1、Designation: D 1082 00 (Reapproved 2005)An American National StandardStandard Test Method forDissipation Factor and Permittivity (Dielectric Constant) ofMica1This standard is issued under the fixed designation D 1082; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the dissi-pation factor a
3、nd the relative permittivity of natural block micahaving thicknesses between 0.007 and 0.030 in. (0.18 and 0.77mm) and mica films or capacitor splits between 0.0008 and0.004 in. (0.02 and 0.10 mm) in thickness.1.2 The values stated in inch-pound units are to be regardedas the standard. The values in
4、 parentheses are for informationpurposes only.1.3 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regul
5、atory limitations prior to use. A specific warningstatement is given in Section 7 and 6.1.1.NOTE 1Procedures for the measurement of dissipation factor andpermittivity are given in IEC Publication 60371-2, but the details of theprocedure are somewhat different from those specified in this test method
6、.2. Referenced Documents2.1 ASTM Standards:2D 150 Test Methods for A-C Loss Characteristics andPermittivity (Dielectric Constant) of Solid Electrical Insu-lationD 374 Test Methods for Thickness of Solid Electrical Insu-lationD 748 Specification for Natural Block Mica and Mica FilmsSuitable for Use i
7、n Fixed Mica-Dielectric Capacitors2.2 IEC Publication:Publication 60371-2 Specification for insulating materialsbased on micaPart 2: Methods of test33. Summary of Test Method3.1 Any of the techniques and apparatus set forth in TestMethods D 150 may be used for measuring dissipation factorand relativ
8、e permittivity of block mica or film. Select anappropriate electrode system from those given in Section 5.3.2 If a relative order of magnitude of dissipation factor isdesired, the use of Method A in the Appendix of SpecificationD 748 is satisfactory.4. Significance and Use4.1 The dissipation factor
9、of natural muscovite mica, asdetermined by this test method, is of practical importance as ameasure of the electrical energy lost as heat in the mica servingas the dielectric substance of capacitors, or in other applica-tions in which the electric field is applied perpendicular to theplane of cleava
10、ge. The dissipation factor is particularly impor-tant in applications using mica at radio frequencies and in someless extensive audio frequency applications. This test method issuitable for specification acceptance and dielectric-loss controltests (See the Significance and Use of Test Methods D 150)
11、.4.2 Relative Permittivity (Dielectric Constant)The per-mittivity of natural muscovite mica is a measure of its relativeability to store electrostatic energy. Since the relative permit-tivity perpendicular to the cleavage plane is fairly uniform,regardless of origin, its practical significance is ma
12、inly foridentification purposes, special uses, research, and design. If aloss index is desired, the value of the permittivity must beknown (see the Significance and Use of Test Methods D 150).5. Apparatus5.1 For a general description of apparatus suitable formeasuring dissipation factor and relative
13、 permittivity, refer toTest Methods D 150.5.2 Select a suitable electrode arrangement from the follow-ing:5.2.1 Steel ElectrodesThree electrodes made of stainlesssteel or nickel-plated tool steel will be required. The electrodesshall be cylindrical in shape and of a diameter sufficient toprovide the
14、 minimum specified capacitance (Note 2). Theupper and lower electrodes shall have a minimum axial lengthof12 in. (12.7 mm) and the center electrode shall have amaximum length of14 in. (6.35 mm). A low-resistance contact1This test method is under the jurisdiction of ASTM Committee D09 onElectrical an
15、d Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products.Current edition approved Apr. 10, 2000. Published June 2000. Originallyapproved in 1949. Last previous edition approved in 1993 as D 1082 87 (1993)e1.2For referenced ASTM st
16、andards, 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.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Flo
17、or, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and conductor to the electrode is essential for dissipation factormeasurements in the order of 0.0001. The upper and lowerelectrodes shall be electrically connect
18、ed together, thus form-ing a two-terminal capacitor, with the center electrode servingas the active or measuring terminal. The surfaces of theelectrodes adjacent to the specimen shall be ground andpolished optically flat, and shall be parallel to each other. Theupper electrode shall be provided with
