ASTM_B_940_-_05_2014.pdf

Designation:B94005(Reapproved 2014)Standard Practice forTesting Non-Chromate Coatings on Zinc and CadmiumSurfaces1This standard is issued under the fixed designation B940;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 covers a procedure for evaluating theprotective value of chemical and electrochemical conversioncoatings produced by non-chromate(chromate being defined asa compound that has chromium in the plus six oxidation state,and as such,chromium compounds in other oxidation states,such as plus three,shall not be excluded)treatments of zinc andcadmium surfaces.1.2 The protective value of a non-chromate coating isusually determined by salt-spray test and by determiningwhether or not the coating possesses adequate abrasion resis-tance when applied for that purpose.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.2.Referenced Documents2.1 ASTM Standards:2B117 Practice for Operating Salt Spray(Fog)Apparatus3.Terminology3.1 Descriptions of Terms:3.1.1 time to failuretime to failure will depend on the typeof coating tested.The minimum expected protective valueobtainable in a given salt spray test is given in Appendix X2.3.1.1.1 DiscussionIn most instances,failure is defined asthe first appearance on significant surfaces of white corrosionproducts visible to the unaided eye at normal reading distance,except that the presence of white corrosion products at sharpedges(for example,on threaded fasteners)and at junctionsbetween dissimilar metals should not be considered failure.Insome instances,it may be desirable to regard the first appear-ance of red rust as failure.3.1.2 significant surfacesin general,significant surfacesare those surfaces that are visible and subject to corrosion orwear,or both,except that surfaces that are normally difficult tocoat by electroplating or mechanical deposition may be ex-empt.The designation of significant surfaces may be indicatedon the drawing.4.Significance and Use4.1 This practice is applicable to non-chromate coatings thatare colorless,colored,electrochemically applied or non-electrochemically applied.The zinc or cadmium,or both,maybe electrodeposited,mechanically deposited,hot-dipped,rolled,or in the form of castings.4.2 Because of variables inherent in the salt-spray testwhich may differ from one test cabinet to another,interpreta-tion of test results for compliance with expected performanceshould be specified by the purchaser.4.3 Properties such as thickness,color,luster,and ability toprovide good paint adhesion are not covered in this practice,nor are the chemical composition and the method of applica-tion of these finishes.5.Conditioning5.1 AgingBefore subjecting a non-chromate coating totest,check with the chemical producer to determine if aging isan issue that needs to be considered.5.2 Preparation of SpecimenThe test surface must be freeof fingerprints and other extraneous stains and must not becleaned except by gentle wiping with a clean,dry,soft cloth toremove loose particles.Oily or greasy surfaces should not beused for testing,and degreasing with organic solvents is notrecommended.6.Procedure6.1Salt Spray TestExpose the clean specimen to a 5%solution salt spray and conduct the test in accordance with the1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatingsand is the direct responsibility of Subcommittee B08.07 onConversion CoatingsCurrent edition approved Nov.1,2014.Published November 2014.Originallyapproved in 2000.Last previous edition approved in 2009 as B940 05(2009)1.DOI:10.1520/B0940-05R14.2For 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 States1 latest revision of Practice B117.Unless otherwise specified,only those surfaces that are positioned in the test chamber inaccordance with Practice B117 are considered pertinent forevaluating failure.The exposed surfaces of the test specimensshall be free of all visible defects,such as scratches or pits,orboth,and shall be flat.The surfaces shall not be cleaned withabrasive materials or abrasive chemical agents that may etchthe exposed surfaces.Corrosion found on surfaces within1