1、Designation:D449621Standard Test Method forD-C Resistance or Conductance of Moderately ConductiveMaterials1This standard is issued under the fixed designation D4496;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last rev
2、ision.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 test method covers the determination of electricalresistance and electrical resistivity of materials that are gener-ally categ
3、orized as moderately conductive and are neither goodelectrical insulators nor good conductors.1.2 This test method applies to the materials that exhibitvolume resistivity in the range of 100to 107-cm or surfaceresistivity in the range of 103to 107(per square).1.3 This test method is designed for mea
4、surements atstandard conditions of 23 C and 50%relative humidity,but itsprinciples of operation can be applied to specimens measuredat lower or higher temperatures and relative humidities.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is the
5、responsibility 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.Specific precautionary statements are given in 8.3.1.5 This international standard was developed in accor-dance with
6、 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:2D25
7、7 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD374/D374M Test Methods for Thickness of Solid Electri-cal InsulationD618 Practice for Conditioning Plastics for TestingD991 Test Method for Rubber PropertyVolume Resistiv-ity Of Electrically Conductive and Antistatic ProductsD171
8、1 Terminology Relating to Electrical Insulation2.2 ASTM Adjuncts:Carbon black test cell(two drawings)33.Terminology3.1 Definitions:3.1.1 moderately conductivea solid material having vol-ume resistivity between 100and 107cm.3.1.2 For definitions of the terms used,but not defined inthis standard,refer
9、 to Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 steady statefor the purpose of this test method,steady-state is attained if any rate of change in the observedresistance(or conductance)averages less than 0.25%s.4.Summary of Test Method4.1 Specimens of the test material
10、are conditioned at pre-scribed conditions and subjected to direct-voltage stress.Re-sistance or conductance is measured and used with the dimen-sional aspects of the specimen to compute the resistivity of thematerial.The apparatus and techniques used in this test methodare selected in accordance wit
11、h the general principles set forthin Test Methods D257 and D991.5.Significance and Use5.1 This test method is useful for the comparison ofmaterials,as a quality control test,and for specificationpurposes.5.2 This test method is useful in the selection and use ofmaterials in wires,cables,bushings,hig
12、h-voltage rotatingmachinery,and other electrical apparatus in which shielding orthe distribution of voltage stress is of value.5.3 Commercially available“moderately conductive”mate-rials frequently are comprised of both conductive and resistivecomponents(that is,cellulose fibers with colloidal carbo
13、nblack particles attached to portions of the surfaces of those1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.12 on Electrical Tests.Current edition approved Jan.1,2021.Published Fe
14、bruary 2021.Originallyapproved in 1985.Last previous edition approved in 2013 as D4496 13.DOI:10.1520/D4496-21.2For 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 standa
15、rds Document Summary page onthe ASTM website.3AvailablefromASTMInternationalHeadquarters.OrderAdjunctNo.ADJD4496.Original adjunct produced in 2015.Adjunct last revised in 2015.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis internation
16、al 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.1fibers,or discrete conductive particles adhered to the surfacesof electrical insulating polymers).Such commercially availablematerials are often manufactured in a manner that results inanisotropy of el