19、 a recess for a steel ball,so that the applied pressure will be uniformly distributed. Theelectrodes shall be carefully and accurately aligned withoutscratching the surface of the mica specimen. It is recommendedthat a slotted V-shaped jig be provided to aid with the aligningof the electrodes.NOTE 2
20、Steel electrodes having diameters of34 ,1,114 , and 112 in.(19, 25, 32, and 38 mm) have been found satisfactory for practicalthicknesses of mica specimens.5.2.2 Mercury ElectrodesThree hollow, stainless steel ornickel-plated cold-rolled steel electrodes mounted with the axishorizontal so that the te
21、st specimens are in a vertical plane, willbe required as shown in Fig. 1. The electrode assembly shall becylindrical in shape and of the same outside diameter, whichshall be large enough to provide the minimum specifiedcapacitance (Note 3). Two adjustable electrodes having axiallengths of approximat
22、ely34 in. (19 mm), provided withsuitable cavities, shall be mounted on screws in a solidstainless steel or nickel-plated cold-rolled steel rectangularyoke. A center, or fixed, electrode consisting of a hollow ringapproximately38 in. (9.5 mm) in length shall be mounted at thecenter of the steel yoke
23、on a support of insulating material suchas polystyrene, hard rubber, low-loss ceramic, or quartz. Allelectrodes shall taper from the inside to rather sharp edgesapproximately164 in. (0.4 mm) in width.5.2.2.1 The two outer electrodes shall be provided with arubber tube attached to18-in. (3.2-mm) stee
24、l tubes located atthe bottom of each electrode. Small vent holes shall beprovided in the top of the outer electrodes to permit the escapeof entrapped air as the mercury rises. The center electrode shallbe filled through a18-in. steel tube projecting approximately18in. above the top of the electrode
25、and extending three fourths ofthe way down inside the steel ring. Vent holes shall be providedon either side of the projecting steel tube to permit entrappedair to escape as the mercury rises. With the test specimensclamped in position, the electrodes shall be in good alignment.As in the case of the
26、 flat, steel electrodes, a two-terminalcapacitor is formed with the center electrode serving as theactive or measuring terminal with the outer electrodes that areconnected together by the steel yoke at the ground.NOTE 3Mercury electrodes having diameters of 134 in. (44.5 mm)have been found satisfact
27、ory for mica specimens 2 by 2 in. by 0.001 to0.030 in. (51 by 51 mm by 0.025 to 0.76 mm).NOTE 4Conducting paint electrodes can be substituted for mercuryelectrodes.5.2.3 Lead-Foil ElectrodesThe use of lead-foil electrodes0.0005 in. (0.013 mm) in thickness and 2.0 in. (51 mm) indiameter is satisfacto
28、ry for block mica 0.015 to 0.030 in. (0.38to 0.76 mm) in thickness. (See also metal-foil electrodesdescribed in the Section of Test Methods D 150 under Elec-trode Systems).5.3 The apparatus for the rapid, direct-reading method is setforth in Appendix of Specification D 748. This technique is foruse
29、only where classification of relative magnitude of dissipa-tion factor (or its reciprocal Q value) of block mica or films isdesired.5.4 Thickness-measuring apparatus shall conform to therequirements set forth in Test MethodAof Test Methods D 374which describes a machinists micrometer caliper with ar
30、atchet or friction thimble.6. Specimen Preparation and Conditioning6.1 The dielectric properties of mica are affected by tem-perature, humidity, pressure, etc. Therefore, preparation andconditioning of the specimen shall be made in the followingmanner:6.1.1 With the exception of the specimens used i
31、n 5.4,thoroughly and carefully clean the surfaces of the specimenwith a camels-hair brush dipped in petroleum ether or vapordegrease using trichloroethylene. Subsequent to the cleaning,exercise care not to contaminate the surfaces in handling.(WarningPetroleum ether and trichlorethylene may be haz-a
32、rdous. Use adequately ventilated work areas and observe allprocedures for the safe handling of these liquids. Keep awayfrom open flames.)6.1.2 After cleaning, place each specimen in an air ovenmaintained at 105 to 110 C, for a period of 1 h. Upon removalfrom the oven, immediately store the specimen
