ASTM B319-1991(2004) Standard Guide for Preparation of Lead and Lead Alloys for Electroplating《电镀用铅和铅合金的制备》.pdf

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1、Designation: B 319 91 (Reapproved 2004)Endorsed by AmericanElectroplaters SocietyEndorsed by NationalAssociation of Metal FinishersStandard Guide forPreparation of Lead and Lead Alloys for Electroplating1This standard is issued under the fixed designation B 319; the number immediately following the

2、designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides metho

3、ds for preparing lead or leadalloy products for the application of electroplated or autocata-lytic coatings.1.2 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-priate safety

4、and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 281 Practice for Preparation of Copper and Copper-Base Alloys for Electroplating and Conversion Coatings3. Significance and Use3.1 The preparation of lead and lea

5、d-alloy surfaces forelectroplating is often critical to the successful performance ofelectrodeposited and autocatalytic metallic coatings.3.2 This standard outlines the process operation proceduresand processing solutions required, that lead to satisfactoryelectrodeposited metallic coatings (includi

6、ng undercoating) onsurfaces of lead and lead-alloys.4. Nature of Lead4.1 The tensile strength of lead and lead alloys ranges from15 to 35 MPa (2000 to 5000 psi), therefore, the measuredadhesion of electroplated coatings cannot be greater than thesevalues.4.2 Difficulties in applying high-quality ele

7、ctroplated coat-ings to lead are due to the following properties of lead:4.2.1 The very active chemical nature of lead, leading to theformation of oxide films in air,4.2.2 The fact that the lead surface will form films ofinsoluble lead salts with most acids used in pickling,4.2.3 The ease with which

8、 lead diffuses in contact withnonferrous metals, and4.2.4 The poor resistance to plastic deformation duringpolishing.5. Process Precautions5.1 The following process precautions should be observed:5.1.1 Precleaning of raw castings is sometimes necessary toremove mold parting compounds, surface oxides

9、, and residuesfrom recessed areas which are never reached by polishing-wheel or scratch-brush operations (Section 6).5.1.2 In high-speed type cyanide electroplating solutions,the initial current density must be controlled and kept lowenough so that no gassing occurs to cause poor adhesion. Thisis re

10、vealed as groups of blisters in the high-current-densityareas of the electroplate.5.1.3 If a strike electroplate is used, it should be thickenough to prevent the next electroplating solution from attack-ing the basis lead. A copper or nickel strike 2.5 m thick shouldbe used, but because there are so

11、 many variables involved, nospecific recommendations can be made.5.1.4 Preplates should be of such thickness that completealloying with the lead does not take place, an occurrence thatcauses poor adhesion of subsequent deposits. This defect isindicated by blistering after prolonged storage or after

12、anaccelerated aging test.5.1.5 The lead compounds formed by the action of acids andalkalies most often used in electroplating are not water soluble.Caution must be taken to remove or prevent the formation ofthese to eliminate subsequent adhesion failure. Acids thatcannot be used are sulfuric, hydroc

13、hloric, and hydrofluoric.(Acids that can be used are sulfamic and fluoboric.) Alkaliesshould not be high in caustic content. Mild or buffered cleanersare preferred in order to minimize attack on the basis leadsurface.5.1.6 Engraving of electroplated finishes on lead cannot beperformed on deposits ov

14、er 5 m thick as the deposit will tearaway from the lead at cross cuts. Engine turning by burnishingcan be done on any thickness of deposits.1This guide is under the jurisdiction of ASTM Committee B08 on Metallic andInorganic Coatings and is the direct responsibility of Subcommittee B08.02 on PreTrea

15、tment.Current edition approved April 1, 2004. Published May 2004. Originallyapproved in 1957. Last previous edition approved in 1997 as B 319 91 (1997).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta

16、ndards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.7 Polishing and coloring of the deposit must be per-formed at slow speeds, and with loose

17、or cooled buffs toeliminate overheating and flowing of basis metal.6. Precleaning6.1 Remove fins and parting lines by use of trimming dies orby scraping, filing, or grinding. Some machining may be doneat this point, such as drilling holes, or milling or cutting slots,groove, flats, or squared surfac

