chemistry of surface and interface

《chemistry of surface and interface》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、ChemistryofSurfaceandInterface郭兴伍Sept.4,20101OutlineIntroductionSurfaceenergy:surfacesofsolidsCapillarity:surfacesofliquids21.Introduction3SurfacetensionholdswaterdropletsontheleavesoftheJapaneseRootIris.Howcananinsectintheabovepicturewalkonthewater?45Electrostaticdischarge(ESD)Timel

2、ineofthehistoricaldevelopmentofsurfacechemistry6WhatisSurface?-surfaceversusbulkSurfaceproperty:Adsorption,catalysis,oxidationFriction,adhesion,lubricationBulkproperty:Electricalconductance,Thermalconductance,Meltingtemperature,HeatcapacityModulus,hardness7通常的材料性能8WhatIsaSurface?Mate

3、rialendsatsomepoint.The“somepoint”isthesurfaceofthematerial.Whentwomaterialsareinphysicalcontact,theirsuperimposed(overlapped)surfacesbecomeaninterface.Surfacesandinterfacesarethematerialboundaries.Eitherthechemicalcompositionorthecrystallographydramaticallychangesacrosstheboundary.9

4、ExamplesofSurfacesandInterfacesWherearethesurfaces?Whatkindofsurfacesarethey?10DifferencesamongSurfacesofGases,Liquids,andSolidsGasses:nosurfaceLiquids:surfacedefectscanberepairedbythemselves.Solids:surfacedefectsarepermanent.11ExamplesofSituationsWhereSurfacesPlayaMajorRoleWaterdrop

5、sandsoapbubblesSurfaceenergykeepsthemsphericalSource:mediastream.bournemouth.ac.uk/NCCA/images/ful...Source:http://courses.ncssm.edu/hsi/splashes/video/splash354_inv.gif12WhyAreSoapBubblesSpherical?Cubevs.SphereMass:1gm=1gmVolume:1cm3=1cm3Surfacearea:6cm2>4.84cm2Foragivenvolume(ormas

6、s)thesurfaceareaisshapedependent.Therefore,totalsurfaceenergyisshapedependent.13WhatAre“Specific”Properties?Specific=>perunitmass,or=>perunitvolumeSpecificarea=areapermass,or=areapervolumeSpecificareaofcubeisgreaterthanspecificareaofsphere.14SurfaceEnergy：Totalsurfaceenergyisthesurfa

7、ceareatimesthespecificsurfaceenergy.15Mass:1+1=2gm=2gmVolume:1+1=2cm3=2cm3Area:6+6=12cm2>10cm2TotalSurfaceEnergy:12γ>10γTolowerthetotalsurfaceenergy,twosmallcubesmergeintoone.SurfaceEnergyasaDrivingForce16SphericalBubbleandSurfaceEnergyTotalsurfaceenergyis4πr2γforasoapbubblewiththera

8、diusr.Ifther