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1、NanoSaucturedMaterials,Vol.12,pp.119-122,1999ElsevierScienceLtdPergamon81999ActaMetallureicaInc.PrintedintheUSA.Allrightskerved09659113l99l.$-seefrontmatterPI1SO9659773(99)00078-lPRODUCTIONOFNANOMETER-SIZEDAlNPOWDERSBYTHEEXPLODINGWIREMETHODY.A.KotovandO.M.
2、SamatovInstituteofElectrophysics,UralDivisionoftheRussianAcademyofSciences34KomsomolskayaSt.,620049Ekaterinburg,RussiaAbstract-Wehaveperformedexperimentstoexplorethepossibilityofmakingpurenanometer-sizedAlNpowdersbyelectricalexplosionofaluminumwireinanatmo
3、sphereofnitrogen-containinggases.Itisshownthatraisingthedensityoftheenergyinjectedintothemetal,applyingincreasedpressures,andahighworking-gasjlowratehelpassuretheproductionofAlNpowderswithaspectficsurfaceupto53m2/g,dBsr=35nm.Particleshaperangesj?omnearlysp
4、hericaltorigorous-cutparticles.Theyieldofsuchpowderaccountsfor50%ofthetotalmassofpowder.Thepowderthusproducedcontainsnomorethan1wt.%ofimpurities,includingoxygen.01999ActaMetallurgicaInc.INTRODUCTIONMuchinterestiscurrentlybeingshownintheproductionofAlNnanop
5、owders.Thisisbecause,AlNceramicscombineshighthermalconductivity,thermalstabilityandelectricalresistivitywithalowthermalexpansioncoefficientandalowleveloflossesathighfrequencies(l-3).Ontheotherhand,nomethodhasasyetbeendevelopedfortheproductionofsuchpowdersa
6、tanacceptablecommercialcost.Electricalexplosionofwire(EEW)isoneofthepromisingmethodsfortheproductionoflow-costnanopowders.Thetypicalparticlesizeofmetalpowdersproducedbythismethodreducessubstantiallywithincreasingsuperheatofthemetal,K=W/Ws(whereWistheenergy
7、injectedintotheexplodingwireandWsthewiresublimationenergy)(4,5),diminishesinconsiderablywithdecreasingwirediameterD(5,S),andincreasesasthesurrounding-gaspressurePisraised(6).TheKdependenceofthespecificsurfaceofAlpowdermadebyexplosioninargonundernormalcondi
8、tionsisgiveninFig.1.TakingintoaccountthedissociationoftherequiredamountofNZ,5.6kJisabsorbedpergramofAlparticipatinginthereactiontoformAlN.Owingtothat,thetemperatureoftheexpandingAlvaporshouldloweratafasterrat
