腐蚀科学术语.docx

腐蚀科学术语.docx

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腐蚀科学术语

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absorption.

Aprocessinwhichliquidmoleculesaretakenupbyaliquidorsolidanddistributedthroughoutthebodyofthatliquidorsolid.Comparewithadsorption..

acceleratedcorrosiontest.

Methoddesignedtoapproximate,inashorttime,thedeterioratingeffectundernormallong-termserviceconditions.

acid.

Achemicalsubstancethatyieldshydrogenions（H+）whendissolvedinwater.Comparewithbase..

acidembrittlement.

Aformofhydrogenembrittlementthatmaybeinducedinsomemetalsbyacid.

acidrain.

AtmosphericprecipitationwithapHbelow3.6to5.7.Burningoffossilfuelsforheatandpoweristhemajorfactorinthegenerationofoxidesofnitrogenandsulfur,whichareconvertedintonitricandsulfuricacidswasheddownintherain.Seealsoatmosphericcorrosion.

acicularferrite.

Ahighlysubstructurednon-equiaxedferriteformeduponcontinuouscoolingbyamixeddiffusionandshearmodeoftransformationthatbeginsatatemperatureslightlyhigherthanthetransformationtemperaturerangeforupperbainite.Itisdistinguishedfrombainiteinthatithasalimitedamountofcarbonavailablethus,thereisonlyasmallamountofcarbidepresent.

acrylic.

Resinpolymerizedfromacrylicacid,methacrylicacid,eatersoftheseacids,oracrylonitrile.

activation.

Thechangingofapassivesurfaceofametaltoachemicallyactivestate.Contrastwithpassivation..

active

Astateinwhichametaltendstocorrode;referringtothenegativedirectionofelectrodepotential（oppositeofpassiveornoble）.

activemetal

Ametalreadytocorrode,orbeingcorroded

activepotential.

Thepotentialofacorrodingmaterial.

activity.

Ameasureofthechemicalpotentialofasubstance,wherechemicalpotentialisnotequaltoconcentration,thatallowsmathematicalrelationsequivalenttothoseforidealsystemstobeusedtocorrelatechangesinanexperimentallymeasuredquantitywithchangesinchemicalpotential.

activity（ion）.

Theionconcentrationcorrectedfordeviationsfromidealbehavior.Concentrationmultipliedbyactivitycoefficient.activitycoefficient.Acharacteristicofaquantityexpressingthedeviationofasolutionfromidealthermodynamicbehavior;oftenusedinconnectionwithelectrolytes.

additionagent.

Asubstanceaddedtoasolutionforthepurposeofalteringorcontrollingaprocess.Examplesincludewettingagentsinacidpickles,brightenersorantipittingagentsinplatingsolutions,andinhibitors.

additive

Asubstanceaddedinasmallamount,usuallytoafluid,foraspecialpurpose,suchastoreducefriction,corrosion,etc.

adsorption.

Thesurfaceretentionofsolid,liquid,orgasmolecules,atoms,orionsbyasolidorliquid.Comparewithabsorption..

aeration.

（1）Exposingtotheactionofair.

（2）Causingairtobubblethrough.（3）Introducingairintoasolutionbyspraying,stirring,orasimilarmethod.（4）Supplyingorinfusingwithair,asinsandorsoil.

aerationCell

Anoxygenconcentrationcell;anelectrolyticcellresultingfromdifferencesindissolvedoxygenattwopoints.Alsoseedifferentialaerationcell..

agehardening.

Hardeningbyaging,usuallyafterrapidcoolingorcoldworking.

aging.

Achangeinthepropertiesofcertainmetalsandalloysthatoccursatambientormoderatelyelevatedtemperaturesafterhotworkingoraheattreatment（quenchaginginferrousalloys,naturalorartificialaginginferrousandnonferrousalloys）orafteracold-workingoperation（strainaging）.Thechangeinpropertiesisoften,butnotalways,duetoaphasechange（precipitation）,butneverinvolvesachangeinchemicalcompositionofthemetaloralloy.Seealsoagehardening,artificialaging,naturalaging,averaging,precipitationhardening,precipitationheattreatment,quenchaging,andstrainaging..

alclad.

Compositewroughtproductcomprisedofanaluminumalloycorehavingononeorbothsurfacesametallurgicallybondedaluminumoraluminumalloycoatingthatisanodictothecoreandthuselectrochemicallyprotectsthecoreagainstcorrosion.

alkalimetal.

AmetalingrouplAoftheperiodicsystem–namely,lithium,sodium,potassium,rubidium,cesium,andfrancium.Theyformstronglyalkalinehydroxides,hencethename.

alkaline.

（1）Havingpropertiesofanalkali.

（2）HavingapHgreaterthan7.

alkalinecleaner.

Amaterialblendedfromalkalihydroxidesandsuchalkalinesaltsasborates,carbonates,phosphates,orsilicates.Thecleaningactionmaybeenhancedbytheadditionofsurface-activeagentsandspecialsolvents.

alkyd.

Resinusedincoatings.Reactionproductsofpolyhydricalcoholsandpolybasicacids.

alkylation.

（1）Achemicalprocessinwhichanalkylradicalisintroducedintoanorganiccompoundbysubstitutionoraddition.

