纳米复合材料-英文版-03.pdf

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1、FillersforNanocompositeApplicationsMECH548DepartmentofMechanicalEngineeringHongKongUniversityofScience&Technology1Outline•IntroductionofNanocompositesanditsBenefitsofDevelopingPolymerNanocomposites•CriteriaforFillerSelection•MontmorilloniteOrganoclays(MMT):Introduction,surfacetreatment,dispe

2、rsionandtypicalproperties•Carbon-basedReinforcements–Carbonnanofibers–Carbonnanotubes–Graphitenanoplatets•PolyhedralOligomericSilsesquioxane(POSS)•NtNanopartiiclles–Nanosilica–NanoaluminumOxide–NanotitaniumOxide–Nanosilver21WhatisNanocomposites?(1/2)•Compositeswithnanometer-scalereinforcemen

3、ts.•Polymernanocomposites(PNC)arepolymers(thermoplastics,thermosetsorelastomers)thathavebeenreinforcedwithsmallquantities(lessthan5%byweight)ofnano-sizedparticleshavinghighaspectsizedparticleshavinghighaspectratios(L/h>300)3WhatisNanocomposites?(2/2)•SmallerfillersizeÆlargefiller-matrixinter

4、faceÎprosandcons–Examplesofpros:goodfortheperformanceofExamplesofpros:goodfortheperformanceofelectro-chemicalelectrodeswheretheelectrochemicalreactionattheinterfacebetweentheelectrodeandtheelectrolyte.–Examplesofcons:Higherelectricalresistivityduetotheelectricalresistanceassociatedwiththeint

5、erface.•Nanocompositesarenotnecessarilysuperiortoconventionalcomposites42NanocompositesSubmicronFilledNanocrystallineMaterialsMaterialsFullyIntegratedSingleWallNanotubeCompositeClayReinforcedRigidRodPolymersComposites&MolecularComposites5ExamplesofNanofillersCarbonnanotubeGraphitenanoplatele

6、tsFusedaluminaCarbonblack63TiO2,nanocementedcarbides,NanocrystallineMaterialsferro-magneticmaterials,superhardmaterials,othernanoceramics.Hall-PetchRelation*:σy=σo+kyd-1/2Issues:Stabilization,costs.Co-WC-C60Cermetcomposite(Fe83C60)5nmgrainsize7GrainBoundaryStrengthening(orHall-PetchStrengthe

7、ning)•Hall-Petchequation:yieldstressandgrainsizerelationship:whereky-thestrengtheningcoefficient(aconstantuniquetoeachmaterial);σo-amaterialsconstantforthestartingstressfordislocationmovement(ortheresistanceofthelatticetodislocationmotion);d-graind