1、Designation: D 351 97 (Reapproved 2008)e1An American National StandardStandard Classification forNatural Muscovite Block Mica and Thins Based on VisualQuality1This standard is issued under the fixed designation D 351; the number immediately following the designation indicates the year oforiginal ado
2、ption 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 Department of Defense.e1
3、NOTEThe units statement in subsection 1.8 was corrected editorially in July 2008.1. 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 charac
4、terized 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 bas
5、ed 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. Incre
6、asing 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 standard
7、s 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, o
8、r 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 describe
9、d.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
10、 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 parenthes
11、es 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 fromISO 5972-1978, but data obtained by either should be identica
12、l.1.11 Section 7 is technically identical to procedures speci-fied in ISO 2185-1972.2. Referenced Documents2.1 ASTM Standards:2D 374 Test Methods for Thickness of Solid Electrical Insu-lationD 1711 Terminology Relating to Electrical Insulation2.2 ISO Publications:ISO 67-1981 Muscovite Mica Blocks, T
13、hins, and FilmsGrading by Size3ISO 2185-1972 Muscovite Mica Blocks, Thins, andFilmsVisual Classification3ISO 5972-1978 Mica Blocks, Thins, Films, and SplittingsMeasurement of Thickness31This classification is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materia
14、ls and is the direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products.Current edition approved May 1, 2008. Published July 2008. Originally approvedin 1932. Last previous edition approved in 2003 as D 351 97(2003)2For referenced ASTM standards, visit the ASTM website, www.a
15、stm.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.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi
16、.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 For definitions of terms relating to mica refer to Termi-nology D 1711, Part III.3.2 Definitions of Terms Specific to This Standard:3.2.1 “A”a series of rulings o
17、r striations intersecting at anangle of about 60.3.2.2 blocksmica thickness of 0.007 in. (0.178 mm)minimum thickness, full-trimmed, unless otherwise desig-nated.3.2.3 buckleone or more large depression(s) and eleva-tion(s).3.2.4 cracksirregular fractures within the crystal that maybe natural or may
18、arise from blasting, rough handling, etc.3.2.5 full-trimmed micamica trimmed on all sides with allcracks, reeves, and cross-grains removed.3.2.6 haircracks or hairline cracksminute, irregularcracks that are barely noticeable until mica is split into films,resulting in production of torn films.3.2.7
19、reeves or cross grainstangled laminations givingimperfect cleavage, that results in tears or breaks duringsplitting.3.2.8 ribboned or rules micamica that breaks into narrowstrips because of parallel fractures.3.2.9 ribs or ridgescrenulations in the form of steps.3.2.10 ripplemultiple short waves.3.2
20、.11 stainsstains arise from foreign materials, resultingin a partial or total loss of transparency. They may be in theform of specks or patches of appreciable area for example,slight stain, “vegetable” stain, clay stain, black stain, red stain,black speckled, light dot or spot, black, red or green d
21、ot or spot,etc. (see “inclusions” in Terminology D 1711).3.2.12 stones and stone holessmall embedded crystals orholes resulting from them.3.2.13 thinsknife-dressed mica, 0.002 in. (0.05 mm) toless than 0.007 in. (0.18 mm) in thickness. They may beclassified as follows:3.2.13.1 Thins, 0.002 to 0.004
22、in. (0.05 to 0.10 mm), and3.2.13.2 Thick-thins, 0.004 to 0.007 in. (0.10 to 0.18 mm).3.2.14 unmanufactured micacommercial form of micaknown as blocks, thins, films, and splittings, as described.3.2.15 wavesalternate elevations and depressions thatmay be classified as slight, medium, or heavy.4. Sign
