nitrides,Carbides,TaxonomyofAdvanced(new)CeramicsMaterialsBasedonApplications,StructureofCeramics,Loosedefinition:Crystallinesolidscomposedofmetallicandnonmetallicmaterials.,Reason,Consistingprimarilyofformsofsilicon,aluminum(铝)andoxygen,Whyceramiccanbeproducedatlesscostthanmetal?,Whatsetsceramicsapartistheirsetofpropertiescommontonearlyallforms:（1）extremehardness,(2)heatresistance(3)corrosionresistance(4）lowelectricalandthermalconductivity（5）lowductility,orbrittleness.,CrystalofStructures,Mainmaterialofceramicsissilicates.ThebasicunitofthesilicatestructureisSiO4tetrahedron.Whenclayisheatedtoover1100inakiln,thewaterisremovedandthelayeredsheetsbondorlockintoarigidstructure.Thesolidstructureiscalledaceramic.,MicrostructuresofStructures,3.Theprocessingofceramics,3.Theprocessingofceramics,TheAdvancedCeramicProcessing,TraditionalCeramicProcessing,3.1AdvancedCeramicProcessing,powderpressing,uniaxialisostatichotpressing,themultistagefabricationprocess,acoldstepahotstep,3.2TraditionalCeramicProcessing,rawmaterials,formingtechniques,dryingandfireing,testing,packingstorige,3.2traditionalceramicprocessing,rawmaterialsClassificationofrawmaterials：ceramicmanufactureandbasicmaterialplasticrawmaterialCeramicrawmaterialnon-plasticrawmaterialClaySilica,3.2Traditionalceramicprocessing,Formingtechniqueshydroplasticformingtwocommonshapingtechniquesslipcastingdryingdryingandfiringfiringtestingpackingstorige,PropertiesofCeramics,MechanicalProperties,PhysicalProperties,ChemicalProperties,Fabricability,OtherProperties,Wearresistance,Thermalshockresistance,MechanicalProperties,Tensilestrength:Itisoftensubstitutedforthetensilemodulusofelasticity(拉伸弹性模量),Yieldstrength:Ceramicsdonothaveayieldstrength,Hardness:Ceramicshavethehardesthardnessoftheengineeringmaterials,Stiffness:Ceramicscomeoutasourstiffestengineeringmaterials,Brittleness:Theirgreatestweaknessisbrittleness,Compressivestrength:Engineeringceramicshaveanexcellentcompressivestrength,Physicalproperties,Density:0.1-0.6comparedto0.06-0.8ofmetals,Meltingpoints:Theyareamongthehighestofallengineeringmaterials,Thermalandelectricalconductivity:MostceramicshavelowthermalconductivityandareelectricalinsulatorsAtenttion:temperature,Waterabsorption:Itcanbeafactorwithceramicsthatcontainporosity.Absorbedmoisturecanlowerelectricalinsulatingpropertiesofporousceramics,ChemicalProperties,Crystalline:Mostofceramicsarecrystalline,but,glassesareamorphous,notcrystallineatall,Chemicalresistance:Ceramicshaveanexcellentchamicalresistance(suchascorrosionresistance),Composition:Ingeneral,wedonotstatethechemicalcompositionofceramics,FabricabilityANDOtherProperties,Fabrication:Ceramicscannotbemeltedandcasttoshapeslikemetals,Costly:Mostceramicsrequireexpensiveprocessingtobringthemtomanymachineparts,andthetechnologyofsol-gel(溶胶凝胶)doesnotexistonacommercialbasisin2000,butitmaycome.Areyou?,Wearresistance,ThermalShockresistance,ApplicationsofCeramic,UsesintheConstructionIndustry,1)Ceramicmaterialsplayanimportantroleinconstructionindustry(2)Productssuchasfloor,wallandroofing-tile,brickarethebuildingblocksintheworldofconstruction,Ceramictile,Claybrick,UseinRefractories,Ceramiccrucible,TheceramicisoneoftherefractoriesRefractoryceramiccanwithstandvolatileandhigh-temperature.,Ceramicfiber,Medical,Surgeonsareusingbio-ceramicmaterialsforrepairandreplacementofhumanhips,knees,andotherbodyparts.Dentistsareusingceramicsfortooth,ElectricalApplications,CeramicisimportantinelectronicindustryCeramichaveawiderangeofelectricalpropertiesincludinginsulating,semi-conducting,superconducting,piezoelectricandmagnetic.,EnvironmentalandspaceapplicationsThecellularceramicshelpcatalyticconvertnoxioushydrocarbonintoharmlesscarbon.ItcanbeusedinoilspillcontainmentboomsCeramicsareusedinspaceshuttleasthermalba