腐蚀科学术语Word格式.docx
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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