18、es.6.2 Clean in alkaline, emulsion type, or other standardcleaning material to remove surface materials (5.1.5).6.3 After rinsing, transfer the parts into one of the followingpickling solutions, the function of which is to remove surfaceoxides, without significant attack on the lead surface.6.3.1 An

19、 aqueous solution containing 250 mL of 48 mass %,fluoboric acid with or without 45 mL of 30 mass % hydrogenperoxide diluted to 1 L. The addition of hydrogen peroxide willincrease the aggressiveness of the pickling solution.6.3.2 An aqueous solution containing 80 mL of glacialacetic acid and 45 mL of

20、 30 mass % hydrogen peroxide dilutedto1L.6.3.3 An aqueous solution containing 100 g of sulfamic aciddiluted to 1 L.NOTE 1These pickling solutions should be held in tanks havingsuitable nonmetallic linings.6.4 After rinsing, an immersion in a water-displacing, film-forming material is advantageous. S

21、ometimes a neutral soap,oil, or synthetic emulsion film may be used according to thetype of polishing compound to be used. These materials areremoved in subsequent operations.7. Assembly of Parts7.1 Precleaned parts then are ready for further assembly,such as soldering to other metals for ornamentat

22、ion or me-chanical reasons.8. Polishing or Buffing8.1 After parting lines, fins, and gate marks are removed,greaseless compounds on loose cloth wheels are used for roughsmoothing followed by a soft leather, chamois, or sheepskinwheel operating at 15 to 25 surface m/s. These are used withwhite lime c

23、ompounds of various grease concentrations. Clothwheels can be used on highly ornamented parts, but not on anysurface having a smooth area, as drag marks will occur.9. Preparation for Electroplating9.1 Precleaning:9.1.1 Solvent or solvent emulsion cleaners can be used if theparts can be rinsed easily

24、 and completely; otherwise alkalinecleaners and ammonia, or wetting agent soaks should be used.Spray washing with alkaline or solvent-type cleaners may beused before the electrocleaning cycle instead of soak cleaning.9.2 Electrocleaning:9.2.1 Cathodic electrocleaning usually is used, especiallyfor d

25、ecorative bright finishes. Anodic electrocleaning dissolvesthe lead and is used sometimes in industrial or specialapplications if stressed or distorted surface layers must beremoved to expose the natural understructure.9.2.2 There are proprietary cleaners designed for specialconditions; however, a c

26、leaner made up using 23 g/L of sodiumcarbonate and 23 g/L of trisodium orthophosphate, anhydrousoperated at 60 to 80C with 6 to 8 V with the work cathodic for30 to 60 s is advantageous. Hand cleaning by mopping andbrushing is performed, but the trend is away from handoperations.9.3 Acid Pickle:9.3.1

27、 An acid pickle of one of the following types is used toremove all oxide residues and insoluble compounds left fromcleaning:9.3.1.1 An aqueous solution containing 120 to 250 mL of 48mass % fluoboric acid diluted to 1 L used at 20 to 25C for 30to 60 s. See Practice B 281.9.3.1.2 An aqueous solution c

28、ontaining 100 g of sulfamicacid dissolved in water and diluted to 1 L used at 20 to 25Cfor 30 to 60 s. A blend of 75 to 85 % by weight sulfamic acidand 15 to 25 % by weight ammonium bifluoride may bedissolved in water at 60 to 120 g/L to form an equivalentsolution.10. Typical Cycles10.1 Stereotype M

29、etal (80 to 84 % Lead, 11 to 13 %Antimony, 4 to 6 % Tin)10.1.1 Preparation for Nickel or Iron Stereotypes:10.1.1.1 Electroclean cathodically and then anodically withthe following solution or a proprietary equivalent:Solution 60 to 90 g/L trisodium orthophosphate crystals(Na3PO42H2O)Temperature 40CVo

30、ltage 6 VCathodic 3 to 4 minAnodic up to 10 sCurrent density 3 A/dm210.1.1.2 Cold water rinse and spray.10.1.1.3 Acid dip with the following solution:Solution 25 volume % of 42 % fluoboric acidTemperature 20 to 25CTime 10 to 15 s10.1.1.4 Cold water rinse and spray.10.1.1.5 Nickel or iron electroplat