33、in a desiccatoruntil ready for the test.6.2 Prepare two similar test specimens of approximatelyequal and uniform thickness for each measurement when usingsteel or mercury electrodes (see Section 5).6.3 Only one test specimen is needed for testing withlead-foil electrodes.6.4 Obtain specimens from th
34、e same block or splitting whentwo specimens are used. Each specimen shall have a sufficientarea and thickness to give a total capacitance of not less than200 pF. Test a sufficient number of specimens to obtainrepresentative data.7. Procedure7.1 When steel, mercury, or lead-foil electrodes are used,d
35、etermine the dissipation factor and relative permittivity of theFIG. 1 Mercury Electrode Test AssemblyD 1082 00 (2005)2mica in accordance with Test Methods D 150 except for sizeand type of electrode.7.2 WarningMercury metal vapor poisoning has longbeen recognized as a hazard in industry. The exposur
36、e limitsare set by governmental agencies and are usually based uponrecommendations made by the American Conference of Gov-ernmental Industrial Hygienists.4The concentration of mer-cury vapor over spills from broken thermometers, barometers,and other instruments using mercury can easily exceed thesee
37、xposure limits. Mercury, being a liquid with high surfacetension and quite heavy, will disperse into small droplets andseep into cracks and crevices in the floor. This increased areaof exposure adds significantly to the mercury vapor concentra-tion in air. The use of a commercially available emergen
38、cy spillkit is recommended whenever a spill occurs. Mercury vaporconcentration is easily monitored using commercially avail-able sniffers. Make spot checks periodically around operationswhere mercury is exposed to the atmosphere. Make thoroughchecks after spills.7.3 Certain types of micas are affect
39、ed by pressure; there-fore, when flat, steel electrodes are used, apply a sufficientrange of pressures (Note 5) so that curves of pressure inpounds-force per square inch versus dissipation factor andrelative permittivity may be plotted.NOTE 5Pressures in the order of 100 to 10 000 psi may be readily
40、obtained by the use of an automobile-type hydraulic jack equipped with apressure gauge.7.4 Mercury and lead-foil electrodes give capacitance val-ues comparable with those obtained at the highest pressureswhen using flat, steel electrodes (Note 6). Use clean mercurythat has a bright surface that is f
41、ree of scum. Observe healthhazard precautions when using mercury, particularly at el-evated temperatures.NOTE 6In order to satisfactorily compare the dissipation factor andrelative permittivity of various specimens of mica, it may be necessary toinvestigate such properties over a wide frequency rang
42、e. However, it isrecommended that at least one measurement be made at 1000 kHz and atemperature of 25 6 5 C, at a pressure of 1000 psi if flat steel electrodesare used.8. Calculation8.1 Since two specimens are used in each measurementwhen using steel or mercury electrodes, use the equivalent“paralle
43、l thickness” in calculating the relative permittivity asfollows:Te5 1/1/t1! 1 1/t2!# (1)where:Te= equivalent parallel thickness,t1= thickness of the upper specimen, andt2= thickness of the lower specimen.9. Report9.1 Report the following information:9.1.1 Identification of the mica tested,9.1.2 The
44、date of testing,9.1.3 The test conditions, including frequency of the appliedvoltage, specimen temperature during testing, voltage stress onthe specimen, relative humidity during testing, type, and size ofelectrodes used.9.1.4 The applied pressure if flat steel electrodes are used,9.1.5 Capacitance
45、of each specimen,9.1.6 The “parallel thickness” of each specimen,9.1.7 Aplot of dissipation factor versus pressure if flat, steelelectrodes are used,9.1.8 A plot of permittivity versus pressure if flat, steelelectrodes are used,9.1.9 The value of the dissipation factor and the relativepermittivity f
46、or each specimen,9.1.10 The method of measurement from Test MethodsD 150, if applicable, and9.1.11 The method used if techniques from SpecificationD 748 were used.10. Precision and Bias10.1 This test method has been in use for many years, but noinformation has been presented to ASTM upon which to ba
47、sea statement of precision. No activity has been planned todevelop such information.10.2 BiasThis test method has no bias because the valuesfor dissipation factor and capacitance are determined solely interms of this test method.11. Keywords11.1 dissipation factor; mica; permittivityASTM Internation
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