23、ificance and Use4.1 The properties included in this standard are thoserequired to control the visual quality, usable area, thickness,hardness, and stiffness.5. Grading for Size5.1 Full-TrimmedAll full-trimmed mica blocks and thinsshall be fully trimmed to remove all cracks, holes, reeves, andcross-g
24、rains according to the quality desired.As far as possible,all marginal cracks should be removed by recutting. Theaverage area of the pieces for Grade 4 and larger shall be notmore than 1.54 times the average area of the largest usablerectangles. This would constitute a minimum yield of 65 %.For Grad
25、es 5 and smaller, the average area of the pieces shallbe not more than two times the average area of the largestusable rectangles. This would constitute a yield of 50 %.5.2 Half-TrimmedFor half-trimmed mica, follow thegrading described in 5.1 for trimmed sides with no cracksextending from the trimme
26、d sides, except for sizes 6 and 512 onwhich only side must be trimmed free of cracks. On theuntrimmed sides, no defects of the designated quality areacceptable within the minimum rectangle of the designatedgrade.5.3 Natural Block and ThinsNatural block and thins,muscovite mica shall be graded for si
27、ze according to the areaof the rectangle (maximum rectangle for full-trimmed, maxi-mum rectangle of designated quality for half-trimmed) havingat least the minimum dimension of one side for the specifiedgrade. The area within such a rectangle shall meet therequirements of the quality specified by th
28、e purchaser as listedin Table 1.5.4 Method of Grading for SizeThe Standard ASTMChart shown in Fig. 1 shall be used for grading natural blockand thins, muscovite mica according to size. In grading naturalblock mica and thins for size, all dimensions apply to thesmaller surface measured from the foot
29、of the bevel-trimmededge. The specimen to be graded shall be laid upon the chart sothat it covers point O and has its maximum and minimumdimensions extending along and covering lines OA and OB,respectively. The specimen shall be shifted until the usable areacompletely covers the largest rectangle, d
30、etermined by adiagonal extending from point O to or beyond a point on anyof the curves. The number of the curve at the greatest distancefrom O cut by the diagonal of the rectangle designates thegrade of the specimen.6. Thickness of Block Mica6.1 Measure the thickness with a micrometer as specified i
31、nTest Methods D 374. In determining thickness of mica thatmust be kept within small permissible variations, or where twoor more specimens are to be measured at once, use Method Aof Test Methods D 374. Where the maximum accuracy is notrequired, Method B may be used.6.2 Because of the abrasive nature
32、of mica, test the mi-crometer frequently for conformity to the requirements speci-fied in Test Methods D 374. Clean the anvil and spindle asTABLE 1 ASTM Grade Sizes of Muscovite Uncut Mica Block andThinsASTMGradeSizesArea ofMinimumRectangleMinimumDimen-sion ofOne Sidein.2Equiva-lent, cm2in.Equiva-le
33、nt, mmOOEE Special 100 650 4 100OEE Special 80 520 4 100EE Special 60 390 4 100E Special 48 310 4 100A-1 (Special) 36 235 312 89No. 1 24 155 3 76No. 2 15 97 2 51No. 3 10 65 2 51No. 4 6 40 112 38No. 5 3 20 1 25No. 512 214 1578 22No. 6 1 6.534 19D 351 97 (2008)e12frequently as necessary to prevent the
34、 accumulation of micadust on the surfaces and to preserve the accuracy of themeasurements. To clean, close the micrometer lightly on aclean sheet of bond paper and move the paper between thesurfaces.6.3 Be careful, when moving from one measurement loca-tion to another, to maintain the surfaces of th
35、e anvil and spindleparallel to the surfaces of the specimen at all times, so as toavoid scratching the mica and accumulating mica dust underthe micrometer surfaces, thereby causing false readings.7. Classification of Visual Quality of Block Mica7.1 The classification of the visual quality of muscovi
36、teblocks and thins shall fall into the following thirteen catego-ries:7.1.1 V-1 Clear7.1.2 V-2 Clear and Slightly Stained7.1.3 V-3 Fair Stained7.1.4 V-4 Good Stained7.1.5 V-5 Stained A Quality7.1.6 V-5.1 Stained A1 Quality7.1.7 V-6 Stained B Quality7.1.8 V-7 Heavy Stained7.1.9 V-8 Densely Stained7.1