31、e, 20 m thick.NOTE 2A small amount of current must be applied prior to and whilethe article is entering the plating solution. After entry, the current shouldbe adjusted to its normal value. Additionally, a nickel strike (see TableX1.1) may be used prior to the nickel or iron electroplate.10.1.2 Alte

32、rnative Preparation for Iron ElectroplatingStereotypes:10.1.2.1 Vapor degrease or wash in Stoddard solvent toremove proof-printing ink.10.1.2.2 Electroclean (see 10.1.1.1).10.1.2.3 Scrub with tampico brush and cleaning solutionused in 10.1.2.2.10.1.2.4 Thoroughly rinse with water.10.1.2.5 Acid dip a

33、s in 10.1.1.3 (see 9.3.1, section 9.3.2, andsection 9.3.3).10.1.2.6 Thoroughly rinse with water.10.1.2.7 Iron electroplate, 20 m thick. (See 10.1.1.5.)NOTE 3The iron may be electrodeposited from the following solu-tion:B 319 91 (2004)2Ferrous ammonium sulfate(FeSO4(NH4)2SO46H2O)340g/LBoric acid (H3B

34、O3) 40 g/LpH 3.1 to 3.4 (adjusted with sulfuric acid)Temperature 60CCurrent density 1 to 5 A/dm211. Decorative Applications11.1 Preparation for Copper Striking:11.1.1 Preclean and water rinse (see 9.1).11.1.2 Electroclean (see 9.2).11.1.3 Water rinse.11.1.4 Dip in acid (see 9.3).11.1.5 Thoroughly wa

35、ter rinse.11.1.6 Cyanide copperstrike to give complete coverage (seeTable X1.3). Other proprietary copper strikes may be used.11.1.7 Water rinse thoroughly to remove all traces ofcyanide.11.1.7.1 Prior to further electroplating, usea1to2%sulfuric acid rinse.11.1.8 Follow with other electrodeposits a

36、s required.11.2 Preparation for Nickel Striking:11.2.1 Preclean and water rinse (see 9.1).11.2.2 Electroclean (see 9.2).11.2.3 Water rinse.11.2.4 Acid dip (see 9.3).11.2.5 Water rinse.11.2.6 Nickel strike to give complete coverage (see TableX1.1 and Table X1.2).11.2.7 Water rinse.11.2.8 Follow with

37、other electrodeposits as required.12. Small Parts12.1 Preparation for Barrel Plating:12.1.1 See Section 6 for precleaning steps.12.1.2 Acid dip (see 9.3).12.1.3 Thoroughly water rinse.12.2 Cyanide copperstrike to give complete coverage (seeTable X1.3). Other proprietary copper strikes may be used.12

38、.2.1 Water rinse thoroughly to remove all traces ofcyanide.12.2.2 Prior to electroplating, usea1to2%sulfuric acidrinse.APPENDIX(Nonmandatory Information)X1. STRIKE SOLUTIONSX1.1 Table X1.1, Table X1.2, and Table X1.3 contain thecomposition of the solutions and the operating conditions fornickel and

39、copper strikes.TABLE X1.1 Nickel Sulfamate Strike SolutionQuantity, g/LNickel sulfamate, Ni(SO3NH2)2) 250Nickel chloride (NiCl26H2O) 25Boric acid (H3BO3)30pH 3.5Temperature 30 to 35CCurrent density 1 to 2 A/dm2B 319 91 (2004)3ASTM International takes no position respecting the validity of any patent

40、 rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at

41、 any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comment

42、s will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted b

43、y ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail

44、); or through the ASTM website(www.astm.org).TABLE X1.2 Nickel Fluoborate Strike SolutionQuantity, g/LNickel fluoborate (Ni(BF4)2) 250Boric acid (H3BO3)30pH (paper) 3.5Temperature 30 to 60CCurrent density 1 to 2 A/dm2TABLE X1.3 Copper Strike SolutionQuantity, g/LCopper cyanide (CuCN) 22.5Sodium cyanide (NaCN) 40Sodium carbonate (Na2CO3)15Total copper (Cu) 16Free cyanide (CNTemperature 40 to 50CCurrent density 1 to 1.5 A/dm2B 319 91 (2004)4