（2）Arefineryprocessforchemicallycombiningisoparaffinwitholefinhydrocarbons.

alligatoring.

（1）Pronouncedwidecrackingovertheentiresurfaceofacoatinghavingtheappearanceofalligatorhide.

（2）Thelongitudinalsplittingofflatslabsinaplaneparalleltotherolledsurface.Alsocalledfish-mouthing.

alloyplating.

Thecodepositionoftwoormoremetallicelements.

alphaferrite.

Seeferrite..

alphairon.

Thebody-centeredcubicformofpureiron,stablebelow910oC（l670oF）.

alternate-immersiontest.

Acorrosiontestinwhichthespecimensareintermittentlyexposedtoaliquidmediumatdefinitetimeintervals.

aluminizing.

Formingofanaluminumoraluminumalloycoatingonametalbyhotdipping,hotspraying,ordiffusion.

amalgam.

Analloyofmercurywithoneormoreothermetals.

ammeter.

Aninstrumentformeasuringthemagnitudeofelectriccurrentflow.

amorphoussolid.

Arigidmaterialwhosestructurelackscrystallineperiodicity;thatis,thepatternofitsconstituentatomsormoleculesdoesnotrepeatperiodicallyinthreedimensions.Seealsometallicglass..

amphoteric.

Atermappliedtooxidesandhydroxideswhichcanactbasictowardstrongacidsandacidictowardstrongalkalis.Substanceswhichcandissociateelectrolyticallytoproducehydrogenorhydroxylionsaccordingtoconditions.

anchorite.

Azinc-ironphosphatecoatingforironandsteel.

anaerobic

Intheabsenceofairorunreactedorfreeoxygen.

anion

Anionorradicalwhichisattractedtotheanodebecauseofthenegativecharge.Seealsocationandion.

annealing.

Agenerictermdenotingatreatment.consistingofheatingtoandholdingatasuitabletemperature,followedbycoolingatasuitablerate,usedprimarilytosoftenmetallicmaterials,butalsotosimultaneouslyproducedesiredchangesinotherpropertiesorinmicrostructure.Thepurposeof'suchchangesmaybe.butisnotconfinedto.improvementofmachinability,facilitationofcoldwork,improvementofmechanicalorelectricalproperties,and/orincreaseinstabilityofdimensions.Whenthetermisusedbyitself,fullannealingisimplied.Whenappliedonlyforthereliefofstress,theprocessisproperlycalledstressrelievingorstress-reliefannealing.

anode

Theelectrodeatwhichoxidationorcorrosionofsomecomponentoccurs（oppositeofcathode）.Electronsflowawayfromtheanodeintheexternalcircuit.

anodecorrosion.

Thedissolutionofametalactingasananode.

anodecorrosionefficiency

RatioofactualtotheoreticalcorrosionbasedonthetotalcurrentflowcalculatedbyFaraday’slawfromthequantityofelectricitythathaspassed.

anodeeffect.

Theeffectproducedbypolarizationoftheanodeinelectrolysis.Itischaracterizedbyasuddenincreaseinvoltageandacorrespondingdecreaseinamperageduetotheanodebecomingvirtuallyseparatedfromtheelectrolytebyagasfilm.

anodeefficiency.

Currentefficiencyoftheanode..

anodefilm.

（1）Theportionofsolutioninimmediatecontactwiththeanode,especiallyiftheconcentrationgradientissteep.

（2）Theouterlayeroftheanodeitself.

anodiccleaning.

Electrolyticcleaninginwhichtheworkistheanode.Alsocalledreverse-currentcleaning.

anodiccoating.

Afilmonametalsurfaceresultingfromanelectrolytictreatmentattheanode..

anodicinhibitor

Achemicalsubstanceorcombinationofsubstancesthatpreventorreducetherateoftheanodicoroxidationreactionbyaphysical,physico-chemicalorchemicalaction.

anodicpolarization

Thechangeintheinitialanodepotentialresultingfromcurrentfloweffectsatorneartheanodesurface.Potentialbecomesmodenoble（morepositive）becauseofanodicpolarization.

anodicpotential

Anappreciablereductionincorrosionbymakingametalananodeandmaintainingthishighlypolarizedconditionwithverylittlecurrentflow.

anodicprotection

Atechniquetoreducecorrosionofametalsurfaceundersomeconditionsbypassingsufficienttoittocauseitselectrodepotentialtoenterandremaininthepassiveregion;imposinganexternalelectricalpotentialtoprotectametalfromcorrosiveattack.（Applicableonlytometalsthatshowactive-passivebehavior.）Contrastwithcathodicprotection..

anodicreaction.

Electrodereactionequivalenttoatransferofpositivechargefromtheelectronictotheionicconductor.Ananodicreactionisanoxidationprocess.Anexamplecommonincorrosionis:

Me->Me（+n）+n（e-）.

anodizing.

Formingaconversioncoatingonametalsurfacebyanodicoxidation;mostfrequentlyappliedtoaluminum.

anolyte

Theelectrolyteadjacenttotheanodeinanelectrolyticcell.

anti-fouling

Intendedtopreventfoulingofunder-waterstructures,suchasthebottomsofships;referstothepreventionofmarineorganism'sattachmentorgrowthonasubmergedmetalsurfac