37、.10 V-9 Black Dotted7.1.11 V-10 Black Spotted7.1.12 V-11 Black Stained7.1.13 V-12 Black/Red Stained7.2 The classification of the visual quality of block micashall be judged in accordance with the requirements specifiedin Table 2 using the visual descriptions given.8. Keywords8.1 Bengal India System;
38、 block; classification; foreign in-clusions; form; grading; muscovite mica; size; thins; visualqualityNOTEThis chart may be readily extended for Grades OOEE Special, OEE Special, EE Special, and E Special, using the information given in Table1 of ASTM Specification D 351.FIG. 1 ASTM Chart for Gradin
39、g Natural Muscovite Block and Film MicaD 351 97 (2008)e13TABLE 2 Quality Classification of Muscovite Block and Thins Based on Visual PropertiesA,BVisualQualityClassificationAir Inclusions Waviness HardnessV-1 Clear 333333333=3333=333333333333V-2 Clearand SlightlyStained=C=3333333=333=333333333333V-3
40、 FairStained=C=333333=33=333333333333V-4 GoodStained=C=D33333=3=3 3 3333333333V-5 StainedA Quality=E33=C3=3=3 3 3333333333V-5.1 StainedA1 Quality=F3=G=C3=3 3 3333333333V-6 StainedB Quality=3=H=H=H=3 3=C333333333V-7 HeavyStained=3=H=I3=3 3=333333333V-8 DenselyStained=I=I=I=I= S =3=V-9 BlackDotted=3=J
41、=3=3=3 3 3333333333V-10 BlackSpotted=3=3=3=3 3=C333333333V-11 BlackStained=H=3=3 3 333333333=V-12 Black/Red Stain=H=3= S 3=C333333333ASymbols:=Permissible3Not permissibleSPermissible only if specifiedFew and tiny in one-fourth of usable area.BIn one-half usable areaCSlightDIn two-thirds usable areaE
42、Uniformly distributedFNot heavily concentrated over more than an area equivalent to14 in. square (6.4 mm square) for grade 5 and up and over more than an area equivalent to18 in.2(3.2mm2) for Grade 512 and lowerGNot exceeding two specks within the usable areaHMediumIHeavyJDispersed black dotsNote 1T
43、he visual properties of block mica usually are judged under the following light conditions:For stains and inclusionsTransmitted daylight or its equivalent.For air inclusionsReflected daylight or its equivalent.For waves, buckles, ridges, etc.Reflected daylight or its equivalent where distortion of p
44、arallel and vertical lines of reflected image, such as a window frame, canbe judged.Note 2The hardness or mechanical properties of muscovite mica are usually judged by a sharp, clear ring when mica is dropped on a hard surface.Note 3Muscovite mica occurs in various colors which are more pronounced t
45、he thicker the block. Some typical colors are ruby, white, light green, rum, etc.Note 4Cracks, tears, stones, or pin holes are judged by transmitted daylight or equivalent.Note 5Rigidity is judged by the relative stiffness when flexing with the fingers.Note 6See Section 3 for definition of terms use
46、d in Table 2.Note 7The following are verbal descriptions of the classification of muscovite blocks and thins, judged in terms of requirements of Table 2:V-1 ClearHard, of uniform color, flat, free from all stains and foreign inclusions, waves, cracks, buckles, and other similar defects.V-2 Clear and
47、 Slightly StainedHard, of uniform color, nearly flat, free from all vegetable and mineral stains, cracks, buckles and other similar defects, and foreigninclusions except for a few tiny air inclusions in not more than one-fourth of the usable area. Slight crystallographic discoloration is permitted t
48、o a limited extent.V-3 Fair StainedHard, of uniform color, free of all vegetable and mineral stains, cracks, buckles and other similar defects, and foreign inclusions, except may beslightly wavy, and may contain slight air inclusions in not more than one-half of the usable area, these inclusions sho
49、uld not be concentrated. Slight crystallographicdiscoloration is permitted to a limited extent.V-4 Good StainedHard, free of vegetable or mineral stains, cracks, buckles and other similar defects, and foreign inclusions, except may be medium wavy but notrippled and may contain medium air inclusions in not more than two-thirds of the usable area, but may not have heavily concentrated air inclusions in any of the usablearea. Slig
