1、Designation: B 629 77 (Reapproved 2008)Standard Practice forPreparation of Molybdenum and Molybdenum Alloys forElectroplating1This standard is issued under the fixed designation B 629; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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 practice covers a procedure for preparing molyb-denum and its alloys for electroplating. The proced
3、ure utilizestechniques, equipment, and chemicals that are common toelectroplating. Specialized procedures such as hydrogen heattreatment and fused salt pickling are not included. These andother procedures can be found in the references listed at the endof this practice.1.2 This standard does not pur
4、port 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Significance and Use2.1 Molybdenum is used
5、 in engineering applications wherestrength and rigidity of component parts are needed, especiallyat high temperatures. Its good strength at high temperatures,low vapor pressure, and good impact and creep resistancemake it attractive for load-bearing items such as turbine blades,mechanical seals, roc
6、ket motor parts, heating elements, andelectronic devices. Molybdenum, however, is easily oxidized,and the oxides are not protective. The volatility of the oxidesabove 800C can lead, in the case of unprotected parts, tocatastrophic oxidation and to losses in dimensions. Electro-plated coatings are ap
7、plied to molybdenum to prevent oxida-tion, to prevent seizing and galling, and to assist joining bysoldering, brazing, and diffusion bonding.3. Procedure3.1 Precleaning:3.1.1 The principles of electroplating on molybdenum aresimilar to those of other metals. The surfaces must be free ofdirt, grease,
8、 and other foreign matter. Solvent, emulsion, andsoak cleaners are suitable for precleaning to remove grosssurface contaminants. If a molybdenum specimen is subjectedto severe forming operations and retains a carbonaceoussurface layer, descale the part by immersion in a 110 g/Lsolution of sodium hyd
9、roxide at or near boiling, or bymechanical finishing. Glass bead blasting can be used toremove uneven coatings of scale without disturbing the finishof the metal.3.1.2 Cathodic alkaline cleaning is preferred for the finalprecleaning so as to avoid anodic oxidation. Proprietaryformulations used for c
10、athodic alkaline cleaning of othermetals are suitable. Cathodic treatment at about 6 V for 30 to60 s is usually adequate, using a cleaner concentration of 60 to75g/L and a solution temperature of 60 to 75C.3.2 RinseHere, and throughout the procedure, the waterrinses should be warm (approximately 50C
11、).3.3 ElectropolishingEither of the following electropol-ishes may be used. The choice of electropolish and timedepends on the amount of material that can be removed and thedegree of surface improvement desired. The cathodes may belead or carbon. The sulfuric acid bath produces a blue film thatis pa
12、rtly removed in the rinse and completely removed in thealkaline dip.3.3.1 Sulfuric Acid:H2SO4(sp gr 1.83) 80 mass % (755 mL of acid/L)Temperature 20 to 30CCurrent density 1100 to 2200 A/m2anodicTime 30 s3.3.2 Sulfuric - Phosphoric Acid:H2SO4(sp gr 1.83) 50 % vol (500 mL/L)H3PO4(85 %) 50 % vol (500 m
13、L/L)Temperature 50 to 55CCurrent density 2500 A/m2anodicTime 180 s3.4 Rinse.3.5 Alkaline DipBriefly immerse the specimen in a 45-g/L solution of sodium hydroxide at room temperature.3.6 Rinse.3.7 Acid DipBriefly immerse the specimen in a 10-mass % solution of sulfuric acid (58 mL of 1.83 sp gr acid/
14、L)at room temperature.3.8 Rinse.1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 onPre Treatment.Current edition approved Aug. 1, 2008. Published September 2008. Originallyapproved in 1977. Last p
15、revious edition approved in 2003 as B 629 77 (2003).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.9 Chromium StrikingElectroplate the specimen in aconventional chromium electroplating solution for 1 to 5 min at1500 to 2500 A/m2at
16、 a temperature of 50C minimum. Insome cases, it may be necessary to first make the part anodic inthe chromium solution for 1 min at 2200A/m2in order to attaingood adhesion.3.10 Rinse.3.11 Nickel StrikingElectroplate the specimen in the fol-lowing solution at 800 A/m2for 120 s.NiCl26H2O 240 g/LHCl (s
17、p gr 1.18) 10 vol % (100 mL/L)Temperature 20 to 30CAnode nickel or carbon3.12 Rinse.3.13 Electroplate the specimen with the desired metal.REFERENCES(1) Beach, J. G., et al. U. S. Patent 2,928,169 (March 15, 1960).(2) Brenner, A., Plating, Vol 43, 1956, p. 1143.(3) Domnikov, L., Metal Finishing, Vol
18、61, April 1963, p. 64.(4) Finne, R. M., and Bracht, W. R., Journal of Electrochemical Society,Vol 113, 1966, p. 551.(5) Freeman, R. R., and Briggs, J. Z., “Electroplating on MolybdenumMetal,” Climax Molybdenum Co., Ann Arbor, MI, September 1958.(6) Korbelak, A., Plating, Vol 40, 1953, p. 1126, U. S.
19、 Patent 2,697,316.(7) Safranek, W. H., and Schaer, G. R., Proceedings, American Electro-platers Society, Vol 43, 1956, p. 105.(8) Schaer, G. R., U. S. Patent 2,859,158 (November 4, 1958).(9) Schaer, G. R., et al, U. S. Patent 2,886,499 (May 12, 1959).(10) Seegmiller, et al, Proceedings, American Ele
20、ctroplaters Society, Vol49, 1962, p. 67.(11) Valler, L. E., et al. USAED Report No. BMI 813, (April 1, 1953)(Obtainable from National Technical Information Service, Spring-field, VA).ASTM International takes no position respecting the validity of any patent rights asserted in connection with any ite
21、m 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 any time by the responsible technical comm
22、ittee 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 comments will receive careful consideration at a m
23、eeting 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 by ASTM International, 100 Barr Harbor Drive
24、, 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); or through the ASTM website(www.astm.org).B 629 77 (2008)2
