电化学腐蚀 chapter 1-2.pptx

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1、CorrosionControlChapter1-2Chapter1Whatiscorrosion?Corrosionisthedamagetometalcausedbyreactionwithitsenvironment.Thecostofcorrosion(2004)inbillionUS$CountryDirectCostIndirectCostUSA303.76200(approximately)Japan59.02FormerUSSR55.01Germany49.26UK8.51Australia7.32Belgium6.75India3.78Pola

2、nd3.53Canada3.38...............Global510.14940(approximately)Bhaskaran,R.,N.Palaniswamy,andN.S.Rengaswamy,GlobalCostofCorrosion—AHistoricalReview,inCorrosion:Materials,Vol13B,ASMHandbook.2005,ASMInternational.Chapter2ThermodynamicsThedrivingforceformetalliccorrosionistheGibbsenergych

3、ange,ΔG.E=－ΔG/nFΔG=－EnFΔG<0SpontaneousΔGΔG=0EquilibriumΔG>0NonspontaneousCorrosionCell(fourcomponents)1.Anode2.Cathode3.Electrolyte4.ConnectionElectrodepotentialsStandardelectrodepotentials(Eº)istheelectromotiveforceformetalinstandardcondition.Nernstequationcouldcalculatethepotential

4、oftherealenvironment.NernstequationFor25℃ClassificationsofCorrosionChemicalCorrosionNoclearseparateidentifica-tionofthecomponentsofanelectrochemicalcellcanbemade.ElectrochemicalCorrosionFourelementsofanelectrochemicalcellarepresentandidentifiable.Corrosion-MechanicalInteractionsErosi

5、on-corrosionStress-corrosioncrackingHydrogendamageCorrosionfatigue