选区激光烧结PSAl2O3纳米复合材料若干关键技术研究

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1、南京航空航天大学博士学位论文AbstractSelectivelasersintering(SLS)isoneofthemostattentiverapidprototypingtechniquesduetoitssuitabilitytoprocessalmostanypowdermaterial.Itisgoingtoexhibithighpotentialapplicationsinmanyfields.ThisthesispresentsthestudyonSLSofpolystyrene/nano

2、-Al2O3powdermixtureforbulkpolymer/Al2O3nanocomposites.Themainworksarefocusedonsuchasthemethodfordevelopingthepowdermixturesystem,thebehaviorofinteractionbetweennanoparticlesandlaserbeam,themechanismsofmelting/solidificationanddensificationinsinteringproces

3、s,therelationshipsbetweenthequalityofsinteredpartandtheprocessparametersaswellasenergydensity,thecharacteristicsofthemorphologyandthemechanicalpropertiesofthesinteredspecimens.Theexperimentalresultsrevealedthatthemethodsforsurfacetreatmentofnanoparticlesar

4、eimportanttonotonlythedispersionofnanoparticleswithinthepolymermatrix,butalsothesinteringbehaviorandthequalityofthesinteredparts.Theseriouscongregationofnanoparticlesleadstothesinteredpartwiththepartiallyincompactstructureandthedifferenceofsurfacepolarityb

5、etweenpolymerandinorganicnanoparticleresultsinalotofvoidswithinthesinteredpart.Bymeansoftheemulsionpolymerization,thecompositeparticlesweremadeforovercomingaboveproblems.Theseparticleshavethecore-shellstructurethateachsinglenanoparticleiscoatedbypolystyren

6、e.Theinteractivemechanismsofnanoparticleswithbothlaserbeamandmeltingpolymerwereinvestigated.Therearethreekindsofbehaviorsfornanoparticlesinthesinteringprocess,thatis“slightlysplashing”underthelaserbeam,“diffuselymoving”withthepolymermeltpoolexpending,and“i

7、nfiltrating”withliquidpolymerintothecranksandvoidsintheconsolidatedlayer.TheaboveconclusionssuggestthatSLSprocesshasthefunctionsofsubsequentlybreakingupthecongregatingnanoparticles,diffusingthegatheringnanoparticlesandpromotingnanoparticlesmoving.Thesebeha

8、viorswereidentifiedbyobservingtheSEMmicrographsaboutthedispersionofnanoparticleswithinthespecimensmadefromSLSprocessingandconventionmodeling.Basedonlargenumberofsinteringexperiments,therelationshipsbetweenthe