1、Designation:D832520Standard Guide forEvaluation of Nuclear Graphite Surface Area and Porosityby Gas Adsorption Measurements1This standard is issued under the fixed designation D8325;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the
2、 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 The purpose of this Guide is to provide methodologicinformation specific to highly graphitized,low surface areamat
3、erials used in the nuclear industry.It applies to nitrogenadsorption measurements at 77 K for the characterization ofgraphite pore structure,such as:(1)specific surface area;(2)cumulative volume of open pores(for pore sizes less thanabout 300 nm);and(3)distribution of pore volumes as afunction of po
4、re sizes(for pore sizes less than about 30 nm).These properties are related to graphites reactivity in oxidativeenvironments,graphites ability to retain fission products,andgas transport through graphites pore system.1.2 Characterization of surface area(also known as theBrunauer-Emmett-Teller“BET”me
5、thod)and porosity innuclear graphite by gas adsorption is challenged by nucleargraphites low specific surface area,weak adsorptioninteractions,and energetic and structural heterogeneity ofsurface sites in gas-accessible pores.This guide providesrecommendations and practical information related to th
6、enitrogen adsorption method,including guidance on specimenpreparation,selection of experimental conditions,dataprocessing,and interpretation of results.1.3 Other porosity characterization methods used fornuclear graphite,such as krypton adsorption at 77 K,argonadsorption at either 77 K or 87 K,heliu
7、m pycnometry(TestMethod B923),and mercury intrusion porosimetry,are not inthe scope of this guide.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,
8、associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally r
9、ecognized 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:2C1274 Test Method for
10、 Advanced Ceramic Specific SurfaceArea by Physical AdsorptionD3663 Test Method for Surface Area of Catalysts andCatalyst CarriersD4641 Practice for Calculation of Pore Size Distributions ofCatalysts and Catalyst Carriers from Nitrogen DesorptionIsothermsD4222 Test Method for Determination of Nitroge
11、n Adsorp-tion and Desorption Isotherms of Catalysts and CatalystCarriers by Static Volumetric MeasurementsD6556 Test Method for Carbon BlackTotal and ExternalSurface Area by Nitrogen AdsorptionD6761 Test Method for Determination of the Total PoreVolume of Catalysts and Catalyst CarriersB923 Test Met
12、hod for Metal Powder Skeletal Density byHelium or Nitrogen Pycnometry2.2 ISO Standards:3ISO 9227 Determination of the specific surface area of solidsby gas adsorption BET method(Second edition)3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 adsorbate,nthe material retained by a
13、dsorption atthe interface between a solid and a gas or liquid.3.1.2 adsorbent,na solid material able to concentratemeasurable quantities of other substances on its accessiblesurface,either external or in pores.1This guide is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fu
14、els,and Lubricants and is the direct responsibility of Subcom-mittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved June 1,2020.Published July 2020.DOI:10.1520/D8325-20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at
15、 serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization(ISO),ISOCentral Secretariat,BIBC II,Chemin de Blandonnet 8,CP 401,1214 Vernier,Geneva,Switzerland,http:/
16、www.iso.org.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.3.1.3 adsorption,nthe process by which molecules areconcentrated o
