1、Designation:B87596(Reapproved 2013)Standard Specification forAluminum Diffusion Coating Applied by Pack CementationProcess1This standard is issued under the fixed designation B875;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the y
2、ear 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 specification covers the requirements for aluminumdiffusion of metals by the pack cementation method.Packdiffus
3、ion employs the chemical vapor deposition of a metalwhich is subsequently diffused into the surface of a substrate athigh temperature.The material to be coated(substrate)isimmersed or suspended in a powder containing aluminum(source),a halide salt(activator),and an inert diluent such asalumina(fille
4、r).When the mixture is heated,the activatorreacts to produce an atmosphere of aluminum halides whichtransfers aluminum to the substrate for subsequent diffusion.The aluminum-rich surface enhances corrosion,thermalstability,and wear-resistant properties.1.2 This standard does not purport to address a
5、ll 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:2B374 Terminology Relati
6、ng to ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inor
7、ganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsC664 Test Methods for Thickness of Diffusion CoatingD3951 Practice for Commercial Packaging3.Terminology3.1 Definitions used in this specification are in accordancewith Terminology B374.3.2 Definitions of Terms Spe
8、cific to This Standard:3.2.1 diffusion coatinga diffusion coating is one producedby causing an element to react with or diffuse into,or both,thesurface of a metallic substrate,thus,chemically altering thesurface of the substrate.3.2.2 retortscontainers in which powder and parts arepacked for process
9、ing.They can be constructed of carbon,stainless,or high alloys and fabricated in all shapes and sizesto accommodate parts being processed.3.2.3 significant surfaceareas that are essential to theserviceability or function of the article.These surfaces must beidentified on a drawing or marked-up sampl
10、e of product.Areascan fall into one of three categories as follows:3.2.4 coating requiredthese surfaces must be in accor-dance with all quality requirements of this specification.3.2.5 no coating requiredthese surfaces are areas whereno coating is allowed due to a number of reasons includingdimensio
11、nal,fabrication,and welding,as well as others.Materials used for masking are commercially available.3.2.6 optionalthese surfaces do not require coating,but atthe same time do not require masking.4.Classification4.1 There are three classes of aluminum diffusion defined bybase(basis)metal category.4.1
12、.1 Class ICarbon steel and low alloy.4.1.2 Class IIStainless steels.4.1.3 Class IIINickel-based alloys.5.Ordering Information5.1 In order to make the application of this specificationcomplete,the purchaser shall supply the following informationto the vendor through a purchase order and drawings:5.1.
13、1 Title,ASTM designation number,and date of issue ofthis specification.5.1.2 Deposit by classification(see Section 4).1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.03 on Engineering Coatings.C
14、urrent edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1996.Last previous edition approved in 2008 as B875 96(2008).DOI:10.1520/B0875-96R13.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.3 Composition and metallurgical condition of substrateto be coated.5.1.4 Location of s
16、ignificant surfaces(see 3.2.3).5.1.5 Samples for destructive metallurgical test(see 8.1).5.1.6 Any post heat treatment required.5.1.7 Acceptance inspection procedure to be used(seeSection 9).5.1.8 Any requirement for certification(see Section 11).6.Processing Requirements6.1 Substrate PreparationThe metal to be aluminizedshall be free of flaws and defects that will be detrimental to thecoating.Thorough cleaning is essential to ensure satisfactorydiffusion.Materials used for cleaning should not d
