WSS-M21P44-A1 to A4-20040914-镀锌镍合金三价铬钝化表面处理-eng.pdf
ENGINEERINGMATERIALSPECIFICATION
CORROSIONPROTECTIVECOATING,ZINCNICKELALLOY,WSS-M21P44-A1
TRIVALENTPASSIVATE,SILVER
CORROSIONPROTECTIVECOATING,ZINCNICKELALLOY,WSS-M21P44-A2
TRIVALENTPASSIVATEWITHORGANICSEAL,SILVER
CORROSIONPROTECTIVECOATING,ZINCNICKELALLOY,WSS-M21P44-A3
TRIVALENTPASSIVATEWITHCATHODICELECTROCOAT,
BLACK
CORROSIONPROTECTIVECOATING,ZINCNICKELALLOY,WSS-M21P44-A4
TRIVALENTPASSIVATEWITHWATERBORNETOPCOAT,
BLACK
1.SCOPE
Thematerialsdefinedbythesespecificationsarecorrosionprotectivecoatingsappliedsequentiallyper
supplierspecificationsoversteel.Theyconsistofanalkalinezincnickelalloyelectrodepositanda
trivalentchromiumpassivate/adhesionpromoter.A2,A3andA4arefollowedrespectivelybyan
organicseal,acathodicelectrocoat,orawaterbornetopcoat.Whenusedwithanintegrallycured
torquemodifiedpostdip,theseprocessesprovideconsistenttorque-tensioncontrol.
Allprocessesarefreeofhexavalentchromium,leadandcadmium.
2.APPLICATION
Thesespecificationswerereleasedformaterialsusedascorrosionprotectivecoatingsoversteel
fastenersandsmallparts.Theprocessesmayinducehydrogenembrittlementandthereforethese
coatingsmustbehydrogenembrittlementrelievedwhenappliedtohighhardnesspartsinaccordance
withWSS-M99A3-A.
ThecuretemperatureoftheorganicsealusedforA2is80to120°C.
Thecuretemperatureofthecathodicsyste