ASTM_B_630_-_88_2017.pdf

Designation:B63088(Reapproved 2017)Standard Practice forPreparation of Chromium for Electroplating with Chromium1This standard is issued under the fixed designation B630;the number immediately following the 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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice is intended to serve as a process guide(notas a standard procedure)for producing adherent electrodepositsof chromium on chromium for engineering use.1.2 Only well-known,generally practical methods usinghexavalent chromium plating baths have been included.Someof the newer proprietary chromium plating processes producechromium plating for which this process is unsuitable.Suppli-ers of the processes should be consulted.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2B177 Guide for Engineering Chromium Electroplating3.Significance and Use3.1 Electrodeposits of chromium on chromium are producedin cases where it is desired to obtain a better performingcoating,to reclaim plated parts that are defective,or restoreworn chromium coatings to original dimensions.4.Preparation of Surface4.1 Surface FinishingThe smoothness of the chromiumcoating before electroplating with chromium should closelyapproximate the requirements of the finished part.It is usuallyachieved by appropriate grinding with a diamond wheel.4.2 Stripping and Basis MetalWith previously electro-plated parts where the chromium deposit has been wornthrough,or where grinding has exposed the basis metal,preferred results are obtained by stripping the remainingchromium completely.However,it is possible to obtain satis-factory deposits on such substrates by careful attention todetails in the pretreatment and electroplating process steps.4.3 Stripping may be done by several methods,includingproprietary processes or inhibited hydrochloric acid solution(10 to 20%by volume),or anodic treatment at 55 to 800A/m2(5 to 75 A/ft2)in a solution of 35 to 50 g/L(5 to 7 oz/gal)ofsodium hydroxide or 60 to 75 g/L(8 to 10 oz/gal)of sodiumcarbonate at 20 to 25C(70 to 80F).4.4 Process Outline:4.4.1 Preclean(see 5.1.1 and 5.1.2),4.4.2 Alkaline electrolytic clean(see 5.1.3),4.4.3 Rinse(cold water),4.4.3.1 Rinse(hot water),4.4.3.2 Dry,4.4.3.3 Mask(see 5.2),4.4.4 Activate(see 5.3),4.4.5 Chromium electroplate,4.4.6 Rinse(cold water),4.4.7 Rinse(hot water),and4.4.8 Dry.5.Procedure5.1 CleaningThe following cleaning treatments may beused for all conditions and types of electrodeposited chro-mium.The choice of the procedures will be governed largelyby the condition of the surface.5.1.1 PrecleaningWhen considerable amounts of greaseand oil are present on the surface,precleaning(emulsion oralkaline spray or soak)is necessary to remove the bulk of thesoil.5.1.2 Abrasive CleaningOxide and other films may beremoved by mechanical techniques using such abrasives as fineemery on a cloth or a wheel,pumice slurry,or greaseless1This 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 May 1,2017.Published May 2017.Originallyapproved in 1977.Last previous edition approved in 2010 as B630 88(2010).DOI:10.1520/B0630-88R17.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 buffing compounds.Grit blasting,shot blasting,wet blasting,or vapor honing may also be used.Abrasive cleaning isgenerally not necessary when suitable mechanical finishingprocedures have been used.5.1.3 Cathodic Alkaline Cl