1、Designation:D35118Standard 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 revi
2、sion.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
3、 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
4、.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 wavin
5、ess,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 ofclassificat
6、ion,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 r
7、elative posi-tions.Variations in the methods of using and applying thesestandards from those herein defined are 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 m
8、inimum 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 thickne
9、ss.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
10、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 specified
11、in ISO 67-1981.1.10 Section 6 differs somewhat in procedure from ISO5972-1978,but data obtained by either is expected to beidentical.1.11 Section 7 is technically identical to procedures speci-fied in ISO 2185-1972.1.12 This international standard was developed in accor-dance with internationally re
12、cognized 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:2D374 Test Methods for
13、Thickness of Solid Electrical Insu-lation(Metric)D0374_D0374MD1711 Terminology Relating to Electrical Insulation1This classification is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.01 on Electrical I
14、nsulating Products.Current edition approved Nov.1,2018.Published November 2018.Originallyapproved in 1932.Last previous edition approved in 2014 as D351 14.DOI:10.1520/D0351-18.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For A
15、nnual 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 StatesThis international standard was developed in accordance with internationally reco
16、gnized 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.1 2.2 ISO Publications:ISO 67-1981 Muscovite Mica Blocks,Thins,and FilmsGrading by Size3ISO 2185-1972 Muscovite Mica Blocks,Thins,and FilmsVisual Classification3ISO 5972-1978 Mica Blocks,Thins,Films,and SplittingsMeasurement of Thickness33.Terminology3.1 For definiti
