Designation:D1732−03(Reapproved2013)StandardPracticesforPreparationofMagnesiumAlloySurfacesforPainting1ThisstandardisissuedunderthefixeddesignationD1732;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thesepracticescovertwoclassesoftreatmentforpreparationofmagnesiumalloysurfacesforpainting,asfollows:ClassI—ChemicalTreatments.ClassII—AnodicTreatments.Ingeneral,thelattertreatmentsarethemoreprotectiveofthetwoclasses.Mechanical(abrasive)treatments,solventcleaning,alkalinesolutiontreatments,andacidpicklesnotresultinginprotectiveconversioncoatingsaresuitableprelimi-narytreatmentsonlyformetaltobeexposedundermildlycorrosive(indoor)exposures.Whenahighdegreeofcorrosionprotectionandpaintadhesionaredesired,asinmanyoutdoorenvironments,surfacepreparationbyoneoftheaboveconversion-coatclassesisnecessary.Thehexavalentchromiumbasedmethodsgivenarenotrecommendedashexavalentchromiumisaknowncarcinogen.NOTE1—TestingofCoatings—Qualitycontroltestsofcoatingsarefrequentlydesirable,andthesegenerallyconsistofexposures,withorwithoutpaint,tosaltspray,humidity,ornaturalenvironments,withsuitableproceduresforassessingthedegreeofbreakdownsufferedafterfixedtimeintervals.Itisrecommendedthatqualitycontroltestsofcoatingsshallbemadeasfaraspossiblewithhigh-puritymaterial(forexampleAZ31Aalloy),2theinherentcorrosionrateofwhichisrelativelyconsistentfrombatchtobatch)andthatprecautionsshallbetakentoremovesurfacecontaminationbeforecoatingsareapplied.Suchcontami-nationshallberemovedbyacidpicklingtoadepthofatleast0.001in.(25µm)perside.1.2Thisstandardmayinvolvehazardousmaterials,operations,andequipment.Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthi...
