ASTM_D_351_-_14.pdf

Designation:D35114Standard Classification forNatural Muscovite Block Mica and Thins Based on VisualQuality1This standard is issued under the fixed designation D351;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This classification covers the determination of commer-cially available natural muscovite block mica and is intended tobe independent of the basic color of the mica or its source.1.2 Muscovite mica is characterized by having an opticalaxial angle between 50 and 75(see Appendix X1);and has aweight loss when heated for 5 min at 600C not exceeding0.2%(based on the weight after drying at 120C).1.3 The visual system of classifying the quality of naturalmuscovite mica covered by this specification is based uponrelative amounts of visible foreign inclusions such as airbubbles,stains,and spots in combination with relative amountsand types of waviness,as well as other physical properties.Inthis system,a perfectly clear,transparent,flat specimen of micais the visual standard of perfection.Increasing amounts ofvisual defects lower the visual quality,and a total of 13 levelsof visual quality are covered by this standard.This method ofclassification,generally known as the Bengal India System,ispurely qualitative and is entirely dependent on personal opin-ion and judgment.1.4 The standards for visual quality classification that arecovered in this classification are the best commercially avail-able concept of the various qualities and their relative posi-tions.Variations in the methods of using and applying thesestandards from those herein defined may be specified by thepurchaser,or defined by agreement between the supplier andthe purchaser.1.5 Standard size classifications are defined,based uponavailable usable rectangular areas and the minimum dimen-sions of the rectangles that the pieces will yield.Precautions tobe taken in making thickness measurements are also described.1.6 This standard covers the following two definite forms ofcommercial preparation:1.6.1 Form 1Full-trimmed natural block mica,0.007 in.(0.178 mm)minimum thickness.1.6.2 Form 2Partially-trimmed natural block mica,0.007in.minimum thickness.1.7 The basic color of mica,such as white,ruby,light green,dark green,brownish green,and rum,as well as other colors,and the method of controlling the color and other problemsassociated with the basic color,are not a part of this classifi-cation.1.8 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.9 Section 5 is technically identical to procedures specifiedin ISO 67-1981.1.10 Section 6 differs somewhat in procedure from ISO5972-1978,but data obtained by either should be identical.1.11 Section 7 is technically identical to procedures speci-fied in ISO 2185-1972.2.Referenced Documents2.1 ASTM Standards:2D374 Test Methods for Thickness of Solid Electrical Insu-lation(Withdrawn 2013)3D1711 Terminology Relating to Electrical Insulation2.2 ISO Publications:ISO 67-1981 Muscovite Mica Blocks,Thins,and FilmsGrading by Size4ISO 2185-1972 Muscovite Mica Blocks,Thins,and FilmsVisual Classification4ISO 5972-1978 Mica Blocks,Thins,Films,and SplittingsMeasurement of Thickness41This classification is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products.Current edition approved Jan.15,2014.Published March 2014.Originallyapproved in 1932.Last previous edition approved in 2008 as D351 97(2008)1.DOI:10.1520/D0351-14.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.Terminology3.1 For definitions of terms relating to mica refer to Termi-nology D1711,Part III.3.2 Definitions of Terms Specific to This Standard:3.2.1“A”a series of rulings or striations intersecting at anangle of about 60.3.2.2 blocksmica thickness of 0.007 in.(0.178 mm)mini-mum thickness,full-trimmed,unless otherwise designated.3.2.3 buckleone or more large depression(s)and eleva-tion(s).3.2.4 cracksirregular fractures within the crystal that maybe