1、Designation:B87796(Reapproved 2013)Standard Test Method forGross Defects and Mechanical Damage in Metallic Coatingsby the Phosphomolybdic Acid(PMA)Method1This standard is issued under the fixed designation B877;the number immediately following the designation indicates the year oforiginal adoption o
2、r,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test standard covers equipment and methods forusing phosphomolybdic acid(PMA)to
3、detect gross defects andmechanical damage including wear through in metallic coat-ings of gold,silver,or palladium.These metals comprise thetopmost metallic layers over substrates of nickel,copper,orcopper alloys.1.2 Recent reviews of porosity testing,which include thosefor gross defects,and testing
4、 methods can be found in theliterature.2,3An ASTM guide to the selection of porosity andgross defect tests for electrodeposits and related metalliccoatings is available as Guide B765.Other related porosity andgross defects test standards are Test Methods B735,B741,B798,B799,B809,and B866,Specificati
5、ons B488,B679,andB689.1.3 The values stated in SI units are the preferred units.Those in parentheses are for information only.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro
6、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:4B374 Terminology Relating to ElectroplatingB488 Specification for Electrodeposited Coatings of Goldfor Engineering UsesB542 Terminology Relating to El
7、ectrical Contacts and TheirUseB679 Specification for Electrodeposited Coatings of Palla-dium for Engineering UseB689 Specification for Electroplated Engineering NickelCoatingsB735 Test Method for Porosity in Gold Coatings on MetalSubstrates by Nitric Acid VaporB741 Test Method for Porosity In Gold C
8、oatings On MetalSubstrates By Paper Electrography(Withdrawn 2005)5B765 Guide for Selection of Porosity and Gross Defect Testsfor Electrodeposits and Related Metallic CoatingsB798 Test Method for Porosity in Gold or Palladium Coat-ings on Metal Substrates by Gel-Bulk ElectrographyB799 Test Method for
9、 Porosity in Gold and PalladiumCoatings by Sulfurous Acid/Sulfur-Dioxide VaporB809 Test Method for Porosity in Metallic Coatings byHumid Sulfur Vapor(“Flowers-of-Sulfur”)B866 Test Method for Gross Defects and Mechanical Dam-age in Metallic Coatings by Polysulfide Immersion3.Terminology3.1 Definition
10、sMany terms in this test method are definedin Terminology B374 or B5423.2 Definitions of Terms Specific to This Standard:3.2.1 base metal,nany metal other than gold,silver,platinum,palladium,iridium,or rhodium.Typical base metalsused as underplates or substrates are copper,nickel,tin,lead,and their
11、alloys.3.2.2 defect indications,ncolored droplets resulting fromthe reaction between the PMA reagent and the underlyingmetal.3.2.3 gross defects,nthose breaks in the coating thatexpose relatively large areas of underlying metal to theenvironment.Gross defects include those produced by me-chanical da
12、mage and wear,as well as as-plated large pores withdiameters an order of magnitude greater than intrinsic porosityand networks of microcracks.1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 onT
13、est Methods.Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1996.Last previous edition approved in 2008 as B877 96(2008).DOI:10.1520/B0877-96R13.2Clarke,M.,“Porosity and Porosity Tests,”Properties of Electrodeposits,ed.bySand,Leidheiser,and Ogburn,The Electrochemica
14、l Society,1975,p.122.3Krumbein,S.J.,“Porosity Testing of Contact Platings,”Trans.Connectors andInterconnection Technology Symposium,Philadelphia,PA,October 1987,p.47.4For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book
15、of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.5The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE1L
16、arge pores and microcrack networks indicate serious devia-tions from acceptable coating practice(dirty substrates and contaminatedor out-of-balance plating baths).3.2.4 intrinsic porosity,nthe normal porosity that ispresent,to some degree,in all commercial thin electrodeposits(precious metal coatings for engineering purposes)that willgenerally follow an inverse relationship with thickness.NOTE2Intrinsic porosity is due to small deviations from ideal platingand surface preparation conditions.Scan
